AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 945 AM MST THU MAR 22 2007 .SYNOPSIS... A STRONG PACIFIC LOW PRESSURE SYSTEM WAS LOCATED JUST OFF THE NORTHERN BAJA CALIFORNIA COAST THIS MORNING. IT WILL MOVE VERY SLOWLY EAST ACROSS NORTHERN MEXICO FRIDAY INTO SATURDAY. THIS STORM SYSTEM WILL BRING INCREASING CLOUDINESS...COOLER DAYTIME HIGHS...AND PERIODS OF SHOWERS AND THUNDERSTORMS TODAY THROUGH SATURDAY...WITH THE BEST CHANCE FOR PRECIPITATION OVER SOUTH-CENTRAL ARIZONA. HIGHER PRESSURE ALOFT FROM THE PACIFIC WILL BRING DRY WEATHER WITH SOME RECOVERY OF TEMPERATURES SUNDAY AND MONDAY. ANOTHER RATHER STRONG WEATHER DISTURBANCE WILL PRODUCE BREEZY TO WINDY CONDITIONS ALONG WITH SOME COOLING NEXT TUESDAY AND WEDNESDAY. && .SHORT TERM... TODAY THROUGH SATURDAY... 12Z POSITION OF CLOSED LOW WAS NEAR 30N/117W WITH SEVERAL VORTICITY CENTERS ROTATING AROUND ITS PERIMETER. NAM/GFS SOLUTIONS APPEARED TO BE SOMEWHAT SOUTH OF LATEST RUC...WITH ALL MODELS INDICATING THE STRONGEST VORT CENTER SOUTH OF THE LOW. THE 500MB WIND SPEEDS WERE ALSO STRONGEST AROUND THE SOUTHERN QUADRANTS OF THE LOW...50-70KTS. AFTER SUNRISE THE CONVECTION PICKED UP IN OUR CWA...AND CONTINUED TO DRIFT INTO YAVAPAI COUNTY. BY FAR THE HEAVIEST PRECIP WAS THROUGH SOUTHERN GILA COUNTY WHERE SPOTTERS/RAWS DATA REPORTED .30 TO .45 INCH UP TO 6 AM. SIGNIFICANT DIFFLUENCE WAS ALSO INDICATED ACROSS EASTERN AZ EARLIER TODAY. UPDATES ISSUED BY 8 AM TO COVER 88D TRENDS. WILL CONTINUE TO EXPECT STRONGEST LIFT AND LOWEST STABILITY INDICES AFTER 18Z FRIDAY...AND THAT FITS NICELY WITH OUR CURRENT FCSTS. ALTHOUGH LATEST NAM GIVES PHX A 24 HR PRECIP AMOUNT OF .38 INCH WE WILL STILL EXPECT GENERALLY LIGHTER AMOUNTS ACROSS ZONE 23. HOWEVER WE COULD SEE MUCH MORE...ACROSS ZONE 24...PER HPC OUTPUT. OUR WESTERN ZONES WILL STAY MUCH DIRER...WITH SOME PATCHY BLWG DUST TODAY. IN FACT ONE SHARP-EYED SPOTTER CALLED IN A REPORT OF BLOWING DUST NEAR A FARM FIELD WEST OF TONOPAH. MODEL TRENDS CONTINUE TO BE VERY CONSISTENT IN KEEPING THE CLOSED LOW OVER NRN MEX INTO FRIDAY NIGHT. BY 12Z SAT LATEST GFS CALLS FOR THE CENTER OF CIRCULATION TO LIFT OUT TO NEAR ABQ...WITH CSDRBL RH THROUGH A DEEP LAYER EVEN WEST OF PHX. UPPER RIDGE AND WARMER TEMPS WILL ALSO SPREAD ACROSS ENTIRE CWA FOR FRIDAY AND SATURDAY. && .LONG TERM... SATURDAY NIGHT THROUGH WEDNESDAY... WITH SLOWER EXIT OF THE SYSTEM AND POTENTIAL FOR MORE MOISTURE... ADDED SOME SLIGHT CHANCE POPS IN EASTERN PORTIONS OF THE FORECAST AREA SATURDAY NIGHT. THIS IS FOLLOWED BY RIDGE BUILDING FOR A QUICK WARMUP. IN THE LATTER PART OF THE EXTENDED...GFS AND ECWMF ARE SHOWING ANOTHER SYSTEM AFFECTING US. HOWEVER...IT LOOKS TO BE OF A DIFFERENT CHARACTER...MUCH LESS APT TO SLOW DOWN AND JOG SOUTHWARD. HOWEVER...THERE ARE SOME DIFFERENCES. THE GFS ENSEMBLE MEAN HAS A SIMILAR TRACK TO THE 12Z OPERATIONAL GFS...TAKING THE BULK OF THE SYSTEM JUST NORTH OF OUR AREA...BUT SHOWS LOWER HEIGHTS. THE ECMWF IS EVEN COOLER LOOKING THAN THE ENSEMBLE MEAN...AND A BIT SLOWER. THUS...UNDERCUT GFS-BASED TEMPERATURE GUIDANCE. TRAJECTORY OF THIS NEXT SYSTEM DOES NOT FAVOR MUCH IN THE WAY OF POPS...SO HELD OFF ON INTRODUCING ANY. IF ECMWF SOLUTION WINDS UP BEING CORRECT...THEN WE MIGHT NEED TO ADD SOME SLIGHT CHANCE POPS AT SOME POINT. ALSO...IF ECMWF SOLUTION PANS OUT...MIGHT NEED EVEN COOLER TEMPS. && .AVIATION... GENERALLY LGT SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH TODAY. WINDS IN THE 6 TO 12 THSD LAYER PROGGED TO REMAIN 180/22 THIS AFTERNOON...WITH MUCH STRONGER SPEEDS ALOFT. SOME GUSTY WINDS TO 35KTS OR SO STILL POSSIBLE IN THE KPHX AREA LATE THIS AFTERNOON AND INTO TONIGHT. WITH ADDITIONAL MOISTURE THROUGH A DEEP LAYER...WE COULD EASILY SEE LOWER CIGS LESS THAN 6-7 THSD FT. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EXPECT PERIODS OF WETTING RAINFALL OVER MUCH OF THE FORECAST AREA THURSDAY THROUGH SATURDAY...MAINLY OVER THE EASTERN ZONES...WITH THE HEAVIEST PRECIPITATION LIKELY OVER SOUTHERN GILA COUNTY AND THE RIM FRI AFTERNOON INTO SAT MORNING. DRY CONDITIONS RETURN TO THE WESTERN PORTION OF THE REGION BY SATURDAY AND THE REMAINDER OF THE FORECAST AREA BY SUNDAY. EARLY NEXT WEEK (MON NIGHT THROUGH TUE)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX 10 az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 905 PM CDT THU MAR 22 2007 .UPDATE... SHORTWAVE EJECTING OUT OF THE SOUTHWEST CONUS UPPER LOW CONTINUES TO RIDE A STALLED OUT BOUNDARY WHICH IS POSITIONED ALONG THE NORTHERN EDGE OF MID LEVEL RIDGE BUILDING INTO THE REGION FROM GULF. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE TEXAS PANHANDLE IN RESPONSE IN AN AREA OF STRONG LIFT. NEW RUC13 AND NAM 12 KEEP AREA OF PRECIPITATION ACROSS FAR NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI OVERNIGHT. NAM12 AND WRF10 DO MOVE SOME PRECIPITATION ACROSS THE NORTHWEST PART OF THE LZK CWA AFTER 12Z BUT CONFIDENCE IS LOW THIS WILL DEVELOP AS OTHER SHORT RANGE MODELS INDICATE RIDGE BUILDING IN THE MID LEVELS THAT WILL KEEP PRECIPITATION OUT OF THE CWA. CURRENT DISTRIBUTION OF SMALL POPS OVER THE NORTHWEST PART OF THE CWA TONIGHT THROUGH PARTS OF FRIDAY LOOKS REASONABLE AND WILL BE LEFT IN PLACE. ONLY CHANGES TO ONGOING FORECAST WERE TO TWEAK SKY...DEW POINT AND RH GRIDS TO REFLECT CURRENT TRENDS. OVERNIGHT LOWS RAISED A TAD AS WELL. UPDATES OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 629 PM CDT THU MAR 22 2007/ AVIATION... CLOUDS WILL CONTINUE TO MOVE IN FROM THE WEST WITH CEILINGS NEAR 7 THSD OR HIGHER. AREAS OF CEILINGS NEAR 35 HND WILL MOVE IN ARND 06Z. SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE NORTH AND WEST AFTER 08Z.(38) PREV DISCUSSION... /ISSUED 235 PM CDT THU MAR 22 2007/ SHORT TERM...TONIGHT THROUGH SUNDAY BLOCKING PATTERN STILL THE MAIN STORY IN THE SHORT TERM...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE GULF COAST. FRONT TO NORTH WILL TRY TO PUSH INTO ARKANSAS LATER TONIGHT/FRIDAY...BUT WILL STALL DUE TO THE HIGH AND SOUTHWEST WINDS ALOFT. EVEN SO...PUT SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS MAINLY IN AREAS NEAR THE ARKANSAS AND MISSOURI BORDER. FRONT WILL LIFT TO THE NORTH FRIDAY NIGHT/SATURDAY...WITH DRY AND WARM WEATHER TO START THE WEEKEND. LATE IN THE WEEKEND AND EARLY NEXT WEEK...LARGE STORM SYSTEM IN THE SOUTHWEST UNITED STATES WILL FINALLY ARRIVE...WITH HIGH PRESSURE SHIFTING SLOWLY TO THE EAST. BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST LATE SUNDAY INTO THE LONG TERM. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE PERIOD. (46) LONG TERM...SUNDAY NIGHT THROUGH THURSDAY REMNANTS OF A WEAKENING UPPER LOW WILL BE CROSSING ARKANSAS AS A SHORT WAVE. IT WILL BE JUST EAST OF THE STATE BY MIDDAY TUESDAY SINCE A LONG WAVE TROF WILL BE TRAVERSING THE INTERMOUNTAIN WEST ON TUESDAY. BY WEDNESDAY AFTERNOON IT WILL BE OVER THE NORTHERN PLAINS AND WEAKENING. THE SURFACE PATTERN WILL KEEP A SOUTHEAST OR SOUTH COMPONENT TO OUR WINDS THAT WILL PUMP MOISTURE NORTHWARD INTO THE PATH OF THE UPPER SYSTEM. WARMTH AND INSTABILITY WILL CAUSE SCATTERED CONVECTION TO DEVELOP SUNDAY NIGHT OVER NORTHWESTER SECTIONS. THEN...IT WILL KEEP ON MOVING EAST DURING THE DAY MONDAY. CONVECTION WILL BE OVER THE EASTERN HALF OF THE FORECAST AREA MONDAY NIGHT AND MOSTLY OUT OF THE STATE TUESDAY AFTERNOON AS THE SHORT WAVE DRIVING IT GOES ON BY ALOFT. WILL KEEP THE FORECAST DRY FROM TUESDAY NIGHT ON THROUGH THE END OF THE LONG TERM. THE UPPER SUPPORT FOR THE NEXT SYSTEM WILL BE SO FAR NORTH THAT DECIDED TO WAIT UNTIL THIS TREND GETS PICKED UP IN OTHER RUNS. NO CHALLENGE TO THE ABOVE NORMAL TRENDS WILL BE MADE DURING THIS PERIOD. (32) && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 59 76 56 76 / 10 20 20 10 CAMDEN AR 60 80 58 79 / 10 10 10 10 HARRISON AR 59 75 55 75 / 30 30 20 10 HOT SPRINGS AR 60 78 58 78 / 10 10 10 10 LITTLE ROCK AR 60 78 58 78 / 10 10 10 10 MONTICELLO AR 59 80 58 80 / 10 10 10 10 MOUNT IDA AR 58 78 57 78 / 10 10 10 10 MOUNTAIN HOME AR 59 75 54 75 / 30 30 20 10 NEWPORT AR 59 77 57 76 / 10 20 20 10 PINE BLUFF AR 60 79 59 79 / 10 10 10 10 RUSSELLVILLE AR 59 77 56 77 / 20 20 10 10 SEARCY AR 60 78 58 77 / 10 10 10 10 STUTTGART AR 60 79 59 78 / 10 10 10 10 && .LZK WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...56 / LONG TERM...38 ar AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 845 PM PDT THU MAR 22 2007 .UPDATE...A FEW PATCHES OF HIGH CLOUDS MOVING THRU...OTHERWISE SKIES ARE CLEAR. MID LEVEL CLOUDS WRAPPING AROUND THE NRN BAJA LOW ARE JUST EAST OF KERN CO. SOME OF THESE MID CLOUDS COULD MOVE ACROSS THE KERN DESERT FROM TIME TO TIME OVERNITE SO PTCLDY THERE LOOKS GOOD. TEMPS THIS EVE RUNNING 6-8 DEGS HIGHER THAN YESTERDAY AT THIS TIME...SO CONTINUED GOOD WARMING EXPECTED TOMORROW. CURRENT FCST ON TRACK AND NO UPDATE NEEDED THIS EVE. && .DISCUSSION...AS THE CLOSED UPPER LOW DRIFTS FURTHER OVER THE DESERT SOUTHWEST...THE WEATHER OVER CENTRAL CALIFORNIA CONTINUES TO SETTLE DOWN. WITH THE SUNSHINE...TEMPERATURES SAW ANOTHER WARMING TREND AS MANY VALLEY LOCATIONS WERE RUNNING 5 TO 10 DEG-F ABOVE THAT OF WEDNESDAY AFTERNOON. WITH THE OFFSHORE FLOW ALOFT SUPPORTING TODAY/S WARMING TEMP/S...WILL HAVE NO PROBLEM REACHING THE 70S. WHILE WRAP AROUND MOISTURE IS BEING OBSERVED OVER THE DESERT SOUTHWEST...ASSOCIATED WITH THE CLOSED UPPER LOW...AND TRACKING NORTHEAST. WHILE SOME CLOUDS SHOULD ADVANCE INTO THE DISTRICT LATE THIS AFTERNOON...RUC ANALYSIS AND VISIBLE SATELLITE IMAGERY IS SHOWING ONLY MINIMAL AMOUNTS REACHING THE AREA. THEREFORE...WILL MAINTAIN MOSTLY CLEAR CONDITIONS WITH NO POSSIBLE WEATHER. YET...THE KERN COUNTY DESERTS MAY BE CLOSER TO THE STORM THEN THE REST OF THE DISTRICT. THEREFORE...WILL MAINTAIN THE SLIGHT CHANCE POPS OVER THE DESERTS (TOKEN) JUST IN CASE THE MOISTURE IS ABLE TO MAKE IT THIS FAR NORTH. IN ADDITION...BECAUSE OF THE SLOW DRIFT OF THE UPPER LOW...STRONG WINDS WILL CONTINUE TO BE OBSERVED OVER THE DESERT AND HIGHER ELEVATIONS OF THE DISTRICT THROUGH THIS EVENING. AS THE UPPER LOW SLOWLY TRACKS EAST OVER THE NEXT SEVERAL DAYS...WILL SEE THE UPPER LEVEL RIDGE DOMINATE THE WEST THROUGH THE WEEKEND. DRY WEATHER WILL PREVAIL WITH A WARMING TREND IN TEMPERATURES THROUGH ABOUT SUNDAY. AROUND SUNDAY...SHORT RANGE MODELS BEGIN LOWERING HEIGHTS AND SWITCH TO A MORE ZONAL FLOW PATTERN BEFORE ALLOWING ANOTHER TROF TO APPROACH THE WEST COAST. LATEST TIMING STILL HAS THE NEXT TROF OVER THE WEST COAST AROUND LATE MONDAY INTO EARLY TUESDAY. ENSEMBLES SHOWING LITTLE PHASE UNCERTAINTY BUT IS SHOWING GOOD SPREAD ON THE AMPLITUDE AROUND 12Z TUESDAY. THEREFORE...WILL KEEP THE BETTER CHANCES OF MEASURABLE PRECIP NORTH OF KERN COUNTY DURING THE EVENT. IN ADDITION...DURING TROF PASSAGE...MEDIUM RANGE MODELS SHOW 500MB TEMP/S DROPPING TO AROUND MINUS 24-28 DEG-C. BEING THAT THIS MAY BE A COLD SYSTEM...WILL MAINTAIN LOW SNOW LEVELS DURING THE STORM. FURTHERMORE...WITH SUCH COLD AIR ALOFT OVER THE REGION AT THIS TIME OF THE YEAR...CONDITIONS MAY BECOME VERY UNSTABLE DURING THE STORM EVENT. LINGERING SHOWERS OVER THE MOUNTAIN TOWARD TUESDAY WILL GIVE WAY TO CLEARING BY WEDNESDAY AND THURSDAY. && .AVIATION...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 06Z SATURDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES... NONE && .HNX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ BINGHAM/MOLINA/MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 232 PM PDT THU MAR 22 2007 .DISCUSSION...AS THE CLOSED UPPER LOW DRIFTS FURTHER OVER THE DESERT SOUTHWEST...THE WEATHER OVER CENTRAL CALIFORNIA CONTINUES TO SETTLE DOWN. WITH THE SUNSHINE...TEMPERATURES SAW ANOTHER WARMING TREND AS MANY VALLEY LOCATIONS WERE RUNNING 5 TO 10 DEG-F ABOVE THAT OF WEDNESDAY AFTERNOON. WITH THE OFFSHORE FLOW ALOFT SUPPORTING TODAY/S WARMING TEMP/S...WILL HAVE NO PROBLEM REACHING THE 70S. WHILE WRAP AROUND MOISTURE IS BEING OBSERVED OVER THE DESERT SOUTHWEST...ASSOCIATED WITH THE CLOSED UPPER LOW...AND TRACKING NORTHEAST. WHILE SOME CLOUDS SHOULD ADVANCE INTO THE DISTRICT LATE THIS AFTERNOON...RUC ANALYSIS AND VISIBLE SATELLITE IMAGERY IS SHOWING ONLY MINIMAL AMOUNTS REACHING THE AREA. THEREFORE...WILL MAINTAIN MOSTLY CLEAR CONDITIONS WITH NO POSSIBLE WEATHER. YET...THE KERN COUNTY DESERTS MAY BE CLOSER TO THE STORM THEN THE REST OF THE DISTRICT. THEREFORE...WILL MAINTAIN THE SLIGHT CHANCE POPS OVER THE DESERTS (TOKEN) JUST IN CASE THE MOISTURE IS ABLE TO MAKE IT THIS FAR NORTH. IN ADDITION...BECAUSE OF THE SLOW DRIFT OF THE UPPER LOW...STRONG WINDS WILL CONTINUE TO BE OBSERVED OVER THE DESERT AND HIGHER ELEVATIONS OF THE DISTRICT THROUGH THIS EVENING. AS THE UPPER LOW SLOWLY TRACKS EAST OVER THE NEXT SEVERAL DAYS...WILL SEE THE UPPER LEVEL RIDGE DOMINATE THE WEST THROUGH THE WEEKEND. DRY WEATHER WILL PREVAIL WITH A WARMING TREND IN TEMPERATURES THROUGH ABOUT SUNDAY. AROUND SUNDAY...SHORT RANGE MODELS BEGIN LOWERING HEIGHTS AND SWITCH TO A MORE ZONAL FLOW PATTERN BEFORE ALLOWING ANOTHER TROF TO APPROACH THE WEST COAST. LATEST TIMING STILL HAS THE NEXT TROF OVER THE WEST COAST AROUND LATE MONDAY INTO EARLY TUESDAY. ENSEMBLES SHOWING LITTLE PHASE UNCERTAINTY BUT IS SHOWING GOOD SPREAD ON THE AMPLITUDE AROUND 12Z TUESDAY. THEREFORE...WILL KEEP THE BETTER CHANCES OF MEASURABLE PRECIP NORTH OF KERN COUNTY DURING THE EVENT. IN ADDITION...DURING TROF PASSAGE...MEDIUM RANGE MODELS SHOW 500MB TEMP/S DROPPING TO AROUND MINUS 24-28 DEG-C. BEING THAT THIS MAY BE A COLD SYSTEM...WILL MAINTAIN LOW SNOW LEVELS DURING THE STORM. FURTHERMORE...WITH SUCH COLD AIR ALOFT OVER THE REGION AT THIS TIME OF THE YEAR...CONDITIONS MAY BECOME VERY UNSTABLE DURING THE STORM EVENT. LINGERING SHOWERS OVER THE MOUNTAIN TOWARD TUESDAY WILL GIVE WAY TO CLEARING BY WEDNESDAY AND THURSDAY. && .AVIATION...GUSTY OFFSHORE WINDS WILL CONTINUE OVER KERN COUNTY DESERTS THROUGH EARLY EVENING THURSDAY...DIMINISHING THEREAFTER. OTHERWISE...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 00Z SATURDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES...NONE. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC:MOLINA AVIATION:MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 945 AM MST THU MAR 22 2007 .SYNOPSIS... A STRONG PACIFIC LOW PRESSURE SYSTEM WAS LOCATED JUST OFF THE NORTHERN BAJA CALIFORNIA COAST THIS MORNING. IT WILL MOVE VERY SLOWLY EAST ACROSS NORTHERN MEXICO FRIDAY INTO SATURDAY. THIS STORM SYSTEM WILL BRING INCREASING CLOUDINESS...COOLER DAYTIME HIGHS...AND PERIODS OF SHOWERS AND THUNDERSTORMS TODAY THROUGH SATURDAY...WITH THE BEST CHANCE FOR PRECIPITATION OVER SOUTH-CENTRAL ARIZONA. HIGHER PRESSURE ALOFT FROM THE PACIFIC WILL BRING DRY WEATHER WITH SOME RECOVERY OF TEMPERATURES SUNDAY AND MONDAY. ANOTHER RATHER STRONG WEATHER DISTURBANCE WILL PRODUCE BREEZY TO WINDY CONDITIONS ALONG WITH SOME COOLING NEXT TUESDAY AND WEDNESDAY. && .SHORT TERM... TODAY THROUGH SATURDAY... 12Z POSITION OF CLOSED LOW WAS NEAR 30N/117W WITH SEVERAL VORTICITY CENTERS ROTATING AROUND ITS PERIMETER. NAM/GFS SOLUTIONS APPEARED TO BE SOMEWHAT SOUTH OF LATEST RUC...WITH ALL MODELS INDICATING THE STRONGEST VORT CENTER SOUTH OF THE LOW. THE 500MB WIND SPEEDS WERE ALSO STRONGEST AROUND THE SOUTHERN QUADRANTS OF THE LOW...50-70KTS. AFTER SUNRISE THE CONVECTION PICKED UP IN OUR CWA...AND CONTINUED TO DRIFT INTO YAVAPAI COUNTY. BY FAR THE HEAVIEST PRECIP WAS THROUGH SOUTHERN GILA COUNTY WHERE SPOTTERS/RAWS DATA REPORTED .30 TO .45 INCH UP TO 6 AM. SIGNIFICANT DIFFLUENCE WAS ALSO INDICATED ACROSS EASTERN AZ EARLIER TODAY. UPDATES ISSUED BY 8 AM TO COVER 88D TRENDS. WILL CONTINUE TO EXPECT STRONGEST LIFT AND LOWEST STABILITY INDICES AFTER 18Z FRIDAY...AND THAT FITS NICELY WITH OUR CURRENT FCSTS. ALTHOUGH LATEST NAM GIVES PHX A 24 HR PRECIP AMOUNT OF .38 INCH WE WILL STILL EXPECT GENERALLY LIGHTER AMOUNTS ACROSS ZONE 23. HOWEVER WE COULD SEE MUCH MORE...ACROSS ZONE 24...PER HPC OUTPUT. OUR WESTERN ZONES WILL STAY MUCH DIRER...WITH SOME PATCHY BLWG DUST TODAY. IN FACT ONE SHARP-EYED SPOTTER CALLED IN A REPORT OF BLOWING DUST NEAR A FARM FIELD WEST OF TONOPAH. MODEL TRENDS CONTINUE TO BE VERY CONSISTENT IN KEEPING THE CLOSED LOW OVER NRN MEX INTO FRIDAY NIGHT. BY 12Z SAT LATEST GFS CALLS FOR THE CENTER OF CIRCULATION TO LIFT OUT TO NEAR ABQ...WITH CSDRBL RH THROUGH A DEEP LAYER EVEN WEST OF PHX. UPPER RIDGE AND WARMER TEMPS WILL ALSO SPREAD ACROSS ENTIRE CWA FOR FRIDAY AND SATURDAY. && .LONG TERM... SATURDAY NIGHT THROUGH WEDNESDAY... WITH SLOWER EXIT OF THE SYSTEM AND POTENTIAL FOR MORE MOISTURE... ADDED SOME SLIGHT CHANCE POPS IN EASTERN PORTIONS OF THE FORECAST AREA SATURDAY NIGHT. THIS IS FOLLOWED BY RIDGE BUILDING FOR A QUICK WARMUP. IN THE LATTER PART OF THE EXTENDED...GFS AND ECWMF ARE SHOWING ANOTHER SYSTEM AFFECTING US. HOWEVER...IT LOOKS TO BE OF A DIFFERENT CHARACTER...MUCH LESS APT TO SLOW DOWN AND JOG SOUTHWARD. HOWEVER...THERE ARE SOME DIFFERENCES. THE GFS ENSEMBLE MEAN HAS A SIMILAR TRACK TO THE 12Z OPERATIONAL GFS...TAKING THE BULK OF THE SYSTEM JUST NORTH OF OUR AREA...BUT SHOWS LOWER HEIGHTS. THE ECMWF IS EVEN COOLER LOOKING THAN THE ENSEMBLE MEAN...AND A BIT SLOWER. THUS...UNDERCUT GFS-BASED TEMPERATURE GUIDANCE. TRAJECTORY OF THIS NEXT SYSTEM DOES NOT FAVOR MUCH IN THE WAY OF POPS...SO HELD OFF ON INTRODUCING ANY. IF ECMWF SOLUTION WINDS UP BEING CORRECT...THEN WE MIGHT NEED TO ADD SOME SLIGHT CHANCE POPS AT SOME POINT. ALSO...IF ECMWF SOLUTION PANS OUT...MIGHT NEED EVEN COOLER TEMPS. && .AVIATION... GENERALLY LGT SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH TODAY. WINDS IN THE 6 TO 12 THSD LAYER PROGGED TO REMAIN 180/22 THIS AFTERNOON...WITH MUCH STRONGER SPEEDS ALOFT. SOME GUSTY WINDS TO 35KTS OR SO STILL POSSIBLE IN THE KPHX AREA LATE THIS AFTERNOON AND INTO TONIGHT. WITH ADDITIONAL MOISTURE THROUGH A DEEP LAYER...WE COULD EASILY SEE LOWER CIGS LESS THAN 6-7 THSD FT. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EXPECT PERIODS OF WETTING RAINFALL OVER MUCH OF THE FORECAST AREA THURSDAY THROUGH SATURDAY...MAINLY OVER THE EASTERN ZONES...WITH THE HEAVIEST PRECIPITATION LIKELY OVER SOUTHERN GILA COUNTY AND THE RIM FRI AFTERNOON INTO SAT MORNING. DRY CONDITIONS RETURN TO THE WESTERN PORTION OF THE REGION BY SATURDAY AND THE REMAINDER OF THE FORECAST AREA BY SUNDAY. EARLY NEXT WEEK (MON NIGHT THROUGH TUE)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX 10 ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 916 AM PDT THU MAR 22 2007 .DISCUSSION...CLOSED UPPER LOW CONTINUES TO SWINGS EASTWARD THIS MORNING AROUND BAJA CALIFORNIA...WITH CHANNELED FLOW OVER THE DISTRICT. AT THE 250MB LEVEL...RUC ANALYSIS HAS A +100KT JET MAX EXITING THE AREA WITH A GOOD DOWNWARD TRANSFER OF WINDS THIS MORNING. WHILE WINDS OVER THE MOUNTAINS AND DESERTS WERE DIMINISHING THIS MID MORNING...WINDS EARLIER WERE ABLE TO REACH 30 TO 40 MPH. AS THE JET MOVES FURTHER AWAY...WILL SEE MOUNTAIN WINDS DECREASE FURTHER AS A SHORT WAVE RIDGE SHIFTS INTO CALIFORNIA. FURTHERMORE...THE FLOW THIS MORNING HAS BEEN OFF-SHORE WHICH WILL SUPPORT THE EXPECTED WARM UP THIS AFTERNOON. OTHERWISE...AS THE CLOSED UPPER LOW MOVES FURTHER OUT...WILL SEE GENERAL CLEARING THROUGH THE END OF THE WEEK AND INTO THE WEEKEND WITH A CONTINUAL WARMING OF TEMPERATURES. NO UPDATES NEEDED. && .AVIATION...LOCAL MVFR CEILINGS AND VISIBILITIES WILL PERSIST ALONG THE EAST SIDE AND SOUTH END OF THE SAN JOAQUIN VALLEY AS WELL AS THE NORTH FACING SLOPES OF THE TEHACHAPI MOUNTAINS UNTIL 17Z. LOCALLY STRONG WINDS WILL ALSO BUFFET THE HIGHER ELEVATIONS OF THE SIERRA NEVADA AND THE INDIAN WELLS VALLEY THIS MORNING. OTHERWISE...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 12Z FRIDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES...NONE. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC:MOLINA AVIATION:MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 940 PM EDT WED MAR 21 2007 .SHORT TERM UPDATE /TONIGHT/... PER RADAR/SATELLITE TRENDS...DEPICTING CLOUDS/SHOWERS PUSHING TOWARD SHORE ON THE SOUTHERN PERIPHERY OF HIGH PRES CENTERED EAST OF NEW ENGLAND...EXPANDED ISOLATED SHOWERS INTO GA COUNTIES OVERNIGHT. 18Z NAM12/WRF AND 0Z RUC40 SUGGEST THAT PRECIP WILL STRUGGLE TO PUSH ONSHORE OVERNIGHT...SO WILL NOT RAISE POPS. HOWEVER...WILL CONTINUE TO MONITOR TRENDS AND MAY YET RAISE POPS IF NEEDED...ESP ACROSS SC COUNTIES. OTHERWISE...DEWPOINTS IN THE 50S AND BREAKS IN THE CLOUD COVER SUPPORT THE ONGOING FORECAST OF PATCHY FOG. && .MARINE... RECENT REPORTS FROM AREA BUOYS AND FROM THE CHARLESTON AND SAVANNAH PILOT BOATS SUGGEST THAT SEAS ARE BUILDING AHEAD OF SCHEDULE...AND CURRENT TRENDS SUGGEST THAT 6 FT SEAS WILL PROBABLY SLIP INTO NEARSHORE WATERS OVERNIGHT. THUS...MOVED UP START TIME OF ONGOING SCAS FOR SC/GA NEARSHORE WATERS FROM NOON THU TO 2 AM THU. && .AVIATION /02Z-24Z/...VFR CONDITIONS WILL PREVAIL UNTIL AFTER 8Z...WHEN AT LEAST MVFR VISIBILITY SHOULD DEVELOP AT KCHS...WHILE OCCASIONAL IFR CIGS/VSBYS SHOULD DEVELOP AT KSAV AROUND DAYBREAK. THEN...AFTER 12Z...VFR CONDITIONS SHOULD PREVAIL FOR THE REMAINDER OF THE FORECAST PERIOD. MEANWHILE...TAFS INDICATE SHOWERS IN THE VICINITY UNTIL 9Z...WILL AMEND AS NEEDED FOR TIMING OF INDIVIDUAL SHOWERS. && .RIP CURRENTS... PERSISTENT ONSHORE FLOW AND DEVELOPING LONG PERIOD EASTERLY SWELL WILL RESULT IN A MODERATE RISK OF RIP CURRENTS THURSDAY. THE INCREASED THREAT OF RIP CURRENTS MAY CONTINUE UNTIL THE SWELL SUBSIDES SATURDAY. && .COASTAL FLOODING/HIGH SURF... GIVEN PERSISTENT ONSHORE FLOW...BUILDING E SWELL AND ASTRONOMICAL COMPONENT OF TIDES...STILL CLOSE TO THE MARCH 19 NEW MOON...WILL CONTINUE TO CLOSELY MONITOR WATER LEVELS AROUND THE TIMES OF HIGH TIDE TONIGHT AND AGAIN THURSDAY NIGHT. ALSO...WILL NEED TO ASSESS NEED FOR A HIGH SURF ADVISORY THU...AS WAVES IN SURF ZONE COULD BE CLOSE TO 5 FT. THIS COULD ALSO CONTRIBUTE TO MINOR BEACH EROSION AT HIGH TIDE...ESPECIALLY THU AND THU NIGHT. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM THURSDAY TO 6 AM EDT FRIDAY FOR AMZ350-352-354. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT SUNDAY FOR AMZ374. && $$ SPR ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 130 PM CDT THU MAR 22 2007 .DISCUSSION FOR ZONES/GRIDS... 11AM...SKIES ARE CLEARING OVER MUCH OF FCST AREA AT LATE MRNG AS WINDS TURN NW AND TEMPS STEADY OUT. COLD ADVECTION ON NW WINDS WILL HOLD TEMPS WITHIN FEW DEG OF CURRENT LEVELS THROUGH THE AFTERNOON. HIGH PERS OVER NW IOWA SHOULD DRIFT ACROSS TONIGHT FOR SOMEHWAT COOLER TEMPS. RETURN MOISTURE AND CLOUDS ETC LKLY TO BEGIN LATER TONIGHT AND CONTINUE FRIDAY. CHARACTER OF THAT RETURN REMAINS TO BE SEEN AND WILL TRIM/DELAY RETURN A LITTLE IN UPDATED GRIDS. FAIRLY MARKED DIFFERENCES IN GFS AND NAM IN GROWING AMPLITUDE OF EJECTING WESTERN TROUGH NEXT 48HRS IS ONE SOURCE OF UNCERTAINTY. KL PREVIOUS DISCUSSION 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... THE COLD FRONT HAS MOVED SOUTH OF THE TAF FORECAST AREA OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA. THE WIND PROFILER DATA SHOWS A WEST WIND IN ILLINOIS AT 700 MB AND AT 850 MB. WITH THIS WIND PATTERN ALOFT THE FRONT WILL PROBABLY STALL OVER CENTRAL ILLINOIS. A HIGH WILL MOVE ACROSS THE NORTH CENTRAL PART OF THE STATE THIS EVENING. THE WIND WILL BECOME SOUTHERLY AND THE FRONT WILL MOVE NORTH INTO NORTH CENTRAL ILLINOIS AND NORTHWEST INDIANA LATE TONIGHT. WE WILL ADD THUNDERSTORMS TOWARD FROM 11 TO 12 UTC. THIS IS THE TIME OF MAXIMUM CONVERGENCE AS THE FRONT MOVES THROUGH. WE WILL HAVE LIGHT RAIN THROUGH THE MORNING ACROSS THE FORECAST AREA. WE EXPECT A SOUTHEAST WIND AFTER MIDNIGHT TONIGHT. WE USED THE NAM AND A LOCALLY RUN WRF MODEL. && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1100 AM CDT THU MAR 22 2007 .DISCUSSION FOR ZONES/GRIDS... 11AM...SKIES ARE CLEARING OVER MUCH OF FCST AREA AT LATE MRNG AS WINDS TURN NW AND TEMPS STEADY OUT. COLD ADVECTION ON NW WINDS WILL HOLD TEMPS WITHIN FEW DEG OF CURRENT LEVELS THROUGH THE AFTERNOON. HIGH PERS OVER NW IOWA SHOULD DRIFT ACROSS TONIGHT FOR SOMEHWAT COOLER TEMPS. RETURN MOISTURE AND CLOUDS ETC LKLY TO BEGIN LATER TONIGHT AND CONTINUE FRIDAY. CHARACTER OF THAT RETURN REMAINS TO BE SEEN AND WILL TRIM/DELAY RETURN A LITTLE IN UPDATED GRIDS. FAIRLY MARKED DIFFERENCES IN GFS AND NAM IN GROWING AMPLITUDE OF EJECTING WESTERN TROUGH NEXT 48HRS IS ONE SOURCE OF UNCERTAINTY. KL PREVIOUS DISCUSSION 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 650 AM CDT MID LVL S/WV TROF CONTINUES TO PLOW INTO WRN GRTLKS REGION THIS MORNING...COLD FRONT PUSHING THRU FCST AREA AT 12Z. BAND OF ELEVATED CONVECTION ASSOCIATED WITH 55 KT LLJ NOW PUSHING OFF TO THE EAST OF FCST AREA AS 950-850 HPA FLOW BECOMING A BIT MORE WESTERLY WITH APPROACH OF TROF...THOUGH A FEW ISOLATED CELLS STILL DVLPG GENERALLY ALONG/SOUTH OF A KVYS...KLOT...KGYY LINE ASSOCIATED WITH ELEVATED INSTABILITY PLUME/LLJ AXIS. EXPECT THESE TO REMAIN SOUTH OF TERMINALS WITH EXCEPTION OF KGYY FIRST COUPLE OF HOURS OF TAF PERIOD EARLY THIS MORNING. OTHERWISE...COLD FROPA HAS OCCURRED AT KRFD AND WILL BE INTO CHI AREA TERMINALS NEXT 1-2 HRS. PATCHY MVFR CIGS IN 1500-2000 FT RANGE IMMEDIATELY BEHIND FRONT...THOUGH STRONG LLVL DRY ADVECTION DVLPG POST FRONTAL SHOULD CLR THIS OUT BY LATE MORNING. STRONG ISALLOBARIC GRADIENT WITH PRESSURE RISES BEHIND FRONT...SO WITH WSFT TO NW XPCT TO CONTINUE TO SEE GUSTS INTO THE LOW/MID 20 KT RANGE THIS MORNING. SFC HIGH PRESSURE BUILDS IN RAPIDLY THIS AFTN/THIS EVE ALLOWING WINDS TO DECREASE QUICKLY...GOING VRBL THIS EVE. WILL LIKELY SEE A BIT OF A LAKE BREEZE TOWARD EVE ALONG IL/IND LAKE MICH SHORE AS GRADIENT RELAXES. NEXT S/WV PROPAGATES ACROSS UPPER MIDWEST TONIGHT...WITH ANOTHER ROUND OF WAA/UPGLIDE DVLPG ACROSS BAROCLINIC FRONTAL ZONE TO SOUTH OF FCST AREA OVRNGT. 06Z NAM/GFS RUNS BOTH FOCUS PCPN SOUTH OF TERMINALS WITH VFR CIG DVLPG. COULD SEE PCPN FARTHER NORTH INTO TERMINAL SITES AFTER 06Z TONIGHT...THOUGH CONFIDENCE THAT FAR NORTH IS LOW ATTM. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 650 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 650 AM CDT MID LVL S/WV TROF CONTINUES TO PLOW INTO WRN GRTLKS REGION THIS MORNING...COLD FRONT PUSHING THRU FCST AREA AT 12Z. BAND OF ELEVATED CONVECTION ASSOCIATED WITH 55 KT LLJ NOW PUSHING OFF TO THE EAST OF FCST AREA AS 950-850 HPA FLOW BECOMING A BIT MORE WESTERLY WITH APPROACH OF TROF...THOUGH A FEW ISOLATED CELLS STILL DVLPG GENERALLY ALONG/SOUTH OF A KVYS...KLOT...KGYY LINE ASSOCIATED WITH ELEVATED INSTABILITY PLUME/LLJ AXIS. EXPECT THESE TO REMAIN SOUTH OF TERMINALS WITH EXCEPTION OF KGYY FIRST COUPLE OF HOURS OF TAF PERIOD EARLY THIS MORNING. OTHERWISE...COLD FROPA HAS OCCURRED AT KRFD AND WILL BE INTO CHI AREA TERMINALS NEXT 1-2 HRS. PATCHY MVFR CIGS IN 1500-2000 FT RANGE IMMEDIATELY BEHIND FRONT...THOUGH STRONG LLVL DRY ADVECTION DVLPG POST FRONTAL SHOULD CLR THIS OUT BY LATE MORNING. STRONG ISALLOBARIC GRADIENT WITH PRESSURE RISES BEHIND FRONT...SO WITH WSFT TO NW XPCT TO CONTINUE TO SEE GUSTS INTO THE LOW/MID 20 KT RANGE THIS MORNING. SFC HIGH PRESSURE BUILDS IN RAPIDLY THIS AFTN/THIS EVE ALLOWING WINDS TO DECREASE QUICKLY...GOING VRBL THIS EVE. WILL LIKELY SEE A BIT OF A LAKE BREEZE TOWARD EVE ALONG IL/IND LAKE MICH SHORE AS GRADIENT RELAXES. NEXT S/WV PROPAGATES ACROSS UPPER MIDWEST TONIGHT...WITH ANOTHER ROUND OF WAA/UPGLIDE DVLPG ACROSS BAROCLINIC FRONTAL ZONE TO SOUTH OF FCST AREA OVRNGT. 06Z NAM/GFS RUNS BOTH FOCUS PCPN SOUTH OF TERMINALS WITH VFR CIG DVLPG. COULD SEE PCPN FARTHER NORTH INTO TERMINAL SITES AFTER 06Z TONIGHT...THOUGH CONFIDENCE THAT FAR NORTH IS LOW ATTM. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 330 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 1254 AM CDT VIGOROUS S/WV TROF PROPAGATING ACROSS NRN PLAINS AND UPPER MIDWEST EARLY THIS MORNING...WITH ASSOCIATED SFC TROF/COLD FRONT FROM NRN WI TO ERN IA AT 05Z. REGIONAL PROFILER DATA...AND 0445Z ACARS SOUNDING OUT OF KRFD INDICATE 55 KT SOUTHWESTERLY LLJ IN 930-850 HPA LAYER AHEAD OF LOW LEVEL TROF/FRONT. SOUNDING ALSO INDICATES STEEP LAPSE RATES IN THIS LAYER...THOUGH A BIT OF A CAP NOTED AROUND 670 MB. ISOLATED WEAK ELEVATED CONVECTIVE CELLS HAVE BEEN TRYING TO INITIATE IN THIS REGION OF MOIST/WAA ACROSS FAR NRN IL...THOUGH APPEARS THEY ARE FIGHTING CAP. NAM FCST SOUNDINGS DEPICT COOLING OF MID/UPR LVLS WITH APPROACH OF S/WV EARLY THIS MORNING HOWEVER...WITH ELEVATED CAPE INCREASING TO 550-650 J/KG FOR PARCELS BASED 875-900 HPA. THIS ALONG WITH INCREASING LLVL CONVERGENCE AHEAD OF FRONT SHOULD BE SUFFICIENT TO RESULT IN SCATTERED TRW AS BOUNDARY ADVANCES ACROSS FCST IL. CURRENT REGIONAL RADAR TRENDS INDICATE STRONG CONVECTION IN SWRN WI AND SRN IA...WITH SOME INCREASE IN CELL DEVELOPMENT ACROSS ERN IA. GIVEN STRONG FAIRLY UNIDIRECTIONAL WIND FIELD MAY SEE SOME GUSTS IN 40 KT RANGE WITH TSTMS...AND PERHAPS SOME SMALL HAIL GIVEN MARGINAL CAPE PROFILES. THUS WILL MAINTAIN TS IN TERMINALS THIS MORNING...MAINLY DURG 09-13Z PERIOD FROM WEST TO EAST AS FRONT MOVES THRU. MAY SEE BRIEF PERIOD OF MVFR CIGS IN FRONTAL ZONE...THOUGH STRONG LLVL DRYING BEHIND FRONT SHOULD DECREASE CLOUDS FAIRLY RAPIDLY WITH VFR CONDITIONS PREVAILING WITHIN A FEW HOURS OF SUNRISE. STRONG SW LLVL WIND FIELD IN TIGHT PRES GRADIENT AHEAD OF COLD FRONT RESULTING IN GUSTY 20-30 KT WINDS ATTM. WILL SEE GRADIENT DECREASE JUST A BIT WITHIN TROF AXIS TOWARD SUNRISE...THEN WSHFT TO NWLY DIRECTION. SOME GUSTINESS AS SFC PRES RISE BUILDS IN EARLY MORNING...THEN DECREASING WINDS THIS AFTN AS WEAK SFC HIGH BUILDS IN. DVLPMNT OF NE WINDS OFF LAKE A GOOD PROBABILITY VERY LATE AFTN/EARLY EVE AS GRADIENT WINDS DECREASE. NEXT S/WV AND ELEVATED PCPN THREAT BEYOND 06Z TONIGHT...MORE ON THAT WITH NEXT FCST ISSUANCE. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 745 PM EDT WED MAR 21 2007 .DISCUSSION FOR 00Z TAFS...WARM SECTOR AIR OVER TAF ROUTES WITH SCT AC AND CI OVR INDIANA WHILE CONVECTION OCCURRING NEAR WRM FNT ACRS SRN GRTLKS. PATCHY MID CLOUD EMBEDDED IN SW FLOW AHEAD OF CDFNT MEANS VFR TO CONTINUE TIL DAYBREAK WHILE GUSTY WINDS AT SUNSET TODAY BECOME STEADY OVRNGT. MODELS TIMING OF CDFNT THU FAIRLY SIMILAR AND APPEARS BEST LIFT WILL OCCUR JUST PRIOR TO AND DURING FROPA SO HAVE KEPT PCPN OUT OF FCST TIL THEN. EXPECT PERIOD OF MVFR VSBY WITH SHRA AND CB DURING CDFNT PASSAGE AND TREND TO MVFR CIGS OVC020 IN COLD AIR BEHIND FNT. INCREASED STABILITY SHOULD LEAD TO END OF TSHRA SHORTLY AFT FROPA. && .PREV DISCUSSION...SURFACE FRONT CURRENTLY LOCATED OVER NORTHERN PLAIN/UPPER MIDWEST WILL MOVE SOUTH INTO THE AREA THURSDAY. HAVE ADJUSTED PRECIP TIMING ACCORDINGLY. HAVE KEPT A CHANCE IN MOST AREAS DURING THE OVERNIGHT HOURS TO ACCOUNT FOR ANY PRE-FRONTAL ELEVATED CONVECTION THAT MAY FIRE AS S/W OVER S. MO AND N. AR MOVES INTO AREA ALONG WITH INCREASING ISENTROPIC LIFT FROM THE LLJ. THE MID LEVEL FORCING ASSOCIATED WITH THE ACCOMPANYING S/W IS FCST TO MOVE ACRS THE UPPER MIDWEST AND LAKES REGION SHOULD REMAIN DISPLACED AWAY FROM CENTRAL INDIANA. THIS WILL TEND TO LIMIT DESTABILIZATION OVERTOP MOIST TONGUE ADVECTING INTO THE REGION TONIGHT AND EARLY TOMORROW. MODEL CONSENSUS FCST SOUNDINGS INDICATING MODEST LOW LEVEL FLOW DURING THE AFTERNOON HOURS TOMORROW BUT SEVERE POTENTIAL WILL BE LIMITED MAINLY BY VERY WEAK INSTABILITY. FRONTOGENESIS MOVES INTO AREA BY THURS MORNING AND REMAINS QUASI STATIONARY OVER THE OH VALLEY THRU SATURDAY ACCORDING TO NAM/GFS. ADDITIONAL EMBEDDED SHORTWAVES IN MEAN FLOW WILL HELP TO TRIGGER OCCASL CONVECTIVE SHOWERS/TSTMS IN CONJUNCTION WITH FRONTAL LIFTING IN REGION. PWATS VALUES WILL BE ON THE ORDER OF 1.2 TO 1.5 INCHES OVERNIGHT AND THURSDAY AS LLJ MOVES INTO THE AREA AND ACTS AS MSTR TRANSPORT MECHANISM...THEREFORE POTENTIAL EXISTS FOR HEAVY RAIN AMOUNTS. HPC GUIDANCE CURRENTLY HAS ROUGHLY 1.5 INCHES ACCUMULATING OVER THE ENTIRE FCST AREA...WITH POTENTIAL FOR UP TO 3 INCH AMOUNTS IN ISOLATED AREAS IN THE NEXT 48-60 HRS. AT THIS TIME...1 TO 2 INCH AMTS APPEAR TO BE THE MORE PROBABLE SCENARIO. WILL ISSUE AN ESF TO INCREASE AWARENESS ABOUT THE WATER THREAT BUT WILL HOLD OFF ON ANYTHING ELSE WHEN/IF FOCUS FOR LIFT BECAUSE MORE APPARENT. HAVE ADJUSTED TEMPS SLIGHTLY TO ALIGN THEM IN A NORTH-SOUTH GRADIENT AS THE MODEL CONSENSUS INDICATES AN EAST-WEST FRONTAL POSITION OVER THE TONIGHT THRU FRIDAY NIGHT PERIOD. LONG TERM...AFT 12Z ON MARCH 24...CONSENSUS IS WARM AND OFTEN WET WITH STRONG SW FLOW AND FRONT WEAVING BACK AND FORTH ACROSS AREA. HOWEVER JUST HOW THE FRONT AND SHORT WAVES MOVING THROUGH AREA INTERACT COULD MAKE A BIG DIFFERENCE IN JUST HOW WARM AND HOW WET WE GET. FOR NOW WILL STICK CLOSE TO NCEP GUIDANCE BECAUSE DONT HAVE A BETTER IDEA...BUT THIS IS NOT A HIGH CONFIDENCE FCST. && .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...SMITH/JK AVIATION...TUCEK in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 410 PM EDT WED MAR 21 2007 .DISCUSSION...SURFACE FRONT CURRENTLY LOCATED OVER NORTHERN PLAIN/UPPER MIDWEST WILL MOVE SOUTH INTO THE AREA THURSDAY. HAVE ADJUSTED PRECIP TIMING ACCORDINGLY. HAVE KEPT A CHANCE IN MOST AREAS DURING THE OVERNIGHT HOURS TO ACCOUNT FOR ANY PRE-FRONTAL ELEVATED CONVECTION THAT MAY FIRE AS S/W OVER S. MO AND N. AR MOVES INTO AREA ALONG WITH INCREASING ISENTROPIC LIFT FROM THE LLJ. THE MID LEVEL FORCING ASSOCIATED WITH THE ACCOMPANYING S/W IS FCST TO MOVE ACRS THE UPPER MIDWEST AND LAKES REGION SHOULD REMAIN DISPLACED AWAY FROM CENTRAL INDIANA. THIS WILL TEND TO LIMIT DESTABILIZATION OVERTOP MOIST TONGUE ADVECTING INTO THE REGION TONIGHT AND EARLY TOMORROW. MODEL CONSENSUS FCST SOUNDINGS INDICATING MODEST LOW LEVEL FLOW DURING THE AFTERNOON HOURS TOMORROW BUT SEVERE POTENTIAL WILL BE LIMITED MAINLY BY VERY WEAK INSTABILITY. FRONTOGENESIS MOVES INTO AREA BY THURS MORNING AND REMAINS QUASI STATIONARY OVER THE OH VALLEY THRU SATURDAY ACCORDING TO NAM/GFS. ADDITIONAL EMBEDDED SHORTWAVES IN MEAN FLOW WILL HELP TO TRIGGER OCCASL CONVECTIVE SHOWERS/TSTMS IN CONJUNCTION WITH FRONTAL LIFTING IN REGION. PWATS VALUES WILL BE ON THE ORDER OF 1.2 TO 1.5 INCHES OVERNIGHT AND THURSDAY AS LLJ MOVES INTO THE AREA AND ACTS AS MSTR TRANSPORT MECHANISM...THEREFORE POTENTIAL EXISTS FOR HEAVY RAIN AMOUNTS. HPC GUIDANCE CURRENTLY HAS ROUGHLY 1.5 INCHES ACCUMULATING OVER THE ENTIRE FCST AREA...WITH POTENTIAL FOR UP TO 3 INCH AMOUNTS IN ISOLATED AREAS IN THE NEXT 48-60 HRS. AT THIS TIME...1 TO 2 INCH AMTS APPEAR TO BE THE MORE PROBABLE SCENARIO. WILL ISSUE AN ESF TO INCREASE AWARENESS ABOUT THE WATER THREAT BUT WILL HOLD OFF ON ANYTHING ELSE WHEN/IF FOCUS FOR LIFT BECAUSE MORE APPARENT. HAVE ADJUSTED TEMPS SLIGHTLY TO ALIGN THEM IN A NORTH-SOUTH GRADIENT AS THE MODEL CONSENSUS INDICATES AN EAST-WEST FRONTAL POSITION OVER THE TONIGHT THRU FRIDAY NIGHT PERIOD. LONG TERM...AFT 12Z ON MARCH 24...CONSENSUS IS WARM AND OFTEN WET WITH STRONG SW FLOW AND FRONT WEAVING BACK AND FORTH ACROSS AREA. HOWEVER JUST HOW THE FRONT AND SHORT WAVES MOVING THROUGH AREA INTERACT COULD MAKE A BIG DIFFERENCE IN JUST HOW WARM AND HOW WET WE GET. FOR NOW WILL STICK CLOSE TO NCEP GUIDANCE BECAUSE DONT HAVE A BETTER IDEA...BUT THIS IS NOT A HIGH CONFIDENCE FCST. && .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...SMITH/JK AVIATION...KOCH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 100 PM EDT WED MAR 21 2007 .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .DISCUSSION...SPLIT UPPR FLOW DVLPG ACRS THE COUNTRY OVR THE NEXT COUPLE OF DAYS. WK DISTURBANCES WL BE EJECTING OUT OF THE SRN PLAINS...WHILE A STRONGER NRN STREAM SYS CURRENTLY LOCATED OVR THE NRN ROCKIES PUSHES EWD INTO THE UPPR GRTLKS ON THURS. THIS SYS WL BRING A CDFNT INTO THE LOCAL AREA BY THURS AFT/NIGHT. MODELS IN RELATIVELY GOOD AGREEMENT ON THE MAIN DETAILS. FCST FOCUS CENTERS ON POPS. LIFT AHEAD OF WK SHORT WV TROF OVR WRN IL CAUSING SHWRS TO BREAK OUT ACRS THE AREA. 21/00Z UA INDICATES NOSE OF LLJ POINTED MORE TOWARDS SRN LI MI...SO WOULD XPCT THE BULK OF THE HVR PCPN TO STAY NW OF THE LOCAL AREA EARLY THIS MORN. BASED ON MODEL DATA...WV SHOULD PUSH OFF TO THE NE BY SUNRISE...SO PCPN THREAT SHOULD DIMINISH BY THAT TIME. H20 LOOP LOOKS PRETTY MESSY IN THE SRN STREAM...WITH INDICATIONS OF ADDITIONAL DISTURBANCES PSBLY OVR NEBRASKA AND ERN OK. CONSIDERING ABV AND THE FACT THAT LLJ WL REMAIN IN THE GENERAL AREA THRU TONIGHT...DECIDED TO LEAVE CHC POPS IN THE FCST THRU TONIGHT. APPEARS CDFNT WL BE MOVG INTO THE NWRN ZONES BY THURS AFT. GOOD INFLOW INTO THE FNT WITH 850MB WNDS PROGGED ARND 40KTS. THIS SUGGESTS FAIRLY WIDESPREAD PCPN SHOULD DVLP INVOF FNT. WL GO WITH HI POPS BY THURS AFT AS A RESULT. MODELS INDICATE FNT MAY STALL OUT NEARBY TOWARDS THE END OF THE WEEK. 850MB FLOW INTO THE FNT REMAINS RATHER HEALTHY AS WELL...SUGGESTING HVY RAINFALL TOTALS PSBL LT IN THE WEEK IF MODEL SOLUTIONS COME TO PASS. BASED ON PROGGED LO LVL THICKNESSES...NGM MOS GUIDANCE TEMPS LOOK REASONABLE AT THIS PT...SO WON/T STRAY TOO FAR FM THEM. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...JAS AVIATION...KOCH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 207 AM EDT WED MAR 21 2007 .AVIATION/UPDATE... CONCERNED WITH FREEZING RAIN POTENTIAL OVERNIGHT AS BAND OF SHOWERS MOVG INTO THE AREA WITH TEMPS AOB FREEZING. RAINFALL INITIALLY IS QUITE LIGHT AS LOW LEVELS DRY AND CONSIDERABLE EVAPORATION OF RAINFALL OCCURRING. ALSO WAA SHOULD CAUSE TEMPS TO RISE OVERNIGHT TO ABOVE FREEZING BY 12Z. SO HAVE ADDED MENTION OF -FZRA TO TAFS FOR FEW HOURS EARLY THIS MORNING AND TO NE 1/2 OF CWA IN GRID/ZFP UPDATE. WARM FRONT OVER SRN IL IS EXPECTED TO LIFT RAPIDLY NORTH ACROSS NRN INDIANA BY MIDDAY CAUSING WINDS TO SHIFT TO SOUTHERLY AND CIGS/VSBYS TO IMPROVE THIS AFTN. NO SGFNT FORCING IN THE WARM SECTOR THIS AFTN/EVE SO LEFT THIS PERIOD DRY THOUGH WITH DESTABILIZATION A FEW SHOWERS COULD POP UP. && .PREV DISCUSSION... AVIATION/UPDATE... HIGH PRES OVR SWRN QB WILL CONT TO SLIDE EWD INADV OF STG SRN STREAM SW TROUGH EJECTING NEWD OUT OF MO. SKC THIS EVENING BUT XPC RAPID MSTR FLUX/THETA-E ADVTN TWD MIDNIGHT AS UPSTREAM LLJ VEERS SW AND PCPN DVLPMNT BY 09Z FM NRN IL INTO WRN IN...AND CONTD E/NE EXPANSION THROUGH DAYBREAK. 18Z GUIDANCE TOO FAR N W/CONVECTIVELY INDUCED MID LVL VORT MAX ACRS WRN MO AT 21Z W/MORE WEIGHT GIVEN TO 21Z RUC WHICH TAKES MID LVL TROUGH AXIS ON A MORE SRN NE EJECTION. THIS FAVORS GOING POP ALIGNMENT ESP WED MORNING ALTHOUGH LIKELY OVERDONE ACRS SE CWA. WILL CONT TO MONITOR UPSTREAM DVLPMNTS THROUGH MID EVENING FOR EVENTUAL UPDATE. VFR CONDS THIS EVENING WILL QUICKLY DEGENERATE TO WIDESPREAD MVFR AFT 09Z W/PD OF IFR CONDS AT KSBN WED AM AND TEMPO TSRA GIVEN FORCING ASSOCD/W INTENSE MID LVL TROUGH AND DEGREE OF DESTABILIZATION ALOFT. KFWA ON THE OTHER HAND LOOKS A BIT REMOVED FM BTR THETA-E RIDGE AND MORE FVRBL MID LVL EML AND WILL CONT W/NO MENTION THERE FOR THE TIME BEING. SHORT TERM... TONIGHT AND WEDNESDAY... HIGH PRESSURE STILL HOLDING ON EARLY THIS EVENING BUT AS IT SLIDES BY TO OUR EAST RETURN FLOW BEGIN EARNEST. THIS ALREADY SEEN IN SATELLITE AND RADAR UPSTREAM ACROSS MO AND SOUTHWEST IL THIS AFTERNOON WITH CLOUDS AND PCPN. MODELS SHOW STRONG THETA E ADVECTION INTO THE AREA AFTER MIDNIGHT WITH STRONG WARM AIR ADVECTION ON NOSE OF INCREASING 40 TO 50KT LOW LEVEL JET. SIMILAR TO SUNDAY NIGHT...EXPECT VERY DRY AIRMASS TO QUICKLY SATURATE AFTER MIDNIGHT WITH PCPN EXPANDING FROM SOUTHWEST TO NORTHEAST ACROSS THE FORECAST AREA. ELEVATED INSTABILITY A BIT BETTER TONIGHT THAN SUNDAY NIGHT AND ALREADY QUITE A BIT OF THUNDERSTORM ACTIVITY IN SOURCE REGION OF EASTERN PLAINS THIS AFTERNOON. HAVE ADDED THUNDER CHANCES TO FORECAST TONIGHT AND WEDNESDAY. AS FOR WEDNESDAY...EXPECT RAIN AND EMBEDDED THUNDERSTORMS ACROSS MUCH OF THE AREA IN THE MORNING. AS NOSE OF LOW LEVEL JET AND MOISTURE FLUX MOVE THROUGH...SHOULD SEE A DECREASE IN AREAL COVERAGE BY AFTERNOON. MOIST AND WARMER AIR WILL BE IN PLACE DURING THE AFTERNOON WITH INDICATIONS OF A SHORT WAVE. HAVE DECREASED POPS TO CHANCE ALL AREAS BUT MODELS FAVORING NORTHWEST AREAS FOR ANOTHER ROUND OF RAIN IN THE AFTERNOON. TEMPERATURES WILL WARM DURING THE DAY TO 60S SOUTHWEST BUT NORTHEAST TO REMAIN COOLER WITH LINGERING CLOUDS AND RAIN INTO THE EARLY AFTERNOON. && LONG TERM... NOT MUCH RAIN IS EXPECTED IF ANY AT ALL FOR WEDNESDAY NIGHT. A COLD FRONT WILL BE APPROACHING THE AREA FROM THE WEST. THE FRONT IS THEN PROGGED TO BEGIN MOVING INTO THE CWA THURSDAY MORNING. DECENT WARM AIR ADVECTION WILL BE TAKING PLACE WEDNESDAY NIGHT...SO NOT EXPECTING TEMPERATURES TO DROP TO LOW. ADDED IN A MENTION OF ISOLATED THUNDER FOR THURSDAY. TOTAL TOTAL VALUES HAVE BEEN IN THE LOWER 50S THE PAST COUPLE OF DAYS FOR THURSDAY. GFS SOUNDINGS IN BUFKIT ARE SHOWING AN INVERSION IN FOR MOST OF THE DAY BELOW 5000 FEET BUT ELEVATED SHOWERS WOULD HAVE SOME CAPE TO WORK WITH TO PRODUCE LIGHTNING. ALSO COULD BE SOME GOOD CONVERGENCE WITH THE FRONT MOVING THROUGH. THEN THE QUESTION FOR THURSDAY NIGHT IS HOW FAR SOUTH WILL THE FRONT GO...AND HOW MUCH STRENGTH WILL THE HIGH HAVE THAT IS PROGGED TO MOVE THROUGH THE SOUTHERN GREAT LAKES THEN. JUST WILL ALTER THE POP SLIGHTLY TO SHOW THAT THE SOUTHERN PART OF THE CWA HAS A BETTER CHANCE FOR RAIN THAN THE NORTHERN PART DOES. IF MODELS STAY CONSISTENT WITH WHAT THEY HAVE BEEN SHOWING...THEN THE FRONT WILL MOVE FAR ENOUGH SOUTHWARD THURSDAY NIGHT FOR THE CWA TO BE DRY. WAITING ON FRIDAY YET. RIGHT NOW THE GFS HAS THE HIGH MOVING MORE OFF TO THE EAST...WITH RETURN FLOW MOVING THE FRONT TO THE SOUTH BACK INTO THE AREA...AND THE GFS HAS SOME IMPULSES MOVING EASTWARD ALONG THE FRONT THROUGH THE AREA. BUT MODELS HAVE CHANGED EVEN FROM YESTERDAY FOR FRIDAY...SO NO CHANGE. NO CHANGES YET FOR FRIDAY NIGHT THROUGH SATURDAY YET EITHER. YESTERDAY THIS TIME FRAME WAS DRY...TWO RUNS AGO OF GFS HAD AN UPPER LEVEL SHORTWAVE MOVING THROUGH THE GREAT LAKES AREA THEN...BUT NOW THE LATEST RUN IS WEAKER WITH THIS UPPER SHORTWAVE. ALSO FOR THIS WEEKEND INTO THE BEGINNING OF NEXT WEEK...WILL HAVE TO WATCH HOW MODELS ARE GOING TO DEAL WITH A CLOSED UPPER LOW OVER THE SOUTHWESTERN U.S. THIS WEEK. THIS UPPER LOW IS PROGGED TO EJECT OUT OF THE SOUTHWEST U.S. AT THE END OF THIS WEEK...CREATING A SURFACE LOW AS IT MOVES INTO THE CENTRAL PLAINS. WILL HAVE TO SEE IF THIS CREATES A WARM FRONT TO MOVE INTO THE AREA GIVING RAIN CHANCES FOR SATURDAY NIGHT OR NOT. THEN RIGHT NOW THE UPPER LOW AND SURFACE LOW ARE PROGGED TO MOVE INTO THE CWA NEXT MONDAY NIGHT WITH PRECIP OUT AHEAD OF THEM...AND THEN WEAKENING AS MOVING ON TO THE EAST ALLOWING HIGH PRESSURE TO MOVE IN FOR NEXT TUESDAY. THIS IS THE SITUATION RIGHT NOW...BUT AS SEEN THE PAST COUPLE OF DAYS...THE SCENARIO CAN BE ALTERED FROM DAY TO DAY. SO AS SEEING THINGS NOT TOO FAR OFF FROM WHAT IS IN THE FORECAST NOW...NOT TOO MANY CHANGES WERE MADE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...LASHLEY LONG TERM...LOTHAMER AVIATION...JT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 309 PM CST WED MAR 21 2007 .SYNOPSIS... CONVECTION ONGOING OVER THE NW FOURTH OF THE CWA THIS AFTERNOON. TSRA MOVED INTO THE WRN COUNTIES AHEAD OF H5 S/W MVNG THROUGH CENTRAL IA...THEN REFORMED INTO AN E/W LINE ALONG INSTABILITY GRADIENT OVER SE IA. SO FAR JUST SOME ISOLATED SEVERE HAIL REPORTS AND WIND GUSTS AROUND 35KTS. COLD FRONT WAS LOCATED FROM THE WRN MN THROUGH ERN NE EARLY THIS AFTERNOON. 12Z UA ANALYSIS SHOWED A POTENT NRN ROCKIES UPPER TROF ASSOCIATED WITH THE FRONT. SO FAR NOT MUCH IN THE WAY OF CONVECTION WAS NOTED WITH SURFACE FRONT WITH STRONG CAP NOTED ON KOAX 18Z SOUNDING...SUPPRESSING DEVELOPMENT. && .SHORT TERM...TONIGHT AND THURSDAY... CONVECTION CURRENTLY OVER THE NRN CWA SHOULD BE EAST OF THE CURRENT WATCH AND ANTICIPATE CANCELLING THE SEVERE WATCH EARLY FOR MOST OF THE WATCH AREA. COLD FRONT PROGGED TO MOVE THROUGH CWA LATE THIS EVENING AND EARLY THURSDAY MORNING AS MID LEVEL S/W CROSSES THE NCNTRL STATES. LOOKING AT A RUC FCST NR KOMA FOR THIS AFTERNOON...IT SHOWS THE STRONG CAP DISSIPATING BY 00Z...SO EXPECT CONVECTION TO FORM IN WRN IA BY EARLY EVENING ON THE FRONT AND REACH THE NWRN CWA AROUND 03Z ...THEN MOVING THROUGH THE SERN CWA BTWN 09Z AND 12Z. FRONT IS THEN EXPECTED TO STALL OVER CENTRAL MO/IL THURSDAY AFTN/EVE. HAVE CONTINUED CATEGORICAL POPS FROM THE PREV FCST FOR TONIGHT. SEVERE THREAT REMAINS WITH SOME MODEST CAPE AROUND 1000J/KG PROGGED TO REMAIN OVER ERN IA THROUGH THE EVENING. BELIEVE SYSTEM WILL BE PROGRESSING EAST FAST ENOUGH TO LIMIT ANY RAINFALL THREAT IN ANY ONE AREA. PROBABLY THE MOST VULNERABLE AREA WILL BE THE SRN MOST COUNTIES WAS THE FRONT SLOWS AS IT BECOMES MORE ALIGNED WITH THE MID LEVEL FLOW. && .LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY... THE GFS/NAM/UKMET ARE IN GOOD AGREEMENT LIFTING THE BOUNDARY BACK NORTH INTO NRN MO/CNTRAL IL LATE THURSDAY NIGHT SETTING UP THE POTENTIAL FOR A HEAVY RAIN AS STRONG/MOIST SLWY LOW LEVEL FLOW INTERSECTS THE BOUNDARY...AND FUELING STORMS ON THE COOL SIDE. REPEAT CONVECTION WILL BE POSSIBLE WITH THE FRONT ORIENTED PARALLEL TO THE MID LEVEL FLOW AND A SWLY LLJ POINTED AT NW MO/SW IA MOST OF THE NIGHT. MODELS DIVERGE FRIDAY INTO THE SATURDAY HANDLING THE WARM FRONT. THE GFS PULLS THE BOUNDARY NORTH WELL INTO IA WHILE THE NAM/UKMET KEEP SOUTH AS THEY BRING S/W ENERGY THROUGH NRN STREAM. SINCE THE GFS IS THE OUTLIER...HAVE LIMITED CHANCE POPS TO THE SRN COUNTIES. FOR SATURDAY NIGHT THROUGH MONDAY THE LONG RANGE MODELS ARE IN BETTER AGREEMENT HANDLING THE SRN STREAM CUT OFF LOW...LIFTING IT NE THROUGH THE MID MS VALLEY BY EARLY MONDAY. BASED ON THIS HAVE STARTED TO TREND POPS HIER ESPECIALLY IN ADVANCE OF THE SYSTEM SATURDAY NIGHT THROUGH SUNDAY NIGHT. LONG RANGE MODELS THEN DEVELOP DEEP LOW PRESSURE OVER THE CENTRAL PLAINS FOR MID WEEK. HAVE OPTED TO KEEP FCST DRY TO MODELS ESTABLISH SOME RUN TO RUN CONTINUITY. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. $$ ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1038 AM CDT THU MAR 22 2007 .UPDATE... SURFACE FRONT HAD BECOME QUASI-STATIONARY GENERALLY JUST SOUTH OF HIGHWAY 50 AT MID-MORNING...WITH THE LATEST NAM AND RUC SUGGESTING A SLIGHT NORTHWARD MOVE INTO THE AFTERNOON. THIS IS SLIGHTLY NORTH OF EARLY MORNING GRID PACKAGE...SO HAVE REFLECTED THE CHANGES IN THE LATEST GRID/FORECAST UPDATE. AS FOR CONVECTIVE CHANCES FOR THIS AFTERNOON...A LOT WILL DEPEND ON DIURNAL HEATING (IE. CLOUD TRENDS) ALONG AND SOUTH OF SURFACE FRONTAL BOUNDARY. DESPITE SOME HOLES INTO MIDDAY...HIGHER LEVEL CLOUDS LOOK TO ENCROACH SOUTH CENTRAL KANSAS DURING THE EARLY AFTERNOON. CONVERGENCE ALONG THE BOUNDARY LOOKS SUFFICIENT TO FOCUS CONVECTION WITH POTENTIAL ML CAPES OF AROUND 1800 J/KG LATER THIS AFTERNOON. SO LITTLE CHANGE TO THE GOING POP FORECAST AND FLOOD WATCH HEADLINE. BETTER CHANCES FOR ELEVATED CONVECTION APPEAR TO BE IN THE OFFING LATE THIS EVENING OR OVERNIGHT...ALONG AND NORTH OF SURFACE FRONT. KED && .PREV DISCUSSION... /ISSUED 328 AM CDT THU MAR 22 2007/ DISCUSSION... FORECAST CONCERNS TODAY ARE TSRA CHANCES FOR TODAY THROUGH THE WEEKEND AND ALSO TEMPS. TODAY: WAVY FRONTAL BOUNDARY MAKING SLOW PROGRESS INTO THE SOUTHERN KS AT THIS TIME. SOME WIDELY SCATTERED TSRA FINALLY HAVE DEVELOPED ALONG THE BOUNDARY AS LOW LEVEL JET INCREASES OVER THE TOP OF THE FRONT HELPING TO GET ELEVATED STORMS GOING. QUESTION TODAY IS HOW FAR SOUTH /IF AT ALL/ THIS FRONT WILL MAKE IT BEFORE STALLING OUT LATER THIS MORNING. SOME PRESSURE RISES STILL NOTED BEHIND THE BOUNDARY SO PREFER THE NAM-WRF FOR FRONTAL PLACEMENT GENERALLY ALONG AN EMP-HUT LINE BEFORE IT STALL. WHERE THE BOUNDARY WILL ULTIMATELY STALL OUT IS THE BIG PROBLEM TODAY AS THIS BOUNDARY WILL PROVIDE THE FOCUS FOR CONVECTION AND POSSIBLE TRAINING ECHOES. EXPECT SOME CONVECTION TO BE ONGOING EARLY IN THE PERIOD...BUT MAIN TSRA CHANCE WILL BE THIS AFTERNOON AS A MID LEVEL IMPULSE IN THE SOUTHWEST FLOW AND INCREASING ISENTROPIC LIFT IN THE 305K LAYER WILL STEEPEN LAPSE RATES ENOUGH FOR A MORE WIDESPREAD CONVECTION CHANCE. INSTABILITY IS MODEST WITH MUCAPE VALUES THIS AFTERNOON ONLY AROUND 1000 J/KG...BUT 0-6KM SHEAR VALUES STILL SUGGEST A POSSIBLE LARGE HAIL THREAT FOR AREAS WHERE SURFACE HEATING CAN BE MAXIMIZED. WITH SOME SURFACE BASED CONVECTION POSSIBLE SOUTH OF THE BOUNDARY OVER AREAS WITH SATURATED GROUNDS...WILL LEAVE THE FLOOD WATCH GOING FOR SOUTH CENTRAL AND SOUTHEAST KS BUT DAY SHIFT WILL PROBABLY HAVE TO BETTER DEFINE THIS ONCE BOUNDARY DECIDES TO STOP ITS SOUTHERN PROGRESS. WILL RAISE MAX TEMPS IN SOUTHERN KS AS BOUNDARY JUST TO THE NORTH OF THIS AREA WILL ALLOW TEMPS TO CLIMB INTO THE LOWER 70S. TONIGHT: BOUNDARY DRIFTS TO THE NORTH SOME AS THE NIGHT PROGRESSES...WITH SOME ISENTROPIC LIFT STILL LOCATED SOUTH OF THE BOUNDARY. SO EXPECT SOME CONVECTION IN SOUTHEAST KS EARLY BUT PROBABLY DIMINISHING OVERNIGHT. THIS LIFT WILL PROBABLY LEAD TO SOME TRANING STORMS IN AND NEAR THE BOUNDARY...SO FLOODING THREAT WILL DEFINATELY HAVE TO BE WATCHED. FRI-FRI NIGHT: NOT ALOT OF CONFIDENCE IN FRONTAL PLACEMENT AND POSSIBLE CONVECTION FOR FRI. MODELS ALSO DIFFER ON MID LEVEL IMPULSES EXPECTED TO MOVE ACROSS THE AREA IN THE SOUTHWEST FLOW. WITH THE BOUNDARY STILL EXPECTED TO BE IN THE AREA WILL LEAVE CHANCE POPS IN MOST LOCATIONS AS ANY WEAK IMPULSE COULD LEAD TO DEVELOPMENT...BUT DO NOT EXPECT TSRA CHANCE TO BE WIDESPREAD. BETTER DEVELOPMENT LOOKS TO BE FRI NIGHT AS ISENTROPIC LIFT AGAIN INCREASES ACROSS THE AREA. WILL STILL ONLY GO CHANCE POPS FOR NOW AS PLACEMENT OF THE BOUNDARY IN LATER RUNS WILL BETTER DEFINE HIGHEST POP AREAS. SAT-SUN: CONFIDENCE REMAINS LOW DURING THIS TIME FRAME AS BOUNDARY REMAINS SOMEWHAT STATIONARY ON SAT FOR BEGINNING TO LIFT TO THE NORTH AGAIN AS A WARM FRONT ON SUN AND MAIN SHORTWAVE REMAINS SOUTHWEST OF THE AREA UNTIL SUN EVENING. WITH LOTS OF LOW LEVEL MOISTURE AROUND HEAVY RAINFALL THREAT WILL ALSO CONTINUE. WILL HAVE TO KEEP AN EYE ON SEVERE THREAT ON SAT AS SHEAR VALUES LOOK FAVORABLE BUT INSTABILITY LOOKS MODEST. MONDAY-WEDNESDAY: PRECIP CHANCES LOOK TO COME TO AN END ON MONDAY AS MED RANGE MODELS FINALLY MOVE THE MAIN SHORTWAVE ACROSS THE AREA. LOOKS LIKE TUESDAY WILL BE A DAY TO DRY OUT WITH WEAK RIDGING IN THE MID LAYERS. A RATHER RIGOROUS SHORTWAVE MOVES INTO THE PLAINS ON WED FOR ANOTHER POSSIBLE ROUND OF CONVECTION. KETCHAM && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 74 59 72 58 / 50 60 40 40 HUTCHINSON 70 58 72 57 / 40 50 40 40 NEWTON 71 58 71 57 / 50 60 40 40 ELDORADO 73 59 72 58 / 60 60 40 40 WINFIELD-KWLD 73 60 73 59 / 60 60 40 40 RUSSELL 61 51 71 53 / 20 30 40 40 GREAT BEND 64 53 71 55 / 30 40 40 40 SALINA 63 52 69 54 / 30 50 40 40 MCPHERSON 67 56 71 56 / 40 50 40 40 COFFEYVILLE 76 61 73 59 / 60 60 40 30 CHANUTE 74 60 72 59 / 60 60 40 30 IOLA 73 59 72 58 / 60 60 40 30 PARSONS-KPPF 74 61 73 59 / 60 60 40 30 && .ICT WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH FRIDAY MORNING FOR KSZ069>072-083-092>096- 098>100. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 440 AM CDT THU MAR 22 2007 .DISCUSSION... THE UNSETTLED PATTERN CONTINUES. INTERESTING SET UP TODAY WITH SFC BNDRY TO THE SOUTH AND GOOD OVER-RUNNING PATTERN DEVELOPING. LATEST RUC SOUNDINGS SHOW GOOD ELEVATED LIFT DEVELOPING NORTH OF THE SFC BNDRY BY MIDDAY ALONG OR JUST SOUTH OF INTERSTATE 70. OPTIMUM ELEVATED LIFT WITH FAIRLY GOOD CHANCE FOR THUNDERSTORMS MOVES SLOWLY NORTH THROUGH THE AFTERNOON AND OVERNIGHT...REACHING THE NORTHERN BORDER AFTER MIDNIGHT. PATTERN SUPPORTIVE OF LOCALLY HEAVY RAINS WITH TRAINING OVER SAME AREAS. NO FLOOD WATCH ISSUED YET...BUT BEARS WATCHING IN 12Z RUN. PRECIPITABLE WATER VALUES EXCEEDINGLY HIGH FOR THIS TIME OF YEAR...RUNNING NEARLY 250% OF NORMAL! THIS HIGH WATER CONTENT CONTINUES INTO THE WEEKEND AND DOES NOT REALLY GET MODIFIED TO ANY GREAT EXTENT UNTIL UPPER SYSTEM FINALLY LIFTS THROUGH FROM THE SOUTHWEST STATES EARLY NEXT WEEK. UNTIL THEN, PERIODIC CHANCES FOR CONVECTION...SOME OF WHICH MAY BE STRONG TO SEVERE. SETUP FOR SEVERE TODAY IS MAXIMIZED ALONG AND NORTH OF THE WARMFRONT. CONSIDERABLE HIGH CLOUDINESS WILL LIMIT SOLAR INSOLATION TO FRONTAL AREA OTHERWISE TEMPERATURES WOULD BE WARMER AND THE THREAT FOR SEVERE HAIL WOULD BE EVEN GREATER. SHEAR SEEMS TO BE SUFFICIENT FOR LARGE HAIL LATER TODAY AS WELL. TEMPERATURES IN TURN A REAL CHALLENGE WITH CLOUDS HANGING TOUGH TO THE NORTH OF THE FRONT. HAVE FOLLOWED NAM CLOSELY WITH IT`S SFC TEMPERATURE FCST. THUS COULD RANGE FROM THE UPPER 40S NORTH TO THE LOWER 70S SOUTH. BY FRIDAY THE FRONT SHOULD RESIDE ALONG THE NORTHERN BORDER WAITING FOR AN UPPER WAVE TO EJECT OUT OF MEAN WESTERN TROF POSITION. THIS COULD TRIGGER ANOTHER ROUND OF CONVECTION FRIDAY NIGHT. BETTER CHANCE APPEARS SATURDAY NIGHT INTO SUNDAY NIGHT AS UPPER SYSTEM LIFTS NORTHEAST INTO THE PLAINS. LATER PERIODS OF THE FORECAST NOT CHANGED MUCH AS IS IMPOSSIBLE TO ADD MUCH DETAIL OR FIND REASONS TO MAKE CHANGES IN SUCH AN UNSETTLED PATTERN. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 358 AM CDT THU MAR 22 2007 .DISCUSSION... DAYS 1-2... A NORTHERN STREAM SHORTWAVE TROUGH PASSED ACROSS THE NORTHERN PLAINS AND INTO THE GREAT LAKES OVERNIGHT. THIS HELPED PUSH A COLD FRONT THROUGH MOST OF SW KS. THE FRONT AS OF 3 AM STRETCHED FROM NORTH OF HUGOTON TO HUTCHINSON. SFC TEMPS WERE VERY BALMY SOUTH OF THE FRONT(71 AT BUFFALO,OK AND 65 AT LIBERAL). THE SFC DRYLINE WAS CURRENTLY MOVING NW THROUGH WEST TEXAS. AN UPPER LOW WAS SITUATED JUST OFF THE SOUTHERN CA COAST. 500MB TEMPS HAVE TURNED OUT TO BE WARMER THAN THE MODELS WERE FORECASTING A FEW DAYS AGO. IN FACT THE NAM HAS 500MB TEMPS AROUND -13C THIS AFTERNOON. SURFACE DEWPOINTS HAVE CLIMBED INTO THE UPPER 50S AND LOWER 60SF ACROSS OK/SOUTHERN KS. A LARGE AREA OF MID TO HIGH LEVEL CLOUD WAS MOVING NE INTO NM AND WEST TX. IN THE ABSENCE OF STRONG SYNOPTIC SCALE DYNAMICS TODAY...THE LOCATION OF SFC BOUNDARIES WILL DETERMINE THE PLACEMENT OF SHOWER/THUNDERSTORM INITIATION. THE NAM/GFS AND SOME OF THE RUC MEMBERS SURGE THE FRONT BACK TO THE NORTH TODAY TO A GCK TO HAYS LINE. I HAVE CHOSEN TO GO WITH THE RUC13 SOLUTION FOR TODAY. THIS MODEL KEEPS THE FRONT NEARLY STATIONARY ALL DAY. WITH BROKEN MID TO HIGH CLOUDS AND LOW LEVEL UPSLOPE FLOW... TEMPS WILL STAY IN THE 60S NORTH OF THE FRONT. BUT LOCATIONS ALONG THE OK STATE LINE COULD REACH THE UPPER 70S. I EXPECT THE SFC DRYLINE TO STRETCH FROM DALHART TO CARLSBAD,NM BY THIS AFTERNOON. THE DRYLINE WILL INTERSECT THE FRONT CLOSE TO DALHART. FAIRLY WEAK CAPPING...SOME ELEVATED HEATING ON THE HIGH PLAINS... AND CONVERGENCE ALONG THE DRYLINE AND NEAR THE FRONT/DRYLINE INTERSECTION WILL ALLOW STORMS TO DEVELOP BY 21Z. LOCAL POOLING OF MOISTURE MAY ALLOW FOR SFC BASED CAPES AS HIGH AS 1000-1500 J/KG FROM P28 TO ENGLEWOOD. AS STORMS MOVE INTO THIS AREA...A FEW OF THEM COULD BECOME SEVERE. VERTICAL SHEAR PROFILES WILL BE FAVORABLE FOR SEVERE STORMS. BUT THE MAIN LIMITING FACTOR FOR SEVERE STORMS WILL BE THE MARGINAL INSTABILITY. BUT AS WE HAVE SEEN IN THE RECENT PAST...STRONG VERTICAL WIND SHEAR AND CAPES AROUND 1000 J/KG CAN BE ENOUGH FOR SEVERE STORMS. ANY STORMS THAT DEVELOP THIS AFTERNOON WILL PROBABLY LINGER INTO TONIGHT. BUT THE STORM ACTIVITY WILL SHIFT OFF TO THE NE BY FRIDAY BEFORE THE MAIN UPPER LOW EJECTS INTO THE PLAINS ON SATURDAY. SOME POPS WERE MAINTAINED FOR FRIDAY FOR CONSISTENCY SAKE AND SINCE THERE IS SOME UNCERTAINTY. DAYS 3-7... NOT GOING TO CHANGE MUCH IN THE GOING EXTENDED. BOTH THE UKMET AND GFS BRING AN ORGANIZED SYSTEM UP FROM SOUTHERN BAHA CALIFORNIA TO WESTERN KANSAS FROM FRIDAY INTO SUNDAY. THE BEST CHANCES FOR PRECIPITATION LOOK TO BE ON SATURDAY AFTERNOON...WHERE WE HAVE 40 POPS GOING NOW. THESE POPS MAY HAVE TO BE RAISED IF THE TRACK OF THE UPPER SYSTEM BEARS OUT. TEMPERATURES LOOKED REASONABLE AND IN LINE WITH SURROUNDING WFO GRIDS. TUESDAY LOOKS TO BE WARM...PERHAPS WITH 80S SOMEWHERE IN OUR CWA. LEFT TUES MAX T`S ALONE FOR NOW...AS OUR SW HAS MID 70S GOING. && .AVIATION... AS LOW LEVEL MOISTURE CONTINUES TO CONVERGE ALONG AND SOUTH OF A FRONTAL BOUNDARY LYING ACROSS SOUTHERN KANSAS...STRATUS WILL LIKELY FORM AT DDC AND GCK IN THE 012 TO 015 FEET RANGE BY 11Z THIS MORNING. DO NOT EXPECT THE STRATUS TO LINGER MUCH BEYOND 15-16Z. ALSO...FOG WITH VSBYS IN THE 4-5SM RANGE WILL FORM AT DDC...GCK AND HYS AND LAST THROUGH 15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 53 71 56 / 20 30 20 20 GCK 64 45 72 53 / 20 20 20 20 EHA 71 47 71 53 / 20 20 20 20 LBL 73 51 71 56 / 20 30 20 20 HYS 61 48 72 55 / 20 20 20 20 P28 76 59 70 61 / 30 30 30 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN24/12 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 200 AM MDT THU MAR 22 2007 .DISCUSSION... PRIMARY UPPER FEATURE FOR THE SHORT TERM PERIOD WILL BE CUT OFF LOW OVER THE DESERT SOUTHWEST. FORECAST AREA TO REMAIN UNDER THE SOUTHWEST FLOW AHEAD OF THE MAIN LOW FOR THE NEXT SEVERAL DAYS. THE UPPER LOW WILL THEN BEGIN TO LIFT NORTH/NORTHEAST OVER THE WEEKEND. UNFORTUNATELY MODELS IN POOR AGREEMENT ON FINER DETAILS. EVEN AS EARLY AS TODAY...NAM BRINGING A FAIRLY WELL DEFINED VORT MAX OVER THE AREA/WHEREAS GFS SHOWS LITTLE IF ANYTHING. WATER VAPOR IMAGERY INCONCLUSIVE...SINCE JUST SEE A BROAD SOUTHWEST FLOW WITH DEEP TROPICAL PLUME AHEAD OF THE MAIN LOW. WITH LITTLE TO GO ON WILL PLAY THE PERCENTAGES AND HAVE SOME SLIGHT/LOW CHANCE POPS THIS AFTERNOON AND EVENING ACROSS SOUTHEAST COUNTIES. SOMEWHAT RELIABLE RUC CEILING FORECAST SHOWS 2KFT BROKEN DECK OVERSPREADING THE CWA FROM THE SOUTH THIS AFTERNOON...WILL FAVOR COOLER GUIDANCE FOR HIGHS AS A RESULT. FRIDAY WILL BE A VIRTUAL REPEAT...THOUGH MODELS SWITCH PLACES WITH GFS WET AND NAM DRY. IT DOES APPEAR THE AREA WILL COME UNDER FAVORABLE RIGHT ENTRANCE REGION OF JET WHICH DEVELOPS FRIDAY NIGHT/SATURDAY MORNING OVER THE MIDWEST. SURFACE FRONT WILL ALSO BE SURGING NORTH INTO THE AREA. NONETHELESS...ISC CONSTRAINTS WILL DICTATE LOW CHANCE POPS. THEN WILL HAVE TO DEAL WITH THE MAIN LOW OVER THE WEEKEND. MODELS ALL OVER THE PLACE...WHICH LENDS LITTLE TO NO CONFIDENCE TO THE PRECIPITATION CHANCES. GFS ENSEMBLE AVERAGES GIVE SOLID CHANCE POPS THROUGH SATURDAY...GRADUALLY DIMINISHING SATURDAY NIGHT AND SUNDAY TO SLIGHT CHANCES. THE ENSEMBLE APPROACH SEEMS REASONABLE GIVEN THE UNCERTAINTIES. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JDK ks AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE DODGE CITY KS 258 PM CDT WED MAR 21 2007 .DISCUSSION... DAYS 1-2... MAIN CONCERN THIS AFTERNOON WILL BE IF/WHEN CONVECTION WILL DEVELOP ALONG A DRYLINE WHICH WAS SLOWLY MOVING EAST ACROSS OUR EASTERN CWA. AT THIS TIME NOT SEEING ANY GOOD UPPER LEVEL DYNAMICS AND BASED ON NAM SOUNDINGS THE CONVECTIVE TEMPS ALONG THE DRYLINE WERE BETWEEN 82-86F. ALSO NOTICING CAPES ALONG AND AHEAD OF THIS FRONT WERE AT 15-2K J/KG WITH IMPROVING MOIST CONV. THE RUC40 ALSO WAS FORECASTING 0-6KM SHEAR OF 30 TO 35KTS. IF THE CONVECTIVE TEMPERATURE CAN BE REACHED LATE TODAY SHOULD SEE A FEW STORMS GO UP QUICKLY WITH THE MAIN HAZARD BEING HAIL. DOES NOT LOOK LIKE ANYTHING WIDESPREAD SO WILL KEEP SLT CHC POPS AND ADJUST AS NEEDED AS WE APPROACH 4 PM BASED ON LATEST OBSERVATIONS/CU DEVELOPMENT. FOR TONIGHT A COLD FRONT MOVES SOUTH ACROSS KANSAS AS A NORTHERN BRANCH S/W TROF MOVES ACROSS THE NORTHERN PLAINS INTO THE MISSISSIPPI VALLEY. THE BETTER DYNAMICS FROM THIS SYSTEM WILL REMAIN WELL TO OUR EAST BUT WITH SOME MOISTURE POOLING BEHIND THE FRONT AND WEAK LIFT OVERNIGHT IN OUR EAST AM UNABLE TO COMPLETELY RULE OUT PCPN CHANCES. WILL THEREFORE KEEP SMALL POPS GOING DURING THE OVERNIGHT HOURS. THE FORECAST THURSDAY THROUGH FRIDAY WILL MAINLY BE DEPENDANT ON WHERE OUR FRONT WILL BE. THROUGH FRIDAY MORNING OUR SURFACE FRONT IS EXPECTED TO REMAIN NEARLY STATIONARY ALONG THE KS/OK BORDER. MUCH LIKE OUR LAST SYSTEM GOOD ISENTROPIC LIFT, MOISTURE AND ISENTROPIC LIFT DEVELOPS ALONG AND NORTH OF THIS BOUNDARY. WILL THEREFORE KEEP HIGH CHC POPS IN OUR SE CWA AND TAPER POPS OFF FURTHER NW AND HIGHLIGHT THE BETTER CHANCE OF PCPN THURSDAY NIGHT. BY FRIDAY THE BULK OF THE PCPN WILL BE MOVING OUT OF SW KS. HOWEVER WILL HAVE TO WATCH LOW LEVEL MOISTURE AND UPSLOPE FLOW EARLY FRIDAY. AT THIS TIME WILL GO WITH AREAS OF FOG AND DRIZZLE EARLY WITH SOME CLEARING LATE IN THE DAY. GIVEN THE CLOUDS AND UPSLOPE FLOW WILL ALSO LEAN TOWARDS THE COOLER MET NUMBERS FOR HIGHS FRIDAY. DAYS 3-7... AFTER LOOKING AT THE OVERALL PICTURE THIS MORNING THE GFS/ECMWF ARE VERY SIMILAR WITH THE NEXT FRONT MOVING INTO THE REGION OVER THE WEEKEND. THE ONSET OF OUR NEXT COLD FRONT MOVING IN FRIDAY NIGHT INTO SATURDAY WILL HELP SET THE SCENCE FOR CONVECTIVE ACTIVITY WITH ANOTHER DRY LINE OVER SOUTHWESTERN KANSAS. LOW LEVEL JET WILL PUSH AMPLE MOISTURE INTO THE REGION...MODELS HAVE ALSO INDICATED THE PRESENCE OF VERY STRONG CONVERGENCE WITHIN THE VICINITY OF THE DRY LINE. WITH UPPER LEVEL SUPPORT TO KICK OFF CONVECTIVE ACTIVITY WILL NOT BE ABLE TO RULE OUT THE CHANCES FOR SEVERE THUNDERSTORMS. AS THE SYSTEM BEGINS TO PUSH OUT OF THE REGION BY MONDAY MUCH DRIER AIR WILL TAKE PLACE OVER SOUTHWESTERN KANSAS FOR THE BEGINNING OF THE WEEK. DECIDED TO TWEAK TEMPERATURES UP A FEW DEGREES FOR THE FIRST PART OF THE WEEK. THEN ON WEDNESDAY LOOKS LIKE MOISTURE RETURNING TO OUR PART OF THE WORLD. HOWEVER JUST TOO EARLY TO SEE IF THIS WILL BECOME A MID WEEK MOISTURE PRODUCER. && .AVIATION... AREAS OF SCT HIGH LVL CLOUDS EXPECTED OVER MOST THE FORECAST AREA. BETWEEN 09-12Z LOW STRATUS CAN BE EXPECTED WITH VSBYS OF 5SM BR AND LGT AND VARIABLE WINDS ARE FORECAST SO CANNOT RULE OUT THE CHANCES FOR THE DEVELOPMENT OF FOG BETWEEN 09-15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 49 63 48 68 / 20 20 20 0 GCK 45 64 46 68 / 20 10 10 0 EHA 47 66 51 72 / 10 10 10 0 LBL 50 68 51 72 / 10 20 20 0 HYS 47 57 47 66 / 30 10 10 0 P28 56 66 54 68 / 30 50 50 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN18/31 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 242 PM CDT WED MAR 21 2007 .DISCUSSION... DAYS 1-2... MAIN CONCERN THIS AFTERNOON WILL BE IF/WHEN CONVECTION WILL DEVELOP ALONG A DRYLINE WHICH WAS SLOWLY MOVING EAST ACROSS OUR EASTERN CWA. AT THIS TIME NOT SEEING ANY GOOD UPPER LEVEL DYNAMICS AND BASED ON NAM SOUNDINGS THE CONVECTIVE TEMPS ALONG THE DRYLINE WERE BETWEEN 82-86F. ALSO NOTICING CAPES ALONG AND AHEAD OF THIS FRONT WERE AT 15-2K J/KG WITH IMPROVING MOIST CONV. THE RUC40 ALSO WAS FORECASTING 0-6KM SHEAR OF 30 TO 35KTS. IF THE CONVECTIVE TEMPERATURE CAN BE REACHED LATE TODAY SHOULD SEE A FEW STORMS GO UP QUICKLY WITH THE MAIN HAZARD BEING HAIL. DOES NOT LOOK LIKE ANYTHING WIDESPREAD SO WILL KEEP SLT CHC POPS AND ADJUST AS NEEDED AS WE APPROACH 4 PM BASED ON LATEST OBSERVATIONS/CU DEVELOPMENT. FOR TONIGHT A COLD FRONT MOVE SOUTH ACROSS KANSAS AS A NORTHERN BRANCH S/W TROF MOVES ACROSS THE NORTHERN PLAINS INTO THE MISSISSIPPI VALLEY. THE BETTER DYNAMIC FROM THIS SYSTEM WILL REMAIN WELL TO OUR EAST BUT WITH SOME MOISTURE POOLING BEHIND THE FRONT AND WEAK LIFT OVERNIGHT IN OUR EAST AM UNABLE TO COMPLETELY RULE OUT PCPN CHANCES. WILL THEREFORE KEEP SMALL POPS GOING DURING THE OVERNIGHT HOURS. THE FORECAST THURSDAY THROUGH FRIDAY WILL MAINLY BE DEPENDANT ON WHERE OUR FRONT WILL BE. THROUGH FRIDAY MORNING OUR SURFACE FRONT IS EXPECTED TO REMAIN NEARLY STATIONARY ALONG THE KS/OK BORDER. MUCH LIKE OUR LAST SYSTEM GOOD ISENTROPIC LIFT, MOISTURE AND ISENTROPIC LIFT DEVELOPS ALONG AND NORTH OF THIS BOUNDARY. WILL THEREFORE KEEP HIGH CHC POPS IN OUR SE CWA AND TAPER POPS OFF FURTHER NW AND HIGHLIGHT THE BETTER CHANCE OF PCPN THURSDAY NIGHT. BY FRIDAY THE BULK OF THE PCPN WILL BE MOVING OUT OF SW KS. HOWEVER WILL HAVE TO WATCH LOW LEVEL MOISTURE AND UPSLOPE FLOW EARLY FRIDAY. AT THIS TIME WILL GO WITH AREAS OF FOG AND DRIZZLE EARLY WITH SOME CLEARING LATE IN THE DAY. GIVEN THE CLOUDS AND UPSLOPE FLOW WILL ALSO LEAN TOWARDS THE COOLER MET NUMBERS FOR HIGHS FRIDAY. DAYS 3-7... AFTER LOOKING AT THE OVERALL PICTURE THIS MORNING SHOWS THE GFS/ECMWF/NAM TO BE VERY SIMILAR WITH THE NEXT FRONT MOVING INTO THE REGION OVER THE WEEKEND. THE ONSET OF OUR NEXT COLD FRONT MOVING IN FRIDAY NIGHT INTO SATURDAY WILL HELP SET THE SCENCE FOR CONVECTIVE ACTIVITY WITH ANOTHER DRY LINE OVER SOUTHWESTERN KANSAS. LOW LEVEL JET WILL PUSH AMPLE MOISTURE INTO THE REGION...MODELS HAVE ALSO INDICATED THE PRESENCE OF VERY STRONG CONVERGENCE WITHIN THE VICINITY OF THE DRY LINE. WITH UPPER LEVEL SUPPORT TO KICK OFF CONVECTIVE ACTIVITY WILL NOT BE ABLE TO RULE OUT THE CHANCES FOR SEVERE THUNDERSTORMS. AS THE SYSTEM BEGINS TO PUSH OUT OF THE REGION BY MONDAY MUCH DRIER AIR WILL TAKE PLACE OVER SOUTHWESTERN KANSAS FOR THE BEGINNING OF THE WEEK. DECIDED TWEAK TEMPERATURES UP A FEW DEGREES FOR THE FIRST PART OF THE WEEK. THEN ON WEDNESDAY LOOKS LIKE MOISTURE RETURNING TO OUR PART OF THE WORLD. HOWEVER JUST TOO EARLY TO SEE IF THIS WILL BECOME A MID WEEK MOISTURE PRODUCER. && .AVIATION... AREAS OF SCT HIGH LVL CLOUDS EXPECTED OVER MOST THE FORECAST AREA. BASED ON SATELLITE IMAGRY CIGS AND VSBYS ARE NOT EXPECTED TO DROP BELOW VFR CONDITIONS. BETWEEN 09-12Z LOW STRATUS CAN BE EXPECTED WITH VSBYS OF 5SM BR AND LGT AND VARIABLE WINDS ARE FORECAST SO CANNOT RULE OUT THE CHANCES FOR THE DEVELOPMENT OF FOG BETWEEN 09-15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 49 63 48 68 / 20 20 20 0 GCK 45 64 46 68 / 20 10 10 0 EHA 47 66 51 72 / 10 10 10 0 LBL 50 68 51 72 / 10 20 20 0 HYS 47 57 47 66 / 30 10 10 0 P28 56 66 54 68 / 30 50 50 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN18/31 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 902 PM CDT THU MAR 22 2007 .UPDATE... FORECAST UPDATED MAINLY TO REMOVE EVENING WORDING. ADDED A SLIGHT CHANCE POP FOR SW INDIANA OVERNIGHT DUE TO THE CLOSE PROXIMITY OF THE SURFACE BOUNDARY. GRADUAL INCREASE IN CONVECTION NOTED OVER CENTRAL IL/CENTRAL MO/EASTERN KS OVER THE PAST COUPLE OF HOURS. THIS CONVECTION IS ALONG THE FRONT...WHICH THE MODELS KEEP QUASI STATIONARY FOR THE NEXT FEW DAYS. THIS CONVECTION MAY PROPAGATE SOUTHEAST AWAY FROM THE BOUNDARY INTO SRN ILLINOIS AND SE MISSOURI OVERNIGHT. RUC MODEL CORFIDI VECTORS INDICATE A SE MOVEMENT TO ANY ORGANIZED MCS THAT DEVELOPS. && .PREVIOUS DISCUSSION... MAIN CONCERNS FOR THIS FORECAST CONTINUE TO BE POPS THROUGH THE ENTIRE PERIOD...AS TEMPERATURES WILL REMAIN MILD THROUGHOUT. ELEVATED CONVECTION HAS SHRUNK DOWN TO A NARROW BAND OF SHOWERS RIGHT THROUGH THE MID-SECTION OF THE AREA...AND IT APPEARS TO BE WEAKENING AND FINALLY PUSHING OFF TO THE EAST. WITH THE AIRMASS THOROUGHLY WORKED OVER...AND THE SURFACE BOUNDARY WELL NORTH OF THE AREA...SEE LITTLE REASON TO HAVE MUCH POP IN THE AREA THIS EVENING. WILL HOWEVER...INCLUDE A SMALL CHANCE IN THE NORTHEAST IN AN ATTEMPT TO FIT IN TO SOME DEGREE WITH NEIGHBORS. OVERNIGHT...THE GFS IS A BIT FASTER BRINGING ANOTHER ROUND OF ELEVATED CONVECTION EASTWARD INTO THE REGION...AS ANOTHER MID-LEVEL DISTURBANCE BRINGS AN AREA OF LOW-LEVEL THETA-E ADVECTION INTO THE REGION. IF THE NAM IS RIGHT...THE CONVECTION WILL STAY TO OUR WEST THROUGH 12Z...BUT THE GFS BRINGS INTO OUR WEST JUST BEFORE 12Z. WILL MENTION A CHANCE OVERNIGHT IN THE WEST...AND THEN RAMP UP TO 50-60 POPS SOUTH TO NORTH ON FRIDAY. THIS SIGNAL HAS BEEN THERE FOR A COUPLE OF DAYS...HOWEVER...IF IT IS AS FOCUSED AS TODAYS CONVECTION HAS BEEN...SOME AREAS MAY NOT GET WET. THEREFORE WILL NOT GO HIGHER THAN 60S FOR NOW. THOSE 60S WILL BE IN THE NORTH WHERE THE MODELS ARE IN BETTER AGREEMENT WITH THE QPF. THE NAM IS NOT SURE ABOUT OUR SOUTHERN ZONES GETTING WET. MAY SEE SOME LINGERING CONVECTION FRIDAY NIGHT MAINLY NORTHEAST...SO WILL LEAVE A 20-30 POP ACROSS MUCH OF THE AREA. ON SATURDAY...THE FRONT RE-LOCATES WELL NORTH OF THE AREA...AND WILL KEEP THE FOCUS FOR CONVECTION TO OUR NORTH AS WELL. THE 12Z NAM TRIES TO REGENERATE CONVECTION ALL OVER THE AREA ON SATURDAY...BUT IT IS THE LONE MODEL THAT DOES NOT BUILD A MID/UPPER-LEVEL RIDGE THROUGH THE AREA. WILL THEREFORE IGNORE ITS SOLUTION FOR NOW. THE WEEKEND SHOULD BE QUITE GLORIOUS WITH TEMPS PUSHING 80 EACH AFTERNOON AND LOWS IN THE 50S. IN THE MEDIUM RANGE...EVEN THE ECMWF IS NOW TRYING TO DRAG SOME REMNANT OF THE SW U.S. CUT OFF LOW ACROSS THE AREA SOMETIME MONDAY OR TUESDAY. WILL THROW IN 20-30 POPS FOR THIS PERIOD WITH THE BEST CHANCES MONDAY NIGHT INTO TUESDAY. TUESDAY NIGHT AND WEDNESDAY LOOK DRY...BUT A MORE SIGNIFICANT SYSTEM MAY BEGIN TO EFFECT THE AREA ON THURSDAY OR FRIDAY. TEMPERATURES WILL CONTINUE TO BE WELL ABOVE NORMAL THROUGH THE ENTIRE 7 DAY PERIOD...WITH HIGHS IN THE 70S OR LOWER 80S AND LOWS IN THE 50S OR LOWER 60S. THE EXCEPTION WILL BE TOMORROW WHERE THE CONVECTION MAY HOLD TEMPS IN THE 60S. HOWEVER...IT IS NOT CERTAIN WHERE THE PRECIPITATION WILL BE FOCUSED ACROSS THE AREA TOMORROW. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ UPDATE...MY PREVIOUS...DRS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 953 PM EDT THU MAR 22 2007 .UPDATE... SMALL UPDATE TO SLIGHTLY LOWER OVERNIGHT LOWS A DEGREE OR TWO ACROSS PORTIONS OR THE NORTHERN AREA AROUND SDF AND LEX...NOT SO MUCH ACROSS THE SOUTHERN HALF OF THE AREA. -SCHOTT && .PREV DISCUSSION... /ISSUED 729 PM EDT THU MAR 22 2007/ EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT AVIATION DISCUSSION (00Z TAFS)... GRADUAL CLEARING APPEARS TO BE DEVELOPING IN THE LATEST VIS SAT LOOP...NOTHING OF ANY SIGNIFICANCE LOOKS TO EFFECT AVIATION CONCERNS THROUGH DAYBREAK FRIDAY. MODEST LOW LEVEL JET DEVELOPS TONIGHT BUT DOESN`T REACH THE 20 KNOTS GREATER THAN SFC WINDS TO MENTION IN THE TAFS...BUT 20 TO 25 KTS AROUND 1500 TO 2000 FEET LOOKS LIKELY OVERNIGHT. VFR CONDITIONS AT ALL THREE TAFS SITES LOOKS AS A GOOD BET THROUGH THE PERIOD...SOME SCATTERED SHOWER AND THUNDERSTORM ACTIVITY LOOKS TO PUSH SOUTH INTO THE NORTHERN TAF SITES OF SDF AND LEX AFTER 14 TO 18Z...WITH SHRA POSSIBLE AT BWG AFTER 22Z. --SCHOTT PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIF CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ AVIATION (18Z TAFS)... SCT TO NUMEROUS SHOWERS WILL STREAM EWD THRU THE AFTN ALONG AND EITHER SIDE OF OH RIVER. STILL A CONVECTIVE THREAT BUT CG LIGHTNING ACTIVITY GRADUALLY DIMINISHING AT THIS TIME. KLVX VWP PROFILE SHOWS UNIFORM SWLY FLOW IN LOW-LEVELS WITH ONLY MODEST INCREASE IN SPEED WITH HEIGHT...THUS LOW-LEVEL WIND SHEAR NO LONGER A SIGNIFICANT HAZARD. CIGS MAY OCCASIONALLY FALL INTO MVFR CATEGORY BUT GENERALLY CIGS EXPECTED ABOVE 3KFT (VFR) DURING FCST PD. AS SHORTWAVE TO OUR N PULLS OUT...PRECIP SHOULD BE MORE SCT LATE TNGT AND EARLY FRI...BEFORE MODELS SHOW NEXT SURGE OF MOISTURE AND PRECIP ARRIVING FRI AFTN. TWF LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 729 PM EDT THU MAR 22 2007 .EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT && .AVIATION DISCUSSION (00Z TAFS)... GRADUAL CLEARING APPEARS TO BE DEVELOPING IN THE LATEST VIS SAT LOOP...NOTHING OF ANY SIGNIFICANCE LOOKS TO EFFECT AVIATION CONCERNS THROUGH DAYBREAK FRIDAY. MODEST LOW LEVEL JET DEVELOPS TONIGHT BUT DOESN`T REACH THE 20 KNOTS GREATER THAN SFC WINDS TO MENTION IN THE TAFS...BUT 20 TO 25 KTS AROUND 1500 TO 2000 FEET LOOKS LIKELY OVERNIGHT. VFR CONDITIONS AT ALL THREE TAFS SITES LOOKS AS A GOOD BET THROUGH THE PERIOD...SOME SCATTERED SHOWER AND THUNDERSTORM ACTIVITY LOOKS TO PUSH SOUTH INTO THE NORTHERN TAF SITES OF SDF AND LEX AFTER 14 TO 18Z...WITH SHRA POSSIBLE AT BWG AFTER 22Z. --SCHOTT && .PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIF CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ AVIATION (18Z TAFS)... SCT TO NUMEROUS SHOWERS WILL STREAM EWD THRU THE AFTN ALONG AND EITHER SIDE OF OH RIVER. STILL A CONVECTIVE THREAT BUT CG LIGHTNING ACTIVITY GRADUALLY DIMINISHING AT THIS TIME. KLVX VWP PROFILE SHOWS UNIFORM SWLY FLOW IN LOW-LEVELS WITH ONLY MODEST INCREASE IN SPEED WITH HEIGHT...THUS LOW-LEVEL WIND SHEAR NO LONGER A SIGNIFICANT HAZARD. CIGS MAY OCCASIONALLY FALL INTO MVFR CATEGORY BUT GENERALLY CIGS EXPECTED ABOVE 3KFT (VFR) DURING FCST PD. AS SHORTWAVE TO OUR N PULLS OUT...PRECIP SHOULD BE MORE SCT LATE TNGT AND EARLY FRI...BEFORE MODELS SHOW NEXT SURGE OF MOISTURE AND PRECIP ARRIVING FRI AFTN. TWF LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 144 PM EDT WED MAR 21 2007 .SHORT TERM.../TODAY THROUGH FRIDAY NIGHT/ ISOLATED SHOWERS MOVED ALONG THE KY/TN BORDER THIS MORNING. RADAR HOWEVER CURRENTLY SHOWS THESE HAVE DISSIPATED. SOME ADDITIONAL SHOWERS ATM ARE JUST NORTH OF OUR NW COUNTIES MOVING W TO EAST JUST SOUTH OF THE OH RIVER. RUC AND WRF-NAM BOTH KEEP PRECIP OUT OF FORECAST AREA FOR MOST OF THE REMAINDER OF 1ST PERIOD. BOTH MODELS ARE SHOWING POSSIBILITY OF SOME ADDITIONAL DEVELOPMENT LATER THIS AFTERNOON..IN ASSOCIATION WITH WEAK UPPER-LEVEL SHORT WAVE. THIS IS CONFINED PRIMARILY IN OUR FAR EASTERN ZONES AND ALONG THE SPINE OF THE APPALACHIANS. BELIEVE THIS IS WAY OVERDONE. HAVE THEREFORE KEPT POPS BELOW SLIGHT CHANCE ENTIRE PERIOD. IF RUC/NAM FORECAST DOES PAN OUT...WE`LL ADDRESS ACTIVITY WITH SHORT-TERM FORECASTS. LOCAL OBSERVATIONS SHOW TEMPERATURES ARE CURRENTLY ON TRACK WITH FORECAST GRIDS. UPDATE ALREADY OUT TO REMOVE DENSE FOG ADVISORY...POPS...AND MORNING WORDING. NEAR TERM WINDS WERE REFRESHED USING RUC GUIDANCE. ...REMAINDER OF EARLIER DISCUSSION FOLLOWS. THE MODELS ARE EXHIBITING SIMILAR DIFFERENCES ALOFT AS THEY WERE LAST NIGHT. THEY ALL HAVE A LONGWAVE PATTERN THAT FEATURES A CLOSING LOW OVER THE DESERT SOUTHWEST...FAST NORTHERN STREAM FLOW WITH A WAVE CROSSING THE GREAT LAKES EARLY THURSDAY AND SOME RIDGING ACROSS THE SOUTHEAST. THE FIRST ITEM OF CONCERN FOR EAST KENTUCKY WILL BE THE WAVE PASSING BY TO THE NORTH. WITH THIS...THE NAM IS A TAD FASTER AND STRONGER THAN THE GFS. AS FOR THE DEVELOPING BAJA LOW THE GFS REMAINS FURTHER EAST THAN THE NAM. IN THE WAKE OF THE NORTHERN STREAM WAVE PASSING AND THE BAJA LOW OPENING UP TOWARD THE END OF THE WORK WEEK...KENTUCKY WILL FIND ITSELF AWASH IN FAST MOVING MINOR WAVES. THESE WILL BE RUNNING EAST FROM THE SOUTHERN PLAINS IN THE ZONAL FLOW FOUND ON THE NORTHERN FRINGE OF THE SOUTHERN RIDGE. DESPITE THE NAM HAVING MORE SUPPORT WITH ITS SOLUTION FOR THE NORTHERN STREAM WAVE EARLY ON...THE GFS IS FAVORED FROM THURSDAY AFTERNOON ON GIVEN ITS APPARENT BETTER HANDLING OF THE OPENING LOW OVER THE SOUTHWEST. FOR FORECAST SPECIFICS HAVE LEANED TOWARD THE GFS FRONTAL POSITION ...BUT FOLLOWED THE NAM/S EVOLUTION AND TIMING OF THE INDIVIDUAL WAVES THAT PASS OVERHEAD AND AMPLIFY THE FRONT THROUGH THE LATTER PART OF THE WORK WEEK. SENSIBLE WEATHER WILL FEATURE AREAS OF DENSE FOG BURNING OFF AND MIXING OUT LATER THIS MORNING REVEALING A PARTLY SUNNY SKY AND ONLY AN SMALL CHANCE FOR A POP-UP SHOWER. HAVE LEFT THUNDER OUT OF THE FORECAST FOR TODAY GIVEN THE LOW POPS AND MARGINAL INSTABILITY. TONIGHT SHOULD BE MORE OF THE SAME WITH THE MOIST BOUNDARY LAYER... AND ONLY PARTIAL CLOUDINESS...RESULTING IN RADIATIONAL FOG. A WAVE SEEN IN THE GFS THAT PASSES BY TO THE NORTHEAST WILL PROBABLY BE TOO FAR AWAY TO WARRANT EVEN SLIGHT CHANCE POPS. NEXT...A COLD FRONT FROM THAT NORTHERN STREAM WAVE WILL SAG TOWARD KENTUCKY ON THURSDAY BEFORE STRETCHING OUT AND BECOMING STATIONARY OVER THE NORTHERN HALF OF THE STATE LATER THAT NIGHT. THIS WILL RESULT IN A PROLONGED AND PERSISTENT PERIOD OF DECENT POPS FOR SHOWERS AND THUNDERSTORMS LASTING INTO FRIDAY NIGHT AS IMPULSES MOVE EAST ALONG THE BOUNDARY... SPURNED ALONG BY THE MINOR UPPER WAVES SPINNING OUT OF THE OPENING SOUTHWESTERN LOW. WITH THE TEMPERATURES...WENT WITH THE WARMER MET NUMBERS TODAY AND THURSDAY...THOUGH HELD THE DIURNAL RISE BACK A BIT THIS MORNING UNTIL THE FOG BURNS OFF. FOR HIGHS FRIDAY...FOLLOWED MORE OF A BLEND. AT NIGHT...THE NUMBERS WERE SIMILAR SO WENT WITH A BLEND...ALONG WITH SOME SITE SPECIFIC TWEAKING. THE POPS ENDED UP CLOSEST TO THE MET NUMBERS THROUGH THE SHORT TERM PART OF THE FORECAST. .LONG TERM.../SATURDAY THROUGH TUESDAY/ A FRONTAL BOUNDARY WILL LINGER ACROSS THE AREA TO END THE WORKWEEK...WITH THE BEST CHANCE OF RAIN REMAINING ALONG AND NORTH OF THE MOUNTAIN PARKWAY. ECMWF AND GFS CONTINUE TO DIFFER WITHIN THE DETAILS OF THE FORECAST INTO EARLY NEXT WEEK. TWO MAIN FEATURES OF INFLUENCE WILL BE A BUILDING SOUTHEASTERN CONUS RIDGE...WITH AN EJECTING UPPER LEVEL LOW APPROACHING OUT OF THE SOUTHWEST. ECMWF WASHES THE AFOREMENTIONED FRONT OUT TO THE SOUTH...WITH A LARGE AREA OF HIGH PRESSURE LENDING IT`S INFLUENCE ACROSS THE AREA THROUGH THE WEEKEND. THE PROGGED RIDGE THEN SLOWS AS WELL DAMPENS THE UPPER LEVEL LOW SIGNIFICANTLY BY EARLY NEXT WEEK. GFS STARTS OUT WITH A MUCH WEAKER AREA OF HIGH PRESSURE PUSHING IN FOR THE BEGINNING OF THE WEEKEND...GENERALLY KEEPING THE FRONT AROUND LONGER AND LINGERING PRECIPITATION INTO EARLY SATURDAY...BEFORE PUSHING BACK NORTH BY SATURDAY AFTERNOON AS MORE MODEST RIDGING TAKES PLACE THROUGH SUNDAY. A MUCH MORE ROBUST PROGGED UPPER LEVEL LOW LIFTS THROUGH MONDAY INTO TUESDAY...WITH SCATTERED PRECIPITATION ASSOCIATED WITH THIS FEATURE. HAVE COMPROMISED BETWEEN THE MODELS. ECMWF HAS BEEN MORE CONSISTENT LATELY...HOWEVER FEEL THAT IT DOES DAMPEN THE UPPER LEVEL LOW A BIT TOO MUCH AS IT BRINGS IT IN. ON THE OTHER HAND...THE GFS SEEMS A BIT OVERDONE WITH THE UPPER LEVEL FEATURE. AS SUCH...WILL KEEP THE MAJORITY OF THE WEEKEND DRY UNDER THE INFLUENCE OF UPPER LEVEL RIDGING...WHILE INTRODUCING CHANCE POPS BY MONDAY AFTERNOON AS THE WAVE APPROACHES. TEMPERATURES CONTINUE TO LOOK ABOVE NORMAL THROUGHOUT THE PERIOD AS WELL. GENERALLY STAYED A BIT WARMER THAN MOS...THINKING THAT THE NUMBERS ARE A BIT COOL WITH THE OVERPLAYED CLOUD COVER AND PRECIPITATION. && .AVIATION.../18Z TO 18Z/...UPDATED WARM FRONT HAS EDGED NORTH TODAY AND IS CURRENTLY LOCATED ALONG OUR NORTHERN TIER OF COUNTIES. A FEW WIDELY SCATTERED SHOWERS KICKED UP EARLIER NORTH OF THE BOUNDARY...BUT SATELLITE CURRENTLY SHOWS NO ACTIVITY. SHORT RANGE FORECAST MODELS SHOW HIGH PRESSURE...LOCATED TO OUR SOUTHEAST HOLDING IN PLACE THROUGH MOST OF THE FORECAST PERIOD. THURSDAY AFTERNOON HOWEVER A COLD FRONTAL BOUNDARY WILL DROP OUT OF THE NORTHWEST...BRINGING SHOWERS AND MVFR CEILINGS BACK INTO THE REGION. TIMING RIGHT NOW LOOKS TO BE OUTSIDE THE 24-HOUR TAF PERIOD...SO CONDITIONS ARE NOT REFLECTED IN THIS 18Z-18Z TAF. SUBSEQUENT ISSUANCES THOUGH WILL NEED TO CONSIDER INCLUDING SHOWERS / LOWERING CEILINGS IN ANOTHER CHANGE GROUP. FOR NOW...CEILINGS/ VISIBILITIES WILL REMAIN VFR...WITH CLOUD BASES GRADUALLY LOWERING THIS EVENING FROM HIGH CIRRUS DECK THIS AFTERNOON TO MID-LEVELS THIS EVENING. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE && $$ SHORT TERM...MCLANE/GREIF LONG TERM....GEOGERIAN AVIATION...MCLANE ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 1120 AM CDT WED MAR 21 2007 .DISCUSSION... A MID LEVEL VORT WAS INDUCING ENOUGH LIFT TO DEVELOP CLOUDS AND WHAT APPEARED TO BE VIRGA OVER THE ERN THIRD OF THE PAH FCST AREA. RUC MODEL INDICATES THIS FEATURE WILL MOVE TO THE ENE OUT OF THE AREA BY 18Z OR SO...WITH NO CLEAR ADDITIONAL FORCING MECHANISMS ARRIVING INTO THE AREA FOR THE AFTN. NUMERICAL GUIDANCE INDICATED VERY LOW POPS THIS AFTN...DUE TO PLENTIFUL WARM AIR ABOVE 850 MB. THEREFORE...WE WILL DROP THE AFTN CHANCES OF RAIN/TSTMS AND LIGHTEN UP ON THE CLOUD WORDING A BIT. THERE SHOULD CONTINUE TO BE A DECENT SFC PRESSURE GRADIENT TODAY...THUS WINDS 10 TO 20 MPH IN MANY AREAS. ZONE UPDATE OUT SOON. .PREVIOUS DISCUSSION... MAIN FORECAST CONCERNS ARE PRECIP CHANCES THROUGH THE FORECAST. LATEST MOSAIC RADAR SHOWS A LARGE AREA OF SHOWERS ACROSS NORTHERN ILLINOIS AND SOME SHOWERS AND STORMS EXTENDING FROM NORTHEAST MISSOURI INTO CENTRAL IOWA. NAM SEEMS TO HAVE THE BEST HANDLE ON THE ONGOING PRECIP...SO LEANED TOWARD ITS SOLUTION FOR TODAY. DROPPED POPS FOR THIS MORNING AND WENT WITH SLIGHT CHANCE POPS THIS AFTERNOON FOR THE NORTHWEST THIRD OF THE PAH FORECAST AREA. EXPECT DRY CONDITIONS TONIGHT...THEN A CHANCE OF SHOWERS AND STORMS RETURNS FOR NORTHERN AND WESTERN PORTIONS OF THE FA ON THURSDAY AS THE COLD FRONT APPROACHES OUR REGION FROM THE NORTHWEST. NAM IS MORE AGGRESSIVE WITH THE FRONT...EXTENDING IT FROM CENTRAL INDIANA INTO SOUTHWEST MISSOURI BY 18Z THU...WITH THE GFS KEEPING IT A LITTLE FARTHER NORTHWEST AND KEEPING ANY SIGNIFICANT QPF OUT OF OUR AREA. LEANED MORE HEAVILY TOWARD THE NAM SOLUTION FOR NOW...FOCUSING POPS ACROSS THE NORTHWEST HALF OF THE FA...WITH BEST POPS IN FAR NORTHERN COUNTIES CLOSER TO THE FRONT FOR BOTH THURSDAY AND INTO THURSDAY NIGHT. BY 12Z FRIDAY...NAM AND GFS ARE A LITTLE MORE IN SYNC WITH THE FRONTAL POSITION...BUT GFS HAS MORE SIGNIFICANT QPF ESPECIALLY ACROSS NORTHERN PORTIONS OF THE FA FOR FRIDAY AND INTO FRIDAY NIGHT. PREFERRING GFS...INCREASED POPS ACROSS THE ENTIRE FA FOR FRIDAY...ESPECIALLY DURING THE AFTERNOON HOURS...WITH HIGHEST CHANCES ACROSS THE NORTHERN HALF. KEPT SLIGHT CHANCE POPS SOUTH TO CHANCE POPS NORTH FOR FRIDAY NIGHT...AND CONTINUED THIS TREND INTO SATURDAY. BOTH GFS AND ECMWF SHOW AN UPPER LEVEL RIDGE BUILDING INTO THE REGION LATE SATURDAY INTO SUNDAY...SO EXPECTING A BREAK IN SHOWER AND THUNDERSTORM ACTIVITY SATURDAY NIGHT INTO SUNDAY. BY LATE SUNDAY NIGHT...GFS SHOWS A COLD FRONT APPROACHING THE MIDDLE MISSISSIPPI VALLEY FROM THE WEST. ECMWF IS MUCH SLOWER WITH THIS FEATURE...SO FOR NOW JUST INCLUDED SLIGHT CHANCE POPS FOR THE WEST HALF OF THE PAH FA...WHICH BLENDED WELL WITH THE GOING SLIGHT CHANCE POPS FOR MONDAY INTO TUESDAY. UNSEASONABLY WARM WEATHER EXPECTED THE REST OF THE WEEK AND THROUGH THE WEEKEND. USED A MAV/MET COMPROMISE FOR THE NEAR TERM TEMPS...WHICH ONLY REQUIRED MINOR CHANGES THROUGH THURSDAY...THEN WARMED UP LOWS AND HIGHS JUST A LITTLE FRIDAY MORNING AND FRIDAY AFTERNOON. IN THE EXTENDED...BASED ON LATEST MEX TWEAKED DOWN LOWS AND HIGHS ON SUNDAY JUST A LITTLE...OTHERWISE MADE LITTLE IF ANY CHANGES. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ RST ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1112 AM EDT WED MAR 21 2007 .SHORT TERM.../TODAY THROUGH FRIDAY NIGHT/...UPDATED ISOLATED SHOWERS MOVED ALONG THE KY/TN BORDER THIS MORNING. RADAR HOWEVER CURRENTLY SHOWS THESE HAVE DISSIPATED. SOME ADDITIONAL SHOWERS ATM ARE JUST NORTH OF OUR NW COUNTIES MOVING W TO EAST JUST SOUTH OF THE OH RIVER. RUC AND WRF-NAM BOTH KEEP PRECIP OUT OF FORECAST AREA FOR MOST OF THE REMAINDER OF 1ST PERIOD. BOTH MODELS ARE SHOWING POSSIBILITY OF SOME ADDITIONAL DEVELOPMENT LATER THIS AFTERNOON..IN ASSOCIATION WITH WEAK UPPER-LEVEL SHORT WAVE. THIS IS CONFINED PRIMARILY IN OUR FAR EASTERN ZONES AND ALONG THE SPINE OF THE APPALACHIANS. BELIEVE THIS IS WAY OVERDONE. HAVE THEREFORE KEPT POPS BELOW SLIGHT CHANCE ENTIRE PERIOD. IF RUC/NAM FORECAST DOES PAN OUT...WE`LL ADDRESS ACTIVITY WITH SHORT-TERM FORECASTS. LOCAL OBSERVATIONS SHOW TEMPERATURES ARE CURRENTLY ON TRACK WITH FORECAST GRIDS. UPDATE ALREADY OUT TO REMOVE DENSE FOG ADVISORY...POPS...AND MORNING WORDING. NEAR TERM WINDS WERE REFRESHED USING RUC GUIDANCE. ...REMAINDER OF EARLIER DISCUSSION FOLLOWS. THE MODELS ARE EXHIBITING SIMILAR DIFFERENCES ALOFT AS THEY WERE LAST NIGHT. THEY ALL HAVE A LONGWAVE PATTERN THAT FEATURES A CLOSING LOW OVER THE DESERT SOUTHWEST...FAST NORTHERN STREAM FLOW WITH A WAVE CROSSING THE GREAT LAKES EARLY THURSDAY AND SOME RIDGING ACROSS THE SOUTHEAST. THE FIRST ITEM OF CONCERN FOR EAST KENTUCKY WILL BE THE WAVE PASSING BY TO THE NORTH. WITH THIS...THE NAM IS A TAD FASTER AND STRONGER THAN THE GFS. AS FOR THE DEVELOPING BAJA LOW THE GFS REMAINS FURTHER EAST THAN THE NAM. IN THE WAKE OF THE NORTHERN STREAM WAVE PASSING AND THE BAJA LOW OPENING UP TOWARD THE END OF THE WORK WEEK...KENTUCKY WILL FIND ITSELF AWASH IN FAST MOVING MINOR WAVES. THESE WILL BE RUNNING EAST FROM THE SOUTHERN PLAINS IN THE ZONAL FLOW FOUND ON THE NORTHERN FRINGE OF THE SOUTHERN RIDGE. DESPITE THE NAM HAVING MORE SUPPORT WITH ITS SOLUTION FOR THE NORTHERN STREAM WAVE EARLY ON...THE GFS IS FAVORED FROM THURSDAY AFTERNOON ON GIVEN ITS APPARENT BETTER HANDLING OF THE OPENING LOW OVER THE SOUTHWEST. FOR FORECAST SPECIFICS HAVE LEANED TOWARD THE GFS FRONTAL POSITION ...BUT FOLLOWED THE NAM/S EVOLUTION AND TIMING OF THE INDIVIDUAL WAVES THAT PASS OVERHEAD AND AMPLIFY THE FRONT THROUGH THE LATTER PART OF THE WORK WEEK. SENSIBLE WEATHER WILL FEATURE AREAS OF DENSE FOG BURNING OFF AND MIXING OUT LATER THIS MORNING REVEALING A PARTLY SUNNY SKY AND ONLY AN SMALL CHANCE FOR A POP-UP SHOWER. HAVE LEFT THUNDER OUT OF THE FORECAST FOR TODAY GIVEN THE LOW POPS AND MARGINAL INSTABILITY. TONIGHT SHOULD BE MORE OF THE SAME WITH THE MOIST BOUNDARY LAYER... AND ONLY PARTIAL CLOUDINESS...RESULTING IN RADIATIONAL FOG. A WAVE SEEN IN THE GFS THAT PASSES BY TO THE NORTHEAST WILL PROBABLY BE TOO FAR AWAY TO WARRANT EVEN SLIGHT CHANCE POPS. NEXT...A COLD FRONT FROM THAT NORTHERN STREAM WAVE WILL SAG TOWARD KENTUCKY ON THURSDAY BEFORE STRETCHING OUT AND BECOMING STATIONARY OVER THE NORTHERN HALF OF THE STATE LATER THAT NIGHT. THIS WILL RESULT IN A PROLONGED AND PERSISTENT PERIOD OF DECENT POPS FOR SHOWERS AND THUNDERSTORMS LASTING INTO FRIDAY NIGHT AS IMPULSES MOVE EAST ALONG THE BOUNDARY... SPURNED ALONG BY THE MINOR UPPER WAVES SPINNING OUT OF THE OPENING SOUTHWESTERN LOW. WITH THE TEMPERATURES...WENT WITH THE WARMER MET NUMBERS TODAY AND THURSDAY...THOUGH HELD THE DIURNAL RISE BACK A BIT THIS MORNING UNTIL THE FOG BURNS OFF. FOR HIGHS FRIDAY...FOLLOWED MORE OF A BLEND. AT NIGHT...THE NUMBERS WERE SIMILAR SO WENT WITH A BLEND...ALONG WITH SOME SITE SPECIFIC TWEAKING. THE POPS ENDED UP CLOSEST TO THE MET NUMBERS THROUGH THE SHORT TERM PART OF THE FORECAST. .LONG TERM.../SATURDAY THROUGH TUESDAY/ A FRONTAL BOUNDARY WILL LINGER ACROSS THE AREA TO END THE WORKWEEK...WITH THE BEST CHANCE OF RAIN REMAINING ALONG AND NORTH OF THE MOUNTAIN PARKWAY. ECMWF AND GFS CONTINUE TO DIFFER WITHIN THE DETAILS OF THE FORECAST INTO EARLY NEXT WEEK. TWO MAIN FEATURES OF INFLUENCE WILL BE A BUILDING SOUTHEASTERN CONUS RIDGE...WITH AN EJECTING UPPER LEVEL LOW APPROACHING OUT OF THE SOUTHWEST. ECMWF WASHES THE AFOREMENTIONED FRONT OUT TO THE SOUTH...WITH A LARGE AREA OF HIGH PRESSURE LENDING IT`S INFLUENCE ACROSS THE AREA THROUGH THE WEEKEND. THE PROGGED RIDGE THEN SLOWS AS WELL DAMPENS THE UPPER LEVEL LOW SIGNIFICANTLY BY EARLY NEXT WEEK. GFS STARTS OUT WITH A MUCH WEAKER AREA OF HIGH PRESSURE PUSHING IN FOR THE BEGINNING OF THE WEEKEND...GENERALLY KEEPING THE FRONT AROUND LONGER AND LINGERING PRECIPITATION INTO EARLY SATURDAY...BEFORE PUSHING BACK NORTH BY SATURDAY AFTERNOON AS MORE MODEST RIDGING TAKES PLACE THROUGH SUNDAY. A MUCH MORE ROBUST PROGGED UPPER LEVEL LOW LIFTS THROUGH MONDAY INTO TUESDAY...WITH SCATTERED PRECIPITATION ASSOCIATED WITH THIS FEATURE. HAVE COMPROMISED BETWEEN THE MODELS. ECMWF HAS BEEN MORE CONSISTENT LATELY...HOWEVER FEEL THAT IT DOES DAMPEN THE UPPER LEVEL LOW A BIT TOO MUCH AS IT BRINGS IT IN. ON THE OTHER HAND...THE GFS SEEMS A BIT OVERDONE WITH THE UPPER LEVEL FEATURE. AS SUCH...WILL KEEP THE MAJORITY OF THE WEEKEND DRY UNDER THE INFLUENCE OF UPPER LEVEL RIDGING...WHILE INTRODUCING CHANCE POPS BY MONDAY AFTERNOON AS THE WAVE APPROACHES. TEMPERATURES CONTINUE TO LOOK ABOVE NORMAL THROUGHOUT THE PERIOD AS WELL. GENERALLY STAYED A BIT WARMER THAN MOS...THINKING THAT THE NUMBERS ARE A BIT COOL WITH THE OVERPLAYED CLOUD COVER AND PRECIPITATION. && .AVIATION.../12Z TO 12Z/ DENSE FOG IS A PROBLEM AT THE TAF SITES AT ISSUANCE TIME. HOWEVER LOZ IS SHOWING SIGNS OF IMPROVING AND SOUTHWESTERLY LOW LEVEL FLOW WILL BE INCREASING AFTER 14Z AS STATIONARY FRONT CURRENTLY BISECTING THE AREA LIFTS NORTH. FOG SHOULD RAPIDLY DISSIPATE AND CIGS RISE INTO THE VFR RANGE BY THAT TIME... WHERE THEY WILL REMAIN THROUGH THE REMAINDER OF THE TAF PERIOD. THERE REMAINS A SLIGHT CHANCE FOR A SHOWER WITH THE FRONT IN THE VICINITY... HOWEVER PROBABILITIES ARE TOO LOW TO MENTION IN THE TAFS AT THIS TIME. && .JKL WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR KYZ044- 050>052-058>060-068-069-079-080-083>088-104-106>120. && $$ SHORT TERM...MCLANE/GREIF LONG TERM....GEOGERIAN AVIATION...ABE/GREIF ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1048 AM EDT THU MAR 22 2007 .SHORT TERM /REST OF TODAY/... AREA MORNING UPPER AIR SOUNDINGS SHOW LAYERED MOISTURE THROUGH MUCH OF THE COLUMN. SFC OBS/SATL DATA CONFIRMS SCT-BKN MULTILAYERED CLOUDS ACRS FORECAST AREA THIS LATE MORNING BUT THE CLOUD PATCHES APPEAR TO BE BREAKING AND THINNING. THEREFORE EXPECT SKY CONDITION WILL AVERAGE PTSUNNY DURING THE AFTN. INSOLATION SHUD BE SUFFICIENT TO ALLOW TEMPS TO REACH FCSTD VALUES RANGING FROM M60S ACRS THE EASTERN SHORE TO M70S OVER PIEDMONT...BUT OF COURSE COOLER WHERE FLOW IS ONSHORE. LTL IF ANY CHANGES NEEDED TO FCST ATTM BUT UPDATED FCST TO REFRESH PRODUCTS. .MARINE UPDATE... DECIDED TO ADD SCA FOR THE CHESAPEAKE BAY WTRS FROM SMITH POINT TO NEW POINT COMFORT...WITH 15-20 KT WINDS AND 2-3 FT WAVES. RUC AND NAM MODELS SUGGEST INCRSG SFC WINDS AFTER 18Z. SOUNDINGS SHOW AROUND 15 KT AT SFC UNDER WEAK INVERSION WITH 25-30 KTS ABOVE INVERSION. EXPECT ENOUGH MIXING TO ALLOW 20 KT GUSTS DOWN TO SFC. STRONGER LOW LEVEL INVERSION TO SOUTH OF NEW POINT COMFORT SO OPTED NOT TO GO FOR SCA FOR SOUTHERN BAY BUT STEADY 15 KT. ON CSTL WTRS...EXPECT 15-20 KT SOUTH WINDS FROM FENWICK DOWN TO PARRAMORE WITH LONGER FETCH BUILDING SEAS TO SCA CRITERIA AFTER 2 PM. DIFFICULT FCST FOR THE WEEKEND WITH BACKDOOR COLD FRONT SAT/SAT NGT. HAVE DECIDED TO GO CLOSER TO NAM/UKMET (GFS IS OUTLIER)...KEEPING SW FLOW SRN ZONES ON SAT...ELY FLOW ACRS THE NORTH. THEN...FRONT CLEARS ENTIRE MARINE AREA SAT NGT/SUN...WITH NNE FLOW AND POSSIBLE SMALL CRAFT CONDITIONS AT THAT TIME. && .PREV DISCUSSION... /ISSUED 513 AM EDT THU MAR 22 2007/ SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... CURRENTLY...HIGH PRESSURE CONTINUES TO PUSH OFFSHORE WHILE A COLD FRONT ADVANCES EAST THROUGH THE WESTERN GREAT LAKES AND MIDWEST REGIONS. THE MAIN FORECAST CONERN TODAY WILL BE WITH CLOUD COVER EXTENT (DEPTH) AND THUS IMPACT ON TEMPS. GFS/NAM ARE IN FAIRLY CLOSE ACCORD IN THE SHORT TERM (THROUGH TONIGHT). BOTH INDICATE THE COLD FRONT DROPPING TO NEAR THE MASON- DIXON LINE BY MIDNIGHT TONIGHT...BECOMING MORE W-E ORIENTED AS THE ASSOCIATED UPPER LEVEL VORT LOBE ENCOUNTERS A ZONAL/FLAT UPPER RIDGE. PRE-FRONTAL FORCING/MOISTURE IS INSUFFICIENT FOR POPS ACROSS THE FCST AREA TODAY. AS FOR SKY COVER...EXPECT THE LOWER CLOUDS TO SCOUR OUT LATER THIS MORNING/AFTN AS THE LOW LEVEL FLOW VEERS TOWARD THE S-SW RESULTING IN MORE APPRECIABLE WARMING (AND RELATIVE DRYING) WITHING THE 1000-850 MB LAYER. STILL EXPECT PERIODIC WAVES OF HIGHER BASED CLOUDS IN THE AFTN AS WE GET INTO THE WARM SECTOR...THUS HAVE WORDED PARTLY SUNNY. BASED ON RECENT TRENDS (YDAY)...HAVE GONE A FEW DEGREES HIGHER THAN MOS TODAY FOR HIGH TEMPS. THIS BASED ON THE LOW LEVEL WAA AND INCREASED SUNSHINE THIS AFTN (ANTICIPATED DEEPER MIXING WITH THE LATE MARCH SUN ANGLE). TONIGHT...FRONT DIPS INTO NRN VA AND THE NRN PTN OF THE DELMARVA. HAVE INCLUDED LOW (30-40%) POPS OVER THE NRN THIRD OF THE CWA CLOSEST TO THE FRONT...THOUGH ONCE AGAIN WITH THE FLATTENING UPPER FLOW (AND NEGLIGIBLE STRAIGHT UPPER JET FORCING)...DYNAMICS AND THUS MOISTURE DEPTHS REMAIN LACKING. S OF FVX-RIC-MFV...MOISTURE IS JUST TOO SHALLOW (PARTICULARLY IN LOW LEVELS) FOR POPS. FRIDAY...COMPARED TO THE NAM/UKMET/ECMWF...THE 00Z GFS IS TOO QUICK WITH THE INITIAL IMPULSE TRACKING FROM THE UPPER MIDWEST- OH VLY-MID ATLC REGION. SIDING MORE TOWARD A NAM/ECMWF BLEND... EXPECT A NW-SE DRAPED SURFACE FRONTAL BNDRY ACROSS THE FCST AREA... WITH THE FRONT TAKING ON THE TYPICAL "SAG" EAST TOWARD THE COOLER COASTAL WATERS. AS A RESULT EXPECT A LARGE TEMP GRADIENT FROM SW-NE... I.E. AROUND 80/LOWER 80S INLAND TO AROUND 60 ALONG THE LOWER ERN SHORE. WILL ALSO MAINTAIN MORE EXTENSIVE CLOUD COVER/LOW POPS OVER THE N-NE ZONES ALONG AND N OF THE PROJECTED FRONTAL ZONE. SATURDAY...GFS IS MUCH COOLER WITH THE LOWER LEVELS COMPARED TO THE OTHER MODELS...BASICALLY A CONSEQUENCE OF THIS MODEL BEING TOO PROGRESSIVE WITH THE INITIAL UPPER SHORTWAVE/WEAK SURFACE LOW ALONG THE STATIONARY FRONT. GFS (MAV) MOS GUIDANCE IN FACT IS SOME 20+ DEGREES COOLER WITH HIGH TEMPS OVER INLAND LOCALES COMPARED TO THE NAM (MET) GUIDANCE! FOR NOW WILL CONTINUE TO LEAN MORE TOWARD THE NAM/ ECMWF...WHICH DOES NOT DROP THE FRONT S OF THE LOWER DELMARVA UNTIL LATE IN THE DAY. BASED ON THESE PROJECTIONS...EXPECT ANOTHER DAY WITH A SIGNIFICANT TEMPERATURE GRADIENT FROM SW (80-85) TO AREAS ALONG THE ATLANTIC SIDE OF THE LOWER MD ERN SHORE (LOW-MID 50S). LONG TERM /SUNDAY THROUGH WEDNESDAY/... BASED ON THE LATEST NAM/ECWMF TRENDS...AND WITH THE LOWER CONFIDENCE IN THE GFS SAT-SUN...DID NOT MAKE TOO MANY CHANGES TO THE FCSTS DURING THE EXTENDED PERIODS. HIGH PRESSURE BUILDING FROM THE N AND EVENTUALLY NE (OFFSHORE) ON SUNDAY WILL MAKE FOR A COOLER DAY OVER THE NERN PTNS OF THE FCST AREA...THOUGH AGAIN EXPECT TEMPS TO REMAIN MUCH MILDER AS YOU HEAD FARTHER SW. TOWARD PETERSBURG/FARMVILLE/SOUTH HILL. AVIATION...VARIABLE CONDITIONS EARLY THIS MORNING...HAVE MVFR CIGS NORTH AND WEST...VFR SOUTH. FLOW TURNS TO S OR SW LATER TODAY WITH INCREASING WIND SPEEDS BY AFTN...AND MAINLY VFR CONDS. MVFR CIGS MAY HANG TOUGH ON THE ERN SHORE THRU 16-18Z. CONTINUED VFR TONIGHT AS MIXING SHOULD INHIBIT SIGNIFICANT FOG FORMATION. MARINE...GRADIENT INCREASES FROM SOUTH TO SOUTHWEST LATER TODAY. CHILLY BAY WATERS WILL MAKE IT DIFFICULT TO EFFICIENTLY MIX THESE WINDS DOWN TO THE SFC...SO OPTED TO KEEP CONDITIONS ON THE BAY & SOUND BELOW SMALL CRAFT (ALTHOUGH IT WILL BE CLOSE LATER THIS AFTN). ON COASTAL WATERS...INCREASING SOUTHERLY FLOW (NEAR 20 KTS BY AFTN) WILL LIKELY BRING SEAS TO MARGINAL SMALL CRAFT CONDITIONS (5 FT WAVES OFFSHORE) N OF PARRAMORE ISL...FROM LATER IN THE AFTN THROUGH ERLY MRNG THU. DIFFICULT FCST FOR THE WEEKEND WITH BACKDOOR COLD FRONT SAT/SAT NGT. HAVE DECIDED TO GO CLOSER TO NAM/UKMET (GFS IS OUTLIER)...KEEPING SW FLOW SRN ZONES ON SAT...ELY FLOW ACRS THE NORTH. THEN...FRONT CLEARS ENTIRE MARINE AREA SAT NGT/SUN...WITH NNE FLOW AND POSSIBLE SMALL CRAFT CONDITIONS AT THAT TIME. FIRE WEATHER...LIGHT SE TO S FLOW THIS MRNG...WITH GUSTY SOUTH...SOUTHWEST WINDS INCREASING BY AFTN FOR MUCH OF INLAND VA. HOWEVER...NOT REALLY A DOWNSLOPE FLOW SO RH VALUES DO NOT DROP OFF THAT MUCH...WITH MOST LOCATIONS BOTTOMING OUT 35-45% AT THE DRIEST. FARTHER EAST...COOLER TEMPERATURES WILL TEND TO INHIBIT MIXING SOMEWHAT SO WINDS LIKELY STAY MORE FROM DUE SOUTH AT 15 KTS OR LESS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM EDT FRIDAY FOR ANZ630-631-650-652. && $$ SHORT TERM UPDATE...CULLEN/FOSTER md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 PM EDT THU MAR 22 2007 .SHORT TERM (TONIGHT AND FRIDAY)... MAIN FCST ISSUE IN THE SHORT TERM IS POSSIBILITY OF SOME -SN TONIGHT. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. SHORTWAVE THAT PASSED ACROSS THE UPPER LAKES EARLIER TODAY IS NOW OVER THE ONTARIO/QUEBEC BORDER. NEXT SHORTWAVE IN THE FAST FLOW IS OVER NW ND. MID CLOUDS ASSOCIATED WITH SHORTWAVE WERE SPREADING ACROSS NRN MN...AND HIGH CLOUDS HAVE ALREADY SPREAD ACROSS ALL OF UPPER MI THIS AFTN. RADARS SHOW A DECENT AREA OF RETURNS ACROSS FAR NE ND/NW MN AND SRN MANITOBA. SFC OBS THAT REPORT VSBY ARE SPARSE IN THAT AREA...SO DIFFICULT TO KNOW HOW MUCH PCPN IS REACHING THE GROUND. HOWEVER...IN THE LAST FEW HRS...A COUPLE OF OBS IN SRN MANITOBA HAVE REPORTED 1-4SM IN -SN. WELL TO THE W...SHORTWAVE THAT DROPPED OUT OF THE WESTERLIES A DAY OR TWO AGO OVER THE W COAST HAS CLOSED OFF INTO A MIDLEVEL LOW CENTERED JUST S OF CA. THIS SYSTEM WILL BE OF INTEREST TO FCST HERE LATE IN THE UPCOMING WEEKEND AS IT GETS KICKED NE BY NEXT TROF APPROACHING THE W COAST. UPSTREAM SHORTWAVE WILL RACE E...CROSSING UPPER MI/LAKE SUPERIOR BTWN 03Z-09Z. BASED ON THE DARKENING SEEN ON WATER VAPOR IMAGERY... THE GFS HAS A BETTER HANDLE ON SHORTWAVE THAN THE WEAKER NAM. LATEST RUC AND 12Z REGIONAL CANADIAN ALSO SUPPORT THE GFS. OVERLAP OF MODEST DEEP LAYER QVECTOR CONVERGENCE AND MOIST ISENTROPIC ASCENT (CONDENSATION PRES DEFICITS UNDER 20MB) ON THE 290K SFC (AROUND 700MB) LINES UP WELL WITH WHERE RADAR RETURNS ARE PRESENT IN NE ND/NW MN AND SRN MANITOBA. STRONGER ISENTROPIC ASCENT IS INDICATED FARTHER S...BUT AIRMASS IS DRIER THERE. LATEST RUC IS VERY SIMILAR TO THE GFS WITH REGARD TO PROGRESSION OF QVECTOR CONVERGENCE/ISENTROPIC ASCENT THRU 06Z. FORCING/ISENTROPIC ASCENT IS TO SHIFT THRU NE MN BEFORE WEAKENING AS IT CROSSES UPPER MI/LAKE SUPERIOR TONIGHT. WITH ANTECEDENT DRY AIR TO OVERCOME...THE WEAKENING FORCING SUGGESTS PCPN THAT IS OCCURRING UPSTREAM WILL TEND TO DISSIPATE AS IT NEARS AND THEN MOVES ACROSS THE FCST AREA. ON THE OTHER HAND...GIVEN THE APPEARANCE ON WATER VAPOR IMAGERY...SHORTWAVE MAY NOT WEAKEN AS FAST AS MODELS INDICATE. SO...SITUATION IS CERTAINLY STILL WORTHY OF SLIGHT CHC/LOW CHC POPS OVER NW LAKE SUPERIOR AND ACROSS THE KEWEENAW. FCST WETBULB ZERO PROFILES INDICATE ANY PCPN THAT OCCURS WILL BE SNOW. FOLLOWING SHORTWAVE...CANADIAN/GFS SHOW MOISTURE LINGERING AROUND 850MB ON FRI...ESPECIALLY OVER THE CNTRL/ERN FCST AREA. SO THERE SHOULD BE A FAIR AMOUNT OF STRATOCU DEVELOPING DURING THE DAY. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE LOW/MID 50S. HOWEVER...SRLY FLOW WILL KEEP TEMPS MUCH COOLER NEAR AND DOWNWIND OF LAKE MICHIGAN. LOCAL COOLING SHOULD ALSO OCCUR NEAR LAKE SUPERIOR OVER THE W AND OVER THE NCNTRL MID/LATE AFTN AS BOUNDARY LAYER WINDS SLACKEN. FROM MUNISING EWD...SRLY FLOW MAY BE SUFFICIENT THRU THE DAY TO PREVENT LAKE BREEZE DEVELOPMENT. .LONG TERM (FRIDAY NIGHT THROUGH NEXT THURSDAY)... CONTINUITY IN MODEL SOLUTIONS IS POOR CURRENTLY MAINLY DUE TO ZONAL WEST TO EAST UPPER FLOW ALONG CANADA/UNITED STATES BORDER. IN RECENT MODEL RUNS...IT APPEARED SHORTWAVE CURRENTLY OFF SHORE OF BRITISH COLUMBIA WAS TO MOVE EAST AND ARRIVE OVR ONTARIO AND UPR LAKES FRI NIGHT INTO EARLY SAT. ALSO...THE WAVE WAS PROGGED TO SHEAR OUT AS IT CAME EAST. NOW...A TREND IS EMERGING THAT RESULTS IN STRONGER WAVE NOT COMING THROUGH UNTIL SAT. NAM MOST EMPHATIC WITH THIS IDEA WHILE UKMET/GFS AND LATEST ECMWF ARE WEAKER. SHORTWAVE ALONG WITH DIVERGENCE FM RRQ OF H3 OVR ONTARIO SHOULD PRODUCE CONSIDERABLE MID CLOUDS. HOWEVER...SOUNDINGS FM GFS AND EVEN NAM ARE VERY DRY BLO H85 SO HAVE KEPT A DRY FCST. MIXING HEIGHTS MAY BE LIMITED DUE TO CLOUDS AND LIGHT WINDS SO LOWERED TEMPS SLIGHTLY. AT THE SFC...RIDGE DRIFTING OVER UPR LAKES WILL MOVE TO THE LOWER GREAT LAKES SAT NIGHT INTO SUN. RETURN FLOW AS HIGH DEPARTS WILL ONLY STRENGTHEN THROUGH MOST OF THE UPCOMING WEEK. IT IS FEASIBLE THAT SAT NIGHT WILL BE THE LAST ONE FOR A WHILE WITH A GOOD PORTION OF CWA EXPERIENCING MIN TEMPS BLO FREEZING. UPR LOW OVR SOUTHWEST EJECTS INTO PLAINS SUN AND LIFTS TOWARD UPR GREAT LAKES SUN NIGHT INTO MON. UKMET/GFS/ECMWF IN GOOD AGREEMENT HERE. NAM IS MUCH SLOWER WITH TROUGH EJECTION AND WAS NOT PREFERRED DUE TO EVEN STRONGER KICKER SHORTWAVE TROUGH BARRELLING INTO WEST COAST AS EARLY AS SUN. LARGE AREA OF H85-H7 WARM AIR ADVECTION... 40KT H85 JET...AND PWATS ECLIPSING AN INCH (250-300 PCT OF NORMAL) ARE MAIN TRIGGERS FOR PCPN SUN INTO SUN NIGHT. WARMING H85 TEMPS COMBINED WITH COOL H5 TEMPS AROUND -15C RESULT IN STEEPENING MID LEVEL LAPSE RATES AND POSSIBILITY OF THUNDER. MAIN SFC WARM FRONT AND UPR TROUGH DO NOT ARRIVE UNTIL LATE SUN NIGHT INTO MON WHICH IS WHEN BEST COVERAGE TO SHOWERS/THUNDERSTORMS IS EXPECTED. 00Z GFS EVEN INDICATED SOME SFC BASED INSTABILITY AHEAD OF PRIMARY COLD FRONT MOVING THROUGH MON EVENING. ECMWF MUCH QUICKER WITH FROPA. ALTHOUGH MOST PCPN WILL BE DONE BY MON NIGHT...KEPT A SMALL CHANCE IN GRIDS FOR TUE AS SECONDARY SFC TROUGH MOVES THROUGH PER HPC AND H5 COLD POOL (-20C AT H5) ALSO ROTATES THROUGH. BRIEF RIDGING BOTH ALOFT AND AT SFC FOR WED...THEN DEEP TROUGH CONTINUES TO DEVELOP OVR MUCH OF WESTERN CONUS. SW FLOW DEVELOPING ALOFT...AND EVENTUALLY AT SFC...LEADS TO AN INCREASE IN RAIN CHANCES LATE NEXT WEEK. TEMPS WILL REMAIN ABOVE NORMAL. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1037 AM EDT THU MAR 22 2007 .UPDATE... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A POTENT SHORTWAVE RACING E ACROSS ERN LAKE SUPERIOR AND ONTARIO. SHARP DRYING/SUBSIDENCE IN THE WAKE OF SHORTWAVE IS LEADING TO A DECREASE IN CLOUD COVER ACROSS THE FCST AREA THIS MORNING. 00Z/12Z KINL SOUNDINGS SHOWED THE INCOMING DRY AIR NICELY AS PRECIPITABLE WATER DROPPED FROM 0.68 TO 0.15 INCHES...AND 12Z SOUNDING INDICATED DWPT DEPRESSIONS OF 15-25C FROM 840MB TO 550MB. A PERIOD OF GUSTY WINDS IS ALSO FOLLOWING THE STRONG SHORTWAVE. WINDS WERE BEING AIDED BY 4-5MB/3HR PRES RISE MAX THAT WAS QUICKLY MOVING E ACROSS THE UPPER LAKES. CORE OF PRES RISES IS NOW OVER CNTRL LAKE SUPERIOR/CNTRL UPPER MI...SO STRONGEST WINDS HAVE JUST ABOUT PASSED THE AREA. NEXT SHORTWAVE IS HEADING ESE THRU SRN SASKATCHEWAN. MID/HIGH CLOUDS ASSOCIATED WITH SHORTWAVE ARE ALREADY STREAMING E THRU ND INTO NRN MN. INHERITED FCST IS IN GOOD SHAPE FOR THE AFTN AND ONLY REQUIRES MINOR ADJUSTMENTS BASED ON MORNING TRENDS. SOME STRATOCU WILL BE AROUND FOR A FEW MORE HRS...MAINLY ACROSS THE N...ASSOCIATED WITH 850MB THERMAL TROF AND LINGERING LOW-LEVEL MOISTURE. STRATOCU SHOULD BE GONE BY MID/LATE AFTN...BUT ALREADY MID/HIGH CLOUDS ASSOCIATED WITH NEXT SHORTWAVE WILL BE SLIPPING INTO THE FCST AREA FROM THE W. AS FOR TEMPS...MIXING TO 800-850MB ON 12Z KINL SOUNDING SUGGESTS HIGH TEMPS IN THE UPPER 30S/LWR 40S ARE ON TRACK OVER THE W AND N. WNW DOWNSLOPING WIND WILL RESULT IN MAX TEMPS SEVERAL DEGREES HIGHER OVER PORTIONS OF THE CNTRL FCST AREA...ESPECIALLY SCNTRL. AS FOR WINDS...WILL MAINTAIN GALE WARNING OVER ERN LAKE SUPERIOR FOR A FEW MORE HRS WITH EXPECTATION OF GALE FORCE GUSTS. OTHERWISE...WINDS WILL CONTINUE TO DIMINISH OVER THE ENTIRE FCST AREA THRU THE DAY AS PRES RISE SHIFTS E OF THE AREA AND SFC HIGH PRES RIDGE OVER MN DRIFTS E. && .PREV DISCUSSION (ISSUED AT 400 AM EDT)... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STRG SHRTWV NEAR LK WINNIPEG EMBEDDED IN ZONAL FLOW ALF ALG THE CNDN BORDER...WITH ANOTHER SHRTWV PRESENT OVER ND. THREE DISTINCT AREAS OF PCPN NOTED AT THE START OF SHIFT. THE FIRST WAS A BAND OF SHRA MOVING INTO WRN LK SUP JUST AHEAD OF COLD FNT IN DPVA/DEEP LYR H85-3 QVECTOR CNVGC ASSOCIATED WITH ND SHRTWV. LLVL MSTR LINGERS BEHIND THIS FNT WITH SC CIGS OBSVD BACK TO THE RED RIVER VALLEY...WHERE DRIER AIR NOTED ON THE BIS SDNG IS WORKING EWD. STRONGER COLD FNT ASSOCIATED WITH SHRTWV OVER LK WINNIPEG MOVING TOWARD THE MN AT 03Z...BUT LTL PCPN OBSVD ALG THIS BNDRY DESPITE SHARPER THERMAL CONTRAST. SECOND CLUSTER OF SHRA WITH EMBEDDED TSRA EXTENDS FM NW WI INTO IA WHERE DPVA/DEEP LYR H85-3 QVECTOR CNVGC/SFC COLD FNT INTERSECTING HIER H85 DWPTS AOA 8C SURGING NEWD IN ADVANCE OF FNT...MSTR NOT AVBL TO BAND FARTHER N IN WRN LK SUP. RAOBS/PROFILERS SHOW H85 SW WINDS AOA 50 KTS AHEAD OF THIS CLUSTER. LARGEST AREA OF SHRA PRESENT OVER ERN WI/LK MI/NW LWR MI AT NOSE OF STRONGEST H85-7 WINDS JUST AHEAD OF WEAK SHRTWV NOTED ON RUC ANALYSIS. SCT SHRA/TSRA ON NRN FRINGE OF THIS AREA ARE IMPACTING THE ERN CWA...BUT FOR THE MOST PART THESE SHRA/TSRA ON TRACK TO MISS THE FA. OTRW...LTL PCPN NOTED OVER THE FA RIGHT NOW...BUT RETURN OF HIER LLVL MSTR OVER MELTING SN HAS CAUSED QUITE A BIT OF ST/FOG...WITH VSBYS AOB 1/4SM AT PLACES ACRS MAINLY THE SCNTRL AND E. UPSTREAM...ANOTHER SHRTWV MOVING THRU BRITISH COLUMBIA. MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND EVOLUTION OF PCPN AREAS AS LATEST RUC/LARGER SCALE MODELS SHOW SHRTWVS OVER ND AND LK WINNIPEG PHASING OVERNGT. FOCUS AFTER COLD FROPA EARLY THIS MRNG SHIFTS TO WINDS/TEMPS. AS SHRTWVS BEGIN TO MERGE TO A 40-UNIT VORT MAX OVER FAR NRN LK SUP BY 12Z THU...EXPECT SHRA AREAS OVER WRN LK SUP/WI TO MERGE OVER THE SCNTRL/ERN CWA WITH SOME LOCALLY HEAVY RA THERE WHERE MSTR CNVGC PHASES BETTER WITH DPVA/FALLING HGTS/DEEP QVECTOR CVNGC BEFORE ACCELERATING INCRSGLY KATAFNT TYPE COLD FNT DRIVES E UNDER JET SURGE REGION OF DEEPENING SHRTWV. WITH RAPID INFLUX OF DRY AIR EXPECTED AS H85 W WINDS INCRS UP TO 50KT...LOOK FOR PCPN/DENSE FOG TO END SOON AFTR COLD FROPA WITH INTENSE DRY ADVCTN/SUBSIDENCE. 00Z RUC/NAM INDICATE DRYING WL REACH ERY ARND 12Z...SO MOST IF NOT ALL PCPN WL BE OVER BY EARLY TDAY. WL CARRY LINGERING SHRA OVER THE ERN COUNTIES EARLY...OTRW HAVE REMOVED POPS ALTOGETHER AS NAM/RUC FCST SDNGS FOLLOWING THE FROPA ARE QUITE DRY. WL EVALUATE NEED TO KEEP GOING DENSE FOG ADVY GOING CLOSE TO FCST ISSUANCE...BUT ANTICIPATE DROPPING ADVY FOR MOST OF THE FA BY FCST ISSUANCE. GFS FCST SDNGS SHOW MORE LLVL MSTR...BUT PREFER THE DRIER LOOK TO THE RUC/NAM FCSTS GIVEN MORE DRYING OBSVD UPSTREAM OVER NW MN/ANTICIPATED DRY SURGE BEHIND DEEPENING SHRTWV. OTRW...LOOK FOR GUSTY WINDS THIS MRNG BEHIND THE BNDRY WITH 35KT WINDS WITHIN THE MIXED LYR TO DIMINISH A BIT THIS AFTN WITH ARRIVAL OF HI PRES RDG. ALTHOUGH PRES GRADIENT SEEMS TO DIMINISH WITH APRCH OF RDG...MIXING/DEEPENING PBL WITH PLENTY OF SUNSHINE IN LLVL CAD SHOULD TAP STRONGER WINDS ALF TO MAINTAIN GUSTINESS THRU THE DAY. MIXING TO H85 ON NAM FCST SDNGS SUGS HI TEMPS WL REACH ARND 45 OVER THE SE COUNTIES...WHERE NW FLOW WL BE DOWNSLOPING. LOOK FOR AN INCRS IN HI CLD LATE TDAY IN ADVANCE OF NEXT SHRTWV NOW MOVING INTO BRITISH COLUMBIA FCST TO MOVE TOWARD NW MN LATE TDAY. FOR TNGT...SHRTWV OVER THE NRN PLAINS PROGGED TO DRIFT ACRS THE UPR GRT LKS...AND GFS/NAM/UKMET SHOW INCRSG MID LVL MSTR. ALTHOUGH LLVLS APPEAR WL BE TOO DRY FOR ANY PCPN...GFS AND ESPECIALLY THE NAM GENERATE SOME GENERALLY LGT QPF OVER THE NW AND LK SUP. NAM ACTUALLY SHOWS SOME SHARP H85-7 FGEN WITH SOME MODEST ISENTROPIC LIFT IN ADVANCE OF THE SHRTWV. SINCE GFS/UKMET ARE MUCH WEAKER WITH FCST DYNAMICS BUT WV IMAGERY INDICATES A WELL DEFINED SHRTWV IN BRITISH COLUMBIA...WL CARRY SLGT CHC -SHSN (FCST WBZ PROFILES SUG ANY PCPN WOULD BE SN) ACRS THE NW CWA ON CYC SIDE OF NAM FCST H3 JET MAX/BEST H85-7 FGEN. EXPECT THE LOWEST MIN TEMPS OVER THE SCNTRL WHERE THE CLDS WL BE THINNEST. FOLLOWING DEPARTURE OF SHRTWV EARLY FRI...SFC-H85 RDG AXIS/MID LVL DRYING FCST TO DOMINATE. GFS/NAM BOTH SHOW SOME HIER DWPTS AT H85 LINGERING HOWEVER...SO EXPECT BKN DIURNAL SC TO DVLP DURING DAY. MIXING TO H85 ON GFS/NAM FCST SDNGS YIELDS HI TEMPS NEAR 55. WITH LGT SW FLOW...EXPECT LK BREEZES/AFTN COOLING TO DVLP MAINLY NEAR LK MI. SOME CONSIDERABLE MODEL DISAGREEMENTS BEGIN TO SHOW IN THE FRI NGT/SAT PDS...NOT SURPRISING CONSIDERING FAST ZONAL FLOW FCST TO PREVAIL. GFS SHOWS A MUCH DEEPER SHRTWV ARRIVING LATE FRI NGT AND GENERATING SGNFT PCPN ON SAT. WL SIDE WITH THE MAJORITY UKMET/ ECWMF/CNDN/NAM THAT SHOW A MUCH WEAKER SHRTWV SHEARING BY ON FRI NGT FOLLOWED BY RDGING ON SAT. OPTED TO REMOVE POPS FRI NGT AND KEEP SAT DRY. WITH H85 TEMPS APRCHG 6C ON SAT...EXPECT TEMPS OVER THE INLAND TO RISE WELL INTO THE 50S TO NEAR 60 PER MIXING TO H8 ON NAM FCST SDNGS. WITH SFC HI CENTER TO THE SE AND CWA IN SYNOPTIC SW FLOW... EXPECT THE MOST SGNFT LK MODERATION OFF LK MI. BUT RELATIVELY WEAK FLOW AND SFC HTG INLAND SHOULD ALLOW LK BREEZES OFF SUPERIOR AS WELL. COORDINATED WITH GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING E HALF OF LAKE SUPERIOR. && $$ ROLFSON (UPDATE) KC (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 AM EDT THU MAR 22 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STRG SHRTWV NEAR LK WINNIPEG EMBEDDED IN ZONAL FLOW ALF ALG THE CNDN BORDER...WITH ANOTHER SHRTWV PRESENT OVER ND. THREE DISTINCT AREAS OF PCPN NOTED AT THE START OF SHIFT. THE FIRST WAS A BAND OF SHRA MOVING INTO WRN LK SUP JUST AHEAD OF COLD FNT IN DPVA/DEEP LYR H85-3 QVECTOR CNVGC ASSOCIATED WITH ND SHRTWV. LLVL MSTR LINGERS BEHIND THIS FNT WITH SC CIGS OBSVD BACK TO THE RED RIVER VALLEY...WHERE DRIER AIR NOTED ON THE BIS SDNG IS WORKING EWD. STRONGER COLD FNT ASSOCIATED WITH SHRTWV OVER LK WINNIPEG MOVING TOWARD THE MN AT 03Z...BUT LTL PCPN OBSVD ALG THIS BNDRY DESPITE SHARPER THERMAL CONTRAST. SECOND CLUSTER OF SHRA WITH EMBEDDED TSRA EXTENDS FM NW WI INTO IA WHERE DPVA/DEEP LYR H85-3 QVECTOR CNVGC/SFC COLD FNT INTERSECTING HIER H85 DWPTS AOA 8C SURGING NEWD IN ADVANCE OF FNT...MSTR NOT AVBL TO BAND FARTHER N IN WRN LK SUP. RAOBS/PROFILERS SHOW H85 SW WINDS AOA 50 KTS AHEAD OF THIS CLUSTER. LARGEST AREA OF SHRA PRESENT OVER ERN WI/LK MI/NW LWR MI AT NOSE OF STRONGEST H85-7 WINDS JUST AHEAD OF WEAK SHRTWV NOTED ON RUC ANALYSIS. SCT SHRA/TSRA ON NRN FRINGE OF THIS AREA ARE IMPACTING THE ERN CWA...BUT FOR THE MOST PART THESE SHRA/TSRA ON TRACK TO MISS THE FA. OTRW...LTL PCPN NOTED OVER THE FA RIGHT NOW...BUT RETURN OF HIER LLVL MSTR OVER MELTING SN HAS CAUSED QUITE A BIT OF ST/FOG...WITH VSBYS AOB 1/4SM AT PLACES ACRS MAINLY THE SCNTRL AND E. UPSTREAM...ANOTHER SHRTWV MOVING THRU BRITISH COLUMBIA. MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND EVOLUTION OF PCPN AREAS AS LATEST RUC/LARGER SCALE MODELS SHOW SHRTWVS OVER ND AND LK WINNIPEG PHASING OVERNGT. FOCUS AFTER COLD FROPA EARLY THIS MRNG SHIFTS TO WINDS/TEMPS. AS SHRTWVS BEGIN TO MERGE TO A 40-UNIT VORT MAX OVER FAR NRN LK SUP BY 12Z THU...EXPECT SHRA AREAS OVER WRN LK SUP/WI TO MERGE OVER THE SCNTRL/ERN CWA WITH SOME LOCALLY HEAVY RA THERE WHERE MSTR CNVGC PHASES BETTER WITH DPVA/FALLING HGTS/DEEP QVECTOR CVNGC BEFORE ACCELERATING INCRSGLY KATAFNT TYPE COLD FNT DRIVES E UNDER JET SURGE REGION OF DEEPENING SHRTWV. WITH RAPID INFLUX OF DRY AIR EXPECTED AS H85 W WINDS INCRS UP TO 50KT...LOOK FOR PCPN/DENSE FOG TO END SOON AFTR COLD FROPA WITH INTENSE DRY ADVCTN/SUBSIDENCE. 00Z RUC/NAM INDICATE DRYING WL REACH ERY ARND 12Z...SO MOST IF NOT ALL PCPN WL BE OVER BY EARLY TDAY. WL CARRY LINGERING SHRA OVER THE ERN COUNTIES EARLY...OTRW HAVE REMOVED POPS ALTOGETHER AS NAM/RUC FCST SDNGS FOLLOWING THE FROPA ARE QUITE DRY. WL EVALUATE NEED TO KEEP GOING DENSE FOG ADVY GOING CLOSE TO FCST ISSUANCE...BUT ANTICIPATE DROPPING ADVY FOR MOST OF THE FA BY FCST ISSUANCE. GFS FCST SDNGS SHOW MORE LLVL MSTR...BUT PREFER THE DRIER LOOK TO THE RUC/NAM FCSTS GIVEN MORE DRYING OBSVD UPSTREAM OVER NW MN/ANTICIPATED DRY SURGE BEHIND DEEPENING SHRTWV. OTRW...LOOK FOR GUSTY WINDS THIS MRNG BEHIND THE BNDRY WITH 35KT WINDS WITHIN THE MIXED LYR TO DIMINISH A BIT THIS AFTN WITH ARRIVAL OF HI PRES RDG. ALTHOUGH PRES GRADIENT SEEMS TO DIMINISH WITH APRCH OF RDG...MIXING/DEEPENING PBL WITH PLENTY OF SUNSHINE IN LLVL CAD SHOULD TAP STRONGER WINDS ALF TO MAINTAIN GUSTINESS THRU THE DAY. MIXING TO H85 ON NAM FCST SDNGS SUGS HI TEMPS WL REACH ARND 45 OVER THE SE COUNTIES...WHERE NW FLOW WL BE DOWNSLOPING. LOOK FOR AN INCRS IN HI CLD LATE TDAY IN ADVANCE OF NEXT SHRTWV NOW MOVING INTO BRITISH COLUMBIA FCST TO MOVE TOWARD NW MN LATE TDAY. FOR TNGT...SHRTWV OVER THE NRN PLAINS PROGGED TO DRIFT ACRS THE UPR GRT LKS...AND GFS/NAM/UKMET SHOW INCRSG MID LVL MSTR. ALTHOUGH LLVLS APPEAR WL BE TOO DRY FOR ANY PCPN...GFS AND ESPECIALLY THE NAM GENERATE SOME GENERALLY LGT QPF OVER THE NW AND LK SUP. NAM ACTUALLY SHOWS SOME SHARP H85-7 FGEN WITH SOME MODEST ISENTROPIC LIFT IN ADVANCE OF THE SHRTWV. SINCE GFS/UKMET ARE MUCH WEAKER WITH FCST DYNAMICS BUT WV IMAGERY INDICATES A WELL DEFINED SHRTWV IN BRITISH COLUMBIA...WL CARRY SLGT CHC -SHSN (FCST WBZ PROFILES SUG ANY PCPN WOULD BE SN) ACRS THE NW CWA ON CYC SIDE OF NAM FCST H3 JET MAX/BEST H85-7 FGEN. EXPECT THE LOWEST MIN TEMPS OVER THE SCNTRL WHERE THE CLDS WL BE THINNEST. FOLLOWING DEPARTURE OF SHRTWV EARLY FRI...SFC-H85 RDG AXIS/MID LVL DRYING FCST TO DOMINATE. GFS/NAM BOTH SHOW SOME HIER DWPTS AT H85 LINGERING HOWEVER...SO EXPECT BKN DIURNAL SC TO DVLP DURING DAY. MIXING TO H85 ON GFS/NAM FCST SDNGS YIELDS HI TEMPS NEAR 55. WITH LGT SW FLOW...EXPECT LK BREEZES/AFTN COOLING TO DVLP MAINLY NEAR LK MI. SOME CONSIDERABLE MODEL DISAGREEMENTS BEGIN TO SHOW IN THE FRI NGT/SAT PDS...NOT SURPRISING CONSIDERING FAST ZONAL FLOW FCST TO PREVAIL. GFS SHOWS A MUCH DEEPER SHRTWV ARRIVING LATE FRI NGT AND GENERATING SGNFT PCPN ON SAT. WL SIDE WITH THE MAJORITY UKMET/ ECWMF/CNDN/NAM THAT SHOW A MUCH WEAKER SHRTWV SHEARING BY ON FRI NGT FOLLOWED BY RDGING ON SAT. OPTED TO REMOVE POPS FRI NGT AND KEEP SAT DRY. WITH H85 TEMPS APRCHG 6C ON SAT...EXPECT TEMPS OVER THE INLAND TO RISE WELL INTO THE 50S TO NEAR 60 PER MIXING TO H8 ON NAM FCST SDNGS. WITH SFC HI CENTER TO THE SE AND CWA IN SYNOPTIC SW FLOW... EXPECT THE MOST SGNFT LK MODERATION OFF LK MI. BUT RELATIVELY WEAK FLOW AND SFC HTG INLAND SHOULD ALLOW LK BREEZES OFF SUPERIOR AS WELL. COORDINATED WITH GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING LAKE SUPERIOR. && $$ KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 221 PM EDT WED MAR 21 2007 .UPDATE...TEMPERATURES STILL STRUGGLING TO GET ABOVE THE FREEZING MARK OVER THE HIGHER TERRAIN AREAS AROUND HTL...WEST BRANCH. WITH ADDITIONAL SHOWERS MOVING THROUGH...FELT COMPELLED TO EXTEND FREEZING RAIN ADVISORY OUT A FEW MORE HOURS. WARM AIR GETTING CLOSER AS WELL AS SFC DEWPOINTS HEADING TOWARD FREEZING. SO HOPEFULLY WE CAN DROP THE ADVISORY WITH THE 4 PM FORECAST. ADAM && .AVIATION...ISSUED AT 144 PM. AN INTERESTING SITUATION AS THE WARM FRONT IS STILL HUNG UP ALONG THE INDIANA/OHIO BORDER. BECAUSE OF THIS, THERE IS A SIZABLE SFC BASED INVERSION THAT WILL CONTINUE THROUGH 12Z THURSDAY WHEN THE COLD FRONT MOVES THROUGH. THE WARM FRONT IS CAUSING LOW LEVEL WIND SHEAR THAT THE KAPX RADAR IS PEGGING AROUND 35 KTS AROUND 1500 FT. THE MODELS SHOW THAT A LOW LEVEL JET MOVES THROUGH AHEAD OF THE COLD FRONT AND BRINGS IN THE POSSIBILITY OF 50+KTS OVERNIGHT AROUND 1500 TO 2000 FEET. OTHERWISE, THE THUNDERSTORMS LOOK TO BE TIMED MORE WITH THE COLD FRONT PASSING THROUGH THE REGION. SO HAVE THE THUNDERSTORMS IN THE HOURS JUST PRIOR TO FROPA. SFC TEMPERATURES ARE ABOVE FREEZING AT THE TAF SITES SO IT LOOKS LIKE AT THE SFC THE FREEZING RAIN IS NO LONGER AN ISSUE. && .UPDATE...ISSUED 1121 AM. OCCLUDED LOW PRESSURE SYSTEM MOVING INTO WESTERN ONTARIO THIS MORNING. ASSOCIATED OCCLUDED FRONT EXTENDS TO A TRIPLE POINT LOW OVER SOUTH DAKOTA...WARM FRONT STRETCHING SE INTO THE OHIO VALLEY. STRONG WARM/MOIST ADVECTION UNDERWAY ACROSS THE WESTERN GREAT LAKES ALONG AND AHEAD OF THE WARM FRONT. 12Z APX SOUNDING REVEALING ABOVE FREEZING WARM NOSE BETWEEN 940 AND 740 MB WITH A MAX TEMP OF +5C WITHIN THE LAYER...A +6C CHANGE IN THE LAST 12 HOURS. LOW LEVEL MOISTURE GRADIENT SITTING BETWEEN APX AND GRB PER 12Z SOUNDINGS AND INITIAL ROUND OF CONVECTIVE SHOWERS HAVE DEVELOPED ALONG THE MOISTURE AXIS (PER MOIST CONVERGENCE PROCESSES) AND NOW PASSING THROUGH NORTHERN LOWER MICHIGAN ATTM. ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOPING UPSTREAM IN THE IOWA/WISCONSIN/ILLINOIS AREA SPURRED ON BY BETTER CONDITIONAL INSTABILITY ALOFT SPREADING EASTWARD OUT OF THE PLAINS AND EXPECTED TO IMPACT THE REGION LATER IN THE AFTERNOON THROUGH TONIGHT. PER RADAR TRENDS...INITIAL ROUND OF SHOWERS LOOKING TO PASS THROUGH NORTHERN LOWER MICHIGAN THROUGH EARLY AFTERNOON WITH THE HEAVIEST QPF FALLING OVER THE SE QUARTER OF THE CWA. SFC TEMPS ACROSS THIS AREA STILL AT OR BELOW FREEZING PARTICULARLY OVER THE HIGHER TERRAIN. A BIT ON THE FENCE WITH THIS ONE...BUT SPOTTER REPORTS FROM GRAND RAPIDS CWA INDICATE SOME ROADWAY ICING OCCURRING IN COUNTIES JUST UPSTREAM AND THE SAME IS LIKELY TO OCCUR UP THROUGH HTL/WEST BRANCH/GLADWIN...ETC. AFTER TALKING IT OVER WITH GRAND RAPIDS OFFICE DECIDED TO ISSUE A FREEZING RAIN ADVISORY VALID THROUGH EARLY AFTERNOON TO HANDLE THIS FIRST ROUND OF SHOWERS. NO OTHER CHANGES MADE FOR THE REST OF THE AFTERNOON AND THIS EVENING. NEXT ROUND OF SHOWERS AND POSSIBLE THUNDER LOOKING TO ARRIVE LATER IN THE AFTERNOON AND PARTICULARLY TONIGHT AS THE COLD FRONT PRESSES IN FROM THE WEST. BASICALLY...LOOKS WET WITH STRONG FORCING/IMPRESSIVE MOIST INFLOW UP INTO THE STATE - PWATS RUNNING 400 PERCENT OF NORMAL AS NOTED BY MIDNIGHT SHIFT. ADAM && .AVIATION...ISSUED AT 720 AM EDT. A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .APX WATCHES/WARNINGS/ADVISORIES...FREEZING RAIN ADVISORY... UNTIL 5 PM...MIZ029-030-034>036-041-042 && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 144 PM EDT WED MAR 21 2007 .AVIATION...AN INTERESTING SITUATION AS THE WARM FRONT IS STILL HUNG UP ALONG THE INDIANA/OHIO BORDER. BECAUSE OF THIS, THERE IS A SIZABLE SFC BASED INVERSION THAT WILL CONTINUE THROUGH 12Z THURSDAY WHEN THE COLD FRONT MOVES THROUGH. THE WARM FRONT IS CAUSING LOW LEVEL WIND SHEAR THAT THE KAPX RADAR IS PEGGING AROUND 35 KTS AROUND 1500 FT. THE MODELS SHOW THAT A LOW LEVEL JET MOVES THROUGH AHEAD OF THE COLD FRONT AND BRINGS IN THE POSSIBILITY OF 50+KTS OVERNIGHT AROUND 1500 TO 2000 FEET. OTHERWISE, THE THUNDERSTORMS LOOK TO BE TIMED MORE WITH THE COLD FRONT PASSING THROUGH THE REGION. SO HAVE THE THUNDERSTORMS IN THE HOURS JUST PRIOR TO FROPA. SFC TEMPERATURES ARE ABOVE FREEZING AT THE TAF SITES SO IT LOOKS LIKE AT THE SFC THE FREEZING RAIN IS NO LONGER AN ISSUE. && .UPDATE...ISSUED 1121 AM. OCCLUDED LOW PRESSURE SYSTEM MOVING INTO WESTERN ONTARIO THIS MORNING. ASSOCIATED OCCLUDED FRONT EXTENDS TO A TRIPLE POINT LOW OVER SOUTH DAKOTA...WARM FRONT STRETCHING SE INTO THE OHIO VALLEY. STRONG WARM/MOIST ADVECTION UNDERWAY ACROSS THE WESTERN GREAT LAKES ALONG AND AHEAD OF THE WARM FRONT. 12Z APX SOUNDING REVEALING ABOVE FREEZING WARM NOSE BETWEEN 940 AND 740 MB WITH A MAX TEMP OF +5C WITHIN THE LAYER...A +6C CHANGE IN THE LAST 12 HOURS. LOW LEVEL MOISTURE GRADIENT SITTING BETWEEN APX AND GRB PER 12Z SOUNDINGS AND INITIAL ROUND OF CONVECTIVE SHOWERS HAVE DEVELOPED ALONG THE MOISTURE AXIS (PER MOIST CONVERGENCE PROCESSES) AND NOW PASSING THROUGH NORTHERN LOWER MICHIGAN ATTM. ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOPING UPSTREAM IN THE IOWA/WISCONSIN/ILLINOIS AREA SPURRED ON BY BETTER CONDITIONAL INSTABILITY ALOFT SPREADING EASTWARD OUT OF THE PLAINS AND EXPECTED TO IMPACT THE REGION LATER IN THE AFTERNOON THROUGH TONIGHT. PER RADAR TRENDS...INITIAL ROUND OF SHOWERS LOOKING TO PASS THROUGH NORTHERN LOWER MICHIGAN THROUGH EARLY AFTERNOON WITH THE HEAVIEST QPF FALLING OVER THE SE QUARTER OF THE CWA. SFC TEMPS ACROSS THIS AREA STILL AT OR BELOW FREEZING PARTICULARLY OVER THE HIGHER TERRAIN. A BIT ON THE FENCE WITH THIS ONE...BUT SPOTTER REPORTS FROM GRAND RAPIDS CWA INDICATE SOME ROADWAY ICING OCCURRING IN COUNTIES JUST UPSTREAM AND THE SAME IS LIKELY TO OCCUR UP THROUGH HTL/WEST BRANCH/GLADWIN...ETC. AFTER TALKING IT OVER WITH GRAND RAPIDS OFFICE DECIDED TO ISSUE A FREEZING RAIN ADVISORY VALID THROUGH EARLY AFTERNOON TO HANDLE THIS FIRST ROUND OF SHOWERS. NO OTHER CHANGES MADE FOR THE REST OF THE AFTERNOON AND THIS EVENING. NEXT ROUND OF SHOWERS AND POSSIBLE THUNDER LOOKING TO ARRIVE LATER IN THE AFTERNOON AND PARTICULARLY TONIGHT AS THE COLD FRONT PRESSES IN FROM THE WEST. BASICALLY...LOOKS WET WITH STRONG FORCING/IMPRESSIVE MOIST INFLOW UP INTO THE STATE - PWATS RUNNING 400 PERCENT OF NORMAL AS NOTED BY MIDNIGHT SHIFT. ADAM && .AVIATION...ISSUED AT 720 AM EDT. A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .APX WATCHES/WARNINGS/ADVISORIES...FREEZING RAIN ADVISORY...UNTIL 2 PM...MIZ028>030-033>036-041-042. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1121 AM EDT WED MAR 21 2007 .UPDATE...OCCLUDED LOW PRESSURE SYSTEM MOVING INTO WESTERN ONTARIO THIS MORNING. ASSOCIATED OCCLUDED FRONT EXTENDS TO A TRIPLE POINT LOW OVER SOUTH DAKOTA...WARM FRONT STRETCHING SE INTO THE OHIO VALLEY. STRONG WARM/MOIST ADVECTION UNDERWAY ACROSS THE WESTERN GREAT LAKES ALONG AND AHEAD OF THE WARM FRONT. 12Z APX SOUNDING REVEALING ABOVE FREEZING WARM NOSE BETWEEN 940 AND 740 MB WITH A MAX TEMP OF +5C WITHIN THE LAYER...A +6C CHANGE IN THE LAST 12 HOURS. LOW LEVEL MOISTURE GRADIENT SITTING BETWEEN APX AND GRB PER 12Z SOUNDINGS AND INITIAL ROUND OF CONVECTIVE SHOWERS HAVE DEVELOPED ALONG THE MOISTURE AXIS (PER MOIST CONVERGENCE PROCESSES) AND NOW PASSING THROUGH NORTHERN LOWER MICHIGAN ATTM. ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOPING UPSTREAM IN THE IOWA/WISCONSIN/ILLINOIS AREA SPURRED ON BY BETTER CONDITIONAL INSTABILITY ALOFT SPREADING EASTWARD OUT OF THE PLAINS AND EXPECTED TO IMPACT THE REGION LATER IN THE AFTERNOON THROUGH TONIGHT. PER RADAR TRENDS...INITIAL ROUND OF SHOWERS LOOKING TO PASS THROUGH NORTHERN LOWER MICHIGAN THROUGH EARLY AFTERNOON WITH THE HEAVIEST QPF FALLING OVER THE SE QUARTER OF THE CWA. SFC TEMPS ACROSS THIS AREA STILL AT OR BELOW FREEZING PARTICULARLY OVER THE HIGHER TERRAIN. A BIT ON THE FENCE WITH THIS ONE...BUT SPOTTER REPORTS FROM GRAND RAPIDS CWA INDICATE SOME ROADWAY ICING OCCURRING IN COUNTIES JUST UPSTREAM AND THE SAME IS LIKELY TO OCCUR UP THROUGH HTL/WEST BRANCH/GLADWIN...ETC. AFTER TALKING IT OVER WITH GRAND RAPIDS OFFICE DECIDED TO ISSUE A FREEZING RAIN ADVISORY VALID THROUGH EARLY AFTERNOON TO HANDLE THIS FIRST ROUND OF SHOWERS. NO OTHER CHANGES MADE FOR THE REST OF THE AFTERNOON AND THIS EVENING. NEXT ROUND OF SHOWERS AND POSSIBLE THUNDER LOOKING TO ARRIVE LATER IN THE AFTERNOON AND PARTICULARLY TONIGHT AS THE COLD FRONT PRESSES IN FROM THE WEST. BASICALLY...LOOKS WET WITH STRONG FORCING/IMPRESSIVE MOIST INFLOW UP INTO THE STATE - PWATS RUNNING 400 PERCENT OF NORMAL AS NOTED BY MIDNIGHT SHIFT. ADAM && .AVIATION...ISSUED AT 720 AM EDT. A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .AVIATION....VFR CONDITIONS WILL PERSIST THROUGH THE REMAINDER OF TONIGHT...AS SOME HIGHER LEVEL CLOUDS WILL INVADE THE REGION FOR THE OVERNIGHT HOURS. SOUTH TO SOUTHEAST WINDS JUST ABOVE THE SURFACE WILL CONTINUE TO INCREASE...REACHING 30 KNOTS AOA 2KFT BY 06-08Z...RESULTING IN WIND SHEAR...UNTIL MIXING BEGINS DURING THE EARLY MORNING HOURS TOMORROW. AT THE SAME TIME...LOOK FOR CLOUDS THICKEN UP AROUND THE TVC AREA...DESCENDING INTO THE MVFR CATEGORY AS A WARM FRONT APPROACHES FROM THE SW. TEMPORARY LIGHT RAIN IS POSSIBLE BY 16Z IN TVC...AND ACROSS THE APN REGION BY 18-19Z...WHILE PLN LOOKS TO HAVE THE LEAST CHANCE AT THIS POINT. THE WARM FRONT WILL PASS THROUGH LATE TOMORROW AFTERNOON AND EVENING...AND LOOKS TO GET HELD UP ACROSS NRN LOWER MICHIGAN...RESULTING IN PREDOMINANT MVFR CEILINGS AOA 2KFT WITH SCATTERED LIGHT RAIN SHOWERS. A COLD FRONT WILL PUSH THROUGH BY THURSDAY MORNING....AND WILL BE ASSOCIATED WITH A BAND OF SHOWERS WITH THE POTENTIAL FOR ISOLATED THUNDERSTORMS. SMD && .APX WATCHES/WARNINGS/ADVISORIES...FREEZING RAIN ADVISORY...UNTIL 2 PM...MIZ028>030-033>036-041-042. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 720 AM EDT WED MAR 21 2007 .AVIATION...A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .AVIATION....VFR CONDITIONS WILL PERSIST THROUGH THE REMAINDER OF TONIGHT...AS SOME HIGHER LEVEL CLOUDS WILL INVADE THE REGION FOR THE OVERNIGHT HOURS. SOUTH TO SOUTHEAST WINDS JUST ABOVE THE SURFACE WILL CONTINUE TO INCREASE...REACHING 30 KNOTS AOA 2KFT BY 06-08Z...RESULTING IN WIND SHEAR...UNTIL MIXING BEGINS DURING THE EARLY MORNING HOURS TOMORROW. AT THE SAME TIME...LOOK FOR CLOUDS THICKEN UP AROUND THE TVC AREA...DESCENDING INTO THE MVFR CATEGORY AS A WARM FRONT APPROACHES FROM THE SW. TEMPORARY LIGHT RAIN IS POSSIBLE BY 16Z IN TVC...AND ACROSS THE APN REGION BY 18-19Z...WHILE PLN LOOKS TO HAVE THE LEAST CHANCE AT THIS POINT. THE WARM FRONT WILL PASS THROUGH LATE TOMORROW AFTERNOON AND EVENING...AND LOOKS TO GET HELD UP ACROSS NRN LOWER MICHIGAN...RESULTING IN PREDOMINANT MVFR CEILINGS AOA 2KFT WITH SCATTERED LIGHT RAIN SHOWERS. A COLD FRONT WILL PUSH THROUGH BY THURSDAY MORNING....AND WILL BE ASSOCIATED WITH A BAND OF SHOWERS WITH THE POTENTIAL FOR ISOLATED THUNDERSTORMS. SMD && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 410 AM EDT WED MAR 21 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW EXPANDING UPR RDG OVER THE GRT LKS BTWN DEPARTING TROF OVER ERN NAMERICA AND TROFFING OVER THE W. DRY/STABLE AIRMASS SHOWN ON 00Z GRB/APX RAOBS ON THE WRN FLANK OF HI PRES MOVING THRU SE CAN HAS BROUGHT A DRY EVNG TO THE FA...BUT STRENGTHENING PRES GRADIENT BTWN DEPARTING HI AND LO PRES TROF IN THE WRN PLAINS THAT HAS DVLPD DOWNSTREAM OF STRG SHRTWV MOVING INTO THE PAC NW/SW CAN HAS CAUSED S WINDS TO INCRS TO GALE FORCE AT STANNARD ROCK LIGHTHOUSE. SOME PLACES ALG THE LK SUP SHORE SHOW S WIND GUSTS TO 35 MPH AS WELL. ALTHOUGH ONLY MID CLD HAVE DVLPD OVER THE FA IN THIS RETURN FLOW THRU MIDNGT AND DESPITE LINGERING SFC-H8 DRY AIR SHOWN ON THE 00Z INL SDNG...SCT ELEVATED -TSRA HAVE DVLPD OVER NE MN UNDER SUBTLE H5 THERMAL TROF ASSOCIATED WITH WEAK SHRTWV DEPICTED ON RUC ANALYSIS AND AT NOSE OF STRONGEST H85-7 SW WINDS (00Z H85/7 WIND SPEED 60KT/50KT AT INL)/H7 WAD/AREA OF H85-5 QVECTOR CNVGC/GREATEST H7-5 DIFFERENTIAL TEMP ADVCTN AND STEEPEST LAPSE RATES (RUC SHOWS H7-5 LAPSE RATE IN THIS AREA AOA 7C/KM). MOST NMRS -SHRA/-TSRA APPEAR TO BE MOVING INTO ONTARIO... BUT SCT -SHRA/FEW LTG STRIKES ARE MAKING PROGRESS TOWARD THE WRN ZNS. UPDATE AT 245 AM...CLUSTER OF SHRA/EMBEDDED TS WITH SML HAIL REPORTED IS BRUSHING THE NW ZNS. CONSIDERING POTENTIAL FOR HEAVIER RA UNDER THE SHRA AND LO TEMPS/DWPTS IN PLACE...OPTED TO ISSUE FZRA ADVY FOR ONTONAGON COUNTY AS WELL AS NRN CMX/KEWEENAW COUNTIES. MAIN FCST CONCERNS THE NEXT FEW DAYS ARE SHRA/TSRA CHCS AND RAINFALL AMTS...MAINLY ASSOCIATED WITH STRG SHRTWV NOW MOVING TOWARD THE NRN ROCKIES. FZRA OVER TH NW OF PRIMARY SHORT TERM FOCUS. CURRENT RADAR TRENDS SHOWING BULK OF -SHRA/-TSRA MOVING INTO ONTARIO IN GOOD AGREEMENT WITH RUC FCST TRACK OF AXIS OF STRONGEST H85-7 WINDS/GREATEST H7-5 LAPSE RATES/H85-5 QVECTOR CVNGC ASSOCIATED WITH WEAK SHRTWV. BUT MODEL INDICATES H7-5 LAPSE RATES OVER THE W HALF OR SO OF THE FA WL INCRS TO 7C/KM BY 12Z...SO PLAN TO KEEP MENTION OF AT LEAST ISOLD SHRA/TS OVER THE W HALF EARLY THIS MRNG. SINCE THE KEWEENAW IS CLOSER TO THE DYNAMICS SWEEPING TO THE N...WL CARRY GREATER SCT COVG THERE AND MAINTAIN GOING FZRA ADVY UNTIL JUST AFT SUNRISE. WEAK SHEAR/MINIMAL POSITIVE AREA IN THE MOST UNSTABLE LYR SUG ANY POTENTIAL FOR SVR TSRA IS AT BEST MINUSCULE DESPITE SML HAIL REPORT. ONCE LLJ DEPARTS TO THE N AFT 12Z...GALES ON LK SUP WL GRDLY DIMINISH. SUSPECT PCPN CHCS WL ALSO DIMINISH WITH LOSS OF DIFFERENTIAL TEMP ADVCTN MECHANISM AND SINCE SHRTWV NOW MOVING INTO THE NRN ROCKIES IS FCST TO REACH ONLY NEAR BIS BY 00Z THU. IN FACT...FA IS FCST TO BE DOMINATED BY DEEPER QVECTOR DVGC SO FAR DOWNSTREAM OF THE SHRTWV. HOWEVER...PLAN TO INCRS POPS AGAIN BY THE AFTN ESPECIALLY ACRS THE SRN TIER AS GUIDANCE SHOWS WARM FNT TO THE S AND SHRTWV NOW APRNT OVER NEBRASKA APRCHG FM THE SW. WL SPREAD THESE POPS GRDLY N LATER...BUT HIEST POPS SHOULD REMAIN TO THE S CLOSER TO SHRTWV TRACK. OTRW...DESPITE CLDY SKIES ASSOCIATED WITH INCRSG SPECIFIC HUMIDITY FCST ON THE 280K ISENTROPIC SFC/EXTENSIVE SC AREA TO THE SW EXPANDING NEWD INTO THE FA SW-NE... SUSPECT TEMPS WL RISE STEADILY OVER AT LEAST THE W...WHERE FLOW WL HAVE DOWNSLOPE COMPONENT. SLY FLOW OFF LK MI SHOULD TEND TO MINIMIZE TEMP RECOVERY OVER THE E. FOR TNGT...VERY GOOD MODEL AGREEMENT SHOWING POTENT SHRTWV MOVING TO NEAR ISLE ROYALE BY 12Z THU. GUIDANCE ALSO SHOWS BEST DPVA/H85-5 QVECTOR CNVGC GOING TO THE N ON CYC SIDE OF THE TRACK OF THIS FEATURE. BUT EVEN THOUGH THE FA WL BE INFLUENCED BY ONLY THE COMMA TAIL OF THIS FEATURE...ACCOMPANYING SHARP FNT/H85-7 FGEN FORCG INTERACTION WITH PWAT AOA 1 INCH AND RATHER IMPRESSIVE INSTABILITY (GFS SHOWS SSI AS LO AS -4 OVER THE SCNTRL) SHOULD BE ENUF TO MAINTAIN CATEGORICAL POPS. IN FACT...MODIFIED GFS FCST SDNG FOR ISQ AT 06Z (TO COOL THE MID LVLS A BIT MORE THAN FCST) SHOWS CAPE OF 1175 J/KG LIFTING FM H85. SHEAR IN UNSTABLE LYR IS RATHER UNIMPRESSIVE...BUT FCST MID LVL DRYING IN JET SURGE REGION TO THE S OF SHRTWV TRACK ABV WITH THE LOWER LEVEL MOISTENING RAISES THE POTENTIAL FOR AN ISOLD SVR HAIL STORM (WBZ FCST JUST ABV 9K FT). ALTHOUGH INSTABILITY IS NOT AS IMPRESSIVE OVER THE NW...THESE AREAS WL BE CLOSER TO THE SHRTWV TRACK/BETTER DPVA AND DEEP LYR H85-3 QVECTOR CNVGC/SOME UPR DVGC IN RRQ OF SUPPORTING H3 JET MAX THAT LIFTS INTO ONTARIO OVERNGT. OTRW...COLD FNT IS FCST TO SWEEP ACRS THE FA OVERNGT. PER NCEP PREFERENCE...BLENDED FASTER NAM WITH SLOWER GFS TO TIME FROPA. CONSIDERING THE TRACK OF THE SHRTWV/SPEED OF THE FROPA...THINK HVY RA THREAT HAS DIMINISHED A BIT EVEN THOUGH SOME LOCALLY HVY RA WL NO DOUBT FALL UNDER THE DEEPER CNVCTN. OTRW... STRG WNW WINDS WL DVLP BEHIND THE FNT WITH GFS FCST H9 WIND UP TO 40 KT AT STANNARD ROCK BY 12Z THU. EXPECT GALES OVER ALL OF LK SUP. ALTHOUGH COLDER AIR WL FOLLOW INTO THE UPR LKS...FCST H85 TEMPS TO -8C AT CMX (NR INVRN BASE) AND QUICK INFLUX OF VERY DRY AIR SUG LES WL NOT BE SGNFT. GOING FLURRIES FCST APPEARS ON TRACK. ANY LINGERING SHRA OVER THE E AND FLURRIES OVER THE NCNTRL WL END THU MRNG WITH STRG WNW WINDS DRIVING DRIER AIR INTO THE FA. OTRW... LOOK FOR BLUSTERY WINDS TO DIMINISH GRDLY WITH ARPCH OF HI PRES RDG LATER IN THE DAY. MIXING TO H85 ON GFS FCST SDNGS SUPPORTS SIMILAR GFS/ETA MOS FOR THU HI TEMPS. BUMPED UP FCST LO TEMPS A BIT THU NGT WITH EXPECTATION OF INCRS IN MID/HI CLD IN ADVANCE OF SHRTWV GFS/ UKMET SHOW MOVING TOWARD THE UPR GRT LKS. HOWEVER...TEMPS OVER THE INTERIOR SHOULD FALL QUICKLY IN THE EVNG WITH LGT WINDS BEFORE CLDS INCRS LATER. MODELS SHOW UNCERTAINTY IN REGARD TO TIMING OF SHRTWV PASSAGE FRI/FRI NGT...SO FEW CHGS MADE TO WX THIS TIME PD. GENERAL SW FLOW AHEAD OF INCOMING SHRTWV/SFC TROUGH ON FRI WL DISCOURAGE LK MODERATION EXCEPT OVER THE ERN ZNS DOWNWIND OF LK MI. COORDINATED WITH GRB. && .MQT WATCHES/WARNINGS/ADVISORIES... FREEZING RAIN ADVISORY UNTIL 8 AM EDT FOR MIZ001>003. GALE WARNING LAKE SUPERIOR. && $$ KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 340 AM EDT WED MAR 21 2007 .DISCUSSION...HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .AVIATION....VFR CONDITIONS WILL PERSIST THROUGH THE REMAINDER OF TONIGHT...AS SOME HIGHER LEVEL CLOUDS WILL INVADE THE REGION FOR THE OVERNIGHT HOURS. SOUTH TO SOUTHEAST WINDS JUST ABOVE THE SURFACE WILL CONTINUE TO INCREASE...REACHING 30 KNOTS AOA 2KFT BY 06-08Z...RESULTING IN WIND SHEAR...UNTIL MIXING BEGINS DURING THE EARLY MORNING HOURS TOMORROW. AT THE SAME TIME...LOOK FOR CLOUDS THICKEN UP AROUND THE TVC AREA...DESCENDING INTO THE MVFR CATEGORY AS A WARM FRONT APPROACHES FROM THE SW. TEMPORARY LIGHT RAIN IS POSSIBLE BY 16Z IN TVC...AND ACROSS THE APN REGION BY 18-19Z...WHILE PLN LOOKS TO HAVE THE LEAST CHANCE AT THIS POINT. THE WARM FRONT WILL PASS THROUGH LATE TOMORROW AFTERNOON AND EVENING...AND LOOKS TO GET HELD UP ACROSS NRN LOWER MICHIGAN...RESULTING IN PREDOMINANT MVFR CEILINGS AOA 2KFT WITH SCATTERED LIGHT RAIN SHOWERS. A COLD FRONT WILL PUSH THROUGH BY THURSDAY MORNING....AND WILL BE ASSOCIATED WITH A BAND OF SHOWERS WITH THE POTENTIAL FOR ISOLATED THUNDERSTORMS. SMD && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 935 AM CDT THU MAR 22 2007 .SHORT TERM...LATEST SATELLITE IMAGERY SHOWS THE REGION UNDER AN UPPER RIDGE...WHICH IS CONTINUING OUR LONG ROUND OF DRY WEATHER. SHOULD GET SOME SCATTERED CLOUDS MOSTLY IN THE FORM OF HIGH LEVEL CLOUDS FOR THIS AFTERNOON. THE FOG HAS LIFTED OVER OUR THE SOUTHEAST ZONES...SO HAVE ALLOWED THE DENSE FOG ADVISORY TO EXPIRE. CURRENT HIGHS IN THE LOWER 80S SEEMS TO BE ON TRACK. SO WILL MAKE NO OTHER CHANGES TO THE ZONES./17/ .AVIATION...PATCHES OF LIFR CIGS/VSBY WILL BE POSSIBLE IN AREAS ALONG AND S OF HIGHWAY 84 FOR FRIDAY MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME AREAWIDE BY 15Z FRIDAY./17/ .PREVIOUS DISCUSSION... TODAY THROUGH FRIDAY...GRADIENT WINDS HAVE CONTINUED OVER MUCH OF CWA THIS MORNING WITH THE EXCEPTION OF SOUTHEAST MISSISSIPPI LAST HOUR. PINE BELT AIRPORT WAS REPORTING VISIBILITY RESTRICTIONS ALREADY. WL CONTINUE TO MONITOR OUR SOUTHEAST ZONES FOR AN ADVISORY AGAIN THIS MORNING...BUT CURRENTLY EXPECTING ANY DENSE FOG DEVELOPMENT TO REMAIN PATCHY. ELSE...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH FRIDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL BUILD INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW DROPPING SOUTH OFF THE SOUTHERN CALIFORNIA COAST. THIS LOW IS PROGGED TO MOVE OVER BAJA DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. SOME MID AND HIGH LEVEL CLOUDS WILL SPREAD OVERHEAD FROM THE WEST BUT WL STILL REACH WELL ABOVE NORMAL...AROUND 80 DEGREES THIS AFTERNOON AND FRIDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ FRIDAY NIGHT THROUGH NEXT WEEK... THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA THIS WEEKEND...TENDING TO DEFLECT ANY POTENTIAL SHORTWAVE TROUGHS. WITH THAT IN MIND...THE GFS SEEMS A LITTLE TOO QUICK IN INCREASING RAIN CHANCES SUNDAY AND SUNDAY NIGHT AND WILL KEEP THE FORECAST DRY. BY MONDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION... THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. THE MID LEVEL RIDGE REBUILDS OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER FOR THE FORECAST AREA. THERE ARE INDICATIONS THAT A MORE ACTIVE PATTERN COULD TAKE SHAPE OVER THE LOWER MS VALLEY REGION NEXT WEEKEND AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS. THE GFS/UKMET/ECMWF ARE ALL IN AGREEMENT ON THIS SCENARIO...BUT PERSISTENCE CERTAINLY ARGUES AGAINST IT. /EC/ .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 230 AM CDT THU MAR 22 2007 .DISCUSSION... TODAY THROUGH FRIDAY...GRADIENT WINDS HAVE CONTINUED OVER MUCH OF CWA THIS MORNING WITH THE EXCEPTION OF SOUTHEAST MISSISSIPPI LAST HOUR. PINE BELT AIRPORT WAS REPORTING VISIBILITY RESTRICTIONS ALREADY. WL CONTINUE TO MONITOR OUR SOUTHEAST ZONES FOR AN ADVISORY AGAIN THIS MORNING...BUT CURRENTLY EXPECTING ANY DENSE FOG DEVELOPMENT TO REMAIN PATCHY. ELSE...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH FRIDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL BUILD INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW DROPPING SOUTH OFF THE SOUTHERN CALIFORNIA COAST. THIS LOW IS PROGGED TO MOVE OVER BAJA DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. SOME MID AND HIGH LEVEL CLOUDS WILL SPREAD OVERHEAD FROM THE WEST BUT WL STILL REACH WELL ABOVE NORMAL...AROUND 80 DEGREES THIS AFTERNOON AND FRIDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ FRIDAY NIGHT THROUGH NEXT WEEK... THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA THIS WEEKEND...TENDING TO DEFLECT ANY POTENTIAL SHORTWAVE TROUGHS. WITH THAT IN MIND...THE GFS SEEMS A LITTLE TOO QUICK IN INCREASING RAIN CHANCES SUNDAY AND SUNDAY NIGHT AND WILL KEEP THE FORECAST DRY. BY MONDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION... THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. THE MID LEVEL RIDGE REBUILDS OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER FOR THE FORECAST AREA. THERE ARE INDICATIONS THAT A MORE ACTIVE PATTERN COULD TAKE SHAPE OVER THE LOWER MS VALLEY REGION NEXT WEEKEND AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS. THE GFS/UKMET/ECMWF ARE ALL IN AGREEMENT ON THIS SCENARIO...BUT PERSISTENCE CERTAINLY ARGUES AGAINST IT. /EC/ && .AVIATION...PATCHES OF LIFR CIG/VSBY WILL BE POSSIBLE IN AREAS ALONG AND S OF HIGHWAY 84 THIS MORNING AND AGAIN FRIDAY MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME AREAWIDE BY 15Z EACH MORNING. /22/ && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 800 PM CDT WED MAR 21 2007 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... COLD FRONT HAS MOVED INTO SOUTHEASTERN NEBRASKA AND NORTH CENTRAL KANSAS WITH A LINE OF THUNDERSTORMS DEVELOPING ALONG THE FRONT FROM NEAR CONCORDIA NORTHEAST TO SOUTH OF OMAHA. REPORTS FROM OAX INDICATED NUMEROUS THREE QUARTER TO ONE AND ONE QUARTER HAIL REPORTS WITH THIS LINE. MLCAPES AROUND 1500-2000 J/KG...STEEP MID LEVEL LAPSE RATES AND SFC-6KM SHEAR FROM 30-40 KNOTS WILL CONTINUE TO SUPPORT THE THREAT OF HAIL AS THE THUNDERSTORMS MOVE EAST INTO EXTREME NORTHWEST MISSOURI. THE LINE OF THUNDERSTORMS WILL CONTINUE TO MOVE SOUTH AND EAST THROUGH THE NIGHT WITH THE SEVERE WEATHER THREAT GRADUALLY DIMINISHING. LATEST RUC AND NAM SUGGEST THAT THE CAP OVER THE CWA WILL GRADUALLY ERODE...BUT WITH THE LACK OF INSOLATION...SBCAPE AND MUCAPE DROP TO 1000-1250 J/KG BETWEEN 09-12Z. SHEAR WILL REMAIN MARGINAL THROUGH THE NIGHT. THE LINE OF CONVECTION IS EXPECTED TO REACH A KANSAS CITY TO PRINCETON LINE BY 08Z. BY 12Z...ONLY SMALL HAIL IS EXPECTED. DB && .PREVIOUS DISCUSSION... 331 PM... VERY CHALLENGING FORECAST THROUGH THE EARLY PERIODS AS LARGE SCALE PATTERN CHANGE HAS PLACED THE LOWER MISSOURI VALLEY REGION IN A FAVORED AREA FOR REPEATED PRECIPITATION EVENTS. 19Z SURFACE ANALYSIS DEPICTS A SEASONABLY MOIST WARM SECTOR AIRMASS OVER THE CWA THIS AFTERNOON...CHARACTERIZED BY DEWPOINTS APPROACHING 60 DEGREES. RUC SOUNDINGS SHOW THAT AN ELEVATED MIXED LAYER WITH STEEP MID-LEVEL LAPSE RATES HAS OVERSPREAD THE REGION...LEAVING THE AREA CAPPED ABOVE AN EXTENSIVE STRATUS CANOPY. PACIFIC COLD FRONT/DRYLINE STRETCHED FROM NORFOLK TO KEARNEY NEBRASKA...AND PER VISIBLE SATELLITE IMAGERY HAS BEEN PRECEDED BY AN INTERESTING GRAVITY WAVE. SHORT MODEL PROGS COLLABORATE WELL WITH OBSERVATIONAL DATA...SHOWING THAT CONVECTION WILL LIKELY DEVELOP OVER SE NEBRASKA IN THE NEXT SEVERAL HOURS WHERE BETTER SURFACE CONVERGENCE IS FOCUSED ALONG THE ADVANCING FRONT AND JUST EAST OF THE ANALYZED SURFACE LOW. ATTENDANT SEVERE THREAT APPEARS TO BE PRIMARILY IN THE FORM OF DAMAGING LINE SEGMENTS WITH ATTENDANT LARGE HAIL AS STEEP MID LEVEL LAPSE RATES COUPLE WITH INCREASING UNIDIRECTIONAL SHEAR AFTER DARK. CERTAINLY STORMS MOVING TOWARD THE NORTHEAST WOULD HAVE THE GREATER THREAT FOR SEVERE. THE QUESTION REMAINS AS TO HOW LONG THE THREAT WILL PERSIST AFTER DARK...AND CURRENT THINKING IS THAT IT MAY TAKE SOME TIME FOR CONVECTION TO WIND DOWN AS LOW LEVEL INSTABILITY IS MAINTAINED BY A WELL MIXED BOUNDARY LAYER AND EXTENSIVE CLOUD COVER. INCREASED LIKELIHOOD OF SEVERE WEATHER REMAINS PRIMARY FOCUSED IN AREAS NORTH AND WEST OF A KANSAS CITY TO TRENTON LINE. SURFACE FRONT WILL BEGIN TO STALL SOMEWHERE ALONG EAX/SGF CWA BORDER TOMORROW MORNING...AND WAFFLE OVER THE NEXT SEVERAL DAYS AS A SERIES OF MID LEVEL DISTURBANCES ARE EJECTED FROM A DEEP UPPER LOW ENTRENCHED IN THE BAJA. VERY UNUSUAL FLOW PATTERN FOR THIS TYPE OF YEAR...BUT THE QUALITY AND DEPTH OF MOISTURE THAT PERSISTS THROUGH THE WEEKEND CERTAINLY RAISES A RED FLAG THAT CUMULATIVE RAINFALL TOTALS COULD LEAD TO FLOODING BY THE WEEKEND. EVEN MORE CHALLENGING WILL BE THE TEMPERATURES AS THE QUASI-STATIONARY BOUNDARY COULD LEAD TO LARGE ERRORS DEPENDING ON ITS DAY TO DAY PLACEMENT AND PROPAGATION. WHERE PERIODIC SUNSHINE IS ABLE TO MANIFEST BETWEEN THESE SYSTEMS...RAPID WARMING INTO THE UPPER 60S-MID 70S COULD OCCUR GIVEN BALMY MID LEVEL TEMPERATURES BENEATH WEAK 500MB RIDGING AND SOUTHWEST UPPER FLOW. EQUALLY POSSIBLE ARE HIGHS IN THE 50S WHERE MCS INDUCED PRECIPITATION/CLOUD DEBRIS KEEP READINGS NEARLY WET BULBED. BOOKBINDER VERY LITTLE CHANGE TO PREVIOUS THINKING REGARDING THE PROGRESS OF THE CLOSED BAJA LOW INTO THE CNTRL CONUS THIS WEEKEND. ECMWF STILL REMAINS THE MODEL OF CHOICE...ALTHOUGH THE OPERATIONAL GFS AND GFS ENSEMBLES HAVE STEADILY BEEN TRENDING TOWARDS THIS SOLUTION THE PAST SEVERAL RUNS. BEFORE THE MAIN BRUNT OF MIDLEVEL ENERGY EJECTS TOWARDS THE REGION LATE SUNDAY...NUMEROUS WEAK SHORTWAVES WILL RIDE OVER THE RIDGE AXIS WHOSE WRN PERIPHERY SHOULD ALIGN ALONG THE LOWER MISSOURI RIVER VALLEY. EACH PASSING SHORTWAVE WILL INVIGORATE LIFT ASSOCIATED WITH WAA ABOVE THE BOUNDARY LAYER...AND LEAD TO SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS. HAVE TRIMMED POPS SLIGHTLY FOR THE SAT NIGHT TIME PERIOD AS SFC AND LOW LEVEL FRONT APPEARS AS IF IT WILL LIFT NORTH OF MISSOURI KEEPING FOCUSING MECHANISM FURTHER NORTH OF THE AREA. SOME CONCERN THAT PRE-EXISTING CONVECTION GENERATED OVER THE HIGH PLAINS WILL DRIFT INTO THE AREA ASSISTED BY A STRENGTHENING NOCTURNAL LLJ...SO HAVE CONTINUED A 30-40 PERCENT POP RANGE. MODELS CONTINUE TO ADVERTISE THE POSSIBILITY OF A POTENT WEATHER SCENARIO FOR SUNDAY. AS WITH PREVIOUS MODEL RUNS...ECMWF LIFTS THE UPPER WAVE A LITTLE FURTHER WEST OF THE AREA SHEARED MORE SO OVER THE RIDGE AXIS. REGARDLESS...AS THE WAVE EJECTS INTO THE CNTRL PLAINS...INCREASING H5/H7 LAPSE RATES IN EXCESS OF 6C/KM WILL ADVECT INTO THE AREA OVERTOP OF INCREASING MODIFIED GULF MOISTURE LEADING TO HEIGHTENED INSTABILITY WITH MUCAPES FORECAST AOA 1000 J/KG. AT THE SAME TIME...STRENGTHENING WINDS ALOFT WILL LEAD TO 0-6KM BULK SHEAR VECTORS AOA 50KT WITH THE REGION SITUATED UNDER THE FAVORABLE LEFT FRONT EXIT REGION OF A 90+ KT UPPER JET. OTHER THAN THE UPPER WAVE AND LOW LEVEL FOCUSING MECHANISM PLACEMENT...MAIN UNCERTAINTY APPEARS TO BE TIED TO ANY MORNING CONVECTION CONTAMINATING THE MODIFIED AIRMASS PROHIBITING FULL AFTERNOON DESTABILIZATION. AFTER THE UPPER WAVE MOVES NORTHEAST OF THE AREA INTO THE GREAT LAKES...A SFC FRONT WILL SAG THROUGH THE AREA...HOWEVER ONCE AGAIN STALL JUST SOUTH OF THE FORECAST AREA AS ANOTHER LARGE CHUNK OF ENERGY ESTABLISHES A LONGWAVE TROUGH OVER THE WRN CONUS. PREFER A SOLUTION SLOWER THAN THE OPERATIONAL GFS WHICH PUSHES THIS LONGWAVE FEATURE EAST INTO THE INTERMOUNTAIN REGION BY NEXT WEDNESDAY. FOLLOWED CLOSER TO THE GFS ENSEMBLE MEAN IN THIS RESPECT WHICH KEEPS THE AREA MAINLY DRY...ALBEIT QUITE WARM FOR THE END OF THE FORECAST PERIOD. 21 && .AVIATION... VFR CEILINGS ARE EXPECTED THIS EVENING WITH THE LINE OF CONVECTION REACHING STJ AROUND 07Z. THE CONVECTION WILL LAST LESS THAN 2 HOURS. AN ISOLATED STORM MAY BE MARGINALLY SEVERE WITH A HAIL THREAT. THE CEILINGS AND VISIBILITIES ARE EXPECTED TO BE MVFR...POSSIBLY VERY BRIEFLY IFR. THE THUNDERSTORMS WILL MOVE SOUTHEAST INTO THE KANSAS CITY AREA BETWEEN 08Z AND 10Z. ONCE THE THUNDERSTORMS MOVE SOUTHEAST OF THE AIRPORTS AND THE COLD FRONT MOVES THROUGH...VFR CEILINGS ARE EXPECTED AFTER 10Z AT STJ AND AFTER 12Z AT MKC AND MCI. ANOTHER ROUND OF THUNDERSTORMS IS POSSIBLE DURING THE AFTERNOON HOURS ON THURSDAY. DB && EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 945 AM MST THU MAR 22 2007 .SYNOPSIS... A STRONG PACIFIC LOW PRESSURE SYSTEM WAS LOCATED JUST OFF THE NORTHERN BAJA CALIFORNIA COAST THIS MORNING. IT WILL MOVE VERY SLOWLY EAST ACROSS NORTHERN MEXICO FRIDAY INTO SATURDAY. THIS STORM SYSTEM WILL BRING INCREASING CLOUDINESS...COOLER DAYTIME HIGHS...AND PERIODS OF SHOWERS AND THUNDERSTORMS TODAY THROUGH SATURDAY...WITH THE BEST CHANCE FOR PRECIPITATION OVER SOUTH-CENTRAL ARIZONA. HIGHER PRESSURE ALOFT FROM THE PACIFIC WILL BRING DRY WEATHER WITH SOME RECOVERY OF TEMPERATURES SUNDAY AND MONDAY. ANOTHER RATHER STRONG WEATHER DISTURBANCE WILL PRODUCE BREEZY TO WINDY CONDITIONS ALONG WITH SOME COOLING NEXT TUESDAY AND WEDNESDAY. && .SHORT TERM... TODAY THROUGH SATURDAY... 12Z POSITION OF CLOSED LOW WAS NEAR 30N/117W WITH SEVERAL VORTICITY CENTERS ROTATING AROUND ITS PERIMETER. NAM/GFS SOLUTIONS APPEARED TO BE SOMEWHAT SOUTH OF LATEST RUC...WITH ALL MODELS INDICATING THE STRONGEST VORT CENTER SOUTH OF THE LOW. THE 500MB WIND SPEEDS WERE ALSO STRONGEST AROUND THE SOUTHERN QUADRANTS OF THE LOW...50-70KTS. AFTER SUNRISE THE CONVECTION PICKED UP IN OUR CWA...AND CONTINUED TO DRIFT INTO YAVAPAI COUNTY. BY FAR THE HEAVIEST PRECIP WAS THROUGH SOUTHERN GILA COUNTY WHERE SPOTTERS/RAWS DATA REPORTED .30 TO .45 INCH UP TO 6 AM. SIGNIFICANT DIFFLUENCE WAS ALSO INDICATED ACROSS EASTERN AZ EARLIER TODAY. UPDATES ISSUED BY 8 AM TO COVER 88D TRENDS. WILL CONTINUE TO EXPECT STRONGEST LIFT AND LOWEST STABILITY INDICES AFTER 18Z FRIDAY...AND THAT FITS NICELY WITH OUR CURRENT FCSTS. ALTHOUGH LATEST NAM GIVES PHX A 24 HR PRECIP AMOUNT OF .38 INCH WE WILL STILL EXPECT GENERALLY LIGHTER AMOUNTS ACROSS ZONE 23. HOWEVER WE COULD SEE MUCH MORE...ACROSS ZONE 24...PER HPC OUTPUT. OUR WESTERN ZONES WILL STAY MUCH DIRER...WITH SOME PATCHY BLWG DUST TODAY. IN FACT ONE SHARP-EYED SPOTTER CALLED IN A REPORT OF BLOWING DUST NEAR A FARM FIELD WEST OF TONOPAH. MODEL TRENDS CONTINUE TO BE VERY CONSISTENT IN KEEPING THE CLOSED LOW OVER NRN MEX INTO FRIDAY NIGHT. BY 12Z SAT LATEST GFS CALLS FOR THE CENTER OF CIRCULATION TO LIFT OUT TO NEAR ABQ...WITH CSDRBL RH THROUGH A DEEP LAYER EVEN WEST OF PHX. UPPER RIDGE AND WARMER TEMPS WILL ALSO SPREAD ACROSS ENTIRE CWA FOR FRIDAY AND SATURDAY. && .LONG TERM... SATURDAY NIGHT THROUGH WEDNESDAY... WITH SLOWER EXIT OF THE SYSTEM AND POTENTIAL FOR MORE MOISTURE... ADDED SOME SLIGHT CHANCE POPS IN EASTERN PORTIONS OF THE FORECAST AREA SATURDAY NIGHT. THIS IS FOLLOWED BY RIDGE BUILDING FOR A QUICK WARMUP. IN THE LATTER PART OF THE EXTENDED...GFS AND ECWMF ARE SHOWING ANOTHER SYSTEM AFFECTING US. HOWEVER...IT LOOKS TO BE OF A DIFFERENT CHARACTER...MUCH LESS APT TO SLOW DOWN AND JOG SOUTHWARD. HOWEVER...THERE ARE SOME DIFFERENCES. THE GFS ENSEMBLE MEAN HAS A SIMILAR TRACK TO THE 12Z OPERATIONAL GFS...TAKING THE BULK OF THE SYSTEM JUST NORTH OF OUR AREA...BUT SHOWS LOWER HEIGHTS. THE ECMWF IS EVEN COOLER LOOKING THAN THE ENSEMBLE MEAN...AND A BIT SLOWER. THUS...UNDERCUT GFS-BASED TEMPERATURE GUIDANCE. TRAJECTORY OF THIS NEXT SYSTEM DOES NOT FAVOR MUCH IN THE WAY OF POPS...SO HELD OFF ON INTRODUCING ANY. IF ECMWF SOLUTION WINDS UP BEING CORRECT...THEN WE MIGHT NEED TO ADD SOME SLIGHT CHANCE POPS AT SOME POINT. ALSO...IF ECMWF SOLUTION PANS OUT...MIGHT NEED EVEN COOLER TEMPS. && .AVIATION... GENERALLY LGT SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH TODAY. WINDS IN THE 6 TO 12 THSD LAYER PROGGED TO REMAIN 180/22 THIS AFTERNOON...WITH MUCH STRONGER SPEEDS ALOFT. SOME GUSTY WINDS TO 35KTS OR SO STILL POSSIBLE IN THE KPHX AREA LATE THIS AFTERNOON AND INTO TONIGHT. WITH ADDITIONAL MOISTURE THROUGH A DEEP LAYER...WE COULD EASILY SEE LOWER CIGS LESS THAN 6-7 THSD FT. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EXPECT PERIODS OF WETTING RAINFALL OVER MUCH OF THE FORECAST AREA THURSDAY THROUGH SATURDAY...MAINLY OVER THE EASTERN ZONES...WITH THE HEAVIEST PRECIPITATION LIKELY OVER SOUTHERN GILA COUNTY AND THE RIM FRI AFTERNOON INTO SAT MORNING. DRY CONDITIONS RETURN TO THE WESTERN PORTION OF THE REGION BY SATURDAY AND THE REMAINDER OF THE FORECAST AREA BY SUNDAY. EARLY NEXT WEEK (MON NIGHT THROUGH TUE)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX 10 az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 1253 AM CDT FRI MAR 23 2007 .AVIATION... HIGH PRESSURE CONTINUES OVER THE SOUTHEAST UNITED STATES. THUNDERSTORMS ARE ONGOING IN OKLAHOMA WITH A SLOW EASTWARD PROGRESSION. EXPECT THUNDERSTORMS TO ONLY AFFECT NORTH ARKANSAS TOWARDS 12Z AND INTERMITTENTLY THROUGH 18Z. MVFR CONDITIONS ARE EXPECTED IN THE NORTH AND VFR ELSEWHERE. CEILINGS IN THE NORTH WILL DROP TO 2500 FT WITH VISIBILITIES DOWN TO 5SM. THE UPPER LEVEL DISTURBANCE TRIGGERING THE THUNDERSTORMS WILL MOVE NORTH OF THE AREA AROUND 18Z. DRY WEATHER IS THEN EXPECTED INTO SATURDAY. && .PREV DISCUSSION... /ISSUED 905 PM CDT THU MAR 22 2007/ UPDATE... SHORTWAVE EJECTING OUT OF THE SOUTHWEST CONUS UPPER LOW CONTINUES TO RIDE A STALLED OUT BOUNDARY WHICH IS POSITIONED ALONG THE NORTHERN EDGE OF MID LEVEL RIDGE BUILDING INTO THE REGION FROM GULF. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE TEXAS PANHANDLE IN RESPONSE IN AN AREA OF STRONG LIFT. NEW RUC13 AND NAM 12 KEEP AREA OF PRECIPITATION ACROSS FAR NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI OVERNIGHT. NAM12 AND WRF10 DO MOVE SOME PRECIPITATION ACROSS THE NORTHWEST PART OF THE LZK CWA AFTER 12Z BUT CONFIDENCE IS LOW THIS WILL DEVELOP AS OTHER SHORT RANGE MODELS INDICATE RIDGE BUILDING IN THE MID LEVELS THAT WILL KEEP PRECIPITATION OUT OF THE CWA. CURRENT DISTRIBUTION OF SMALL POPS OVER THE NORTHWEST PART OF THE CWA TONIGHT THROUGH PARTS OF FRIDAY LOOKS REASONABLE AND WILL BE LEFT IN PLACE. ONLY CHANGES TO ONGOING FORECAST WERE TO TWEAK SKY...DEW POINT AND RH GRIDS TO REFLECT CURRENT TRENDS. OVERNIGHT LOWS RAISED A TAD AS WELL. UPDATES OUT SHORTLY. PREV DISCUSSION... /ISSUED 629 PM CDT THU MAR 22 2007/ AVIATION... CLOUDS WILL CONTINUE TO MOVE IN FROM THE WEST WITH CEILINGS NEAR 7 THSD OR HIGHER. AREAS OF CEILINGS NEAR 35 HND WILL MOVE IN ARND 06Z. SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE NORTH AND WEST AFTER 08Z.(38) PREV DISCUSSION... /ISSUED 235 PM CDT THU MAR 22 2007/ SHORT TERM...TONIGHT THROUGH SUNDAY BLOCKING PATTERN STILL THE MAIN STORY IN THE SHORT TERM...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE GULF COAST. FRONT TO NORTH WILL TRY TO PUSH INTO ARKANSAS LATER TONIGHT/FRIDAY...BUT WILL STALL DUE TO THE HIGH AND SOUTHWEST WINDS ALOFT. EVEN SO...PUT SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS MAINLY IN AREAS NEAR THE ARKANSAS AND MISSOURI BORDER. FRONT WILL LIFT TO THE NORTH FRIDAY NIGHT/SATURDAY...WITH DRY AND WARM WEATHER TO START THE WEEKEND. LATE IN THE WEEKEND AND EARLY NEXT WEEK...LARGE STORM SYSTEM IN THE SOUTHWEST UNITED STATES WILL FINALLY ARRIVE...WITH HIGH PRESSURE SHIFTING SLOWLY TO THE EAST. BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST LATE SUNDAY INTO THE LONG TERM. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE PERIOD. (46) LONG TERM...SUNDAY NIGHT THROUGH THURSDAY REMNANTS OF A WEAKENING UPPER LOW WILL BE CROSSING ARKANSAS AS A SHORT WAVE. IT WILL BE JUST EAST OF THE STATE BY MIDDAY TUESDAY SINCE A LONG WAVE TROF WILL BE TRAVERSING THE INTERMOUNTAIN WEST ON TUESDAY. BY WEDNESDAY AFTERNOON IT WILL BE OVER THE NORTHERN PLAINS AND WEAKENING. THE SURFACE PATTERN WILL KEEP A SOUTHEAST OR SOUTH COMPONENT TO OUR WINDS THAT WILL PUMP MOISTURE NORTHWARD INTO THE PATH OF THE UPPER SYSTEM. WARMTH AND INSTABILITY WILL CAUSE SCATTERED CONVECTION TO DEVELOP SUNDAY NIGHT OVER NORTHWESTER SECTIONS. THEN...IT WILL KEEP ON MOVING EAST DURING THE DAY MONDAY. CONVECTION WILL BE OVER THE EASTERN HALF OF THE FORECAST AREA MONDAY NIGHT AND MOSTLY OUT OF THE STATE TUESDAY AFTERNOON AS THE SHORT WAVE DRIVING IT GOES ON BY ALOFT. WILL KEEP THE FORECAST DRY FROM TUESDAY NIGHT ON THROUGH THE END OF THE LONG TERM. THE UPPER SUPPORT FOR THE NEXT SYSTEM WILL BE SO FAR NORTH THAT DECIDED TO WAIT UNTIL THIS TREND GETS PICKED UP IN OTHER RUNS. NO CHALLENGE TO THE ABOVE NORMAL TRENDS WILL BE MADE DURING THIS PERIOD. (32) && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 56 76 58 76 / 20 10 10 20 CAMDEN AR 58 79 61 78 / 10 10 10 20 HARRISON AR 55 75 58 73 / 20 10 10 40 HOT SPRINGS AR 58 78 59 76 / 10 10 10 40 LITTLE ROCK AR 58 78 60 77 / 10 10 10 20 MONTICELLO AR 58 80 60 80 / 10 10 10 20 MOUNT IDA AR 57 78 59 75 / 10 10 10 40 MOUNTAIN HOME AR 54 75 56 75 / 20 10 10 40 NEWPORT AR 57 76 58 77 / 20 10 10 20 PINE BLUFF AR 59 79 61 78 / 10 10 10 20 RUSSELLVILLE AR 56 77 59 75 / 10 10 10 40 SEARCY AR 58 77 59 77 / 10 10 10 20 STUTTGART AR 59 78 60 78 / 10 10 10 20 && .LZK WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION...51 ar AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 905 PM CDT THU MAR 22 2007 .UPDATE... SHORTWAVE EJECTING OUT OF THE SOUTHWEST CONUS UPPER LOW CONTINUES TO RIDE A STALLED OUT BOUNDARY WHICH IS POSITIONED ALONG THE NORTHERN EDGE OF MID LEVEL RIDGE BUILDING INTO THE REGION FROM GULF. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE TEXAS PANHANDLE IN RESPONSE IN AN AREA OF STRONG LIFT. NEW RUC13 AND NAM 12 KEEP AREA OF PRECIPITATION ACROSS FAR NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI OVERNIGHT. NAM12 AND WRF10 DO MOVE SOME PRECIPITATION ACROSS THE NORTHWEST PART OF THE LZK CWA AFTER 12Z BUT CONFIDENCE IS LOW THIS WILL DEVELOP AS OTHER SHORT RANGE MODELS INDICATE RIDGE BUILDING IN THE MID LEVELS THAT WILL KEEP PRECIPITATION OUT OF THE CWA. CURRENT DISTRIBUTION OF SMALL POPS OVER THE NORTHWEST PART OF THE CWA TONIGHT THROUGH PARTS OF FRIDAY LOOKS REASONABLE AND WILL BE LEFT IN PLACE. ONLY CHANGES TO ONGOING FORECAST WERE TO TWEAK SKY...DEW POINT AND RH GRIDS TO REFLECT CURRENT TRENDS. OVERNIGHT LOWS RAISED A TAD AS WELL. UPDATES OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 629 PM CDT THU MAR 22 2007/ AVIATION... CLOUDS WILL CONTINUE TO MOVE IN FROM THE WEST WITH CEILINGS NEAR 7 THSD OR HIGHER. AREAS OF CEILINGS NEAR 35 HND WILL MOVE IN ARND 06Z. SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE NORTH AND WEST AFTER 08Z.(38) PREV DISCUSSION... /ISSUED 235 PM CDT THU MAR 22 2007/ SHORT TERM...TONIGHT THROUGH SUNDAY BLOCKING PATTERN STILL THE MAIN STORY IN THE SHORT TERM...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE GULF COAST. FRONT TO NORTH WILL TRY TO PUSH INTO ARKANSAS LATER TONIGHT/FRIDAY...BUT WILL STALL DUE TO THE HIGH AND SOUTHWEST WINDS ALOFT. EVEN SO...PUT SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS MAINLY IN AREAS NEAR THE ARKANSAS AND MISSOURI BORDER. FRONT WILL LIFT TO THE NORTH FRIDAY NIGHT/SATURDAY...WITH DRY AND WARM WEATHER TO START THE WEEKEND. LATE IN THE WEEKEND AND EARLY NEXT WEEK...LARGE STORM SYSTEM IN THE SOUTHWEST UNITED STATES WILL FINALLY ARRIVE...WITH HIGH PRESSURE SHIFTING SLOWLY TO THE EAST. BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST LATE SUNDAY INTO THE LONG TERM. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE PERIOD. (46) LONG TERM...SUNDAY NIGHT THROUGH THURSDAY REMNANTS OF A WEAKENING UPPER LOW WILL BE CROSSING ARKANSAS AS A SHORT WAVE. IT WILL BE JUST EAST OF THE STATE BY MIDDAY TUESDAY SINCE A LONG WAVE TROF WILL BE TRAVERSING THE INTERMOUNTAIN WEST ON TUESDAY. BY WEDNESDAY AFTERNOON IT WILL BE OVER THE NORTHERN PLAINS AND WEAKENING. THE SURFACE PATTERN WILL KEEP A SOUTHEAST OR SOUTH COMPONENT TO OUR WINDS THAT WILL PUMP MOISTURE NORTHWARD INTO THE PATH OF THE UPPER SYSTEM. WARMTH AND INSTABILITY WILL CAUSE SCATTERED CONVECTION TO DEVELOP SUNDAY NIGHT OVER NORTHWESTER SECTIONS. THEN...IT WILL KEEP ON MOVING EAST DURING THE DAY MONDAY. CONVECTION WILL BE OVER THE EASTERN HALF OF THE FORECAST AREA MONDAY NIGHT AND MOSTLY OUT OF THE STATE TUESDAY AFTERNOON AS THE SHORT WAVE DRIVING IT GOES ON BY ALOFT. WILL KEEP THE FORECAST DRY FROM TUESDAY NIGHT ON THROUGH THE END OF THE LONG TERM. THE UPPER SUPPORT FOR THE NEXT SYSTEM WILL BE SO FAR NORTH THAT DECIDED TO WAIT UNTIL THIS TREND GETS PICKED UP IN OTHER RUNS. NO CHALLENGE TO THE ABOVE NORMAL TRENDS WILL BE MADE DURING THIS PERIOD. (32) && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 59 76 56 76 / 10 20 20 10 CAMDEN AR 60 80 58 79 / 10 10 10 10 HARRISON AR 59 75 55 75 / 30 30 20 10 HOT SPRINGS AR 60 78 58 78 / 10 10 10 10 LITTLE ROCK AR 60 78 58 78 / 10 10 10 10 MONTICELLO AR 59 80 58 80 / 10 10 10 10 MOUNT IDA AR 58 78 57 78 / 10 10 10 10 MOUNTAIN HOME AR 59 75 54 75 / 30 30 20 10 NEWPORT AR 59 77 57 76 / 10 20 20 10 PINE BLUFF AR 60 79 59 79 / 10 10 10 10 RUSSELLVILLE AR 59 77 56 77 / 20 20 10 10 SEARCY AR 60 78 58 77 / 10 10 10 10 STUTTGART AR 60 79 59 78 / 10 10 10 10 && .LZK WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...56 / LONG TERM...38 ar AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 845 PM PDT THU MAR 22 2007 .UPDATE...A FEW PATCHES OF HIGH CLOUDS MOVING THRU...OTHERWISE SKIES ARE CLEAR. MID LEVEL CLOUDS WRAPPING AROUND THE NRN BAJA LOW ARE JUST EAST OF KERN CO. SOME OF THESE MID CLOUDS COULD MOVE ACROSS THE KERN DESERT FROM TIME TO TIME OVERNITE SO PTCLDY THERE LOOKS GOOD. TEMPS THIS EVE RUNNING 6-8 DEGS HIGHER THAN YESTERDAY AT THIS TIME...SO CONTINUED GOOD WARMING EXPECTED TOMORROW. CURRENT FCST ON TRACK AND NO UPDATE NEEDED THIS EVE. && .DISCUSSION...AS THE CLOSED UPPER LOW DRIFTS FURTHER OVER THE DESERT SOUTHWEST...THE WEATHER OVER CENTRAL CALIFORNIA CONTINUES TO SETTLE DOWN. WITH THE SUNSHINE...TEMPERATURES SAW ANOTHER WARMING TREND AS MANY VALLEY LOCATIONS WERE RUNNING 5 TO 10 DEG-F ABOVE THAT OF WEDNESDAY AFTERNOON. WITH THE OFFSHORE FLOW ALOFT SUPPORTING TODAY/S WARMING TEMP/S...WILL HAVE NO PROBLEM REACHING THE 70S. WHILE WRAP AROUND MOISTURE IS BEING OBSERVED OVER THE DESERT SOUTHWEST...ASSOCIATED WITH THE CLOSED UPPER LOW...AND TRACKING NORTHEAST. WHILE SOME CLOUDS SHOULD ADVANCE INTO THE DISTRICT LATE THIS AFTERNOON...RUC ANALYSIS AND VISIBLE SATELLITE IMAGERY IS SHOWING ONLY MINIMAL AMOUNTS REACHING THE AREA. THEREFORE...WILL MAINTAIN MOSTLY CLEAR CONDITIONS WITH NO POSSIBLE WEATHER. YET...THE KERN COUNTY DESERTS MAY BE CLOSER TO THE STORM THEN THE REST OF THE DISTRICT. THEREFORE...WILL MAINTAIN THE SLIGHT CHANCE POPS OVER THE DESERTS (TOKEN) JUST IN CASE THE MOISTURE IS ABLE TO MAKE IT THIS FAR NORTH. IN ADDITION...BECAUSE OF THE SLOW DRIFT OF THE UPPER LOW...STRONG WINDS WILL CONTINUE TO BE OBSERVED OVER THE DESERT AND HIGHER ELEVATIONS OF THE DISTRICT THROUGH THIS EVENING. AS THE UPPER LOW SLOWLY TRACKS EAST OVER THE NEXT SEVERAL DAYS...WILL SEE THE UPPER LEVEL RIDGE DOMINATE THE WEST THROUGH THE WEEKEND. DRY WEATHER WILL PREVAIL WITH A WARMING TREND IN TEMPERATURES THROUGH ABOUT SUNDAY. AROUND SUNDAY...SHORT RANGE MODELS BEGIN LOWERING HEIGHTS AND SWITCH TO A MORE ZONAL FLOW PATTERN BEFORE ALLOWING ANOTHER TROF TO APPROACH THE WEST COAST. LATEST TIMING STILL HAS THE NEXT TROF OVER THE WEST COAST AROUND LATE MONDAY INTO EARLY TUESDAY. ENSEMBLES SHOWING LITTLE PHASE UNCERTAINTY BUT IS SHOWING GOOD SPREAD ON THE AMPLITUDE AROUND 12Z TUESDAY. THEREFORE...WILL KEEP THE BETTER CHANCES OF MEASURABLE PRECIP NORTH OF KERN COUNTY DURING THE EVENT. IN ADDITION...DURING TROF PASSAGE...MEDIUM RANGE MODELS SHOW 500MB TEMP/S DROPPING TO AROUND MINUS 24-28 DEG-C. BEING THAT THIS MAY BE A COLD SYSTEM...WILL MAINTAIN LOW SNOW LEVELS DURING THE STORM. FURTHERMORE...WITH SUCH COLD AIR ALOFT OVER THE REGION AT THIS TIME OF THE YEAR...CONDITIONS MAY BECOME VERY UNSTABLE DURING THE STORM EVENT. LINGERING SHOWERS OVER THE MOUNTAIN TOWARD TUESDAY WILL GIVE WAY TO CLEARING BY WEDNESDAY AND THURSDAY. && .AVIATION...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 06Z SATURDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES... NONE && .HNX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ BINGHAM/MOLINA/MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 232 PM PDT THU MAR 22 2007 .DISCUSSION...AS THE CLOSED UPPER LOW DRIFTS FURTHER OVER THE DESERT SOUTHWEST...THE WEATHER OVER CENTRAL CALIFORNIA CONTINUES TO SETTLE DOWN. WITH THE SUNSHINE...TEMPERATURES SAW ANOTHER WARMING TREND AS MANY VALLEY LOCATIONS WERE RUNNING 5 TO 10 DEG-F ABOVE THAT OF WEDNESDAY AFTERNOON. WITH THE OFFSHORE FLOW ALOFT SUPPORTING TODAY/S WARMING TEMP/S...WILL HAVE NO PROBLEM REACHING THE 70S. WHILE WRAP AROUND MOISTURE IS BEING OBSERVED OVER THE DESERT SOUTHWEST...ASSOCIATED WITH THE CLOSED UPPER LOW...AND TRACKING NORTHEAST. WHILE SOME CLOUDS SHOULD ADVANCE INTO THE DISTRICT LATE THIS AFTERNOON...RUC ANALYSIS AND VISIBLE SATELLITE IMAGERY IS SHOWING ONLY MINIMAL AMOUNTS REACHING THE AREA. THEREFORE...WILL MAINTAIN MOSTLY CLEAR CONDITIONS WITH NO POSSIBLE WEATHER. YET...THE KERN COUNTY DESERTS MAY BE CLOSER TO THE STORM THEN THE REST OF THE DISTRICT. THEREFORE...WILL MAINTAIN THE SLIGHT CHANCE POPS OVER THE DESERTS (TOKEN) JUST IN CASE THE MOISTURE IS ABLE TO MAKE IT THIS FAR NORTH. IN ADDITION...BECAUSE OF THE SLOW DRIFT OF THE UPPER LOW...STRONG WINDS WILL CONTINUE TO BE OBSERVED OVER THE DESERT AND HIGHER ELEVATIONS OF THE DISTRICT THROUGH THIS EVENING. AS THE UPPER LOW SLOWLY TRACKS EAST OVER THE NEXT SEVERAL DAYS...WILL SEE THE UPPER LEVEL RIDGE DOMINATE THE WEST THROUGH THE WEEKEND. DRY WEATHER WILL PREVAIL WITH A WARMING TREND IN TEMPERATURES THROUGH ABOUT SUNDAY. AROUND SUNDAY...SHORT RANGE MODELS BEGIN LOWERING HEIGHTS AND SWITCH TO A MORE ZONAL FLOW PATTERN BEFORE ALLOWING ANOTHER TROF TO APPROACH THE WEST COAST. LATEST TIMING STILL HAS THE NEXT TROF OVER THE WEST COAST AROUND LATE MONDAY INTO EARLY TUESDAY. ENSEMBLES SHOWING LITTLE PHASE UNCERTAINTY BUT IS SHOWING GOOD SPREAD ON THE AMPLITUDE AROUND 12Z TUESDAY. THEREFORE...WILL KEEP THE BETTER CHANCES OF MEASURABLE PRECIP NORTH OF KERN COUNTY DURING THE EVENT. IN ADDITION...DURING TROF PASSAGE...MEDIUM RANGE MODELS SHOW 500MB TEMP/S DROPPING TO AROUND MINUS 24-28 DEG-C. BEING THAT THIS MAY BE A COLD SYSTEM...WILL MAINTAIN LOW SNOW LEVELS DURING THE STORM. FURTHERMORE...WITH SUCH COLD AIR ALOFT OVER THE REGION AT THIS TIME OF THE YEAR...CONDITIONS MAY BECOME VERY UNSTABLE DURING THE STORM EVENT. LINGERING SHOWERS OVER THE MOUNTAIN TOWARD TUESDAY WILL GIVE WAY TO CLEARING BY WEDNESDAY AND THURSDAY. && .AVIATION...GUSTY OFFSHORE WINDS WILL CONTINUE OVER KERN COUNTY DESERTS THROUGH EARLY EVENING THURSDAY...DIMINISHING THEREAFTER. OTHERWISE...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 00Z SATURDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES...NONE. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC:MOLINA AVIATION:MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 945 AM MST THU MAR 22 2007 .SYNOPSIS... A STRONG PACIFIC LOW PRESSURE SYSTEM WAS LOCATED JUST OFF THE NORTHERN BAJA CALIFORNIA COAST THIS MORNING. IT WILL MOVE VERY SLOWLY EAST ACROSS NORTHERN MEXICO FRIDAY INTO SATURDAY. THIS STORM SYSTEM WILL BRING INCREASING CLOUDINESS...COOLER DAYTIME HIGHS...AND PERIODS OF SHOWERS AND THUNDERSTORMS TODAY THROUGH SATURDAY...WITH THE BEST CHANCE FOR PRECIPITATION OVER SOUTH-CENTRAL ARIZONA. HIGHER PRESSURE ALOFT FROM THE PACIFIC WILL BRING DRY WEATHER WITH SOME RECOVERY OF TEMPERATURES SUNDAY AND MONDAY. ANOTHER RATHER STRONG WEATHER DISTURBANCE WILL PRODUCE BREEZY TO WINDY CONDITIONS ALONG WITH SOME COOLING NEXT TUESDAY AND WEDNESDAY. && .SHORT TERM... TODAY THROUGH SATURDAY... 12Z POSITION OF CLOSED LOW WAS NEAR 30N/117W WITH SEVERAL VORTICITY CENTERS ROTATING AROUND ITS PERIMETER. NAM/GFS SOLUTIONS APPEARED TO BE SOMEWHAT SOUTH OF LATEST RUC...WITH ALL MODELS INDICATING THE STRONGEST VORT CENTER SOUTH OF THE LOW. THE 500MB WIND SPEEDS WERE ALSO STRONGEST AROUND THE SOUTHERN QUADRANTS OF THE LOW...50-70KTS. AFTER SUNRISE THE CONVECTION PICKED UP IN OUR CWA...AND CONTINUED TO DRIFT INTO YAVAPAI COUNTY. BY FAR THE HEAVIEST PRECIP WAS THROUGH SOUTHERN GILA COUNTY WHERE SPOTTERS/RAWS DATA REPORTED .30 TO .45 INCH UP TO 6 AM. SIGNIFICANT DIFFLUENCE WAS ALSO INDICATED ACROSS EASTERN AZ EARLIER TODAY. UPDATES ISSUED BY 8 AM TO COVER 88D TRENDS. WILL CONTINUE TO EXPECT STRONGEST LIFT AND LOWEST STABILITY INDICES AFTER 18Z FRIDAY...AND THAT FITS NICELY WITH OUR CURRENT FCSTS. ALTHOUGH LATEST NAM GIVES PHX A 24 HR PRECIP AMOUNT OF .38 INCH WE WILL STILL EXPECT GENERALLY LIGHTER AMOUNTS ACROSS ZONE 23. HOWEVER WE COULD SEE MUCH MORE...ACROSS ZONE 24...PER HPC OUTPUT. OUR WESTERN ZONES WILL STAY MUCH DIRER...WITH SOME PATCHY BLWG DUST TODAY. IN FACT ONE SHARP-EYED SPOTTER CALLED IN A REPORT OF BLOWING DUST NEAR A FARM FIELD WEST OF TONOPAH. MODEL TRENDS CONTINUE TO BE VERY CONSISTENT IN KEEPING THE CLOSED LOW OVER NRN MEX INTO FRIDAY NIGHT. BY 12Z SAT LATEST GFS CALLS FOR THE CENTER OF CIRCULATION TO LIFT OUT TO NEAR ABQ...WITH CSDRBL RH THROUGH A DEEP LAYER EVEN WEST OF PHX. UPPER RIDGE AND WARMER TEMPS WILL ALSO SPREAD ACROSS ENTIRE CWA FOR FRIDAY AND SATURDAY. && .LONG TERM... SATURDAY NIGHT THROUGH WEDNESDAY... WITH SLOWER EXIT OF THE SYSTEM AND POTENTIAL FOR MORE MOISTURE... ADDED SOME SLIGHT CHANCE POPS IN EASTERN PORTIONS OF THE FORECAST AREA SATURDAY NIGHT. THIS IS FOLLOWED BY RIDGE BUILDING FOR A QUICK WARMUP. IN THE LATTER PART OF THE EXTENDED...GFS AND ECWMF ARE SHOWING ANOTHER SYSTEM AFFECTING US. HOWEVER...IT LOOKS TO BE OF A DIFFERENT CHARACTER...MUCH LESS APT TO SLOW DOWN AND JOG SOUTHWARD. HOWEVER...THERE ARE SOME DIFFERENCES. THE GFS ENSEMBLE MEAN HAS A SIMILAR TRACK TO THE 12Z OPERATIONAL GFS...TAKING THE BULK OF THE SYSTEM JUST NORTH OF OUR AREA...BUT SHOWS LOWER HEIGHTS. THE ECMWF IS EVEN COOLER LOOKING THAN THE ENSEMBLE MEAN...AND A BIT SLOWER. THUS...UNDERCUT GFS-BASED TEMPERATURE GUIDANCE. TRAJECTORY OF THIS NEXT SYSTEM DOES NOT FAVOR MUCH IN THE WAY OF POPS...SO HELD OFF ON INTRODUCING ANY. IF ECMWF SOLUTION WINDS UP BEING CORRECT...THEN WE MIGHT NEED TO ADD SOME SLIGHT CHANCE POPS AT SOME POINT. ALSO...IF ECMWF SOLUTION PANS OUT...MIGHT NEED EVEN COOLER TEMPS. && .AVIATION... GENERALLY LGT SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH TODAY. WINDS IN THE 6 TO 12 THSD LAYER PROGGED TO REMAIN 180/22 THIS AFTERNOON...WITH MUCH STRONGER SPEEDS ALOFT. SOME GUSTY WINDS TO 35KTS OR SO STILL POSSIBLE IN THE KPHX AREA LATE THIS AFTERNOON AND INTO TONIGHT. WITH ADDITIONAL MOISTURE THROUGH A DEEP LAYER...WE COULD EASILY SEE LOWER CIGS LESS THAN 6-7 THSD FT. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EXPECT PERIODS OF WETTING RAINFALL OVER MUCH OF THE FORECAST AREA THURSDAY THROUGH SATURDAY...MAINLY OVER THE EASTERN ZONES...WITH THE HEAVIEST PRECIPITATION LIKELY OVER SOUTHERN GILA COUNTY AND THE RIM FRI AFTERNOON INTO SAT MORNING. DRY CONDITIONS RETURN TO THE WESTERN PORTION OF THE REGION BY SATURDAY AND THE REMAINDER OF THE FORECAST AREA BY SUNDAY. EARLY NEXT WEEK (MON NIGHT THROUGH TUE)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX 10 ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 916 AM PDT THU MAR 22 2007 .DISCUSSION...CLOSED UPPER LOW CONTINUES TO SWINGS EASTWARD THIS MORNING AROUND BAJA CALIFORNIA...WITH CHANNELED FLOW OVER THE DISTRICT. AT THE 250MB LEVEL...RUC ANALYSIS HAS A +100KT JET MAX EXITING THE AREA WITH A GOOD DOWNWARD TRANSFER OF WINDS THIS MORNING. WHILE WINDS OVER THE MOUNTAINS AND DESERTS WERE DIMINISHING THIS MID MORNING...WINDS EARLIER WERE ABLE TO REACH 30 TO 40 MPH. AS THE JET MOVES FURTHER AWAY...WILL SEE MOUNTAIN WINDS DECREASE FURTHER AS A SHORT WAVE RIDGE SHIFTS INTO CALIFORNIA. FURTHERMORE...THE FLOW THIS MORNING HAS BEEN OFF-SHORE WHICH WILL SUPPORT THE EXPECTED WARM UP THIS AFTERNOON. OTHERWISE...AS THE CLOSED UPPER LOW MOVES FURTHER OUT...WILL SEE GENERAL CLEARING THROUGH THE END OF THE WEEK AND INTO THE WEEKEND WITH A CONTINUAL WARMING OF TEMPERATURES. NO UPDATES NEEDED. && .AVIATION...LOCAL MVFR CEILINGS AND VISIBILITIES WILL PERSIST ALONG THE EAST SIDE AND SOUTH END OF THE SAN JOAQUIN VALLEY AS WELL AS THE NORTH FACING SLOPES OF THE TEHACHAPI MOUNTAINS UNTIL 17Z. LOCALLY STRONG WINDS WILL ALSO BUFFET THE HIGHER ELEVATIONS OF THE SIERRA NEVADA AND THE INDIAN WELLS VALLEY THIS MORNING. OTHERWISE...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 12Z FRIDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES...NONE. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC:MOLINA AVIATION:MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 328 AM EDT FRI MAR 23 2007 .SYNOPSIS...SFC HIGH PRES RIDGE JUST OUR N WITH PREVAILING LOW LEVEL NE TO E FLOW OVER THE FORECAST AREA. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW THE MID-UPPER RIDGE FROM CENTRAL GOMEX NEWD INTO THE SE STATES. MOIST BOUNDARY LAYER...CLEAR SKIES AND CALM WINDS OVER SE GA SUPPORTING FOG DEVELOPMENT WITH ALMA OCCASIONAL REPORTING VIS BELOW 1SM. EXPECT MORE FOG DEVELOPMENT OVER ENTIRE CWA NEXT FEW HOURS WITH THE DENSE FOG MAINLY CONFINED IN INTERIOR SE GA. && .SHORT TERM...HIGH PRES SFC AND ALOFT WILL DOMINATE THE REGION WITH A 1026 MB SFC HIGH PINCHING OFF OVER SRN AL AND GA SAT-SUN. STRONG RIDGING ALOFT WILL ENSURE A DEFINITE WARMING TREND FOR MOST AREAS TODAY THROUGH SUNDAY. TODAY...PATCHY DENSE FOG EXPECTED THROUGH EARLY MORNING OVER SE GA WITH PATCHY FOG MOST OTHER AREAS. FOR MAX TEMPS PREFERRED A BLEND BUT MOSTLY LIKED THE MAV GUIDANCE AS MET VERIFYING A BIT TOO COOL. MID 80S ARE POSSIBLE INLAND SECTIONS. WEAKER PRES GRADIENT WILL PROVIDE MOSTLY ELY 10-15 MPH WINDS BUT STILL SOME GUSTINESS IN AFTERNOON BUT LOWER THAN PREVIOUS DAYS. TONIGHT...STRONGER HIGH PRES ALOFT WITH WEAKER BOUNDARY LAYER WINDS SPELLS FOR ANOTHER ROUND OF AREAS OF FOG AFTER MIDNIGHT LESS THAN 1SM AT TIMES BUT OTHERWISE MOSTLY CLEAR SKIES. LOWS MOSTLY IN THE MID 50S. SAT...MORNING FOG DISSIPATES GIVING WAY TO PARTLY TO MOSTLY SUNNY SKIES AND WARM TEMPS WITH MID 80S INLAND...UPPER 70S NEAR THE COAST. SAT NIGHT...MOSTLY CLEAR SKIES AND PATCHY TO AREAS OF FOG EXPECTED. LOWS CONTINUE TO BE MOSTLY MID 50S. SUNDAY...SFC HIGH PRES CONTINUES WITH WARM TEMPS FROM MID 80S TO UPPER 70S AGAIN. WILL BE SEEING A BACK-DOOR COLD FRONT SLIDE DOWN THE E COAST THROUGH CAROLINAS LATE IN THE DAY. .LONG TERM...SUN NIGHT-THU. MODEL GUIDANCE FASTER THAN YESTERDAY`S RUN SHOWING BACK-DOOR FRONT MOVING INTO THE FORECAST AREA. NAM AND GFS SHOWING FRONT MOVING INTO SE GA BETWEEN 06Z-12Z MON WITH POSSIBLE LIGHT SHOWERS ACCOMPANYING THE FRONT. FRONT PUSHES THROUGH ALL THE CWA WITH TEMPS A BIT COOLER ON NE FLOW THANKS TO 1033 MB HIGH OFF THE MID ATLC. PRES GRADIENT WILL HAVE INCREASED MON WITH BREEZY CONDS DEVELOPING OVER ERN ZONES. HAVE MOVED UP POPS TO MON AT 20% FOR PORTIONS OF SE GA AND NE FL AS ASSOCD MOISTURE WITH FRONT PUSHES THROUGH. SFC HIGH PRES RIDGE BUILDS SWD TUE-THU WITH NO MENTION OF POPS WITH SLIGHTLY WARMER TEMPS ANTICIPATED. && .AVIATION...WILL SEE TEMPO MVFR AT ALL TAF SITES BETWEEN 09Z AND 12Z DUE MAINLY TO VSBY. OTHERWISE VFR. EAST WINDS INCREASE BY EARLY THIS AFTERNOON WITH GUSTS TO NEAR 20 KNOTS AFTER 16Z. && .MARINE...WITH RIDGE BUILDING IN...WINDS AND EASTERLY SWELLS WILL SUBSIDE TODAY AND THROUGH THE WEEKEND. WILL KEEP THE ADVISORY FOR SEAS GOING THROUGH SATURDAY AND DROP ON SUNDAY. A STRONG BACK DOOR FRONT MOVES DOWN THE COAST MONDAY AND WILL PROBABLY SEE SCA CONDITIONS RETURN AGAIN. && .FIRE WX...BRIEF DURATIONS OF RH`S AOB 35% POSSIBLE TODAY AND SAT AFTN ACROSS THE SUWANNEE RIVER VALLEY IN NE FL. OTHERWISE NO MAJOR CONCERNS THROUGH THE WEEKEND. WINDS ARE EXPECTED TO INCREASE TO 15 MPH INLAND AND 15 TO 20 MPH ALONG THE COAST MONDAY WHEN A BACK DOOR FRONT SWEEPS THROUGH THE AREA. && .PRELIMINARY POINT TEMPS/POPS... AMG 83 54 85 53 / 10 10 10 10 SSI 74 58 76 57 / 0 0 0 10 JAX 79 55 81 55 / 10 10 10 10 SGJ 74 59 75 60 / 10 10 0 10 GNV 83 53 83 55 / 10 10 0 10 OCF 83 55 83 55 / 10 10 0 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 3 PM EDT SATURDAY FOR ALTAMAHA SOUND GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE-FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE-ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 PM EDT THIS EVENING FOR FERNANDINA BEACH TO ST AUGUSTINE FL OUT 20 NM- ST AUGUSTINE TO FLAGLER BEACH FL OUT 20 NM. && $$ SHASHY/PETERSON fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 940 PM EDT WED MAR 21 2007 .SHORT TERM UPDATE /TONIGHT/... PER RADAR/SATELLITE TRENDS...DEPICTING CLOUDS/SHOWERS PUSHING TOWARD SHORE ON THE SOUTHERN PERIPHERY OF HIGH PRES CENTERED EAST OF NEW ENGLAND...EXPANDED ISOLATED SHOWERS INTO GA COUNTIES OVERNIGHT. 18Z NAM12/WRF AND 0Z RUC40 SUGGEST THAT PRECIP WILL STRUGGLE TO PUSH ONSHORE OVERNIGHT...SO WILL NOT RAISE POPS. HOWEVER...WILL CONTINUE TO MONITOR TRENDS AND MAY YET RAISE POPS IF NEEDED...ESP ACROSS SC COUNTIES. OTHERWISE...DEWPOINTS IN THE 50S AND BREAKS IN THE CLOUD COVER SUPPORT THE ONGOING FORECAST OF PATCHY FOG. && .MARINE... RECENT REPORTS FROM AREA BUOYS AND FROM THE CHARLESTON AND SAVANNAH PILOT BOATS SUGGEST THAT SEAS ARE BUILDING AHEAD OF SCHEDULE...AND CURRENT TRENDS SUGGEST THAT 6 FT SEAS WILL PROBABLY SLIP INTO NEARSHORE WATERS OVERNIGHT. THUS...MOVED UP START TIME OF ONGOING SCAS FOR SC/GA NEARSHORE WATERS FROM NOON THU TO 2 AM THU. && .AVIATION /02Z-24Z/...VFR CONDITIONS WILL PREVAIL UNTIL AFTER 8Z...WHEN AT LEAST MVFR VISIBILITY SHOULD DEVELOP AT KCHS...WHILE OCCASIONAL IFR CIGS/VSBYS SHOULD DEVELOP AT KSAV AROUND DAYBREAK. THEN...AFTER 12Z...VFR CONDITIONS SHOULD PREVAIL FOR THE REMAINDER OF THE FORECAST PERIOD. MEANWHILE...TAFS INDICATE SHOWERS IN THE VICINITY UNTIL 9Z...WILL AMEND AS NEEDED FOR TIMING OF INDIVIDUAL SHOWERS. && .RIP CURRENTS... PERSISTENT ONSHORE FLOW AND DEVELOPING LONG PERIOD EASTERLY SWELL WILL RESULT IN A MODERATE RISK OF RIP CURRENTS THURSDAY. THE INCREASED THREAT OF RIP CURRENTS MAY CONTINUE UNTIL THE SWELL SUBSIDES SATURDAY. && .COASTAL FLOODING/HIGH SURF... GIVEN PERSISTENT ONSHORE FLOW...BUILDING E SWELL AND ASTRONOMICAL COMPONENT OF TIDES...STILL CLOSE TO THE MARCH 19 NEW MOON...WILL CONTINUE TO CLOSELY MONITOR WATER LEVELS AROUND THE TIMES OF HIGH TIDE TONIGHT AND AGAIN THURSDAY NIGHT. ALSO...WILL NEED TO ASSESS NEED FOR A HIGH SURF ADVISORY THU...AS WAVES IN SURF ZONE COULD BE CLOSE TO 5 FT. THIS COULD ALSO CONTRIBUTE TO MINOR BEACH EROSION AT HIGH TIDE...ESPECIALLY THU AND THU NIGHT. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM THURSDAY TO 6 AM EDT FRIDAY FOR AMZ350-352-354. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT SUNDAY FOR AMZ374. && $$ SPR ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 130 PM CDT THU MAR 22 2007 .DISCUSSION FOR ZONES/GRIDS... 11AM...SKIES ARE CLEARING OVER MUCH OF FCST AREA AT LATE MRNG AS WINDS TURN NW AND TEMPS STEADY OUT. COLD ADVECTION ON NW WINDS WILL HOLD TEMPS WITHIN FEW DEG OF CURRENT LEVELS THROUGH THE AFTERNOON. HIGH PERS OVER NW IOWA SHOULD DRIFT ACROSS TONIGHT FOR SOMEHWAT COOLER TEMPS. RETURN MOISTURE AND CLOUDS ETC LKLY TO BEGIN LATER TONIGHT AND CONTINUE FRIDAY. CHARACTER OF THAT RETURN REMAINS TO BE SEEN AND WILL TRIM/DELAY RETURN A LITTLE IN UPDATED GRIDS. FAIRLY MARKED DIFFERENCES IN GFS AND NAM IN GROWING AMPLITUDE OF EJECTING WESTERN TROUGH NEXT 48HRS IS ONE SOURCE OF UNCERTAINTY. KL PREVIOUS DISCUSSION 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... THE COLD FRONT HAS MOVED SOUTH OF THE TAF FORECAST AREA OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA. THE WIND PROFILER DATA SHOWS A WEST WIND IN ILLINOIS AT 700 MB AND AT 850 MB. WITH THIS WIND PATTERN ALOFT THE FRONT WILL PROBABLY STALL OVER CENTRAL ILLINOIS. A HIGH WILL MOVE ACROSS THE NORTH CENTRAL PART OF THE STATE THIS EVENING. THE WIND WILL BECOME SOUTHERLY AND THE FRONT WILL MOVE NORTH INTO NORTH CENTRAL ILLINOIS AND NORTHWEST INDIANA LATE TONIGHT. WE WILL ADD THUNDERSTORMS TOWARD FROM 11 TO 12 UTC. THIS IS THE TIME OF MAXIMUM CONVERGENCE AS THE FRONT MOVES THROUGH. WE WILL HAVE LIGHT RAIN THROUGH THE MORNING ACROSS THE FORECAST AREA. WE EXPECT A SOUTHEAST WIND AFTER MIDNIGHT TONIGHT. WE USED THE NAM AND A LOCALLY RUN WRF MODEL. && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1100 AM CDT THU MAR 22 2007 .DISCUSSION FOR ZONES/GRIDS... 11AM...SKIES ARE CLEARING OVER MUCH OF FCST AREA AT LATE MRNG AS WINDS TURN NW AND TEMPS STEADY OUT. COLD ADVECTION ON NW WINDS WILL HOLD TEMPS WITHIN FEW DEG OF CURRENT LEVELS THROUGH THE AFTERNOON. HIGH PERS OVER NW IOWA SHOULD DRIFT ACROSS TONIGHT FOR SOMEHWAT COOLER TEMPS. RETURN MOISTURE AND CLOUDS ETC LKLY TO BEGIN LATER TONIGHT AND CONTINUE FRIDAY. CHARACTER OF THAT RETURN REMAINS TO BE SEEN AND WILL TRIM/DELAY RETURN A LITTLE IN UPDATED GRIDS. FAIRLY MARKED DIFFERENCES IN GFS AND NAM IN GROWING AMPLITUDE OF EJECTING WESTERN TROUGH NEXT 48HRS IS ONE SOURCE OF UNCERTAINTY. KL PREVIOUS DISCUSSION 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 650 AM CDT MID LVL S/WV TROF CONTINUES TO PLOW INTO WRN GRTLKS REGION THIS MORNING...COLD FRONT PUSHING THRU FCST AREA AT 12Z. BAND OF ELEVATED CONVECTION ASSOCIATED WITH 55 KT LLJ NOW PUSHING OFF TO THE EAST OF FCST AREA AS 950-850 HPA FLOW BECOMING A BIT MORE WESTERLY WITH APPROACH OF TROF...THOUGH A FEW ISOLATED CELLS STILL DVLPG GENERALLY ALONG/SOUTH OF A KVYS...KLOT...KGYY LINE ASSOCIATED WITH ELEVATED INSTABILITY PLUME/LLJ AXIS. EXPECT THESE TO REMAIN SOUTH OF TERMINALS WITH EXCEPTION OF KGYY FIRST COUPLE OF HOURS OF TAF PERIOD EARLY THIS MORNING. OTHERWISE...COLD FROPA HAS OCCURRED AT KRFD AND WILL BE INTO CHI AREA TERMINALS NEXT 1-2 HRS. PATCHY MVFR CIGS IN 1500-2000 FT RANGE IMMEDIATELY BEHIND FRONT...THOUGH STRONG LLVL DRY ADVECTION DVLPG POST FRONTAL SHOULD CLR THIS OUT BY LATE MORNING. STRONG ISALLOBARIC GRADIENT WITH PRESSURE RISES BEHIND FRONT...SO WITH WSFT TO NW XPCT TO CONTINUE TO SEE GUSTS INTO THE LOW/MID 20 KT RANGE THIS MORNING. SFC HIGH PRESSURE BUILDS IN RAPIDLY THIS AFTN/THIS EVE ALLOWING WINDS TO DECREASE QUICKLY...GOING VRBL THIS EVE. WILL LIKELY SEE A BIT OF A LAKE BREEZE TOWARD EVE ALONG IL/IND LAKE MICH SHORE AS GRADIENT RELAXES. NEXT S/WV PROPAGATES ACROSS UPPER MIDWEST TONIGHT...WITH ANOTHER ROUND OF WAA/UPGLIDE DVLPG ACROSS BAROCLINIC FRONTAL ZONE TO SOUTH OF FCST AREA OVRNGT. 06Z NAM/GFS RUNS BOTH FOCUS PCPN SOUTH OF TERMINALS WITH VFR CIG DVLPG. COULD SEE PCPN FARTHER NORTH INTO TERMINAL SITES AFTER 06Z TONIGHT...THOUGH CONFIDENCE THAT FAR NORTH IS LOW ATTM. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 650 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 650 AM CDT MID LVL S/WV TROF CONTINUES TO PLOW INTO WRN GRTLKS REGION THIS MORNING...COLD FRONT PUSHING THRU FCST AREA AT 12Z. BAND OF ELEVATED CONVECTION ASSOCIATED WITH 55 KT LLJ NOW PUSHING OFF TO THE EAST OF FCST AREA AS 950-850 HPA FLOW BECOMING A BIT MORE WESTERLY WITH APPROACH OF TROF...THOUGH A FEW ISOLATED CELLS STILL DVLPG GENERALLY ALONG/SOUTH OF A KVYS...KLOT...KGYY LINE ASSOCIATED WITH ELEVATED INSTABILITY PLUME/LLJ AXIS. EXPECT THESE TO REMAIN SOUTH OF TERMINALS WITH EXCEPTION OF KGYY FIRST COUPLE OF HOURS OF TAF PERIOD EARLY THIS MORNING. OTHERWISE...COLD FROPA HAS OCCURRED AT KRFD AND WILL BE INTO CHI AREA TERMINALS NEXT 1-2 HRS. PATCHY MVFR CIGS IN 1500-2000 FT RANGE IMMEDIATELY BEHIND FRONT...THOUGH STRONG LLVL DRY ADVECTION DVLPG POST FRONTAL SHOULD CLR THIS OUT BY LATE MORNING. STRONG ISALLOBARIC GRADIENT WITH PRESSURE RISES BEHIND FRONT...SO WITH WSFT TO NW XPCT TO CONTINUE TO SEE GUSTS INTO THE LOW/MID 20 KT RANGE THIS MORNING. SFC HIGH PRESSURE BUILDS IN RAPIDLY THIS AFTN/THIS EVE ALLOWING WINDS TO DECREASE QUICKLY...GOING VRBL THIS EVE. WILL LIKELY SEE A BIT OF A LAKE BREEZE TOWARD EVE ALONG IL/IND LAKE MICH SHORE AS GRADIENT RELAXES. NEXT S/WV PROPAGATES ACROSS UPPER MIDWEST TONIGHT...WITH ANOTHER ROUND OF WAA/UPGLIDE DVLPG ACROSS BAROCLINIC FRONTAL ZONE TO SOUTH OF FCST AREA OVRNGT. 06Z NAM/GFS RUNS BOTH FOCUS PCPN SOUTH OF TERMINALS WITH VFR CIG DVLPG. COULD SEE PCPN FARTHER NORTH INTO TERMINAL SITES AFTER 06Z TONIGHT...THOUGH CONFIDENCE THAT FAR NORTH IS LOW ATTM. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 330 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 1254 AM CDT VIGOROUS S/WV TROF PROPAGATING ACROSS NRN PLAINS AND UPPER MIDWEST EARLY THIS MORNING...WITH ASSOCIATED SFC TROF/COLD FRONT FROM NRN WI TO ERN IA AT 05Z. REGIONAL PROFILER DATA...AND 0445Z ACARS SOUNDING OUT OF KRFD INDICATE 55 KT SOUTHWESTERLY LLJ IN 930-850 HPA LAYER AHEAD OF LOW LEVEL TROF/FRONT. SOUNDING ALSO INDICATES STEEP LAPSE RATES IN THIS LAYER...THOUGH A BIT OF A CAP NOTED AROUND 670 MB. ISOLATED WEAK ELEVATED CONVECTIVE CELLS HAVE BEEN TRYING TO INITIATE IN THIS REGION OF MOIST/WAA ACROSS FAR NRN IL...THOUGH APPEARS THEY ARE FIGHTING CAP. NAM FCST SOUNDINGS DEPICT COOLING OF MID/UPR LVLS WITH APPROACH OF S/WV EARLY THIS MORNING HOWEVER...WITH ELEVATED CAPE INCREASING TO 550-650 J/KG FOR PARCELS BASED 875-900 HPA. THIS ALONG WITH INCREASING LLVL CONVERGENCE AHEAD OF FRONT SHOULD BE SUFFICIENT TO RESULT IN SCATTERED TRW AS BOUNDARY ADVANCES ACROSS FCST IL. CURRENT REGIONAL RADAR TRENDS INDICATE STRONG CONVECTION IN SWRN WI AND SRN IA...WITH SOME INCREASE IN CELL DEVELOPMENT ACROSS ERN IA. GIVEN STRONG FAIRLY UNIDIRECTIONAL WIND FIELD MAY SEE SOME GUSTS IN 40 KT RANGE WITH TSTMS...AND PERHAPS SOME SMALL HAIL GIVEN MARGINAL CAPE PROFILES. THUS WILL MAINTAIN TS IN TERMINALS THIS MORNING...MAINLY DURG 09-13Z PERIOD FROM WEST TO EAST AS FRONT MOVES THRU. MAY SEE BRIEF PERIOD OF MVFR CIGS IN FRONTAL ZONE...THOUGH STRONG LLVL DRYING BEHIND FRONT SHOULD DECREASE CLOUDS FAIRLY RAPIDLY WITH VFR CONDITIONS PREVAILING WITHIN A FEW HOURS OF SUNRISE. STRONG SW LLVL WIND FIELD IN TIGHT PRES GRADIENT AHEAD OF COLD FRONT RESULTING IN GUSTY 20-30 KT WINDS ATTM. WILL SEE GRADIENT DECREASE JUST A BIT WITHIN TROF AXIS TOWARD SUNRISE...THEN WSHFT TO NWLY DIRECTION. SOME GUSTINESS AS SFC PRES RISE BUILDS IN EARLY MORNING...THEN DECREASING WINDS THIS AFTN AS WEAK SFC HIGH BUILDS IN. DVLPMNT OF NE WINDS OFF LAKE A GOOD PROBABILITY VERY LATE AFTN/EARLY EVE AS GRADIENT WINDS DECREASE. NEXT S/WV AND ELEVATED PCPN THREAT BEYOND 06Z TONIGHT...MORE ON THAT WITH NEXT FCST ISSUANCE. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 745 PM EDT WED MAR 21 2007 .DISCUSSION FOR 00Z TAFS...WARM SECTOR AIR OVER TAF ROUTES WITH SCT AC AND CI OVR INDIANA WHILE CONVECTION OCCURRING NEAR WRM FNT ACRS SRN GRTLKS. PATCHY MID CLOUD EMBEDDED IN SW FLOW AHEAD OF CDFNT MEANS VFR TO CONTINUE TIL DAYBREAK WHILE GUSTY WINDS AT SUNSET TODAY BECOME STEADY OVRNGT. MODELS TIMING OF CDFNT THU FAIRLY SIMILAR AND APPEARS BEST LIFT WILL OCCUR JUST PRIOR TO AND DURING FROPA SO HAVE KEPT PCPN OUT OF FCST TIL THEN. EXPECT PERIOD OF MVFR VSBY WITH SHRA AND CB DURING CDFNT PASSAGE AND TREND TO MVFR CIGS OVC020 IN COLD AIR BEHIND FNT. INCREASED STABILITY SHOULD LEAD TO END OF TSHRA SHORTLY AFT FROPA. && .PREV DISCUSSION...SURFACE FRONT CURRENTLY LOCATED OVER NORTHERN PLAIN/UPPER MIDWEST WILL MOVE SOUTH INTO THE AREA THURSDAY. HAVE ADJUSTED PRECIP TIMING ACCORDINGLY. HAVE KEPT A CHANCE IN MOST AREAS DURING THE OVERNIGHT HOURS TO ACCOUNT FOR ANY PRE-FRONTAL ELEVATED CONVECTION THAT MAY FIRE AS S/W OVER S. MO AND N. AR MOVES INTO AREA ALONG WITH INCREASING ISENTROPIC LIFT FROM THE LLJ. THE MID LEVEL FORCING ASSOCIATED WITH THE ACCOMPANYING S/W IS FCST TO MOVE ACRS THE UPPER MIDWEST AND LAKES REGION SHOULD REMAIN DISPLACED AWAY FROM CENTRAL INDIANA. THIS WILL TEND TO LIMIT DESTABILIZATION OVERTOP MOIST TONGUE ADVECTING INTO THE REGION TONIGHT AND EARLY TOMORROW. MODEL CONSENSUS FCST SOUNDINGS INDICATING MODEST LOW LEVEL FLOW DURING THE AFTERNOON HOURS TOMORROW BUT SEVERE POTENTIAL WILL BE LIMITED MAINLY BY VERY WEAK INSTABILITY. FRONTOGENESIS MOVES INTO AREA BY THURS MORNING AND REMAINS QUASI STATIONARY OVER THE OH VALLEY THRU SATURDAY ACCORDING TO NAM/GFS. ADDITIONAL EMBEDDED SHORTWAVES IN MEAN FLOW WILL HELP TO TRIGGER OCCASL CONVECTIVE SHOWERS/TSTMS IN CONJUNCTION WITH FRONTAL LIFTING IN REGION. PWATS VALUES WILL BE ON THE ORDER OF 1.2 TO 1.5 INCHES OVERNIGHT AND THURSDAY AS LLJ MOVES INTO THE AREA AND ACTS AS MSTR TRANSPORT MECHANISM...THEREFORE POTENTIAL EXISTS FOR HEAVY RAIN AMOUNTS. HPC GUIDANCE CURRENTLY HAS ROUGHLY 1.5 INCHES ACCUMULATING OVER THE ENTIRE FCST AREA...WITH POTENTIAL FOR UP TO 3 INCH AMOUNTS IN ISOLATED AREAS IN THE NEXT 48-60 HRS. AT THIS TIME...1 TO 2 INCH AMTS APPEAR TO BE THE MORE PROBABLE SCENARIO. WILL ISSUE AN ESF TO INCREASE AWARENESS ABOUT THE WATER THREAT BUT WILL HOLD OFF ON ANYTHING ELSE WHEN/IF FOCUS FOR LIFT BECAUSE MORE APPARENT. HAVE ADJUSTED TEMPS SLIGHTLY TO ALIGN THEM IN A NORTH-SOUTH GRADIENT AS THE MODEL CONSENSUS INDICATES AN EAST-WEST FRONTAL POSITION OVER THE TONIGHT THRU FRIDAY NIGHT PERIOD. LONG TERM...AFT 12Z ON MARCH 24...CONSENSUS IS WARM AND OFTEN WET WITH STRONG SW FLOW AND FRONT WEAVING BACK AND FORTH ACROSS AREA. HOWEVER JUST HOW THE FRONT AND SHORT WAVES MOVING THROUGH AREA INTERACT COULD MAKE A BIG DIFFERENCE IN JUST HOW WARM AND HOW WET WE GET. FOR NOW WILL STICK CLOSE TO NCEP GUIDANCE BECAUSE DONT HAVE A BETTER IDEA...BUT THIS IS NOT A HIGH CONFIDENCE FCST. && .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...SMITH/JK AVIATION...TUCEK in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 410 PM EDT WED MAR 21 2007 .DISCUSSION...SURFACE FRONT CURRENTLY LOCATED OVER NORTHERN PLAIN/UPPER MIDWEST WILL MOVE SOUTH INTO THE AREA THURSDAY. HAVE ADJUSTED PRECIP TIMING ACCORDINGLY. HAVE KEPT A CHANCE IN MOST AREAS DURING THE OVERNIGHT HOURS TO ACCOUNT FOR ANY PRE-FRONTAL ELEVATED CONVECTION THAT MAY FIRE AS S/W OVER S. MO AND N. AR MOVES INTO AREA ALONG WITH INCREASING ISENTROPIC LIFT FROM THE LLJ. THE MID LEVEL FORCING ASSOCIATED WITH THE ACCOMPANYING S/W IS FCST TO MOVE ACRS THE UPPER MIDWEST AND LAKES REGION SHOULD REMAIN DISPLACED AWAY FROM CENTRAL INDIANA. THIS WILL TEND TO LIMIT DESTABILIZATION OVERTOP MOIST TONGUE ADVECTING INTO THE REGION TONIGHT AND EARLY TOMORROW. MODEL CONSENSUS FCST SOUNDINGS INDICATING MODEST LOW LEVEL FLOW DURING THE AFTERNOON HOURS TOMORROW BUT SEVERE POTENTIAL WILL BE LIMITED MAINLY BY VERY WEAK INSTABILITY. FRONTOGENESIS MOVES INTO AREA BY THURS MORNING AND REMAINS QUASI STATIONARY OVER THE OH VALLEY THRU SATURDAY ACCORDING TO NAM/GFS. ADDITIONAL EMBEDDED SHORTWAVES IN MEAN FLOW WILL HELP TO TRIGGER OCCASL CONVECTIVE SHOWERS/TSTMS IN CONJUNCTION WITH FRONTAL LIFTING IN REGION. PWATS VALUES WILL BE ON THE ORDER OF 1.2 TO 1.5 INCHES OVERNIGHT AND THURSDAY AS LLJ MOVES INTO THE AREA AND ACTS AS MSTR TRANSPORT MECHANISM...THEREFORE POTENTIAL EXISTS FOR HEAVY RAIN AMOUNTS. HPC GUIDANCE CURRENTLY HAS ROUGHLY 1.5 INCHES ACCUMULATING OVER THE ENTIRE FCST AREA...WITH POTENTIAL FOR UP TO 3 INCH AMOUNTS IN ISOLATED AREAS IN THE NEXT 48-60 HRS. AT THIS TIME...1 TO 2 INCH AMTS APPEAR TO BE THE MORE PROBABLE SCENARIO. WILL ISSUE AN ESF TO INCREASE AWARENESS ABOUT THE WATER THREAT BUT WILL HOLD OFF ON ANYTHING ELSE WHEN/IF FOCUS FOR LIFT BECAUSE MORE APPARENT. HAVE ADJUSTED TEMPS SLIGHTLY TO ALIGN THEM IN A NORTH-SOUTH GRADIENT AS THE MODEL CONSENSUS INDICATES AN EAST-WEST FRONTAL POSITION OVER THE TONIGHT THRU FRIDAY NIGHT PERIOD. LONG TERM...AFT 12Z ON MARCH 24...CONSENSUS IS WARM AND OFTEN WET WITH STRONG SW FLOW AND FRONT WEAVING BACK AND FORTH ACROSS AREA. HOWEVER JUST HOW THE FRONT AND SHORT WAVES MOVING THROUGH AREA INTERACT COULD MAKE A BIG DIFFERENCE IN JUST HOW WARM AND HOW WET WE GET. FOR NOW WILL STICK CLOSE TO NCEP GUIDANCE BECAUSE DONT HAVE A BETTER IDEA...BUT THIS IS NOT A HIGH CONFIDENCE FCST. && .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...SMITH/JK AVIATION...KOCH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 100 PM EDT WED MAR 21 2007 .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .DISCUSSION...SPLIT UPPR FLOW DVLPG ACRS THE COUNTRY OVR THE NEXT COUPLE OF DAYS. WK DISTURBANCES WL BE EJECTING OUT OF THE SRN PLAINS...WHILE A STRONGER NRN STREAM SYS CURRENTLY LOCATED OVR THE NRN ROCKIES PUSHES EWD INTO THE UPPR GRTLKS ON THURS. THIS SYS WL BRING A CDFNT INTO THE LOCAL AREA BY THURS AFT/NIGHT. MODELS IN RELATIVELY GOOD AGREEMENT ON THE MAIN DETAILS. FCST FOCUS CENTERS ON POPS. LIFT AHEAD OF WK SHORT WV TROF OVR WRN IL CAUSING SHWRS TO BREAK OUT ACRS THE AREA. 21/00Z UA INDICATES NOSE OF LLJ POINTED MORE TOWARDS SRN LI MI...SO WOULD XPCT THE BULK OF THE HVR PCPN TO STAY NW OF THE LOCAL AREA EARLY THIS MORN. BASED ON MODEL DATA...WV SHOULD PUSH OFF TO THE NE BY SUNRISE...SO PCPN THREAT SHOULD DIMINISH BY THAT TIME. H20 LOOP LOOKS PRETTY MESSY IN THE SRN STREAM...WITH INDICATIONS OF ADDITIONAL DISTURBANCES PSBLY OVR NEBRASKA AND ERN OK. CONSIDERING ABV AND THE FACT THAT LLJ WL REMAIN IN THE GENERAL AREA THRU TONIGHT...DECIDED TO LEAVE CHC POPS IN THE FCST THRU TONIGHT. APPEARS CDFNT WL BE MOVG INTO THE NWRN ZONES BY THURS AFT. GOOD INFLOW INTO THE FNT WITH 850MB WNDS PROGGED ARND 40KTS. THIS SUGGESTS FAIRLY WIDESPREAD PCPN SHOULD DVLP INVOF FNT. WL GO WITH HI POPS BY THURS AFT AS A RESULT. MODELS INDICATE FNT MAY STALL OUT NEARBY TOWARDS THE END OF THE WEEK. 850MB FLOW INTO THE FNT REMAINS RATHER HEALTHY AS WELL...SUGGESTING HVY RAINFALL TOTALS PSBL LT IN THE WEEK IF MODEL SOLUTIONS COME TO PASS. BASED ON PROGGED LO LVL THICKNESSES...NGM MOS GUIDANCE TEMPS LOOK REASONABLE AT THIS PT...SO WON/T STRAY TOO FAR FM THEM. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...JAS AVIATION...KOCH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 309 PM CST WED MAR 21 2007 .SYNOPSIS... CONVECTION ONGOING OVER THE NW FOURTH OF THE CWA THIS AFTERNOON. TSRA MOVED INTO THE WRN COUNTIES AHEAD OF H5 S/W MVNG THROUGH CENTRAL IA...THEN REFORMED INTO AN E/W LINE ALONG INSTABILITY GRADIENT OVER SE IA. SO FAR JUST SOME ISOLATED SEVERE HAIL REPORTS AND WIND GUSTS AROUND 35KTS. COLD FRONT WAS LOCATED FROM THE WRN MN THROUGH ERN NE EARLY THIS AFTERNOON. 12Z UA ANALYSIS SHOWED A POTENT NRN ROCKIES UPPER TROF ASSOCIATED WITH THE FRONT. SO FAR NOT MUCH IN THE WAY OF CONVECTION WAS NOTED WITH SURFACE FRONT WITH STRONG CAP NOTED ON KOAX 18Z SOUNDING...SUPPRESSING DEVELOPMENT. && .SHORT TERM...TONIGHT AND THURSDAY... CONVECTION CURRENTLY OVER THE NRN CWA SHOULD BE EAST OF THE CURRENT WATCH AND ANTICIPATE CANCELLING THE SEVERE WATCH EARLY FOR MOST OF THE WATCH AREA. COLD FRONT PROGGED TO MOVE THROUGH CWA LATE THIS EVENING AND EARLY THURSDAY MORNING AS MID LEVEL S/W CROSSES THE NCNTRL STATES. LOOKING AT A RUC FCST NR KOMA FOR THIS AFTERNOON...IT SHOWS THE STRONG CAP DISSIPATING BY 00Z...SO EXPECT CONVECTION TO FORM IN WRN IA BY EARLY EVENING ON THE FRONT AND REACH THE NWRN CWA AROUND 03Z ...THEN MOVING THROUGH THE SERN CWA BTWN 09Z AND 12Z. FRONT IS THEN EXPECTED TO STALL OVER CENTRAL MO/IL THURSDAY AFTN/EVE. HAVE CONTINUED CATEGORICAL POPS FROM THE PREV FCST FOR TONIGHT. SEVERE THREAT REMAINS WITH SOME MODEST CAPE AROUND 1000J/KG PROGGED TO REMAIN OVER ERN IA THROUGH THE EVENING. BELIEVE SYSTEM WILL BE PROGRESSING EAST FAST ENOUGH TO LIMIT ANY RAINFALL THREAT IN ANY ONE AREA. PROBABLY THE MOST VULNERABLE AREA WILL BE THE SRN MOST COUNTIES WAS THE FRONT SLOWS AS IT BECOMES MORE ALIGNED WITH THE MID LEVEL FLOW. && .LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY... THE GFS/NAM/UKMET ARE IN GOOD AGREEMENT LIFTING THE BOUNDARY BACK NORTH INTO NRN MO/CNTRAL IL LATE THURSDAY NIGHT SETTING UP THE POTENTIAL FOR A HEAVY RAIN AS STRONG/MOIST SLWY LOW LEVEL FLOW INTERSECTS THE BOUNDARY...AND FUELING STORMS ON THE COOL SIDE. REPEAT CONVECTION WILL BE POSSIBLE WITH THE FRONT ORIENTED PARALLEL TO THE MID LEVEL FLOW AND A SWLY LLJ POINTED AT NW MO/SW IA MOST OF THE NIGHT. MODELS DIVERGE FRIDAY INTO THE SATURDAY HANDLING THE WARM FRONT. THE GFS PULLS THE BOUNDARY NORTH WELL INTO IA WHILE THE NAM/UKMET KEEP SOUTH AS THEY BRING S/W ENERGY THROUGH NRN STREAM. SINCE THE GFS IS THE OUTLIER...HAVE LIMITED CHANCE POPS TO THE SRN COUNTIES. FOR SATURDAY NIGHT THROUGH MONDAY THE LONG RANGE MODELS ARE IN BETTER AGREEMENT HANDLING THE SRN STREAM CUT OFF LOW...LIFTING IT NE THROUGH THE MID MS VALLEY BY EARLY MONDAY. BASED ON THIS HAVE STARTED TO TREND POPS HIER ESPECIALLY IN ADVANCE OF THE SYSTEM SATURDAY NIGHT THROUGH SUNDAY NIGHT. LONG RANGE MODELS THEN DEVELOP DEEP LOW PRESSURE OVER THE CENTRAL PLAINS FOR MID WEEK. HAVE OPTED TO KEEP FCST DRY TO MODELS ESTABLISH SOME RUN TO RUN CONTINUITY. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. $$ ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1038 AM CDT THU MAR 22 2007 .UPDATE... SURFACE FRONT HAD BECOME QUASI-STATIONARY GENERALLY JUST SOUTH OF HIGHWAY 50 AT MID-MORNING...WITH THE LATEST NAM AND RUC SUGGESTING A SLIGHT NORTHWARD MOVE INTO THE AFTERNOON. THIS IS SLIGHTLY NORTH OF EARLY MORNING GRID PACKAGE...SO HAVE REFLECTED THE CHANGES IN THE LATEST GRID/FORECAST UPDATE. AS FOR CONVECTIVE CHANCES FOR THIS AFTERNOON...A LOT WILL DEPEND ON DIURNAL HEATING (IE. CLOUD TRENDS) ALONG AND SOUTH OF SURFACE FRONTAL BOUNDARY. DESPITE SOME HOLES INTO MIDDAY...HIGHER LEVEL CLOUDS LOOK TO ENCROACH SOUTH CENTRAL KANSAS DURING THE EARLY AFTERNOON. CONVERGENCE ALONG THE BOUNDARY LOOKS SUFFICIENT TO FOCUS CONVECTION WITH POTENTIAL ML CAPES OF AROUND 1800 J/KG LATER THIS AFTERNOON. SO LITTLE CHANGE TO THE GOING POP FORECAST AND FLOOD WATCH HEADLINE. BETTER CHANCES FOR ELEVATED CONVECTION APPEAR TO BE IN THE OFFING LATE THIS EVENING OR OVERNIGHT...ALONG AND NORTH OF SURFACE FRONT. KED && .PREV DISCUSSION... /ISSUED 328 AM CDT THU MAR 22 2007/ DISCUSSION... FORECAST CONCERNS TODAY ARE TSRA CHANCES FOR TODAY THROUGH THE WEEKEND AND ALSO TEMPS. TODAY: WAVY FRONTAL BOUNDARY MAKING SLOW PROGRESS INTO THE SOUTHERN KS AT THIS TIME. SOME WIDELY SCATTERED TSRA FINALLY HAVE DEVELOPED ALONG THE BOUNDARY AS LOW LEVEL JET INCREASES OVER THE TOP OF THE FRONT HELPING TO GET ELEVATED STORMS GOING. QUESTION TODAY IS HOW FAR SOUTH /IF AT ALL/ THIS FRONT WILL MAKE IT BEFORE STALLING OUT LATER THIS MORNING. SOME PRESSURE RISES STILL NOTED BEHIND THE BOUNDARY SO PREFER THE NAM-WRF FOR FRONTAL PLACEMENT GENERALLY ALONG AN EMP-HUT LINE BEFORE IT STALL. WHERE THE BOUNDARY WILL ULTIMATELY STALL OUT IS THE BIG PROBLEM TODAY AS THIS BOUNDARY WILL PROVIDE THE FOCUS FOR CONVECTION AND POSSIBLE TRAINING ECHOES. EXPECT SOME CONVECTION TO BE ONGOING EARLY IN THE PERIOD...BUT MAIN TSRA CHANCE WILL BE THIS AFTERNOON AS A MID LEVEL IMPULSE IN THE SOUTHWEST FLOW AND INCREASING ISENTROPIC LIFT IN THE 305K LAYER WILL STEEPEN LAPSE RATES ENOUGH FOR A MORE WIDESPREAD CONVECTION CHANCE. INSTABILITY IS MODEST WITH MUCAPE VALUES THIS AFTERNOON ONLY AROUND 1000 J/KG...BUT 0-6KM SHEAR VALUES STILL SUGGEST A POSSIBLE LARGE HAIL THREAT FOR AREAS WHERE SURFACE HEATING CAN BE MAXIMIZED. WITH SOME SURFACE BASED CONVECTION POSSIBLE SOUTH OF THE BOUNDARY OVER AREAS WITH SATURATED GROUNDS...WILL LEAVE THE FLOOD WATCH GOING FOR SOUTH CENTRAL AND SOUTHEAST KS BUT DAY SHIFT WILL PROBABLY HAVE TO BETTER DEFINE THIS ONCE BOUNDARY DECIDES TO STOP ITS SOUTHERN PROGRESS. WILL RAISE MAX TEMPS IN SOUTHERN KS AS BOUNDARY JUST TO THE NORTH OF THIS AREA WILL ALLOW TEMPS TO CLIMB INTO THE LOWER 70S. TONIGHT: BOUNDARY DRIFTS TO THE NORTH SOME AS THE NIGHT PROGRESSES...WITH SOME ISENTROPIC LIFT STILL LOCATED SOUTH OF THE BOUNDARY. SO EXPECT SOME CONVECTION IN SOUTHEAST KS EARLY BUT PROBABLY DIMINISHING OVERNIGHT. THIS LIFT WILL PROBABLY LEAD TO SOME TRANING STORMS IN AND NEAR THE BOUNDARY...SO FLOODING THREAT WILL DEFINATELY HAVE TO BE WATCHED. FRI-FRI NIGHT: NOT ALOT OF CONFIDENCE IN FRONTAL PLACEMENT AND POSSIBLE CONVECTION FOR FRI. MODELS ALSO DIFFER ON MID LEVEL IMPULSES EXPECTED TO MOVE ACROSS THE AREA IN THE SOUTHWEST FLOW. WITH THE BOUNDARY STILL EXPECTED TO BE IN THE AREA WILL LEAVE CHANCE POPS IN MOST LOCATIONS AS ANY WEAK IMPULSE COULD LEAD TO DEVELOPMENT...BUT DO NOT EXPECT TSRA CHANCE TO BE WIDESPREAD. BETTER DEVELOPMENT LOOKS TO BE FRI NIGHT AS ISENTROPIC LIFT AGAIN INCREASES ACROSS THE AREA. WILL STILL ONLY GO CHANCE POPS FOR NOW AS PLACEMENT OF THE BOUNDARY IN LATER RUNS WILL BETTER DEFINE HIGHEST POP AREAS. SAT-SUN: CONFIDENCE REMAINS LOW DURING THIS TIME FRAME AS BOUNDARY REMAINS SOMEWHAT STATIONARY ON SAT FOR BEGINNING TO LIFT TO THE NORTH AGAIN AS A WARM FRONT ON SUN AND MAIN SHORTWAVE REMAINS SOUTHWEST OF THE AREA UNTIL SUN EVENING. WITH LOTS OF LOW LEVEL MOISTURE AROUND HEAVY RAINFALL THREAT WILL ALSO CONTINUE. WILL HAVE TO KEEP AN EYE ON SEVERE THREAT ON SAT AS SHEAR VALUES LOOK FAVORABLE BUT INSTABILITY LOOKS MODEST. MONDAY-WEDNESDAY: PRECIP CHANCES LOOK TO COME TO AN END ON MONDAY AS MED RANGE MODELS FINALLY MOVE THE MAIN SHORTWAVE ACROSS THE AREA. LOOKS LIKE TUESDAY WILL BE A DAY TO DRY OUT WITH WEAK RIDGING IN THE MID LAYERS. A RATHER RIGOROUS SHORTWAVE MOVES INTO THE PLAINS ON WED FOR ANOTHER POSSIBLE ROUND OF CONVECTION. KETCHAM && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 74 59 72 58 / 50 60 40 40 HUTCHINSON 70 58 72 57 / 40 50 40 40 NEWTON 71 58 71 57 / 50 60 40 40 ELDORADO 73 59 72 58 / 60 60 40 40 WINFIELD-KWLD 73 60 73 59 / 60 60 40 40 RUSSELL 61 51 71 53 / 20 30 40 40 GREAT BEND 64 53 71 55 / 30 40 40 40 SALINA 63 52 69 54 / 30 50 40 40 MCPHERSON 67 56 71 56 / 40 50 40 40 COFFEYVILLE 76 61 73 59 / 60 60 40 30 CHANUTE 74 60 72 59 / 60 60 40 30 IOLA 73 59 72 58 / 60 60 40 30 PARSONS-KPPF 74 61 73 59 / 60 60 40 30 && .ICT WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH FRIDAY MORNING FOR KSZ069>072-083-092>096- 098>100. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 440 AM CDT THU MAR 22 2007 .DISCUSSION... THE UNSETTLED PATTERN CONTINUES. INTERESTING SET UP TODAY WITH SFC BNDRY TO THE SOUTH AND GOOD OVER-RUNNING PATTERN DEVELOPING. LATEST RUC SOUNDINGS SHOW GOOD ELEVATED LIFT DEVELOPING NORTH OF THE SFC BNDRY BY MIDDAY ALONG OR JUST SOUTH OF INTERSTATE 70. OPTIMUM ELEVATED LIFT WITH FAIRLY GOOD CHANCE FOR THUNDERSTORMS MOVES SLOWLY NORTH THROUGH THE AFTERNOON AND OVERNIGHT...REACHING THE NORTHERN BORDER AFTER MIDNIGHT. PATTERN SUPPORTIVE OF LOCALLY HEAVY RAINS WITH TRAINING OVER SAME AREAS. NO FLOOD WATCH ISSUED YET...BUT BEARS WATCHING IN 12Z RUN. PRECIPITABLE WATER VALUES EXCEEDINGLY HIGH FOR THIS TIME OF YEAR...RUNNING NEARLY 250% OF NORMAL! THIS HIGH WATER CONTENT CONTINUES INTO THE WEEKEND AND DOES NOT REALLY GET MODIFIED TO ANY GREAT EXTENT UNTIL UPPER SYSTEM FINALLY LIFTS THROUGH FROM THE SOUTHWEST STATES EARLY NEXT WEEK. UNTIL THEN, PERIODIC CHANCES FOR CONVECTION...SOME OF WHICH MAY BE STRONG TO SEVERE. SETUP FOR SEVERE TODAY IS MAXIMIZED ALONG AND NORTH OF THE WARMFRONT. CONSIDERABLE HIGH CLOUDINESS WILL LIMIT SOLAR INSOLATION TO FRONTAL AREA OTHERWISE TEMPERATURES WOULD BE WARMER AND THE THREAT FOR SEVERE HAIL WOULD BE EVEN GREATER. SHEAR SEEMS TO BE SUFFICIENT FOR LARGE HAIL LATER TODAY AS WELL. TEMPERATURES IN TURN A REAL CHALLENGE WITH CLOUDS HANGING TOUGH TO THE NORTH OF THE FRONT. HAVE FOLLOWED NAM CLOSELY WITH IT`S SFC TEMPERATURE FCST. THUS COULD RANGE FROM THE UPPER 40S NORTH TO THE LOWER 70S SOUTH. BY FRIDAY THE FRONT SHOULD RESIDE ALONG THE NORTHERN BORDER WAITING FOR AN UPPER WAVE TO EJECT OUT OF MEAN WESTERN TROF POSITION. THIS COULD TRIGGER ANOTHER ROUND OF CONVECTION FRIDAY NIGHT. BETTER CHANCE APPEARS SATURDAY NIGHT INTO SUNDAY NIGHT AS UPPER SYSTEM LIFTS NORTHEAST INTO THE PLAINS. LATER PERIODS OF THE FORECAST NOT CHANGED MUCH AS IS IMPOSSIBLE TO ADD MUCH DETAIL OR FIND REASONS TO MAKE CHANGES IN SUCH AN UNSETTLED PATTERN. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 358 AM CDT THU MAR 22 2007 .DISCUSSION... DAYS 1-2... A NORTHERN STREAM SHORTWAVE TROUGH PASSED ACROSS THE NORTHERN PLAINS AND INTO THE GREAT LAKES OVERNIGHT. THIS HELPED PUSH A COLD FRONT THROUGH MOST OF SW KS. THE FRONT AS OF 3 AM STRETCHED FROM NORTH OF HUGOTON TO HUTCHINSON. SFC TEMPS WERE VERY BALMY SOUTH OF THE FRONT(71 AT BUFFALO,OK AND 65 AT LIBERAL). THE SFC DRYLINE WAS CURRENTLY MOVING NW THROUGH WEST TEXAS. AN UPPER LOW WAS SITUATED JUST OFF THE SOUTHERN CA COAST. 500MB TEMPS HAVE TURNED OUT TO BE WARMER THAN THE MODELS WERE FORECASTING A FEW DAYS AGO. IN FACT THE NAM HAS 500MB TEMPS AROUND -13C THIS AFTERNOON. SURFACE DEWPOINTS HAVE CLIMBED INTO THE UPPER 50S AND LOWER 60SF ACROSS OK/SOUTHERN KS. A LARGE AREA OF MID TO HIGH LEVEL CLOUD WAS MOVING NE INTO NM AND WEST TX. IN THE ABSENCE OF STRONG SYNOPTIC SCALE DYNAMICS TODAY...THE LOCATION OF SFC BOUNDARIES WILL DETERMINE THE PLACEMENT OF SHOWER/THUNDERSTORM INITIATION. THE NAM/GFS AND SOME OF THE RUC MEMBERS SURGE THE FRONT BACK TO THE NORTH TODAY TO A GCK TO HAYS LINE. I HAVE CHOSEN TO GO WITH THE RUC13 SOLUTION FOR TODAY. THIS MODEL KEEPS THE FRONT NEARLY STATIONARY ALL DAY. WITH BROKEN MID TO HIGH CLOUDS AND LOW LEVEL UPSLOPE FLOW... TEMPS WILL STAY IN THE 60S NORTH OF THE FRONT. BUT LOCATIONS ALONG THE OK STATE LINE COULD REACH THE UPPER 70S. I EXPECT THE SFC DRYLINE TO STRETCH FROM DALHART TO CARLSBAD,NM BY THIS AFTERNOON. THE DRYLINE WILL INTERSECT THE FRONT CLOSE TO DALHART. FAIRLY WEAK CAPPING...SOME ELEVATED HEATING ON THE HIGH PLAINS... AND CONVERGENCE ALONG THE DRYLINE AND NEAR THE FRONT/DRYLINE INTERSECTION WILL ALLOW STORMS TO DEVELOP BY 21Z. LOCAL POOLING OF MOISTURE MAY ALLOW FOR SFC BASED CAPES AS HIGH AS 1000-1500 J/KG FROM P28 TO ENGLEWOOD. AS STORMS MOVE INTO THIS AREA...A FEW OF THEM COULD BECOME SEVERE. VERTICAL SHEAR PROFILES WILL BE FAVORABLE FOR SEVERE STORMS. BUT THE MAIN LIMITING FACTOR FOR SEVERE STORMS WILL BE THE MARGINAL INSTABILITY. BUT AS WE HAVE SEEN IN THE RECENT PAST...STRONG VERTICAL WIND SHEAR AND CAPES AROUND 1000 J/KG CAN BE ENOUGH FOR SEVERE STORMS. ANY STORMS THAT DEVELOP THIS AFTERNOON WILL PROBABLY LINGER INTO TONIGHT. BUT THE STORM ACTIVITY WILL SHIFT OFF TO THE NE BY FRIDAY BEFORE THE MAIN UPPER LOW EJECTS INTO THE PLAINS ON SATURDAY. SOME POPS WERE MAINTAINED FOR FRIDAY FOR CONSISTENCY SAKE AND SINCE THERE IS SOME UNCERTAINTY. DAYS 3-7... NOT GOING TO CHANGE MUCH IN THE GOING EXTENDED. BOTH THE UKMET AND GFS BRING AN ORGANIZED SYSTEM UP FROM SOUTHERN BAHA CALIFORNIA TO WESTERN KANSAS FROM FRIDAY INTO SUNDAY. THE BEST CHANCES FOR PRECIPITATION LOOK TO BE ON SATURDAY AFTERNOON...WHERE WE HAVE 40 POPS GOING NOW. THESE POPS MAY HAVE TO BE RAISED IF THE TRACK OF THE UPPER SYSTEM BEARS OUT. TEMPERATURES LOOKED REASONABLE AND IN LINE WITH SURROUNDING WFO GRIDS. TUESDAY LOOKS TO BE WARM...PERHAPS WITH 80S SOMEWHERE IN OUR CWA. LEFT TUES MAX T`S ALONE FOR NOW...AS OUR SW HAS MID 70S GOING. && .AVIATION... AS LOW LEVEL MOISTURE CONTINUES TO CONVERGE ALONG AND SOUTH OF A FRONTAL BOUNDARY LYING ACROSS SOUTHERN KANSAS...STRATUS WILL LIKELY FORM AT DDC AND GCK IN THE 012 TO 015 FEET RANGE BY 11Z THIS MORNING. DO NOT EXPECT THE STRATUS TO LINGER MUCH BEYOND 15-16Z. ALSO...FOG WITH VSBYS IN THE 4-5SM RANGE WILL FORM AT DDC...GCK AND HYS AND LAST THROUGH 15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 53 71 56 / 20 30 20 20 GCK 64 45 72 53 / 20 20 20 20 EHA 71 47 71 53 / 20 20 20 20 LBL 73 51 71 56 / 20 30 20 20 HYS 61 48 72 55 / 20 20 20 20 P28 76 59 70 61 / 30 30 30 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN24/12 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 200 AM MDT THU MAR 22 2007 .DISCUSSION... PRIMARY UPPER FEATURE FOR THE SHORT TERM PERIOD WILL BE CUT OFF LOW OVER THE DESERT SOUTHWEST. FORECAST AREA TO REMAIN UNDER THE SOUTHWEST FLOW AHEAD OF THE MAIN LOW FOR THE NEXT SEVERAL DAYS. THE UPPER LOW WILL THEN BEGIN TO LIFT NORTH/NORTHEAST OVER THE WEEKEND. UNFORTUNATELY MODELS IN POOR AGREEMENT ON FINER DETAILS. EVEN AS EARLY AS TODAY...NAM BRINGING A FAIRLY WELL DEFINED VORT MAX OVER THE AREA/WHEREAS GFS SHOWS LITTLE IF ANYTHING. WATER VAPOR IMAGERY INCONCLUSIVE...SINCE JUST SEE A BROAD SOUTHWEST FLOW WITH DEEP TROPICAL PLUME AHEAD OF THE MAIN LOW. WITH LITTLE TO GO ON WILL PLAY THE PERCENTAGES AND HAVE SOME SLIGHT/LOW CHANCE POPS THIS AFTERNOON AND EVENING ACROSS SOUTHEAST COUNTIES. SOMEWHAT RELIABLE RUC CEILING FORECAST SHOWS 2KFT BROKEN DECK OVERSPREADING THE CWA FROM THE SOUTH THIS AFTERNOON...WILL FAVOR COOLER GUIDANCE FOR HIGHS AS A RESULT. FRIDAY WILL BE A VIRTUAL REPEAT...THOUGH MODELS SWITCH PLACES WITH GFS WET AND NAM DRY. IT DOES APPEAR THE AREA WILL COME UNDER FAVORABLE RIGHT ENTRANCE REGION OF JET WHICH DEVELOPS FRIDAY NIGHT/SATURDAY MORNING OVER THE MIDWEST. SURFACE FRONT WILL ALSO BE SURGING NORTH INTO THE AREA. NONETHELESS...ISC CONSTRAINTS WILL DICTATE LOW CHANCE POPS. THEN WILL HAVE TO DEAL WITH THE MAIN LOW OVER THE WEEKEND. MODELS ALL OVER THE PLACE...WHICH LENDS LITTLE TO NO CONFIDENCE TO THE PRECIPITATION CHANCES. GFS ENSEMBLE AVERAGES GIVE SOLID CHANCE POPS THROUGH SATURDAY...GRADUALLY DIMINISHING SATURDAY NIGHT AND SUNDAY TO SLIGHT CHANCES. THE ENSEMBLE APPROACH SEEMS REASONABLE GIVEN THE UNCERTAINTIES. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JDK ks AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE DODGE CITY KS 258 PM CDT WED MAR 21 2007 .DISCUSSION... DAYS 1-2... MAIN CONCERN THIS AFTERNOON WILL BE IF/WHEN CONVECTION WILL DEVELOP ALONG A DRYLINE WHICH WAS SLOWLY MOVING EAST ACROSS OUR EASTERN CWA. AT THIS TIME NOT SEEING ANY GOOD UPPER LEVEL DYNAMICS AND BASED ON NAM SOUNDINGS THE CONVECTIVE TEMPS ALONG THE DRYLINE WERE BETWEEN 82-86F. ALSO NOTICING CAPES ALONG AND AHEAD OF THIS FRONT WERE AT 15-2K J/KG WITH IMPROVING MOIST CONV. THE RUC40 ALSO WAS FORECASTING 0-6KM SHEAR OF 30 TO 35KTS. IF THE CONVECTIVE TEMPERATURE CAN BE REACHED LATE TODAY SHOULD SEE A FEW STORMS GO UP QUICKLY WITH THE MAIN HAZARD BEING HAIL. DOES NOT LOOK LIKE ANYTHING WIDESPREAD SO WILL KEEP SLT CHC POPS AND ADJUST AS NEEDED AS WE APPROACH 4 PM BASED ON LATEST OBSERVATIONS/CU DEVELOPMENT. FOR TONIGHT A COLD FRONT MOVES SOUTH ACROSS KANSAS AS A NORTHERN BRANCH S/W TROF MOVES ACROSS THE NORTHERN PLAINS INTO THE MISSISSIPPI VALLEY. THE BETTER DYNAMICS FROM THIS SYSTEM WILL REMAIN WELL TO OUR EAST BUT WITH SOME MOISTURE POOLING BEHIND THE FRONT AND WEAK LIFT OVERNIGHT IN OUR EAST AM UNABLE TO COMPLETELY RULE OUT PCPN CHANCES. WILL THEREFORE KEEP SMALL POPS GOING DURING THE OVERNIGHT HOURS. THE FORECAST THURSDAY THROUGH FRIDAY WILL MAINLY BE DEPENDANT ON WHERE OUR FRONT WILL BE. THROUGH FRIDAY MORNING OUR SURFACE FRONT IS EXPECTED TO REMAIN NEARLY STATIONARY ALONG THE KS/OK BORDER. MUCH LIKE OUR LAST SYSTEM GOOD ISENTROPIC LIFT, MOISTURE AND ISENTROPIC LIFT DEVELOPS ALONG AND NORTH OF THIS BOUNDARY. WILL THEREFORE KEEP HIGH CHC POPS IN OUR SE CWA AND TAPER POPS OFF FURTHER NW AND HIGHLIGHT THE BETTER CHANCE OF PCPN THURSDAY NIGHT. BY FRIDAY THE BULK OF THE PCPN WILL BE MOVING OUT OF SW KS. HOWEVER WILL HAVE TO WATCH LOW LEVEL MOISTURE AND UPSLOPE FLOW EARLY FRIDAY. AT THIS TIME WILL GO WITH AREAS OF FOG AND DRIZZLE EARLY WITH SOME CLEARING LATE IN THE DAY. GIVEN THE CLOUDS AND UPSLOPE FLOW WILL ALSO LEAN TOWARDS THE COOLER MET NUMBERS FOR HIGHS FRIDAY. DAYS 3-7... AFTER LOOKING AT THE OVERALL PICTURE THIS MORNING THE GFS/ECMWF ARE VERY SIMILAR WITH THE NEXT FRONT MOVING INTO THE REGION OVER THE WEEKEND. THE ONSET OF OUR NEXT COLD FRONT MOVING IN FRIDAY NIGHT INTO SATURDAY WILL HELP SET THE SCENCE FOR CONVECTIVE ACTIVITY WITH ANOTHER DRY LINE OVER SOUTHWESTERN KANSAS. LOW LEVEL JET WILL PUSH AMPLE MOISTURE INTO THE REGION...MODELS HAVE ALSO INDICATED THE PRESENCE OF VERY STRONG CONVERGENCE WITHIN THE VICINITY OF THE DRY LINE. WITH UPPER LEVEL SUPPORT TO KICK OFF CONVECTIVE ACTIVITY WILL NOT BE ABLE TO RULE OUT THE CHANCES FOR SEVERE THUNDERSTORMS. AS THE SYSTEM BEGINS TO PUSH OUT OF THE REGION BY MONDAY MUCH DRIER AIR WILL TAKE PLACE OVER SOUTHWESTERN KANSAS FOR THE BEGINNING OF THE WEEK. DECIDED TO TWEAK TEMPERATURES UP A FEW DEGREES FOR THE FIRST PART OF THE WEEK. THEN ON WEDNESDAY LOOKS LIKE MOISTURE RETURNING TO OUR PART OF THE WORLD. HOWEVER JUST TOO EARLY TO SEE IF THIS WILL BECOME A MID WEEK MOISTURE PRODUCER. && .AVIATION... AREAS OF SCT HIGH LVL CLOUDS EXPECTED OVER MOST THE FORECAST AREA. BETWEEN 09-12Z LOW STRATUS CAN BE EXPECTED WITH VSBYS OF 5SM BR AND LGT AND VARIABLE WINDS ARE FORECAST SO CANNOT RULE OUT THE CHANCES FOR THE DEVELOPMENT OF FOG BETWEEN 09-15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 49 63 48 68 / 20 20 20 0 GCK 45 64 46 68 / 20 10 10 0 EHA 47 66 51 72 / 10 10 10 0 LBL 50 68 51 72 / 10 20 20 0 HYS 47 57 47 66 / 30 10 10 0 P28 56 66 54 68 / 30 50 50 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN18/31 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 242 PM CDT WED MAR 21 2007 .DISCUSSION... DAYS 1-2... MAIN CONCERN THIS AFTERNOON WILL BE IF/WHEN CONVECTION WILL DEVELOP ALONG A DRYLINE WHICH WAS SLOWLY MOVING EAST ACROSS OUR EASTERN CWA. AT THIS TIME NOT SEEING ANY GOOD UPPER LEVEL DYNAMICS AND BASED ON NAM SOUNDINGS THE CONVECTIVE TEMPS ALONG THE DRYLINE WERE BETWEEN 82-86F. ALSO NOTICING CAPES ALONG AND AHEAD OF THIS FRONT WERE AT 15-2K J/KG WITH IMPROVING MOIST CONV. THE RUC40 ALSO WAS FORECASTING 0-6KM SHEAR OF 30 TO 35KTS. IF THE CONVECTIVE TEMPERATURE CAN BE REACHED LATE TODAY SHOULD SEE A FEW STORMS GO UP QUICKLY WITH THE MAIN HAZARD BEING HAIL. DOES NOT LOOK LIKE ANYTHING WIDESPREAD SO WILL KEEP SLT CHC POPS AND ADJUST AS NEEDED AS WE APPROACH 4 PM BASED ON LATEST OBSERVATIONS/CU DEVELOPMENT. FOR TONIGHT A COLD FRONT MOVE SOUTH ACROSS KANSAS AS A NORTHERN BRANCH S/W TROF MOVES ACROSS THE NORTHERN PLAINS INTO THE MISSISSIPPI VALLEY. THE BETTER DYNAMIC FROM THIS SYSTEM WILL REMAIN WELL TO OUR EAST BUT WITH SOME MOISTURE POOLING BEHIND THE FRONT AND WEAK LIFT OVERNIGHT IN OUR EAST AM UNABLE TO COMPLETELY RULE OUT PCPN CHANCES. WILL THEREFORE KEEP SMALL POPS GOING DURING THE OVERNIGHT HOURS. THE FORECAST THURSDAY THROUGH FRIDAY WILL MAINLY BE DEPENDANT ON WHERE OUR FRONT WILL BE. THROUGH FRIDAY MORNING OUR SURFACE FRONT IS EXPECTED TO REMAIN NEARLY STATIONARY ALONG THE KS/OK BORDER. MUCH LIKE OUR LAST SYSTEM GOOD ISENTROPIC LIFT, MOISTURE AND ISENTROPIC LIFT DEVELOPS ALONG AND NORTH OF THIS BOUNDARY. WILL THEREFORE KEEP HIGH CHC POPS IN OUR SE CWA AND TAPER POPS OFF FURTHER NW AND HIGHLIGHT THE BETTER CHANCE OF PCPN THURSDAY NIGHT. BY FRIDAY THE BULK OF THE PCPN WILL BE MOVING OUT OF SW KS. HOWEVER WILL HAVE TO WATCH LOW LEVEL MOISTURE AND UPSLOPE FLOW EARLY FRIDAY. AT THIS TIME WILL GO WITH AREAS OF FOG AND DRIZZLE EARLY WITH SOME CLEARING LATE IN THE DAY. GIVEN THE CLOUDS AND UPSLOPE FLOW WILL ALSO LEAN TOWARDS THE COOLER MET NUMBERS FOR HIGHS FRIDAY. DAYS 3-7... AFTER LOOKING AT THE OVERALL PICTURE THIS MORNING SHOWS THE GFS/ECMWF/NAM TO BE VERY SIMILAR WITH THE NEXT FRONT MOVING INTO THE REGION OVER THE WEEKEND. THE ONSET OF OUR NEXT COLD FRONT MOVING IN FRIDAY NIGHT INTO SATURDAY WILL HELP SET THE SCENCE FOR CONVECTIVE ACTIVITY WITH ANOTHER DRY LINE OVER SOUTHWESTERN KANSAS. LOW LEVEL JET WILL PUSH AMPLE MOISTURE INTO THE REGION...MODELS HAVE ALSO INDICATED THE PRESENCE OF VERY STRONG CONVERGENCE WITHIN THE VICINITY OF THE DRY LINE. WITH UPPER LEVEL SUPPORT TO KICK OFF CONVECTIVE ACTIVITY WILL NOT BE ABLE TO RULE OUT THE CHANCES FOR SEVERE THUNDERSTORMS. AS THE SYSTEM BEGINS TO PUSH OUT OF THE REGION BY MONDAY MUCH DRIER AIR WILL TAKE PLACE OVER SOUTHWESTERN KANSAS FOR THE BEGINNING OF THE WEEK. DECIDED TWEAK TEMPERATURES UP A FEW DEGREES FOR THE FIRST PART OF THE WEEK. THEN ON WEDNESDAY LOOKS LIKE MOISTURE RETURNING TO OUR PART OF THE WORLD. HOWEVER JUST TOO EARLY TO SEE IF THIS WILL BECOME A MID WEEK MOISTURE PRODUCER. && .AVIATION... AREAS OF SCT HIGH LVL CLOUDS EXPECTED OVER MOST THE FORECAST AREA. BASED ON SATELLITE IMAGRY CIGS AND VSBYS ARE NOT EXPECTED TO DROP BELOW VFR CONDITIONS. BETWEEN 09-12Z LOW STRATUS CAN BE EXPECTED WITH VSBYS OF 5SM BR AND LGT AND VARIABLE WINDS ARE FORECAST SO CANNOT RULE OUT THE CHANCES FOR THE DEVELOPMENT OF FOG BETWEEN 09-15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 49 63 48 68 / 20 20 20 0 GCK 45 64 46 68 / 20 10 10 0 EHA 47 66 51 72 / 10 10 10 0 LBL 50 68 51 72 / 10 20 20 0 HYS 47 57 47 66 / 30 10 10 0 P28 56 66 54 68 / 30 50 50 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN18/31 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 100 AM EDT FRI MAR 23 2007 AVIATION (06Z TAFS)... NO AVIATION CONCERNS THROUGH THE MORNING HOURS FRIDAY EXCEPT FOR SOME HIGH CLOUDINESS EXPECTED AT SDF AND LEX. THESE HIGH CLOUDS ARE CONVECTIVE DEBRIS CLOUDS DOWNSTREAM FROM WIDESPREAD CONVECTION ACROSS CENTRAL INDIANA AND ILLINOIS. SKIES WILL REMAIN CLEAR AT BWG OVERNIGHT. FOG FORMATION WILL NOT BE A FACTOR AS DECENT SOUTHERLY WINDS AT 1500FT (25KT) WILL KEEP THE BOUNDARY LAYER SOMEWHAT MIXED. ALSO NOTED THAT A 10-15 DEGREE DEWPOINT DEPRESSIONS ARE PRESENT EVEN NOW WITH THE LATEST SURFACE OBS. SKIES WILL BECOME INCREASINGLY CLOUDY LATE THIS AFTERNOON. SCATTERED SHOWER MAY DEVELOP AFTER 18Z ACROSS LEX AND SDF. CEILINGS WILL STAY VFR TOMORROW AFTERNOON EXCEPT UNDERNEATH ANY LOCAL SHOWERS. JSD && .PREV DISCUSSION... /ISSUED 729 PM EDT THU MAR 22 2007/ EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIFY CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 902 PM CDT THU MAR 22 2007 .UPDATE... FORECAST UPDATED MAINLY TO REMOVE EVENING WORDING. ADDED A SLIGHT CHANCE POP FOR SW INDIANA OVERNIGHT DUE TO THE CLOSE PROXIMITY OF THE SURFACE BOUNDARY. GRADUAL INCREASE IN CONVECTION NOTED OVER CENTRAL IL/CENTRAL MO/EASTERN KS OVER THE PAST COUPLE OF HOURS. THIS CONVECTION IS ALONG THE FRONT...WHICH THE MODELS KEEP QUASI STATIONARY FOR THE NEXT FEW DAYS. THIS CONVECTION MAY PROPAGATE SOUTHEAST AWAY FROM THE BOUNDARY INTO SRN ILLINOIS AND SE MISSOURI OVERNIGHT. RUC MODEL CORFIDI VECTORS INDICATE A SE MOVEMENT TO ANY ORGANIZED MCS THAT DEVELOPS. && .PREVIOUS DISCUSSION... MAIN CONCERNS FOR THIS FORECAST CONTINUE TO BE POPS THROUGH THE ENTIRE PERIOD...AS TEMPERATURES WILL REMAIN MILD THROUGHOUT. ELEVATED CONVECTION HAS SHRUNK DOWN TO A NARROW BAND OF SHOWERS RIGHT THROUGH THE MID-SECTION OF THE AREA...AND IT APPEARS TO BE WEAKENING AND FINALLY PUSHING OFF TO THE EAST. WITH THE AIRMASS THOROUGHLY WORKED OVER...AND THE SURFACE BOUNDARY WELL NORTH OF THE AREA...SEE LITTLE REASON TO HAVE MUCH POP IN THE AREA THIS EVENING. WILL HOWEVER...INCLUDE A SMALL CHANCE IN THE NORTHEAST IN AN ATTEMPT TO FIT IN TO SOME DEGREE WITH NEIGHBORS. OVERNIGHT...THE GFS IS A BIT FASTER BRINGING ANOTHER ROUND OF ELEVATED CONVECTION EASTWARD INTO THE REGION...AS ANOTHER MID-LEVEL DISTURBANCE BRINGS AN AREA OF LOW-LEVEL THETA-E ADVECTION INTO THE REGION. IF THE NAM IS RIGHT...THE CONVECTION WILL STAY TO OUR WEST THROUGH 12Z...BUT THE GFS BRINGS INTO OUR WEST JUST BEFORE 12Z. WILL MENTION A CHANCE OVERNIGHT IN THE WEST...AND THEN RAMP UP TO 50-60 POPS SOUTH TO NORTH ON FRIDAY. THIS SIGNAL HAS BEEN THERE FOR A COUPLE OF DAYS...HOWEVER...IF IT IS AS FOCUSED AS TODAYS CONVECTION HAS BEEN...SOME AREAS MAY NOT GET WET. THEREFORE WILL NOT GO HIGHER THAN 60S FOR NOW. THOSE 60S WILL BE IN THE NORTH WHERE THE MODELS ARE IN BETTER AGREEMENT WITH THE QPF. THE NAM IS NOT SURE ABOUT OUR SOUTHERN ZONES GETTING WET. MAY SEE SOME LINGERING CONVECTION FRIDAY NIGHT MAINLY NORTHEAST...SO WILL LEAVE A 20-30 POP ACROSS MUCH OF THE AREA. ON SATURDAY...THE FRONT RE-LOCATES WELL NORTH OF THE AREA...AND WILL KEEP THE FOCUS FOR CONVECTION TO OUR NORTH AS WELL. THE 12Z NAM TRIES TO REGENERATE CONVECTION ALL OVER THE AREA ON SATURDAY...BUT IT IS THE LONE MODEL THAT DOES NOT BUILD A MID/UPPER-LEVEL RIDGE THROUGH THE AREA. WILL THEREFORE IGNORE ITS SOLUTION FOR NOW. THE WEEKEND SHOULD BE QUITE GLORIOUS WITH TEMPS PUSHING 80 EACH AFTERNOON AND LOWS IN THE 50S. IN THE MEDIUM RANGE...EVEN THE ECMWF IS NOW TRYING TO DRAG SOME REMNANT OF THE SW U.S. CUT OFF LOW ACROSS THE AREA SOMETIME MONDAY OR TUESDAY. WILL THROW IN 20-30 POPS FOR THIS PERIOD WITH THE BEST CHANCES MONDAY NIGHT INTO TUESDAY. TUESDAY NIGHT AND WEDNESDAY LOOK DRY...BUT A MORE SIGNIFICANT SYSTEM MAY BEGIN TO EFFECT THE AREA ON THURSDAY OR FRIDAY. TEMPERATURES WILL CONTINUE TO BE WELL ABOVE NORMAL THROUGH THE ENTIRE 7 DAY PERIOD...WITH HIGHS IN THE 70S OR LOWER 80S AND LOWS IN THE 50S OR LOWER 60S. THE EXCEPTION WILL BE TOMORROW WHERE THE CONVECTION MAY HOLD TEMPS IN THE 60S. HOWEVER...IT IS NOT CERTAIN WHERE THE PRECIPITATION WILL BE FOCUSED ACROSS THE AREA TOMORROW. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ UPDATE...MY PREVIOUS...DRS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 953 PM EDT THU MAR 22 2007 .UPDATE... SMALL UPDATE TO SLIGHTLY LOWER OVERNIGHT LOWS A DEGREE OR TWO ACROSS PORTIONS OR THE NORTHERN AREA AROUND SDF AND LEX...NOT SO MUCH ACROSS THE SOUTHERN HALF OF THE AREA. -SCHOTT && .PREV DISCUSSION... /ISSUED 729 PM EDT THU MAR 22 2007/ EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT AVIATION DISCUSSION (00Z TAFS)... GRADUAL CLEARING APPEARS TO BE DEVELOPING IN THE LATEST VIS SAT LOOP...NOTHING OF ANY SIGNIFICANCE LOOKS TO EFFECT AVIATION CONCERNS THROUGH DAYBREAK FRIDAY. MODEST LOW LEVEL JET DEVELOPS TONIGHT BUT DOESN`T REACH THE 20 KNOTS GREATER THAN SFC WINDS TO MENTION IN THE TAFS...BUT 20 TO 25 KTS AROUND 1500 TO 2000 FEET LOOKS LIKELY OVERNIGHT. VFR CONDITIONS AT ALL THREE TAFS SITES LOOKS AS A GOOD BET THROUGH THE PERIOD...SOME SCATTERED SHOWER AND THUNDERSTORM ACTIVITY LOOKS TO PUSH SOUTH INTO THE NORTHERN TAF SITES OF SDF AND LEX AFTER 14 TO 18Z...WITH SHRA POSSIBLE AT BWG AFTER 22Z. --SCHOTT PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIF CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ AVIATION (18Z TAFS)... SCT TO NUMEROUS SHOWERS WILL STREAM EWD THRU THE AFTN ALONG AND EITHER SIDE OF OH RIVER. STILL A CONVECTIVE THREAT BUT CG LIGHTNING ACTIVITY GRADUALLY DIMINISHING AT THIS TIME. KLVX VWP PROFILE SHOWS UNIFORM SWLY FLOW IN LOW-LEVELS WITH ONLY MODEST INCREASE IN SPEED WITH HEIGHT...THUS LOW-LEVEL WIND SHEAR NO LONGER A SIGNIFICANT HAZARD. CIGS MAY OCCASIONALLY FALL INTO MVFR CATEGORY BUT GENERALLY CIGS EXPECTED ABOVE 3KFT (VFR) DURING FCST PD. AS SHORTWAVE TO OUR N PULLS OUT...PRECIP SHOULD BE MORE SCT LATE TNGT AND EARLY FRI...BEFORE MODELS SHOW NEXT SURGE OF MOISTURE AND PRECIP ARRIVING FRI AFTN. TWF LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 729 PM EDT THU MAR 22 2007 .EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT && .AVIATION DISCUSSION (00Z TAFS)... GRADUAL CLEARING APPEARS TO BE DEVELOPING IN THE LATEST VIS SAT LOOP...NOTHING OF ANY SIGNIFICANCE LOOKS TO EFFECT AVIATION CONCERNS THROUGH DAYBREAK FRIDAY. MODEST LOW LEVEL JET DEVELOPS TONIGHT BUT DOESN`T REACH THE 20 KNOTS GREATER THAN SFC WINDS TO MENTION IN THE TAFS...BUT 20 TO 25 KTS AROUND 1500 TO 2000 FEET LOOKS LIKELY OVERNIGHT. VFR CONDITIONS AT ALL THREE TAFS SITES LOOKS AS A GOOD BET THROUGH THE PERIOD...SOME SCATTERED SHOWER AND THUNDERSTORM ACTIVITY LOOKS TO PUSH SOUTH INTO THE NORTHERN TAF SITES OF SDF AND LEX AFTER 14 TO 18Z...WITH SHRA POSSIBLE AT BWG AFTER 22Z. --SCHOTT && .PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIF CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ AVIATION (18Z TAFS)... SCT TO NUMEROUS SHOWERS WILL STREAM EWD THRU THE AFTN ALONG AND EITHER SIDE OF OH RIVER. STILL A CONVECTIVE THREAT BUT CG LIGHTNING ACTIVITY GRADUALLY DIMINISHING AT THIS TIME. KLVX VWP PROFILE SHOWS UNIFORM SWLY FLOW IN LOW-LEVELS WITH ONLY MODEST INCREASE IN SPEED WITH HEIGHT...THUS LOW-LEVEL WIND SHEAR NO LONGER A SIGNIFICANT HAZARD. CIGS MAY OCCASIONALLY FALL INTO MVFR CATEGORY BUT GENERALLY CIGS EXPECTED ABOVE 3KFT (VFR) DURING FCST PD. AS SHORTWAVE TO OUR N PULLS OUT...PRECIP SHOULD BE MORE SCT LATE TNGT AND EARLY FRI...BEFORE MODELS SHOW NEXT SURGE OF MOISTURE AND PRECIP ARRIVING FRI AFTN. TWF LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 144 PM EDT WED MAR 21 2007 .SHORT TERM.../TODAY THROUGH FRIDAY NIGHT/ ISOLATED SHOWERS MOVED ALONG THE KY/TN BORDER THIS MORNING. RADAR HOWEVER CURRENTLY SHOWS THESE HAVE DISSIPATED. SOME ADDITIONAL SHOWERS ATM ARE JUST NORTH OF OUR NW COUNTIES MOVING W TO EAST JUST SOUTH OF THE OH RIVER. RUC AND WRF-NAM BOTH KEEP PRECIP OUT OF FORECAST AREA FOR MOST OF THE REMAINDER OF 1ST PERIOD. BOTH MODELS ARE SHOWING POSSIBILITY OF SOME ADDITIONAL DEVELOPMENT LATER THIS AFTERNOON..IN ASSOCIATION WITH WEAK UPPER-LEVEL SHORT WAVE. THIS IS CONFINED PRIMARILY IN OUR FAR EASTERN ZONES AND ALONG THE SPINE OF THE APPALACHIANS. BELIEVE THIS IS WAY OVERDONE. HAVE THEREFORE KEPT POPS BELOW SLIGHT CHANCE ENTIRE PERIOD. IF RUC/NAM FORECAST DOES PAN OUT...WE`LL ADDRESS ACTIVITY WITH SHORT-TERM FORECASTS. LOCAL OBSERVATIONS SHOW TEMPERATURES ARE CURRENTLY ON TRACK WITH FORECAST GRIDS. UPDATE ALREADY OUT TO REMOVE DENSE FOG ADVISORY...POPS...AND MORNING WORDING. NEAR TERM WINDS WERE REFRESHED USING RUC GUIDANCE. ...REMAINDER OF EARLIER DISCUSSION FOLLOWS. THE MODELS ARE EXHIBITING SIMILAR DIFFERENCES ALOFT AS THEY WERE LAST NIGHT. THEY ALL HAVE A LONGWAVE PATTERN THAT FEATURES A CLOSING LOW OVER THE DESERT SOUTHWEST...FAST NORTHERN STREAM FLOW WITH A WAVE CROSSING THE GREAT LAKES EARLY THURSDAY AND SOME RIDGING ACROSS THE SOUTHEAST. THE FIRST ITEM OF CONCERN FOR EAST KENTUCKY WILL BE THE WAVE PASSING BY TO THE NORTH. WITH THIS...THE NAM IS A TAD FASTER AND STRONGER THAN THE GFS. AS FOR THE DEVELOPING BAJA LOW THE GFS REMAINS FURTHER EAST THAN THE NAM. IN THE WAKE OF THE NORTHERN STREAM WAVE PASSING AND THE BAJA LOW OPENING UP TOWARD THE END OF THE WORK WEEK...KENTUCKY WILL FIND ITSELF AWASH IN FAST MOVING MINOR WAVES. THESE WILL BE RUNNING EAST FROM THE SOUTHERN PLAINS IN THE ZONAL FLOW FOUND ON THE NORTHERN FRINGE OF THE SOUTHERN RIDGE. DESPITE THE NAM HAVING MORE SUPPORT WITH ITS SOLUTION FOR THE NORTHERN STREAM WAVE EARLY ON...THE GFS IS FAVORED FROM THURSDAY AFTERNOON ON GIVEN ITS APPARENT BETTER HANDLING OF THE OPENING LOW OVER THE SOUTHWEST. FOR FORECAST SPECIFICS HAVE LEANED TOWARD THE GFS FRONTAL POSITION ...BUT FOLLOWED THE NAM/S EVOLUTION AND TIMING OF THE INDIVIDUAL WAVES THAT PASS OVERHEAD AND AMPLIFY THE FRONT THROUGH THE LATTER PART OF THE WORK WEEK. SENSIBLE WEATHER WILL FEATURE AREAS OF DENSE FOG BURNING OFF AND MIXING OUT LATER THIS MORNING REVEALING A PARTLY SUNNY SKY AND ONLY AN SMALL CHANCE FOR A POP-UP SHOWER. HAVE LEFT THUNDER OUT OF THE FORECAST FOR TODAY GIVEN THE LOW POPS AND MARGINAL INSTABILITY. TONIGHT SHOULD BE MORE OF THE SAME WITH THE MOIST BOUNDARY LAYER... AND ONLY PARTIAL CLOUDINESS...RESULTING IN RADIATIONAL FOG. A WAVE SEEN IN THE GFS THAT PASSES BY TO THE NORTHEAST WILL PROBABLY BE TOO FAR AWAY TO WARRANT EVEN SLIGHT CHANCE POPS. NEXT...A COLD FRONT FROM THAT NORTHERN STREAM WAVE WILL SAG TOWARD KENTUCKY ON THURSDAY BEFORE STRETCHING OUT AND BECOMING STATIONARY OVER THE NORTHERN HALF OF THE STATE LATER THAT NIGHT. THIS WILL RESULT IN A PROLONGED AND PERSISTENT PERIOD OF DECENT POPS FOR SHOWERS AND THUNDERSTORMS LASTING INTO FRIDAY NIGHT AS IMPULSES MOVE EAST ALONG THE BOUNDARY... SPURNED ALONG BY THE MINOR UPPER WAVES SPINNING OUT OF THE OPENING SOUTHWESTERN LOW. WITH THE TEMPERATURES...WENT WITH THE WARMER MET NUMBERS TODAY AND THURSDAY...THOUGH HELD THE DIURNAL RISE BACK A BIT THIS MORNING UNTIL THE FOG BURNS OFF. FOR HIGHS FRIDAY...FOLLOWED MORE OF A BLEND. AT NIGHT...THE NUMBERS WERE SIMILAR SO WENT WITH A BLEND...ALONG WITH SOME SITE SPECIFIC TWEAKING. THE POPS ENDED UP CLOSEST TO THE MET NUMBERS THROUGH THE SHORT TERM PART OF THE FORECAST. .LONG TERM.../SATURDAY THROUGH TUESDAY/ A FRONTAL BOUNDARY WILL LINGER ACROSS THE AREA TO END THE WORKWEEK...WITH THE BEST CHANCE OF RAIN REMAINING ALONG AND NORTH OF THE MOUNTAIN PARKWAY. ECMWF AND GFS CONTINUE TO DIFFER WITHIN THE DETAILS OF THE FORECAST INTO EARLY NEXT WEEK. TWO MAIN FEATURES OF INFLUENCE WILL BE A BUILDING SOUTHEASTERN CONUS RIDGE...WITH AN EJECTING UPPER LEVEL LOW APPROACHING OUT OF THE SOUTHWEST. ECMWF WASHES THE AFOREMENTIONED FRONT OUT TO THE SOUTH...WITH A LARGE AREA OF HIGH PRESSURE LENDING IT`S INFLUENCE ACROSS THE AREA THROUGH THE WEEKEND. THE PROGGED RIDGE THEN SLOWS AS WELL DAMPENS THE UPPER LEVEL LOW SIGNIFICANTLY BY EARLY NEXT WEEK. GFS STARTS OUT WITH A MUCH WEAKER AREA OF HIGH PRESSURE PUSHING IN FOR THE BEGINNING OF THE WEEKEND...GENERALLY KEEPING THE FRONT AROUND LONGER AND LINGERING PRECIPITATION INTO EARLY SATURDAY...BEFORE PUSHING BACK NORTH BY SATURDAY AFTERNOON AS MORE MODEST RIDGING TAKES PLACE THROUGH SUNDAY. A MUCH MORE ROBUST PROGGED UPPER LEVEL LOW LIFTS THROUGH MONDAY INTO TUESDAY...WITH SCATTERED PRECIPITATION ASSOCIATED WITH THIS FEATURE. HAVE COMPROMISED BETWEEN THE MODELS. ECMWF HAS BEEN MORE CONSISTENT LATELY...HOWEVER FEEL THAT IT DOES DAMPEN THE UPPER LEVEL LOW A BIT TOO MUCH AS IT BRINGS IT IN. ON THE OTHER HAND...THE GFS SEEMS A BIT OVERDONE WITH THE UPPER LEVEL FEATURE. AS SUCH...WILL KEEP THE MAJORITY OF THE WEEKEND DRY UNDER THE INFLUENCE OF UPPER LEVEL RIDGING...WHILE INTRODUCING CHANCE POPS BY MONDAY AFTERNOON AS THE WAVE APPROACHES. TEMPERATURES CONTINUE TO LOOK ABOVE NORMAL THROUGHOUT THE PERIOD AS WELL. GENERALLY STAYED A BIT WARMER THAN MOS...THINKING THAT THE NUMBERS ARE A BIT COOL WITH THE OVERPLAYED CLOUD COVER AND PRECIPITATION. && .AVIATION.../18Z TO 18Z/...UPDATED WARM FRONT HAS EDGED NORTH TODAY AND IS CURRENTLY LOCATED ALONG OUR NORTHERN TIER OF COUNTIES. A FEW WIDELY SCATTERED SHOWERS KICKED UP EARLIER NORTH OF THE BOUNDARY...BUT SATELLITE CURRENTLY SHOWS NO ACTIVITY. SHORT RANGE FORECAST MODELS SHOW HIGH PRESSURE...LOCATED TO OUR SOUTHEAST HOLDING IN PLACE THROUGH MOST OF THE FORECAST PERIOD. THURSDAY AFTERNOON HOWEVER A COLD FRONTAL BOUNDARY WILL DROP OUT OF THE NORTHWEST...BRINGING SHOWERS AND MVFR CEILINGS BACK INTO THE REGION. TIMING RIGHT NOW LOOKS TO BE OUTSIDE THE 24-HOUR TAF PERIOD...SO CONDITIONS ARE NOT REFLECTED IN THIS 18Z-18Z TAF. SUBSEQUENT ISSUANCES THOUGH WILL NEED TO CONSIDER INCLUDING SHOWERS / LOWERING CEILINGS IN ANOTHER CHANGE GROUP. FOR NOW...CEILINGS/ VISIBILITIES WILL REMAIN VFR...WITH CLOUD BASES GRADUALLY LOWERING THIS EVENING FROM HIGH CIRRUS DECK THIS AFTERNOON TO MID-LEVELS THIS EVENING. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE && $$ SHORT TERM...MCLANE/GREIF LONG TERM....GEOGERIAN AVIATION...MCLANE ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 1120 AM CDT WED MAR 21 2007 .DISCUSSION... A MID LEVEL VORT WAS INDUCING ENOUGH LIFT TO DEVELOP CLOUDS AND WHAT APPEARED TO BE VIRGA OVER THE ERN THIRD OF THE PAH FCST AREA. RUC MODEL INDICATES THIS FEATURE WILL MOVE TO THE ENE OUT OF THE AREA BY 18Z OR SO...WITH NO CLEAR ADDITIONAL FORCING MECHANISMS ARRIVING INTO THE AREA FOR THE AFTN. NUMERICAL GUIDANCE INDICATED VERY LOW POPS THIS AFTN...DUE TO PLENTIFUL WARM AIR ABOVE 850 MB. THEREFORE...WE WILL DROP THE AFTN CHANCES OF RAIN/TSTMS AND LIGHTEN UP ON THE CLOUD WORDING A BIT. THERE SHOULD CONTINUE TO BE A DECENT SFC PRESSURE GRADIENT TODAY...THUS WINDS 10 TO 20 MPH IN MANY AREAS. ZONE UPDATE OUT SOON. .PREVIOUS DISCUSSION... MAIN FORECAST CONCERNS ARE PRECIP CHANCES THROUGH THE FORECAST. LATEST MOSAIC RADAR SHOWS A LARGE AREA OF SHOWERS ACROSS NORTHERN ILLINOIS AND SOME SHOWERS AND STORMS EXTENDING FROM NORTHEAST MISSOURI INTO CENTRAL IOWA. NAM SEEMS TO HAVE THE BEST HANDLE ON THE ONGOING PRECIP...SO LEANED TOWARD ITS SOLUTION FOR TODAY. DROPPED POPS FOR THIS MORNING AND WENT WITH SLIGHT CHANCE POPS THIS AFTERNOON FOR THE NORTHWEST THIRD OF THE PAH FORECAST AREA. EXPECT DRY CONDITIONS TONIGHT...THEN A CHANCE OF SHOWERS AND STORMS RETURNS FOR NORTHERN AND WESTERN PORTIONS OF THE FA ON THURSDAY AS THE COLD FRONT APPROACHES OUR REGION FROM THE NORTHWEST. NAM IS MORE AGGRESSIVE WITH THE FRONT...EXTENDING IT FROM CENTRAL INDIANA INTO SOUTHWEST MISSOURI BY 18Z THU...WITH THE GFS KEEPING IT A LITTLE FARTHER NORTHWEST AND KEEPING ANY SIGNIFICANT QPF OUT OF OUR AREA. LEANED MORE HEAVILY TOWARD THE NAM SOLUTION FOR NOW...FOCUSING POPS ACROSS THE NORTHWEST HALF OF THE FA...WITH BEST POPS IN FAR NORTHERN COUNTIES CLOSER TO THE FRONT FOR BOTH THURSDAY AND INTO THURSDAY NIGHT. BY 12Z FRIDAY...NAM AND GFS ARE A LITTLE MORE IN SYNC WITH THE FRONTAL POSITION...BUT GFS HAS MORE SIGNIFICANT QPF ESPECIALLY ACROSS NORTHERN PORTIONS OF THE FA FOR FRIDAY AND INTO FRIDAY NIGHT. PREFERRING GFS...INCREASED POPS ACROSS THE ENTIRE FA FOR FRIDAY...ESPECIALLY DURING THE AFTERNOON HOURS...WITH HIGHEST CHANCES ACROSS THE NORTHERN HALF. KEPT SLIGHT CHANCE POPS SOUTH TO CHANCE POPS NORTH FOR FRIDAY NIGHT...AND CONTINUED THIS TREND INTO SATURDAY. BOTH GFS AND ECMWF SHOW AN UPPER LEVEL RIDGE BUILDING INTO THE REGION LATE SATURDAY INTO SUNDAY...SO EXPECTING A BREAK IN SHOWER AND THUNDERSTORM ACTIVITY SATURDAY NIGHT INTO SUNDAY. BY LATE SUNDAY NIGHT...GFS SHOWS A COLD FRONT APPROACHING THE MIDDLE MISSISSIPPI VALLEY FROM THE WEST. ECMWF IS MUCH SLOWER WITH THIS FEATURE...SO FOR NOW JUST INCLUDED SLIGHT CHANCE POPS FOR THE WEST HALF OF THE PAH FA...WHICH BLENDED WELL WITH THE GOING SLIGHT CHANCE POPS FOR MONDAY INTO TUESDAY. UNSEASONABLY WARM WEATHER EXPECTED THE REST OF THE WEEK AND THROUGH THE WEEKEND. USED A MAV/MET COMPROMISE FOR THE NEAR TERM TEMPS...WHICH ONLY REQUIRED MINOR CHANGES THROUGH THURSDAY...THEN WARMED UP LOWS AND HIGHS JUST A LITTLE FRIDAY MORNING AND FRIDAY AFTERNOON. IN THE EXTENDED...BASED ON LATEST MEX TWEAKED DOWN LOWS AND HIGHS ON SUNDAY JUST A LITTLE...OTHERWISE MADE LITTLE IF ANY CHANGES. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ RST ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1112 AM EDT WED MAR 21 2007 .SHORT TERM.../TODAY THROUGH FRIDAY NIGHT/...UPDATED ISOLATED SHOWERS MOVED ALONG THE KY/TN BORDER THIS MORNING. RADAR HOWEVER CURRENTLY SHOWS THESE HAVE DISSIPATED. SOME ADDITIONAL SHOWERS ATM ARE JUST NORTH OF OUR NW COUNTIES MOVING W TO EAST JUST SOUTH OF THE OH RIVER. RUC AND WRF-NAM BOTH KEEP PRECIP OUT OF FORECAST AREA FOR MOST OF THE REMAINDER OF 1ST PERIOD. BOTH MODELS ARE SHOWING POSSIBILITY OF SOME ADDITIONAL DEVELOPMENT LATER THIS AFTERNOON..IN ASSOCIATION WITH WEAK UPPER-LEVEL SHORT WAVE. THIS IS CONFINED PRIMARILY IN OUR FAR EASTERN ZONES AND ALONG THE SPINE OF THE APPALACHIANS. BELIEVE THIS IS WAY OVERDONE. HAVE THEREFORE KEPT POPS BELOW SLIGHT CHANCE ENTIRE PERIOD. IF RUC/NAM FORECAST DOES PAN OUT...WE`LL ADDRESS ACTIVITY WITH SHORT-TERM FORECASTS. LOCAL OBSERVATIONS SHOW TEMPERATURES ARE CURRENTLY ON TRACK WITH FORECAST GRIDS. UPDATE ALREADY OUT TO REMOVE DENSE FOG ADVISORY...POPS...AND MORNING WORDING. NEAR TERM WINDS WERE REFRESHED USING RUC GUIDANCE. ...REMAINDER OF EARLIER DISCUSSION FOLLOWS. THE MODELS ARE EXHIBITING SIMILAR DIFFERENCES ALOFT AS THEY WERE LAST NIGHT. THEY ALL HAVE A LONGWAVE PATTERN THAT FEATURES A CLOSING LOW OVER THE DESERT SOUTHWEST...FAST NORTHERN STREAM FLOW WITH A WAVE CROSSING THE GREAT LAKES EARLY THURSDAY AND SOME RIDGING ACROSS THE SOUTHEAST. THE FIRST ITEM OF CONCERN FOR EAST KENTUCKY WILL BE THE WAVE PASSING BY TO THE NORTH. WITH THIS...THE NAM IS A TAD FASTER AND STRONGER THAN THE GFS. AS FOR THE DEVELOPING BAJA LOW THE GFS REMAINS FURTHER EAST THAN THE NAM. IN THE WAKE OF THE NORTHERN STREAM WAVE PASSING AND THE BAJA LOW OPENING UP TOWARD THE END OF THE WORK WEEK...KENTUCKY WILL FIND ITSELF AWASH IN FAST MOVING MINOR WAVES. THESE WILL BE RUNNING EAST FROM THE SOUTHERN PLAINS IN THE ZONAL FLOW FOUND ON THE NORTHERN FRINGE OF THE SOUTHERN RIDGE. DESPITE THE NAM HAVING MORE SUPPORT WITH ITS SOLUTION FOR THE NORTHERN STREAM WAVE EARLY ON...THE GFS IS FAVORED FROM THURSDAY AFTERNOON ON GIVEN ITS APPARENT BETTER HANDLING OF THE OPENING LOW OVER THE SOUTHWEST. FOR FORECAST SPECIFICS HAVE LEANED TOWARD THE GFS FRONTAL POSITION ...BUT FOLLOWED THE NAM/S EVOLUTION AND TIMING OF THE INDIVIDUAL WAVES THAT PASS OVERHEAD AND AMPLIFY THE FRONT THROUGH THE LATTER PART OF THE WORK WEEK. SENSIBLE WEATHER WILL FEATURE AREAS OF DENSE FOG BURNING OFF AND MIXING OUT LATER THIS MORNING REVEALING A PARTLY SUNNY SKY AND ONLY AN SMALL CHANCE FOR A POP-UP SHOWER. HAVE LEFT THUNDER OUT OF THE FORECAST FOR TODAY GIVEN THE LOW POPS AND MARGINAL INSTABILITY. TONIGHT SHOULD BE MORE OF THE SAME WITH THE MOIST BOUNDARY LAYER... AND ONLY PARTIAL CLOUDINESS...RESULTING IN RADIATIONAL FOG. A WAVE SEEN IN THE GFS THAT PASSES BY TO THE NORTHEAST WILL PROBABLY BE TOO FAR AWAY TO WARRANT EVEN SLIGHT CHANCE POPS. NEXT...A COLD FRONT FROM THAT NORTHERN STREAM WAVE WILL SAG TOWARD KENTUCKY ON THURSDAY BEFORE STRETCHING OUT AND BECOMING STATIONARY OVER THE NORTHERN HALF OF THE STATE LATER THAT NIGHT. THIS WILL RESULT IN A PROLONGED AND PERSISTENT PERIOD OF DECENT POPS FOR SHOWERS AND THUNDERSTORMS LASTING INTO FRIDAY NIGHT AS IMPULSES MOVE EAST ALONG THE BOUNDARY... SPURNED ALONG BY THE MINOR UPPER WAVES SPINNING OUT OF THE OPENING SOUTHWESTERN LOW. WITH THE TEMPERATURES...WENT WITH THE WARMER MET NUMBERS TODAY AND THURSDAY...THOUGH HELD THE DIURNAL RISE BACK A BIT THIS MORNING UNTIL THE FOG BURNS OFF. FOR HIGHS FRIDAY...FOLLOWED MORE OF A BLEND. AT NIGHT...THE NUMBERS WERE SIMILAR SO WENT WITH A BLEND...ALONG WITH SOME SITE SPECIFIC TWEAKING. THE POPS ENDED UP CLOSEST TO THE MET NUMBERS THROUGH THE SHORT TERM PART OF THE FORECAST. .LONG TERM.../SATURDAY THROUGH TUESDAY/ A FRONTAL BOUNDARY WILL LINGER ACROSS THE AREA TO END THE WORKWEEK...WITH THE BEST CHANCE OF RAIN REMAINING ALONG AND NORTH OF THE MOUNTAIN PARKWAY. ECMWF AND GFS CONTINUE TO DIFFER WITHIN THE DETAILS OF THE FORECAST INTO EARLY NEXT WEEK. TWO MAIN FEATURES OF INFLUENCE WILL BE A BUILDING SOUTHEASTERN CONUS RIDGE...WITH AN EJECTING UPPER LEVEL LOW APPROACHING OUT OF THE SOUTHWEST. ECMWF WASHES THE AFOREMENTIONED FRONT OUT TO THE SOUTH...WITH A LARGE AREA OF HIGH PRESSURE LENDING IT`S INFLUENCE ACROSS THE AREA THROUGH THE WEEKEND. THE PROGGED RIDGE THEN SLOWS AS WELL DAMPENS THE UPPER LEVEL LOW SIGNIFICANTLY BY EARLY NEXT WEEK. GFS STARTS OUT WITH A MUCH WEAKER AREA OF HIGH PRESSURE PUSHING IN FOR THE BEGINNING OF THE WEEKEND...GENERALLY KEEPING THE FRONT AROUND LONGER AND LINGERING PRECIPITATION INTO EARLY SATURDAY...BEFORE PUSHING BACK NORTH BY SATURDAY AFTERNOON AS MORE MODEST RIDGING TAKES PLACE THROUGH SUNDAY. A MUCH MORE ROBUST PROGGED UPPER LEVEL LOW LIFTS THROUGH MONDAY INTO TUESDAY...WITH SCATTERED PRECIPITATION ASSOCIATED WITH THIS FEATURE. HAVE COMPROMISED BETWEEN THE MODELS. ECMWF HAS BEEN MORE CONSISTENT LATELY...HOWEVER FEEL THAT IT DOES DAMPEN THE UPPER LEVEL LOW A BIT TOO MUCH AS IT BRINGS IT IN. ON THE OTHER HAND...THE GFS SEEMS A BIT OVERDONE WITH THE UPPER LEVEL FEATURE. AS SUCH...WILL KEEP THE MAJORITY OF THE WEEKEND DRY UNDER THE INFLUENCE OF UPPER LEVEL RIDGING...WHILE INTRODUCING CHANCE POPS BY MONDAY AFTERNOON AS THE WAVE APPROACHES. TEMPERATURES CONTINUE TO LOOK ABOVE NORMAL THROUGHOUT THE PERIOD AS WELL. GENERALLY STAYED A BIT WARMER THAN MOS...THINKING THAT THE NUMBERS ARE A BIT COOL WITH THE OVERPLAYED CLOUD COVER AND PRECIPITATION. && .AVIATION.../12Z TO 12Z/ DENSE FOG IS A PROBLEM AT THE TAF SITES AT ISSUANCE TIME. HOWEVER LOZ IS SHOWING SIGNS OF IMPROVING AND SOUTHWESTERLY LOW LEVEL FLOW WILL BE INCREASING AFTER 14Z AS STATIONARY FRONT CURRENTLY BISECTING THE AREA LIFTS NORTH. FOG SHOULD RAPIDLY DISSIPATE AND CIGS RISE INTO THE VFR RANGE BY THAT TIME... WHERE THEY WILL REMAIN THROUGH THE REMAINDER OF THE TAF PERIOD. THERE REMAINS A SLIGHT CHANCE FOR A SHOWER WITH THE FRONT IN THE VICINITY... HOWEVER PROBABILITIES ARE TOO LOW TO MENTION IN THE TAFS AT THIS TIME. && .JKL WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR KYZ044- 050>052-058>060-068-069-079-080-083>088-104-106>120. && $$ SHORT TERM...MCLANE/GREIF LONG TERM....GEOGERIAN AVIATION...ABE/GREIF ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1048 AM EDT THU MAR 22 2007 .SHORT TERM /REST OF TODAY/... AREA MORNING UPPER AIR SOUNDINGS SHOW LAYERED MOISTURE THROUGH MUCH OF THE COLUMN. SFC OBS/SATL DATA CONFIRMS SCT-BKN MULTILAYERED CLOUDS ACRS FORECAST AREA THIS LATE MORNING BUT THE CLOUD PATCHES APPEAR TO BE BREAKING AND THINNING. THEREFORE EXPECT SKY CONDITION WILL AVERAGE PTSUNNY DURING THE AFTN. INSOLATION SHUD BE SUFFICIENT TO ALLOW TEMPS TO REACH FCSTD VALUES RANGING FROM M60S ACRS THE EASTERN SHORE TO M70S OVER PIEDMONT...BUT OF COURSE COOLER WHERE FLOW IS ONSHORE. LTL IF ANY CHANGES NEEDED TO FCST ATTM BUT UPDATED FCST TO REFRESH PRODUCTS. .MARINE UPDATE... DECIDED TO ADD SCA FOR THE CHESAPEAKE BAY WTRS FROM SMITH POINT TO NEW POINT COMFORT...WITH 15-20 KT WINDS AND 2-3 FT WAVES. RUC AND NAM MODELS SUGGEST INCRSG SFC WINDS AFTER 18Z. SOUNDINGS SHOW AROUND 15 KT AT SFC UNDER WEAK INVERSION WITH 25-30 KTS ABOVE INVERSION. EXPECT ENOUGH MIXING TO ALLOW 20 KT GUSTS DOWN TO SFC. STRONGER LOW LEVEL INVERSION TO SOUTH OF NEW POINT COMFORT SO OPTED NOT TO GO FOR SCA FOR SOUTHERN BAY BUT STEADY 15 KT. ON CSTL WTRS...EXPECT 15-20 KT SOUTH WINDS FROM FENWICK DOWN TO PARRAMORE WITH LONGER FETCH BUILDING SEAS TO SCA CRITERIA AFTER 2 PM. DIFFICULT FCST FOR THE WEEKEND WITH BACKDOOR COLD FRONT SAT/SAT NGT. HAVE DECIDED TO GO CLOSER TO NAM/UKMET (GFS IS OUTLIER)...KEEPING SW FLOW SRN ZONES ON SAT...ELY FLOW ACRS THE NORTH. THEN...FRONT CLEARS ENTIRE MARINE AREA SAT NGT/SUN...WITH NNE FLOW AND POSSIBLE SMALL CRAFT CONDITIONS AT THAT TIME. && .PREV DISCUSSION... /ISSUED 513 AM EDT THU MAR 22 2007/ SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... CURRENTLY...HIGH PRESSURE CONTINUES TO PUSH OFFSHORE WHILE A COLD FRONT ADVANCES EAST THROUGH THE WESTERN GREAT LAKES AND MIDWEST REGIONS. THE MAIN FORECAST CONERN TODAY WILL BE WITH CLOUD COVER EXTENT (DEPTH) AND THUS IMPACT ON TEMPS. GFS/NAM ARE IN FAIRLY CLOSE ACCORD IN THE SHORT TERM (THROUGH TONIGHT). BOTH INDICATE THE COLD FRONT DROPPING TO NEAR THE MASON- DIXON LINE BY MIDNIGHT TONIGHT...BECOMING MORE W-E ORIENTED AS THE ASSOCIATED UPPER LEVEL VORT LOBE ENCOUNTERS A ZONAL/FLAT UPPER RIDGE. PRE-FRONTAL FORCING/MOISTURE IS INSUFFICIENT FOR POPS ACROSS THE FCST AREA TODAY. AS FOR SKY COVER...EXPECT THE LOWER CLOUDS TO SCOUR OUT LATER THIS MORNING/AFTN AS THE LOW LEVEL FLOW VEERS TOWARD THE S-SW RESULTING IN MORE APPRECIABLE WARMING (AND RELATIVE DRYING) WITHING THE 1000-850 MB LAYER. STILL EXPECT PERIODIC WAVES OF HIGHER BASED CLOUDS IN THE AFTN AS WE GET INTO THE WARM SECTOR...THUS HAVE WORDED PARTLY SUNNY. BASED ON RECENT TRENDS (YDAY)...HAVE GONE A FEW DEGREES HIGHER THAN MOS TODAY FOR HIGH TEMPS. THIS BASED ON THE LOW LEVEL WAA AND INCREASED SUNSHINE THIS AFTN (ANTICIPATED DEEPER MIXING WITH THE LATE MARCH SUN ANGLE). TONIGHT...FRONT DIPS INTO NRN VA AND THE NRN PTN OF THE DELMARVA. HAVE INCLUDED LOW (30-40%) POPS OVER THE NRN THIRD OF THE CWA CLOSEST TO THE FRONT...THOUGH ONCE AGAIN WITH THE FLATTENING UPPER FLOW (AND NEGLIGIBLE STRAIGHT UPPER JET FORCING)...DYNAMICS AND THUS MOISTURE DEPTHS REMAIN LACKING. S OF FVX-RIC-MFV...MOISTURE IS JUST TOO SHALLOW (PARTICULARLY IN LOW LEVELS) FOR POPS. FRIDAY...COMPARED TO THE NAM/UKMET/ECMWF...THE 00Z GFS IS TOO QUICK WITH THE INITIAL IMPULSE TRACKING FROM THE UPPER MIDWEST- OH VLY-MID ATLC REGION. SIDING MORE TOWARD A NAM/ECMWF BLEND... EXPECT A NW-SE DRAPED SURFACE FRONTAL BNDRY ACROSS THE FCST AREA... WITH THE FRONT TAKING ON THE TYPICAL "SAG" EAST TOWARD THE COOLER COASTAL WATERS. AS A RESULT EXPECT A LARGE TEMP GRADIENT FROM SW-NE... I.E. AROUND 80/LOWER 80S INLAND TO AROUND 60 ALONG THE LOWER ERN SHORE. WILL ALSO MAINTAIN MORE EXTENSIVE CLOUD COVER/LOW POPS OVER THE N-NE ZONES ALONG AND N OF THE PROJECTED FRONTAL ZONE. SATURDAY...GFS IS MUCH COOLER WITH THE LOWER LEVELS COMPARED TO THE OTHER MODELS...BASICALLY A CONSEQUENCE OF THIS MODEL BEING TOO PROGRESSIVE WITH THE INITIAL UPPER SHORTWAVE/WEAK SURFACE LOW ALONG THE STATIONARY FRONT. GFS (MAV) MOS GUIDANCE IN FACT IS SOME 20+ DEGREES COOLER WITH HIGH TEMPS OVER INLAND LOCALES COMPARED TO THE NAM (MET) GUIDANCE! FOR NOW WILL CONTINUE TO LEAN MORE TOWARD THE NAM/ ECMWF...WHICH DOES NOT DROP THE FRONT S OF THE LOWER DELMARVA UNTIL LATE IN THE DAY. BASED ON THESE PROJECTIONS...EXPECT ANOTHER DAY WITH A SIGNIFICANT TEMPERATURE GRADIENT FROM SW (80-85) TO AREAS ALONG THE ATLANTIC SIDE OF THE LOWER MD ERN SHORE (LOW-MID 50S). LONG TERM /SUNDAY THROUGH WEDNESDAY/... BASED ON THE LATEST NAM/ECWMF TRENDS...AND WITH THE LOWER CONFIDENCE IN THE GFS SAT-SUN...DID NOT MAKE TOO MANY CHANGES TO THE FCSTS DURING THE EXTENDED PERIODS. HIGH PRESSURE BUILDING FROM THE N AND EVENTUALLY NE (OFFSHORE) ON SUNDAY WILL MAKE FOR A COOLER DAY OVER THE NERN PTNS OF THE FCST AREA...THOUGH AGAIN EXPECT TEMPS TO REMAIN MUCH MILDER AS YOU HEAD FARTHER SW. TOWARD PETERSBURG/FARMVILLE/SOUTH HILL. AVIATION...VARIABLE CONDITIONS EARLY THIS MORNING...HAVE MVFR CIGS NORTH AND WEST...VFR SOUTH. FLOW TURNS TO S OR SW LATER TODAY WITH INCREASING WIND SPEEDS BY AFTN...AND MAINLY VFR CONDS. MVFR CIGS MAY HANG TOUGH ON THE ERN SHORE THRU 16-18Z. CONTINUED VFR TONIGHT AS MIXING SHOULD INHIBIT SIGNIFICANT FOG FORMATION. MARINE...GRADIENT INCREASES FROM SOUTH TO SOUTHWEST LATER TODAY. CHILLY BAY WATERS WILL MAKE IT DIFFICULT TO EFFICIENTLY MIX THESE WINDS DOWN TO THE SFC...SO OPTED TO KEEP CONDITIONS ON THE BAY & SOUND BELOW SMALL CRAFT (ALTHOUGH IT WILL BE CLOSE LATER THIS AFTN). ON COASTAL WATERS...INCREASING SOUTHERLY FLOW (NEAR 20 KTS BY AFTN) WILL LIKELY BRING SEAS TO MARGINAL SMALL CRAFT CONDITIONS (5 FT WAVES OFFSHORE) N OF PARRAMORE ISL...FROM LATER IN THE AFTN THROUGH ERLY MRNG THU. DIFFICULT FCST FOR THE WEEKEND WITH BACKDOOR COLD FRONT SAT/SAT NGT. HAVE DECIDED TO GO CLOSER TO NAM/UKMET (GFS IS OUTLIER)...KEEPING SW FLOW SRN ZONES ON SAT...ELY FLOW ACRS THE NORTH. THEN...FRONT CLEARS ENTIRE MARINE AREA SAT NGT/SUN...WITH NNE FLOW AND POSSIBLE SMALL CRAFT CONDITIONS AT THAT TIME. FIRE WEATHER...LIGHT SE TO S FLOW THIS MRNG...WITH GUSTY SOUTH...SOUTHWEST WINDS INCREASING BY AFTN FOR MUCH OF INLAND VA. HOWEVER...NOT REALLY A DOWNSLOPE FLOW SO RH VALUES DO NOT DROP OFF THAT MUCH...WITH MOST LOCATIONS BOTTOMING OUT 35-45% AT THE DRIEST. FARTHER EAST...COOLER TEMPERATURES WILL TEND TO INHIBIT MIXING SOMEWHAT SO WINDS LIKELY STAY MORE FROM DUE SOUTH AT 15 KTS OR LESS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM EDT FRIDAY FOR ANZ630-631-650-652. && $$ SHORT TERM UPDATE...CULLEN/FOSTER md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 530 AM EDT FRI MAR 23 2007 .DISCUSSION... MAIN FCST CONCERNS IN SHORT TERM ARE CLOUDS/TEMPS THEN FOCUS WILL BE ON TIMING OF NEXT CHC OF RAIN/THUNDERSTORMS FOR SUN AFTERNOON. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. ONE SHORTWAVE IS MOVING THROUGH THE UPR GREAT LAKES EARLY THIS MORNING WHILE ANOTHER IS UPSTREAM OVER SRN ALBERTA. SHORTWAVE MOVING THROUGH UPR GREAT LAKES PRODUCED A FEW FLURRIES THIS MORNING NORTH OF LAKE SUPERIOR IN AREA OF WEAK Q-VECT CONV AND ISENTROPIC ASCENT. MODEL SNDGS CONSISTENT IN SHOWING LINGERING MOISTURE AROUND 850 MB IN WAKE OF SHORTWAVE SO KEPT IN A BIT MORE CLOUD COVER TODAY IN ANTICIPATION OF STRATOCU DEVELOPING DURING THE DAY. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE LOW/MID 50S OVER THE WRN INTERIOR. SRLY FLOW WILL KEEP TEMPS MUCH COOLER OVER THE ERN FCST AREA NEAR AND DOWNWIND OF LAKE MICHIGAN. LOCAL COOLING SHOULD ALSO OCCUR NEAR LAKE SUPERIOR OVER THE W AND NCNTRL AREAS MID/LATE AFTN WHERE BOUNDARY LAYER WINDS WILL BE LIGHTER. FROM MUNISING EWD...SRLY FLOW MAY STRONG ENOUGH 10-15 KT TO SUPRESS LAKE BREEZE DEVELOPMENT. NEXT SHORTWAVE FROM ALBERTA IS DUE TO MOVE INTO THE UPR GREAT LAKES LATE FRI NIGHT AND SAT. UPR DIV IN RRQ OF 100 KT 3H JET SHOULD PRODUCE SOME MID CLOUDS PER MODEL SNDGS BUT OTHERWISE MODEL SNDGS LOOK PRETTY DRY AT LOW LEVELS. WEAK PRES GRADIENTS WITH SFC HIGH OVERHEAD WILL ALLOW FOR LAKE BREEZES TO DEVELOP SAT OFF BOTH LAKES SUPERIOR AND MICHIGAN...KEEPING TEMPS COOLER (40S) ALONG LAKESHORE AREAS. MIXING TO AROUND 850 MB OVER THE WESTERN INTERIOR WILL ALLOW MAX TEMPS TO REACH NEAR TO MID 50S. SAT NIGHT...INFLUENCE OF SFC HIGH JUST TO THE NE OF LAKE SUPERIOR WILL ALLOW FOR LIGHT WIND AND GENERALLY CLEAR TO PARTLY CLOUDY SKIES. EXPECT LOWS TO REACH INTO THE 20S OVER THE INTERIOR...CLOSER TO COOLER GFS MOS GUIDANCE. MODELS STILL IN GOOD AGREEMENT SHOWING UPR LOW EJECTING OUT OF THE PLAINS AND INTO THE UPR GREAT LAKES SUN NIGHT INTO MON. AN INCREASING RIBBON OF MOISTURE/ISENTROPIC ASCENT ON THE 300K SFC... A 40KT H85 JET...AND PWATS AROUND AN INCH ARE MAIN TRIGGERS FOR SHOWERS LATE SUN INTO SUN NIGHT. NEG 850-500 MB THETA-E LAPSE RATES COULD ALSO RESULT IN THUNDER. BUMPED UP POPS TO LIKELY SUN NIGHT WITH ARRIVAL OF SFC WARM FRONT AND UPR TROUGH. DEPARTURE OF SHORTWAVE AND ASSOC SFC TROF/WARM FRONT SHOULD TAPER OFF RAIN CHCS BY MON AFTERNOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 PM EDT THU MAR 22 2007 .SHORT TERM (TONIGHT AND FRIDAY)... MAIN FCST ISSUE IN THE SHORT TERM IS POSSIBILITY OF SOME -SN TONIGHT. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. SHORTWAVE THAT PASSED ACROSS THE UPPER LAKES EARLIER TODAY IS NOW OVER THE ONTARIO/QUEBEC BORDER. NEXT SHORTWAVE IN THE FAST FLOW IS OVER NW ND. MID CLOUDS ASSOCIATED WITH SHORTWAVE WERE SPREADING ACROSS NRN MN...AND HIGH CLOUDS HAVE ALREADY SPREAD ACROSS ALL OF UPPER MI THIS AFTN. RADARS SHOW A DECENT AREA OF RETURNS ACROSS FAR NE ND/NW MN AND SRN MANITOBA. SFC OBS THAT REPORT VSBY ARE SPARSE IN THAT AREA...SO DIFFICULT TO KNOW HOW MUCH PCPN IS REACHING THE GROUND. HOWEVER...IN THE LAST FEW HRS...A COUPLE OF OBS IN SRN MANITOBA HAVE REPORTED 1-4SM IN -SN. WELL TO THE W...SHORTWAVE THAT DROPPED OUT OF THE WESTERLIES A DAY OR TWO AGO OVER THE W COAST HAS CLOSED OFF INTO A MIDLEVEL LOW CENTERED JUST S OF CA. THIS SYSTEM WILL BE OF INTEREST TO FCST HERE LATE IN THE UPCOMING WEEKEND AS IT GETS KICKED NE BY NEXT TROF APPROACHING THE W COAST. UPSTREAM SHORTWAVE WILL RACE E...CROSSING UPPER MI/LAKE SUPERIOR BTWN 03Z-09Z. BASED ON THE DARKENING SEEN ON WATER VAPOR IMAGERY... THE GFS HAS A BETTER HANDLE ON SHORTWAVE THAN THE WEAKER NAM. LATEST RUC AND 12Z REGIONAL CANADIAN ALSO SUPPORT THE GFS. OVERLAP OF MODEST DEEP LAYER QVECTOR CONVERGENCE AND MOIST ISENTROPIC ASCENT (CONDENSATION PRES DEFICITS UNDER 20MB) ON THE 290K SFC (AROUND 700MB) LINES UP WELL WITH WHERE RADAR RETURNS ARE PRESENT IN NE ND/NW MN AND SRN MANITOBA. STRONGER ISENTROPIC ASCENT IS INDICATED FARTHER S...BUT AIRMASS IS DRIER THERE. LATEST RUC IS VERY SIMILAR TO THE GFS WITH REGARD TO PROGRESSION OF QVECTOR CONVERGENCE/ISENTROPIC ASCENT THRU 06Z. FORCING/ISENTROPIC ASCENT IS TO SHIFT THRU NE MN BEFORE WEAKENING AS IT CROSSES UPPER MI/LAKE SUPERIOR TONIGHT. WITH ANTECEDENT DRY AIR TO OVERCOME...THE WEAKENING FORCING SUGGESTS PCPN THAT IS OCCURRING UPSTREAM WILL TEND TO DISSIPATE AS IT NEARS AND THEN MOVES ACROSS THE FCST AREA. ON THE OTHER HAND...GIVEN THE APPEARANCE ON WATER VAPOR IMAGERY...SHORTWAVE MAY NOT WEAKEN AS FAST AS MODELS INDICATE. SO...SITUATION IS CERTAINLY STILL WORTHY OF SLIGHT CHC/LOW CHC POPS OVER NW LAKE SUPERIOR AND ACROSS THE KEWEENAW. FCST WETBULB ZERO PROFILES INDICATE ANY PCPN THAT OCCURS WILL BE SNOW. FOLLOWING SHORTWAVE...CANADIAN/GFS SHOW MOISTURE LINGERING AROUND 850MB ON FRI...ESPECIALLY OVER THE CNTRL/ERN FCST AREA. SO THERE SHOULD BE A FAIR AMOUNT OF STRATOCU DEVELOPING DURING THE DAY. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE LOW/MID 50S. HOWEVER...SRLY FLOW WILL KEEP TEMPS MUCH COOLER NEAR AND DOWNWIND OF LAKE MICHIGAN. LOCAL COOLING SHOULD ALSO OCCUR NEAR LAKE SUPERIOR OVER THE W AND OVER THE NCNTRL MID/LATE AFTN AS BOUNDARY LAYER WINDS SLACKEN. FROM MUNISING EWD...SRLY FLOW MAY BE SUFFICIENT THRU THE DAY TO PREVENT LAKE BREEZE DEVELOPMENT. .LONG TERM (FRIDAY NIGHT THROUGH NEXT THURSDAY)... CONTINUITY IN MODEL SOLUTIONS IS POOR CURRENTLY MAINLY DUE TO ZONAL WEST TO EAST UPPER FLOW ALONG CANADA/UNITED STATES BORDER. IN RECENT MODEL RUNS...IT APPEARED SHORTWAVE CURRENTLY OFF SHORE OF BRITISH COLUMBIA WAS TO MOVE EAST AND ARRIVE OVR ONTARIO AND UPR LAKES FRI NIGHT INTO EARLY SAT. ALSO...THE WAVE WAS PROGGED TO SHEAR OUT AS IT CAME EAST. NOW...A TREND IS EMERGING THAT RESULTS IN STRONGER WAVE NOT COMING THROUGH UNTIL SAT. NAM MOST EMPHATIC WITH THIS IDEA WHILE UKMET/GFS AND LATEST ECMWF ARE WEAKER. SHORTWAVE ALONG WITH DIVERGENCE FM RRQ OF H3 OVR ONTARIO SHOULD PRODUCE CONSIDERABLE MID CLOUDS. HOWEVER...SOUNDINGS FM GFS AND EVEN NAM ARE VERY DRY BLO H85 SO HAVE KEPT A DRY FCST. MIXING HEIGHTS MAY BE LIMITED DUE TO CLOUDS AND LIGHT WINDS SO LOWERED TEMPS SLIGHTLY. AT THE SFC...RIDGE DRIFTING OVER UPR LAKES WILL MOVE TO THE LOWER GREAT LAKES SAT NIGHT INTO SUN. RETURN FLOW AS HIGH DEPARTS WILL ONLY STRENGTHEN THROUGH MOST OF THE UPCOMING WEEK. IT IS FEASIBLE THAT SAT NIGHT WILL BE THE LAST ONE FOR A WHILE WITH A GOOD PORTION OF CWA EXPERIENCING MIN TEMPS BLO FREEZING. UPR LOW OVR SOUTHWEST EJECTS INTO PLAINS SUN AND LIFTS TOWARD UPR GREAT LAKES SUN NIGHT INTO MON. UKMET/GFS/ECMWF IN GOOD AGREEMENT HERE. NAM IS MUCH SLOWER WITH TROUGH EJECTION AND WAS NOT PREFERRED DUE TO EVEN STRONGER KICKER SHORTWAVE TROUGH BARRELLING INTO WEST COAST AS EARLY AS SUN. LARGE AREA OF H85-H7 WARM AIR ADVECTION... 40KT H85 JET...AND PWATS ECLIPSING AN INCH (250-300 PCT OF NORMAL) ARE MAIN TRIGGERS FOR PCPN SUN INTO SUN NIGHT. WARMING H85 TEMPS COMBINED WITH COOL H5 TEMPS AROUND -15C RESULT IN STEEPENING MID LEVEL LAPSE RATES AND POSSIBILITY OF THUNDER. MAIN SFC WARM FRONT AND UPR TROUGH DO NOT ARRIVE UNTIL LATE SUN NIGHT INTO MON WHICH IS WHEN BEST COVERAGE TO SHOWERS/THUNDERSTORMS IS EXPECTED. 00Z GFS EVEN INDICATED SOME SFC BASED INSTABILITY AHEAD OF PRIMARY COLD FRONT MOVING THROUGH MON EVENING. ECMWF MUCH QUICKER WITH FROPA. ALTHOUGH MOST PCPN WILL BE DONE BY MON NIGHT...KEPT A SMALL CHANCE IN GRIDS FOR TUE AS SECONDARY SFC TROUGH MOVES THROUGH PER HPC AND H5 COLD POOL (-20C AT H5) ALSO ROTATES THROUGH. BRIEF RIDGING BOTH ALOFT AND AT SFC FOR WED...THEN DEEP TROUGH CONTINUES TO DEVELOP OVR MUCH OF WESTERN CONUS. SW FLOW DEVELOPING ALOFT...AND EVENTUALLY AT SFC...LEADS TO AN INCREASE IN RAIN CHANCES LATE NEXT WEEK. TEMPS WILL REMAIN ABOVE NORMAL. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1037 AM EDT THU MAR 22 2007 .UPDATE... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A POTENT SHORTWAVE RACING E ACROSS ERN LAKE SUPERIOR AND ONTARIO. SHARP DRYING/SUBSIDENCE IN THE WAKE OF SHORTWAVE IS LEADING TO A DECREASE IN CLOUD COVER ACROSS THE FCST AREA THIS MORNING. 00Z/12Z KINL SOUNDINGS SHOWED THE INCOMING DRY AIR NICELY AS PRECIPITABLE WATER DROPPED FROM 0.68 TO 0.15 INCHES...AND 12Z SOUNDING INDICATED DWPT DEPRESSIONS OF 15-25C FROM 840MB TO 550MB. A PERIOD OF GUSTY WINDS IS ALSO FOLLOWING THE STRONG SHORTWAVE. WINDS WERE BEING AIDED BY 4-5MB/3HR PRES RISE MAX THAT WAS QUICKLY MOVING E ACROSS THE UPPER LAKES. CORE OF PRES RISES IS NOW OVER CNTRL LAKE SUPERIOR/CNTRL UPPER MI...SO STRONGEST WINDS HAVE JUST ABOUT PASSED THE AREA. NEXT SHORTWAVE IS HEADING ESE THRU SRN SASKATCHEWAN. MID/HIGH CLOUDS ASSOCIATED WITH SHORTWAVE ARE ALREADY STREAMING E THRU ND INTO NRN MN. INHERITED FCST IS IN GOOD SHAPE FOR THE AFTN AND ONLY REQUIRES MINOR ADJUSTMENTS BASED ON MORNING TRENDS. SOME STRATOCU WILL BE AROUND FOR A FEW MORE HRS...MAINLY ACROSS THE N...ASSOCIATED WITH 850MB THERMAL TROF AND LINGERING LOW-LEVEL MOISTURE. STRATOCU SHOULD BE GONE BY MID/LATE AFTN...BUT ALREADY MID/HIGH CLOUDS ASSOCIATED WITH NEXT SHORTWAVE WILL BE SLIPPING INTO THE FCST AREA FROM THE W. AS FOR TEMPS...MIXING TO 800-850MB ON 12Z KINL SOUNDING SUGGESTS HIGH TEMPS IN THE UPPER 30S/LWR 40S ARE ON TRACK OVER THE W AND N. WNW DOWNSLOPING WIND WILL RESULT IN MAX TEMPS SEVERAL DEGREES HIGHER OVER PORTIONS OF THE CNTRL FCST AREA...ESPECIALLY SCNTRL. AS FOR WINDS...WILL MAINTAIN GALE WARNING OVER ERN LAKE SUPERIOR FOR A FEW MORE HRS WITH EXPECTATION OF GALE FORCE GUSTS. OTHERWISE...WINDS WILL CONTINUE TO DIMINISH OVER THE ENTIRE FCST AREA THRU THE DAY AS PRES RISE SHIFTS E OF THE AREA AND SFC HIGH PRES RIDGE OVER MN DRIFTS E. && .PREV DISCUSSION (ISSUED AT 400 AM EDT)... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STRG SHRTWV NEAR LK WINNIPEG EMBEDDED IN ZONAL FLOW ALF ALG THE CNDN BORDER...WITH ANOTHER SHRTWV PRESENT OVER ND. THREE DISTINCT AREAS OF PCPN NOTED AT THE START OF SHIFT. THE FIRST WAS A BAND OF SHRA MOVING INTO WRN LK SUP JUST AHEAD OF COLD FNT IN DPVA/DEEP LYR H85-3 QVECTOR CNVGC ASSOCIATED WITH ND SHRTWV. LLVL MSTR LINGERS BEHIND THIS FNT WITH SC CIGS OBSVD BACK TO THE RED RIVER VALLEY...WHERE DRIER AIR NOTED ON THE BIS SDNG IS WORKING EWD. STRONGER COLD FNT ASSOCIATED WITH SHRTWV OVER LK WINNIPEG MOVING TOWARD THE MN AT 03Z...BUT LTL PCPN OBSVD ALG THIS BNDRY DESPITE SHARPER THERMAL CONTRAST. SECOND CLUSTER OF SHRA WITH EMBEDDED TSRA EXTENDS FM NW WI INTO IA WHERE DPVA/DEEP LYR H85-3 QVECTOR CNVGC/SFC COLD FNT INTERSECTING HIER H85 DWPTS AOA 8C SURGING NEWD IN ADVANCE OF FNT...MSTR NOT AVBL TO BAND FARTHER N IN WRN LK SUP. RAOBS/PROFILERS SHOW H85 SW WINDS AOA 50 KTS AHEAD OF THIS CLUSTER. LARGEST AREA OF SHRA PRESENT OVER ERN WI/LK MI/NW LWR MI AT NOSE OF STRONGEST H85-7 WINDS JUST AHEAD OF WEAK SHRTWV NOTED ON RUC ANALYSIS. SCT SHRA/TSRA ON NRN FRINGE OF THIS AREA ARE IMPACTING THE ERN CWA...BUT FOR THE MOST PART THESE SHRA/TSRA ON TRACK TO MISS THE FA. OTRW...LTL PCPN NOTED OVER THE FA RIGHT NOW...BUT RETURN OF HIER LLVL MSTR OVER MELTING SN HAS CAUSED QUITE A BIT OF ST/FOG...WITH VSBYS AOB 1/4SM AT PLACES ACRS MAINLY THE SCNTRL AND E. UPSTREAM...ANOTHER SHRTWV MOVING THRU BRITISH COLUMBIA. MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND EVOLUTION OF PCPN AREAS AS LATEST RUC/LARGER SCALE MODELS SHOW SHRTWVS OVER ND AND LK WINNIPEG PHASING OVERNGT. FOCUS AFTER COLD FROPA EARLY THIS MRNG SHIFTS TO WINDS/TEMPS. AS SHRTWVS BEGIN TO MERGE TO A 40-UNIT VORT MAX OVER FAR NRN LK SUP BY 12Z THU...EXPECT SHRA AREAS OVER WRN LK SUP/WI TO MERGE OVER THE SCNTRL/ERN CWA WITH SOME LOCALLY HEAVY RA THERE WHERE MSTR CNVGC PHASES BETTER WITH DPVA/FALLING HGTS/DEEP QVECTOR CVNGC BEFORE ACCELERATING INCRSGLY KATAFNT TYPE COLD FNT DRIVES E UNDER JET SURGE REGION OF DEEPENING SHRTWV. WITH RAPID INFLUX OF DRY AIR EXPECTED AS H85 W WINDS INCRS UP TO 50KT...LOOK FOR PCPN/DENSE FOG TO END SOON AFTR COLD FROPA WITH INTENSE DRY ADVCTN/SUBSIDENCE. 00Z RUC/NAM INDICATE DRYING WL REACH ERY ARND 12Z...SO MOST IF NOT ALL PCPN WL BE OVER BY EARLY TDAY. WL CARRY LINGERING SHRA OVER THE ERN COUNTIES EARLY...OTRW HAVE REMOVED POPS ALTOGETHER AS NAM/RUC FCST SDNGS FOLLOWING THE FROPA ARE QUITE DRY. WL EVALUATE NEED TO KEEP GOING DENSE FOG ADVY GOING CLOSE TO FCST ISSUANCE...BUT ANTICIPATE DROPPING ADVY FOR MOST OF THE FA BY FCST ISSUANCE. GFS FCST SDNGS SHOW MORE LLVL MSTR...BUT PREFER THE DRIER LOOK TO THE RUC/NAM FCSTS GIVEN MORE DRYING OBSVD UPSTREAM OVER NW MN/ANTICIPATED DRY SURGE BEHIND DEEPENING SHRTWV. OTRW...LOOK FOR GUSTY WINDS THIS MRNG BEHIND THE BNDRY WITH 35KT WINDS WITHIN THE MIXED LYR TO DIMINISH A BIT THIS AFTN WITH ARRIVAL OF HI PRES RDG. ALTHOUGH PRES GRADIENT SEEMS TO DIMINISH WITH APRCH OF RDG...MIXING/DEEPENING PBL WITH PLENTY OF SUNSHINE IN LLVL CAD SHOULD TAP STRONGER WINDS ALF TO MAINTAIN GUSTINESS THRU THE DAY. MIXING TO H85 ON NAM FCST SDNGS SUGS HI TEMPS WL REACH ARND 45 OVER THE SE COUNTIES...WHERE NW FLOW WL BE DOWNSLOPING. LOOK FOR AN INCRS IN HI CLD LATE TDAY IN ADVANCE OF NEXT SHRTWV NOW MOVING INTO BRITISH COLUMBIA FCST TO MOVE TOWARD NW MN LATE TDAY. FOR TNGT...SHRTWV OVER THE NRN PLAINS PROGGED TO DRIFT ACRS THE UPR GRT LKS...AND GFS/NAM/UKMET SHOW INCRSG MID LVL MSTR. ALTHOUGH LLVLS APPEAR WL BE TOO DRY FOR ANY PCPN...GFS AND ESPECIALLY THE NAM GENERATE SOME GENERALLY LGT QPF OVER THE NW AND LK SUP. NAM ACTUALLY SHOWS SOME SHARP H85-7 FGEN WITH SOME MODEST ISENTROPIC LIFT IN ADVANCE OF THE SHRTWV. SINCE GFS/UKMET ARE MUCH WEAKER WITH FCST DYNAMICS BUT WV IMAGERY INDICATES A WELL DEFINED SHRTWV IN BRITISH COLUMBIA...WL CARRY SLGT CHC -SHSN (FCST WBZ PROFILES SUG ANY PCPN WOULD BE SN) ACRS THE NW CWA ON CYC SIDE OF NAM FCST H3 JET MAX/BEST H85-7 FGEN. EXPECT THE LOWEST MIN TEMPS OVER THE SCNTRL WHERE THE CLDS WL BE THINNEST. FOLLOWING DEPARTURE OF SHRTWV EARLY FRI...SFC-H85 RDG AXIS/MID LVL DRYING FCST TO DOMINATE. GFS/NAM BOTH SHOW SOME HIER DWPTS AT H85 LINGERING HOWEVER...SO EXPECT BKN DIURNAL SC TO DVLP DURING DAY. MIXING TO H85 ON GFS/NAM FCST SDNGS YIELDS HI TEMPS NEAR 55. WITH LGT SW FLOW...EXPECT LK BREEZES/AFTN COOLING TO DVLP MAINLY NEAR LK MI. SOME CONSIDERABLE MODEL DISAGREEMENTS BEGIN TO SHOW IN THE FRI NGT/SAT PDS...NOT SURPRISING CONSIDERING FAST ZONAL FLOW FCST TO PREVAIL. GFS SHOWS A MUCH DEEPER SHRTWV ARRIVING LATE FRI NGT AND GENERATING SGNFT PCPN ON SAT. WL SIDE WITH THE MAJORITY UKMET/ ECWMF/CNDN/NAM THAT SHOW A MUCH WEAKER SHRTWV SHEARING BY ON FRI NGT FOLLOWED BY RDGING ON SAT. OPTED TO REMOVE POPS FRI NGT AND KEEP SAT DRY. WITH H85 TEMPS APRCHG 6C ON SAT...EXPECT TEMPS OVER THE INLAND TO RISE WELL INTO THE 50S TO NEAR 60 PER MIXING TO H8 ON NAM FCST SDNGS. WITH SFC HI CENTER TO THE SE AND CWA IN SYNOPTIC SW FLOW... EXPECT THE MOST SGNFT LK MODERATION OFF LK MI. BUT RELATIVELY WEAK FLOW AND SFC HTG INLAND SHOULD ALLOW LK BREEZES OFF SUPERIOR AS WELL. COORDINATED WITH GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING E HALF OF LAKE SUPERIOR. && $$ ROLFSON (UPDATE) KC (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 AM EDT THU MAR 22 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STRG SHRTWV NEAR LK WINNIPEG EMBEDDED IN ZONAL FLOW ALF ALG THE CNDN BORDER...WITH ANOTHER SHRTWV PRESENT OVER ND. THREE DISTINCT AREAS OF PCPN NOTED AT THE START OF SHIFT. THE FIRST WAS A BAND OF SHRA MOVING INTO WRN LK SUP JUST AHEAD OF COLD FNT IN DPVA/DEEP LYR H85-3 QVECTOR CNVGC ASSOCIATED WITH ND SHRTWV. LLVL MSTR LINGERS BEHIND THIS FNT WITH SC CIGS OBSVD BACK TO THE RED RIVER VALLEY...WHERE DRIER AIR NOTED ON THE BIS SDNG IS WORKING EWD. STRONGER COLD FNT ASSOCIATED WITH SHRTWV OVER LK WINNIPEG MOVING TOWARD THE MN AT 03Z...BUT LTL PCPN OBSVD ALG THIS BNDRY DESPITE SHARPER THERMAL CONTRAST. SECOND CLUSTER OF SHRA WITH EMBEDDED TSRA EXTENDS FM NW WI INTO IA WHERE DPVA/DEEP LYR H85-3 QVECTOR CNVGC/SFC COLD FNT INTERSECTING HIER H85 DWPTS AOA 8C SURGING NEWD IN ADVANCE OF FNT...MSTR NOT AVBL TO BAND FARTHER N IN WRN LK SUP. RAOBS/PROFILERS SHOW H85 SW WINDS AOA 50 KTS AHEAD OF THIS CLUSTER. LARGEST AREA OF SHRA PRESENT OVER ERN WI/LK MI/NW LWR MI AT NOSE OF STRONGEST H85-7 WINDS JUST AHEAD OF WEAK SHRTWV NOTED ON RUC ANALYSIS. SCT SHRA/TSRA ON NRN FRINGE OF THIS AREA ARE IMPACTING THE ERN CWA...BUT FOR THE MOST PART THESE SHRA/TSRA ON TRACK TO MISS THE FA. OTRW...LTL PCPN NOTED OVER THE FA RIGHT NOW...BUT RETURN OF HIER LLVL MSTR OVER MELTING SN HAS CAUSED QUITE A BIT OF ST/FOG...WITH VSBYS AOB 1/4SM AT PLACES ACRS MAINLY THE SCNTRL AND E. UPSTREAM...ANOTHER SHRTWV MOVING THRU BRITISH COLUMBIA. MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND EVOLUTION OF PCPN AREAS AS LATEST RUC/LARGER SCALE MODELS SHOW SHRTWVS OVER ND AND LK WINNIPEG PHASING OVERNGT. FOCUS AFTER COLD FROPA EARLY THIS MRNG SHIFTS TO WINDS/TEMPS. AS SHRTWVS BEGIN TO MERGE TO A 40-UNIT VORT MAX OVER FAR NRN LK SUP BY 12Z THU...EXPECT SHRA AREAS OVER WRN LK SUP/WI TO MERGE OVER THE SCNTRL/ERN CWA WITH SOME LOCALLY HEAVY RA THERE WHERE MSTR CNVGC PHASES BETTER WITH DPVA/FALLING HGTS/DEEP QVECTOR CVNGC BEFORE ACCELERATING INCRSGLY KATAFNT TYPE COLD FNT DRIVES E UNDER JET SURGE REGION OF DEEPENING SHRTWV. WITH RAPID INFLUX OF DRY AIR EXPECTED AS H85 W WINDS INCRS UP TO 50KT...LOOK FOR PCPN/DENSE FOG TO END SOON AFTR COLD FROPA WITH INTENSE DRY ADVCTN/SUBSIDENCE. 00Z RUC/NAM INDICATE DRYING WL REACH ERY ARND 12Z...SO MOST IF NOT ALL PCPN WL BE OVER BY EARLY TDAY. WL CARRY LINGERING SHRA OVER THE ERN COUNTIES EARLY...OTRW HAVE REMOVED POPS ALTOGETHER AS NAM/RUC FCST SDNGS FOLLOWING THE FROPA ARE QUITE DRY. WL EVALUATE NEED TO KEEP GOING DENSE FOG ADVY GOING CLOSE TO FCST ISSUANCE...BUT ANTICIPATE DROPPING ADVY FOR MOST OF THE FA BY FCST ISSUANCE. GFS FCST SDNGS SHOW MORE LLVL MSTR...BUT PREFER THE DRIER LOOK TO THE RUC/NAM FCSTS GIVEN MORE DRYING OBSVD UPSTREAM OVER NW MN/ANTICIPATED DRY SURGE BEHIND DEEPENING SHRTWV. OTRW...LOOK FOR GUSTY WINDS THIS MRNG BEHIND THE BNDRY WITH 35KT WINDS WITHIN THE MIXED LYR TO DIMINISH A BIT THIS AFTN WITH ARRIVAL OF HI PRES RDG. ALTHOUGH PRES GRADIENT SEEMS TO DIMINISH WITH APRCH OF RDG...MIXING/DEEPENING PBL WITH PLENTY OF SUNSHINE IN LLVL CAD SHOULD TAP STRONGER WINDS ALF TO MAINTAIN GUSTINESS THRU THE DAY. MIXING TO H85 ON NAM FCST SDNGS SUGS HI TEMPS WL REACH ARND 45 OVER THE SE COUNTIES...WHERE NW FLOW WL BE DOWNSLOPING. LOOK FOR AN INCRS IN HI CLD LATE TDAY IN ADVANCE OF NEXT SHRTWV NOW MOVING INTO BRITISH COLUMBIA FCST TO MOVE TOWARD NW MN LATE TDAY. FOR TNGT...SHRTWV OVER THE NRN PLAINS PROGGED TO DRIFT ACRS THE UPR GRT LKS...AND GFS/NAM/UKMET SHOW INCRSG MID LVL MSTR. ALTHOUGH LLVLS APPEAR WL BE TOO DRY FOR ANY PCPN...GFS AND ESPECIALLY THE NAM GENERATE SOME GENERALLY LGT QPF OVER THE NW AND LK SUP. NAM ACTUALLY SHOWS SOME SHARP H85-7 FGEN WITH SOME MODEST ISENTROPIC LIFT IN ADVANCE OF THE SHRTWV. SINCE GFS/UKMET ARE MUCH WEAKER WITH FCST DYNAMICS BUT WV IMAGERY INDICATES A WELL DEFINED SHRTWV IN BRITISH COLUMBIA...WL CARRY SLGT CHC -SHSN (FCST WBZ PROFILES SUG ANY PCPN WOULD BE SN) ACRS THE NW CWA ON CYC SIDE OF NAM FCST H3 JET MAX/BEST H85-7 FGEN. EXPECT THE LOWEST MIN TEMPS OVER THE SCNTRL WHERE THE CLDS WL BE THINNEST. FOLLOWING DEPARTURE OF SHRTWV EARLY FRI...SFC-H85 RDG AXIS/MID LVL DRYING FCST TO DOMINATE. GFS/NAM BOTH SHOW SOME HIER DWPTS AT H85 LINGERING HOWEVER...SO EXPECT BKN DIURNAL SC TO DVLP DURING DAY. MIXING TO H85 ON GFS/NAM FCST SDNGS YIELDS HI TEMPS NEAR 55. WITH LGT SW FLOW...EXPECT LK BREEZES/AFTN COOLING TO DVLP MAINLY NEAR LK MI. SOME CONSIDERABLE MODEL DISAGREEMENTS BEGIN TO SHOW IN THE FRI NGT/SAT PDS...NOT SURPRISING CONSIDERING FAST ZONAL FLOW FCST TO PREVAIL. GFS SHOWS A MUCH DEEPER SHRTWV ARRIVING LATE FRI NGT AND GENERATING SGNFT PCPN ON SAT. WL SIDE WITH THE MAJORITY UKMET/ ECWMF/CNDN/NAM THAT SHOW A MUCH WEAKER SHRTWV SHEARING BY ON FRI NGT FOLLOWED BY RDGING ON SAT. OPTED TO REMOVE POPS FRI NGT AND KEEP SAT DRY. WITH H85 TEMPS APRCHG 6C ON SAT...EXPECT TEMPS OVER THE INLAND TO RISE WELL INTO THE 50S TO NEAR 60 PER MIXING TO H8 ON NAM FCST SDNGS. WITH SFC HI CENTER TO THE SE AND CWA IN SYNOPTIC SW FLOW... EXPECT THE MOST SGNFT LK MODERATION OFF LK MI. BUT RELATIVELY WEAK FLOW AND SFC HTG INLAND SHOULD ALLOW LK BREEZES OFF SUPERIOR AS WELL. COORDINATED WITH GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING LAKE SUPERIOR. && $$ KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 221 PM EDT WED MAR 21 2007 .UPDATE...TEMPERATURES STILL STRUGGLING TO GET ABOVE THE FREEZING MARK OVER THE HIGHER TERRAIN AREAS AROUND HTL...WEST BRANCH. WITH ADDITIONAL SHOWERS MOVING THROUGH...FELT COMPELLED TO EXTEND FREEZING RAIN ADVISORY OUT A FEW MORE HOURS. WARM AIR GETTING CLOSER AS WELL AS SFC DEWPOINTS HEADING TOWARD FREEZING. SO HOPEFULLY WE CAN DROP THE ADVISORY WITH THE 4 PM FORECAST. ADAM && .AVIATION...ISSUED AT 144 PM. AN INTERESTING SITUATION AS THE WARM FRONT IS STILL HUNG UP ALONG THE INDIANA/OHIO BORDER. BECAUSE OF THIS, THERE IS A SIZABLE SFC BASED INVERSION THAT WILL CONTINUE THROUGH 12Z THURSDAY WHEN THE COLD FRONT MOVES THROUGH. THE WARM FRONT IS CAUSING LOW LEVEL WIND SHEAR THAT THE KAPX RADAR IS PEGGING AROUND 35 KTS AROUND 1500 FT. THE MODELS SHOW THAT A LOW LEVEL JET MOVES THROUGH AHEAD OF THE COLD FRONT AND BRINGS IN THE POSSIBILITY OF 50+KTS OVERNIGHT AROUND 1500 TO 2000 FEET. OTHERWISE, THE THUNDERSTORMS LOOK TO BE TIMED MORE WITH THE COLD FRONT PASSING THROUGH THE REGION. SO HAVE THE THUNDERSTORMS IN THE HOURS JUST PRIOR TO FROPA. SFC TEMPERATURES ARE ABOVE FREEZING AT THE TAF SITES SO IT LOOKS LIKE AT THE SFC THE FREEZING RAIN IS NO LONGER AN ISSUE. && .UPDATE...ISSUED 1121 AM. OCCLUDED LOW PRESSURE SYSTEM MOVING INTO WESTERN ONTARIO THIS MORNING. ASSOCIATED OCCLUDED FRONT EXTENDS TO A TRIPLE POINT LOW OVER SOUTH DAKOTA...WARM FRONT STRETCHING SE INTO THE OHIO VALLEY. STRONG WARM/MOIST ADVECTION UNDERWAY ACROSS THE WESTERN GREAT LAKES ALONG AND AHEAD OF THE WARM FRONT. 12Z APX SOUNDING REVEALING ABOVE FREEZING WARM NOSE BETWEEN 940 AND 740 MB WITH A MAX TEMP OF +5C WITHIN THE LAYER...A +6C CHANGE IN THE LAST 12 HOURS. LOW LEVEL MOISTURE GRADIENT SITTING BETWEEN APX AND GRB PER 12Z SOUNDINGS AND INITIAL ROUND OF CONVECTIVE SHOWERS HAVE DEVELOPED ALONG THE MOISTURE AXIS (PER MOIST CONVERGENCE PROCESSES) AND NOW PASSING THROUGH NORTHERN LOWER MICHIGAN ATTM. ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOPING UPSTREAM IN THE IOWA/WISCONSIN/ILLINOIS AREA SPURRED ON BY BETTER CONDITIONAL INSTABILITY ALOFT SPREADING EASTWARD OUT OF THE PLAINS AND EXPECTED TO IMPACT THE REGION LATER IN THE AFTERNOON THROUGH TONIGHT. PER RADAR TRENDS...INITIAL ROUND OF SHOWERS LOOKING TO PASS THROUGH NORTHERN LOWER MICHIGAN THROUGH EARLY AFTERNOON WITH THE HEAVIEST QPF FALLING OVER THE SE QUARTER OF THE CWA. SFC TEMPS ACROSS THIS AREA STILL AT OR BELOW FREEZING PARTICULARLY OVER THE HIGHER TERRAIN. A BIT ON THE FENCE WITH THIS ONE...BUT SPOTTER REPORTS FROM GRAND RAPIDS CWA INDICATE SOME ROADWAY ICING OCCURRING IN COUNTIES JUST UPSTREAM AND THE SAME IS LIKELY TO OCCUR UP THROUGH HTL/WEST BRANCH/GLADWIN...ETC. AFTER TALKING IT OVER WITH GRAND RAPIDS OFFICE DECIDED TO ISSUE A FREEZING RAIN ADVISORY VALID THROUGH EARLY AFTERNOON TO HANDLE THIS FIRST ROUND OF SHOWERS. NO OTHER CHANGES MADE FOR THE REST OF THE AFTERNOON AND THIS EVENING. NEXT ROUND OF SHOWERS AND POSSIBLE THUNDER LOOKING TO ARRIVE LATER IN THE AFTERNOON AND PARTICULARLY TONIGHT AS THE COLD FRONT PRESSES IN FROM THE WEST. BASICALLY...LOOKS WET WITH STRONG FORCING/IMPRESSIVE MOIST INFLOW UP INTO THE STATE - PWATS RUNNING 400 PERCENT OF NORMAL AS NOTED BY MIDNIGHT SHIFT. ADAM && .AVIATION...ISSUED AT 720 AM EDT. A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .APX WATCHES/WARNINGS/ADVISORIES...FREEZING RAIN ADVISORY... UNTIL 5 PM...MIZ029-030-034>036-041-042 && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 144 PM EDT WED MAR 21 2007 .AVIATION...AN INTERESTING SITUATION AS THE WARM FRONT IS STILL HUNG UP ALONG THE INDIANA/OHIO BORDER. BECAUSE OF THIS, THERE IS A SIZABLE SFC BASED INVERSION THAT WILL CONTINUE THROUGH 12Z THURSDAY WHEN THE COLD FRONT MOVES THROUGH. THE WARM FRONT IS CAUSING LOW LEVEL WIND SHEAR THAT THE KAPX RADAR IS PEGGING AROUND 35 KTS AROUND 1500 FT. THE MODELS SHOW THAT A LOW LEVEL JET MOVES THROUGH AHEAD OF THE COLD FRONT AND BRINGS IN THE POSSIBILITY OF 50+KTS OVERNIGHT AROUND 1500 TO 2000 FEET. OTHERWISE, THE THUNDERSTORMS LOOK TO BE TIMED MORE WITH THE COLD FRONT PASSING THROUGH THE REGION. SO HAVE THE THUNDERSTORMS IN THE HOURS JUST PRIOR TO FROPA. SFC TEMPERATURES ARE ABOVE FREEZING AT THE TAF SITES SO IT LOOKS LIKE AT THE SFC THE FREEZING RAIN IS NO LONGER AN ISSUE. && .UPDATE...ISSUED 1121 AM. OCCLUDED LOW PRESSURE SYSTEM MOVING INTO WESTERN ONTARIO THIS MORNING. ASSOCIATED OCCLUDED FRONT EXTENDS TO A TRIPLE POINT LOW OVER SOUTH DAKOTA...WARM FRONT STRETCHING SE INTO THE OHIO VALLEY. STRONG WARM/MOIST ADVECTION UNDERWAY ACROSS THE WESTERN GREAT LAKES ALONG AND AHEAD OF THE WARM FRONT. 12Z APX SOUNDING REVEALING ABOVE FREEZING WARM NOSE BETWEEN 940 AND 740 MB WITH A MAX TEMP OF +5C WITHIN THE LAYER...A +6C CHANGE IN THE LAST 12 HOURS. LOW LEVEL MOISTURE GRADIENT SITTING BETWEEN APX AND GRB PER 12Z SOUNDINGS AND INITIAL ROUND OF CONVECTIVE SHOWERS HAVE DEVELOPED ALONG THE MOISTURE AXIS (PER MOIST CONVERGENCE PROCESSES) AND NOW PASSING THROUGH NORTHERN LOWER MICHIGAN ATTM. ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOPING UPSTREAM IN THE IOWA/WISCONSIN/ILLINOIS AREA SPURRED ON BY BETTER CONDITIONAL INSTABILITY ALOFT SPREADING EASTWARD OUT OF THE PLAINS AND EXPECTED TO IMPACT THE REGION LATER IN THE AFTERNOON THROUGH TONIGHT. PER RADAR TRENDS...INITIAL ROUND OF SHOWERS LOOKING TO PASS THROUGH NORTHERN LOWER MICHIGAN THROUGH EARLY AFTERNOON WITH THE HEAVIEST QPF FALLING OVER THE SE QUARTER OF THE CWA. SFC TEMPS ACROSS THIS AREA STILL AT OR BELOW FREEZING PARTICULARLY OVER THE HIGHER TERRAIN. A BIT ON THE FENCE WITH THIS ONE...BUT SPOTTER REPORTS FROM GRAND RAPIDS CWA INDICATE SOME ROADWAY ICING OCCURRING IN COUNTIES JUST UPSTREAM AND THE SAME IS LIKELY TO OCCUR UP THROUGH HTL/WEST BRANCH/GLADWIN...ETC. AFTER TALKING IT OVER WITH GRAND RAPIDS OFFICE DECIDED TO ISSUE A FREEZING RAIN ADVISORY VALID THROUGH EARLY AFTERNOON TO HANDLE THIS FIRST ROUND OF SHOWERS. NO OTHER CHANGES MADE FOR THE REST OF THE AFTERNOON AND THIS EVENING. NEXT ROUND OF SHOWERS AND POSSIBLE THUNDER LOOKING TO ARRIVE LATER IN THE AFTERNOON AND PARTICULARLY TONIGHT AS THE COLD FRONT PRESSES IN FROM THE WEST. BASICALLY...LOOKS WET WITH STRONG FORCING/IMPRESSIVE MOIST INFLOW UP INTO THE STATE - PWATS RUNNING 400 PERCENT OF NORMAL AS NOTED BY MIDNIGHT SHIFT. ADAM && .AVIATION...ISSUED AT 720 AM EDT. A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .APX WATCHES/WARNINGS/ADVISORIES...FREEZING RAIN ADVISORY...UNTIL 2 PM...MIZ028>030-033>036-041-042. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1121 AM EDT WED MAR 21 2007 .UPDATE...OCCLUDED LOW PRESSURE SYSTEM MOVING INTO WESTERN ONTARIO THIS MORNING. ASSOCIATED OCCLUDED FRONT EXTENDS TO A TRIPLE POINT LOW OVER SOUTH DAKOTA...WARM FRONT STRETCHING SE INTO THE OHIO VALLEY. STRONG WARM/MOIST ADVECTION UNDERWAY ACROSS THE WESTERN GREAT LAKES ALONG AND AHEAD OF THE WARM FRONT. 12Z APX SOUNDING REVEALING ABOVE FREEZING WARM NOSE BETWEEN 940 AND 740 MB WITH A MAX TEMP OF +5C WITHIN THE LAYER...A +6C CHANGE IN THE LAST 12 HOURS. LOW LEVEL MOISTURE GRADIENT SITTING BETWEEN APX AND GRB PER 12Z SOUNDINGS AND INITIAL ROUND OF CONVECTIVE SHOWERS HAVE DEVELOPED ALONG THE MOISTURE AXIS (PER MOIST CONVERGENCE PROCESSES) AND NOW PASSING THROUGH NORTHERN LOWER MICHIGAN ATTM. ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOPING UPSTREAM IN THE IOWA/WISCONSIN/ILLINOIS AREA SPURRED ON BY BETTER CONDITIONAL INSTABILITY ALOFT SPREADING EASTWARD OUT OF THE PLAINS AND EXPECTED TO IMPACT THE REGION LATER IN THE AFTERNOON THROUGH TONIGHT. PER RADAR TRENDS...INITIAL ROUND OF SHOWERS LOOKING TO PASS THROUGH NORTHERN LOWER MICHIGAN THROUGH EARLY AFTERNOON WITH THE HEAVIEST QPF FALLING OVER THE SE QUARTER OF THE CWA. SFC TEMPS ACROSS THIS AREA STILL AT OR BELOW FREEZING PARTICULARLY OVER THE HIGHER TERRAIN. A BIT ON THE FENCE WITH THIS ONE...BUT SPOTTER REPORTS FROM GRAND RAPIDS CWA INDICATE SOME ROADWAY ICING OCCURRING IN COUNTIES JUST UPSTREAM AND THE SAME IS LIKELY TO OCCUR UP THROUGH HTL/WEST BRANCH/GLADWIN...ETC. AFTER TALKING IT OVER WITH GRAND RAPIDS OFFICE DECIDED TO ISSUE A FREEZING RAIN ADVISORY VALID THROUGH EARLY AFTERNOON TO HANDLE THIS FIRST ROUND OF SHOWERS. NO OTHER CHANGES MADE FOR THE REST OF THE AFTERNOON AND THIS EVENING. NEXT ROUND OF SHOWERS AND POSSIBLE THUNDER LOOKING TO ARRIVE LATER IN THE AFTERNOON AND PARTICULARLY TONIGHT AS THE COLD FRONT PRESSES IN FROM THE WEST. BASICALLY...LOOKS WET WITH STRONG FORCING/IMPRESSIVE MOIST INFLOW UP INTO THE STATE - PWATS RUNNING 400 PERCENT OF NORMAL AS NOTED BY MIDNIGHT SHIFT. ADAM && .AVIATION...ISSUED AT 720 AM EDT. A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .AVIATION....VFR CONDITIONS WILL PERSIST THROUGH THE REMAINDER OF TONIGHT...AS SOME HIGHER LEVEL CLOUDS WILL INVADE THE REGION FOR THE OVERNIGHT HOURS. SOUTH TO SOUTHEAST WINDS JUST ABOVE THE SURFACE WILL CONTINUE TO INCREASE...REACHING 30 KNOTS AOA 2KFT BY 06-08Z...RESULTING IN WIND SHEAR...UNTIL MIXING BEGINS DURING THE EARLY MORNING HOURS TOMORROW. AT THE SAME TIME...LOOK FOR CLOUDS THICKEN UP AROUND THE TVC AREA...DESCENDING INTO THE MVFR CATEGORY AS A WARM FRONT APPROACHES FROM THE SW. TEMPORARY LIGHT RAIN IS POSSIBLE BY 16Z IN TVC...AND ACROSS THE APN REGION BY 18-19Z...WHILE PLN LOOKS TO HAVE THE LEAST CHANCE AT THIS POINT. THE WARM FRONT WILL PASS THROUGH LATE TOMORROW AFTERNOON AND EVENING...AND LOOKS TO GET HELD UP ACROSS NRN LOWER MICHIGAN...RESULTING IN PREDOMINANT MVFR CEILINGS AOA 2KFT WITH SCATTERED LIGHT RAIN SHOWERS. A COLD FRONT WILL PUSH THROUGH BY THURSDAY MORNING....AND WILL BE ASSOCIATED WITH A BAND OF SHOWERS WITH THE POTENTIAL FOR ISOLATED THUNDERSTORMS. SMD && .APX WATCHES/WARNINGS/ADVISORIES...FREEZING RAIN ADVISORY...UNTIL 2 PM...MIZ028>030-033>036-041-042. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 720 AM EDT WED MAR 21 2007 .AVIATION...A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .AVIATION....VFR CONDITIONS WILL PERSIST THROUGH THE REMAINDER OF TONIGHT...AS SOME HIGHER LEVEL CLOUDS WILL INVADE THE REGION FOR THE OVERNIGHT HOURS. SOUTH TO SOUTHEAST WINDS JUST ABOVE THE SURFACE WILL CONTINUE TO INCREASE...REACHING 30 KNOTS AOA 2KFT BY 06-08Z...RESULTING IN WIND SHEAR...UNTIL MIXING BEGINS DURING THE EARLY MORNING HOURS TOMORROW. AT THE SAME TIME...LOOK FOR CLOUDS THICKEN UP AROUND THE TVC AREA...DESCENDING INTO THE MVFR CATEGORY AS A WARM FRONT APPROACHES FROM THE SW. TEMPORARY LIGHT RAIN IS POSSIBLE BY 16Z IN TVC...AND ACROSS THE APN REGION BY 18-19Z...WHILE PLN LOOKS TO HAVE THE LEAST CHANCE AT THIS POINT. THE WARM FRONT WILL PASS THROUGH LATE TOMORROW AFTERNOON AND EVENING...AND LOOKS TO GET HELD UP ACROSS NRN LOWER MICHIGAN...RESULTING IN PREDOMINANT MVFR CEILINGS AOA 2KFT WITH SCATTERED LIGHT RAIN SHOWERS. A COLD FRONT WILL PUSH THROUGH BY THURSDAY MORNING....AND WILL BE ASSOCIATED WITH A BAND OF SHOWERS WITH THE POTENTIAL FOR ISOLATED THUNDERSTORMS. SMD && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 252 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY THROUGH SATURDAY)...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH SATURDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL NOSE INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW OVER BAJA. THIS LOW IS PROGGED TO MOVE TO THE NORTHEAST OVER THE FOUR CORNERS REGION DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO SPREAD OVERHEAD FROM THE WEST BUT WL BE WELL ABOVE NORMAL EACH DAY...IN THE LOWER 80S THIS AFTERNOON AND SATURDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)...THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA INTO MONDAY...CONTINUING TO DEFLECT POTENTIAL SHORTWAVE ENERGY. BY LATE MONDAY AND TUESDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION...THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. WITH PASSAGE OF THE TROUGH THE MID LEVEL RIDGE IS FORECAST TO REBUILD OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER. THERE ARE STILL INDICATIONS IN THE MODELS THAT A MORE ACTIVE PATTERN WILL TAKE SHAPE OVER THE LOWER MS VALLEY REGION BY NEXT FRIDAY AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS AND FORCE A BREAKDOWN OF THE RIDGE. THE GFS/ ECMWF ARE CONSISTENT IN SHOWING THIS BREAK-DOWN...AND WILL KEEP THE CHANCE POPS OFFERED BY MEX MOS. /EC/ && .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI THIS MORNING AND AGAIN SATURDAY MORNING. IFR CONDITIONS ARE EXPECTED TO DEVELOP AROUND 11Z AT HBG AGAIN THIS MORNING AND SATURDAY MORNINGS. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA EACH MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 82 54 84 55 / 2 2 3 3 MERIDIAN 83 52 85 54 / 2 2 2 2 VICKSBURG 82 56 84 57 / 3 2 3 3 HATTIESBURG 82 54 84 54 / 3 2 2 5 NATCHEZ 81 56 83 58 / 3 2 3 4 GREENVILLE 81 57 83 57 / 7 2 3 3 GREENWOOD 83 56 85 57 / 6 2 3 3 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 935 AM CDT THU MAR 22 2007 .SHORT TERM...LATEST SATELLITE IMAGERY SHOWS THE REGION UNDER AN UPPER RIDGE...WHICH IS CONTINUING OUR LONG ROUND OF DRY WEATHER. SHOULD GET SOME SCATTERED CLOUDS MOSTLY IN THE FORM OF HIGH LEVEL CLOUDS FOR THIS AFTERNOON. THE FOG HAS LIFTED OVER OUR THE SOUTHEAST ZONES...SO HAVE ALLOWED THE DENSE FOG ADVISORY TO EXPIRE. CURRENT HIGHS IN THE LOWER 80S SEEMS TO BE ON TRACK. SO WILL MAKE NO OTHER CHANGES TO THE ZONES./17/ .AVIATION...PATCHES OF LIFR CIGS/VSBY WILL BE POSSIBLE IN AREAS ALONG AND S OF HIGHWAY 84 FOR FRIDAY MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME AREAWIDE BY 15Z FRIDAY./17/ .PREVIOUS DISCUSSION... TODAY THROUGH FRIDAY...GRADIENT WINDS HAVE CONTINUED OVER MUCH OF CWA THIS MORNING WITH THE EXCEPTION OF SOUTHEAST MISSISSIPPI LAST HOUR. PINE BELT AIRPORT WAS REPORTING VISIBILITY RESTRICTIONS ALREADY. WL CONTINUE TO MONITOR OUR SOUTHEAST ZONES FOR AN ADVISORY AGAIN THIS MORNING...BUT CURRENTLY EXPECTING ANY DENSE FOG DEVELOPMENT TO REMAIN PATCHY. ELSE...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH FRIDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL BUILD INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW DROPPING SOUTH OFF THE SOUTHERN CALIFORNIA COAST. THIS LOW IS PROGGED TO MOVE OVER BAJA DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. SOME MID AND HIGH LEVEL CLOUDS WILL SPREAD OVERHEAD FROM THE WEST BUT WL STILL REACH WELL ABOVE NORMAL...AROUND 80 DEGREES THIS AFTERNOON AND FRIDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ FRIDAY NIGHT THROUGH NEXT WEEK... THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA THIS WEEKEND...TENDING TO DEFLECT ANY POTENTIAL SHORTWAVE TROUGHS. WITH THAT IN MIND...THE GFS SEEMS A LITTLE TOO QUICK IN INCREASING RAIN CHANCES SUNDAY AND SUNDAY NIGHT AND WILL KEEP THE FORECAST DRY. BY MONDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION... THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. THE MID LEVEL RIDGE REBUILDS OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER FOR THE FORECAST AREA. THERE ARE INDICATIONS THAT A MORE ACTIVE PATTERN COULD TAKE SHAPE OVER THE LOWER MS VALLEY REGION NEXT WEEKEND AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS. THE GFS/UKMET/ECMWF ARE ALL IN AGREEMENT ON THIS SCENARIO...BUT PERSISTENCE CERTAINLY ARGUES AGAINST IT. /EC/ .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 230 AM CDT THU MAR 22 2007 .DISCUSSION... TODAY THROUGH FRIDAY...GRADIENT WINDS HAVE CONTINUED OVER MUCH OF CWA THIS MORNING WITH THE EXCEPTION OF SOUTHEAST MISSISSIPPI LAST HOUR. PINE BELT AIRPORT WAS REPORTING VISIBILITY RESTRICTIONS ALREADY. WL CONTINUE TO MONITOR OUR SOUTHEAST ZONES FOR AN ADVISORY AGAIN THIS MORNING...BUT CURRENTLY EXPECTING ANY DENSE FOG DEVELOPMENT TO REMAIN PATCHY. ELSE...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH FRIDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL BUILD INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW DROPPING SOUTH OFF THE SOUTHERN CALIFORNIA COAST. THIS LOW IS PROGGED TO MOVE OVER BAJA DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. SOME MID AND HIGH LEVEL CLOUDS WILL SPREAD OVERHEAD FROM THE WEST BUT WL STILL REACH WELL ABOVE NORMAL...AROUND 80 DEGREES THIS AFTERNOON AND FRIDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ FRIDAY NIGHT THROUGH NEXT WEEK... THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA THIS WEEKEND...TENDING TO DEFLECT ANY POTENTIAL SHORTWAVE TROUGHS. WITH THAT IN MIND...THE GFS SEEMS A LITTLE TOO QUICK IN INCREASING RAIN CHANCES SUNDAY AND SUNDAY NIGHT AND WILL KEEP THE FORECAST DRY. BY MONDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION... THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. THE MID LEVEL RIDGE REBUILDS OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER FOR THE FORECAST AREA. THERE ARE INDICATIONS THAT A MORE ACTIVE PATTERN COULD TAKE SHAPE OVER THE LOWER MS VALLEY REGION NEXT WEEKEND AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS. THE GFS/UKMET/ECMWF ARE ALL IN AGREEMENT ON THIS SCENARIO...BUT PERSISTENCE CERTAINLY ARGUES AGAINST IT. /EC/ && .AVIATION...PATCHES OF LIFR CIG/VSBY WILL BE POSSIBLE IN AREAS ALONG AND S OF HIGHWAY 84 THIS MORNING AND AGAIN FRIDAY MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME AREAWIDE BY 15Z EACH MORNING. /22/ && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 800 PM CDT WED MAR 21 2007 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... COLD FRONT HAS MOVED INTO SOUTHEASTERN NEBRASKA AND NORTH CENTRAL KANSAS WITH A LINE OF THUNDERSTORMS DEVELOPING ALONG THE FRONT FROM NEAR CONCORDIA NORTHEAST TO SOUTH OF OMAHA. REPORTS FROM OAX INDICATED NUMEROUS THREE QUARTER TO ONE AND ONE QUARTER HAIL REPORTS WITH THIS LINE. MLCAPES AROUND 1500-2000 J/KG...STEEP MID LEVEL LAPSE RATES AND SFC-6KM SHEAR FROM 30-40 KNOTS WILL CONTINUE TO SUPPORT THE THREAT OF HAIL AS THE THUNDERSTORMS MOVE EAST INTO EXTREME NORTHWEST MISSOURI. THE LINE OF THUNDERSTORMS WILL CONTINUE TO MOVE SOUTH AND EAST THROUGH THE NIGHT WITH THE SEVERE WEATHER THREAT GRADUALLY DIMINISHING. LATEST RUC AND NAM SUGGEST THAT THE CAP OVER THE CWA WILL GRADUALLY ERODE...BUT WITH THE LACK OF INSOLATION...SBCAPE AND MUCAPE DROP TO 1000-1250 J/KG BETWEEN 09-12Z. SHEAR WILL REMAIN MARGINAL THROUGH THE NIGHT. THE LINE OF CONVECTION IS EXPECTED TO REACH A KANSAS CITY TO PRINCETON LINE BY 08Z. BY 12Z...ONLY SMALL HAIL IS EXPECTED. DB && .PREVIOUS DISCUSSION... 331 PM... VERY CHALLENGING FORECAST THROUGH THE EARLY PERIODS AS LARGE SCALE PATTERN CHANGE HAS PLACED THE LOWER MISSOURI VALLEY REGION IN A FAVORED AREA FOR REPEATED PRECIPITATION EVENTS. 19Z SURFACE ANALYSIS DEPICTS A SEASONABLY MOIST WARM SECTOR AIRMASS OVER THE CWA THIS AFTERNOON...CHARACTERIZED BY DEWPOINTS APPROACHING 60 DEGREES. RUC SOUNDINGS SHOW THAT AN ELEVATED MIXED LAYER WITH STEEP MID-LEVEL LAPSE RATES HAS OVERSPREAD THE REGION...LEAVING THE AREA CAPPED ABOVE AN EXTENSIVE STRATUS CANOPY. PACIFIC COLD FRONT/DRYLINE STRETCHED FROM NORFOLK TO KEARNEY NEBRASKA...AND PER VISIBLE SATELLITE IMAGERY HAS BEEN PRECEDED BY AN INTERESTING GRAVITY WAVE. SHORT MODEL PROGS COLLABORATE WELL WITH OBSERVATIONAL DATA...SHOWING THAT CONVECTION WILL LIKELY DEVELOP OVER SE NEBRASKA IN THE NEXT SEVERAL HOURS WHERE BETTER SURFACE CONVERGENCE IS FOCUSED ALONG THE ADVANCING FRONT AND JUST EAST OF THE ANALYZED SURFACE LOW. ATTENDANT SEVERE THREAT APPEARS TO BE PRIMARILY IN THE FORM OF DAMAGING LINE SEGMENTS WITH ATTENDANT LARGE HAIL AS STEEP MID LEVEL LAPSE RATES COUPLE WITH INCREASING UNIDIRECTIONAL SHEAR AFTER DARK. CERTAINLY STORMS MOVING TOWARD THE NORTHEAST WOULD HAVE THE GREATER THREAT FOR SEVERE. THE QUESTION REMAINS AS TO HOW LONG THE THREAT WILL PERSIST AFTER DARK...AND CURRENT THINKING IS THAT IT MAY TAKE SOME TIME FOR CONVECTION TO WIND DOWN AS LOW LEVEL INSTABILITY IS MAINTAINED BY A WELL MIXED BOUNDARY LAYER AND EXTENSIVE CLOUD COVER. INCREASED LIKELIHOOD OF SEVERE WEATHER REMAINS PRIMARY FOCUSED IN AREAS NORTH AND WEST OF A KANSAS CITY TO TRENTON LINE. SURFACE FRONT WILL BEGIN TO STALL SOMEWHERE ALONG EAX/SGF CWA BORDER TOMORROW MORNING...AND WAFFLE OVER THE NEXT SEVERAL DAYS AS A SERIES OF MID LEVEL DISTURBANCES ARE EJECTED FROM A DEEP UPPER LOW ENTRENCHED IN THE BAJA. VERY UNUSUAL FLOW PATTERN FOR THIS TYPE OF YEAR...BUT THE QUALITY AND DEPTH OF MOISTURE THAT PERSISTS THROUGH THE WEEKEND CERTAINLY RAISES A RED FLAG THAT CUMULATIVE RAINFALL TOTALS COULD LEAD TO FLOODING BY THE WEEKEND. EVEN MORE CHALLENGING WILL BE THE TEMPERATURES AS THE QUASI-STATIONARY BOUNDARY COULD LEAD TO LARGE ERRORS DEPENDING ON ITS DAY TO DAY PLACEMENT AND PROPAGATION. WHERE PERIODIC SUNSHINE IS ABLE TO MANIFEST BETWEEN THESE SYSTEMS...RAPID WARMING INTO THE UPPER 60S-MID 70S COULD OCCUR GIVEN BALMY MID LEVEL TEMPERATURES BENEATH WEAK 500MB RIDGING AND SOUTHWEST UPPER FLOW. EQUALLY POSSIBLE ARE HIGHS IN THE 50S WHERE MCS INDUCED PRECIPITATION/CLOUD DEBRIS KEEP READINGS NEARLY WET BULBED. BOOKBINDER VERY LITTLE CHANGE TO PREVIOUS THINKING REGARDING THE PROGRESS OF THE CLOSED BAJA LOW INTO THE CNTRL CONUS THIS WEEKEND. ECMWF STILL REMAINS THE MODEL OF CHOICE...ALTHOUGH THE OPERATIONAL GFS AND GFS ENSEMBLES HAVE STEADILY BEEN TRENDING TOWARDS THIS SOLUTION THE PAST SEVERAL RUNS. BEFORE THE MAIN BRUNT OF MIDLEVEL ENERGY EJECTS TOWARDS THE REGION LATE SUNDAY...NUMEROUS WEAK SHORTWAVES WILL RIDE OVER THE RIDGE AXIS WHOSE WRN PERIPHERY SHOULD ALIGN ALONG THE LOWER MISSOURI RIVER VALLEY. EACH PASSING SHORTWAVE WILL INVIGORATE LIFT ASSOCIATED WITH WAA ABOVE THE BOUNDARY LAYER...AND LEAD TO SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS. HAVE TRIMMED POPS SLIGHTLY FOR THE SAT NIGHT TIME PERIOD AS SFC AND LOW LEVEL FRONT APPEARS AS IF IT WILL LIFT NORTH OF MISSOURI KEEPING FOCUSING MECHANISM FURTHER NORTH OF THE AREA. SOME CONCERN THAT PRE-EXISTING CONVECTION GENERATED OVER THE HIGH PLAINS WILL DRIFT INTO THE AREA ASSISTED BY A STRENGTHENING NOCTURNAL LLJ...SO HAVE CONTINUED A 30-40 PERCENT POP RANGE. MODELS CONTINUE TO ADVERTISE THE POSSIBILITY OF A POTENT WEATHER SCENARIO FOR SUNDAY. AS WITH PREVIOUS MODEL RUNS...ECMWF LIFTS THE UPPER WAVE A LITTLE FURTHER WEST OF THE AREA SHEARED MORE SO OVER THE RIDGE AXIS. REGARDLESS...AS THE WAVE EJECTS INTO THE CNTRL PLAINS...INCREASING H5/H7 LAPSE RATES IN EXCESS OF 6C/KM WILL ADVECT INTO THE AREA OVERTOP OF INCREASING MODIFIED GULF MOISTURE LEADING TO HEIGHTENED INSTABILITY WITH MUCAPES FORECAST AOA 1000 J/KG. AT THE SAME TIME...STRENGTHENING WINDS ALOFT WILL LEAD TO 0-6KM BULK SHEAR VECTORS AOA 50KT WITH THE REGION SITUATED UNDER THE FAVORABLE LEFT FRONT EXIT REGION OF A 90+ KT UPPER JET. OTHER THAN THE UPPER WAVE AND LOW LEVEL FOCUSING MECHANISM PLACEMENT...MAIN UNCERTAINTY APPEARS TO BE TIED TO ANY MORNING CONVECTION CONTAMINATING THE MODIFIED AIRMASS PROHIBITING FULL AFTERNOON DESTABILIZATION. AFTER THE UPPER WAVE MOVES NORTHEAST OF THE AREA INTO THE GREAT LAKES...A SFC FRONT WILL SAG THROUGH THE AREA...HOWEVER ONCE AGAIN STALL JUST SOUTH OF THE FORECAST AREA AS ANOTHER LARGE CHUNK OF ENERGY ESTABLISHES A LONGWAVE TROUGH OVER THE WRN CONUS. PREFER A SOLUTION SLOWER THAN THE OPERATIONAL GFS WHICH PUSHES THIS LONGWAVE FEATURE EAST INTO THE INTERMOUNTAIN REGION BY NEXT WEDNESDAY. FOLLOWED CLOSER TO THE GFS ENSEMBLE MEAN IN THIS RESPECT WHICH KEEPS THE AREA MAINLY DRY...ALBEIT QUITE WARM FOR THE END OF THE FORECAST PERIOD. 21 && .AVIATION... VFR CEILINGS ARE EXPECTED THIS EVENING WITH THE LINE OF CONVECTION REACHING STJ AROUND 07Z. THE CONVECTION WILL LAST LESS THAN 2 HOURS. AN ISOLATED STORM MAY BE MARGINALLY SEVERE WITH A HAIL THREAT. THE CEILINGS AND VISIBILITIES ARE EXPECTED TO BE MVFR...POSSIBLY VERY BRIEFLY IFR. THE THUNDERSTORMS WILL MOVE SOUTHEAST INTO THE KANSAS CITY AREA BETWEEN 08Z AND 10Z. ONCE THE THUNDERSTORMS MOVE SOUTHEAST OF THE AIRPORTS AND THE COLD FRONT MOVES THROUGH...VFR CEILINGS ARE EXPECTED AFTER 10Z AT STJ AND AFTER 12Z AT MKC AND MCI. ANOTHER ROUND OF THUNDERSTORMS IS POSSIBLE DURING THE AFTERNOON HOURS ON THURSDAY. DB && EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 945 AM MST THU MAR 22 2007 .SYNOPSIS... A STRONG PACIFIC LOW PRESSURE SYSTEM WAS LOCATED JUST OFF THE NORTHERN BAJA CALIFORNIA COAST THIS MORNING. IT WILL MOVE VERY SLOWLY EAST ACROSS NORTHERN MEXICO FRIDAY INTO SATURDAY. THIS STORM SYSTEM WILL BRING INCREASING CLOUDINESS...COOLER DAYTIME HIGHS...AND PERIODS OF SHOWERS AND THUNDERSTORMS TODAY THROUGH SATURDAY...WITH THE BEST CHANCE FOR PRECIPITATION OVER SOUTH-CENTRAL ARIZONA. HIGHER PRESSURE ALOFT FROM THE PACIFIC WILL BRING DRY WEATHER WITH SOME RECOVERY OF TEMPERATURES SUNDAY AND MONDAY. ANOTHER RATHER STRONG WEATHER DISTURBANCE WILL PRODUCE BREEZY TO WINDY CONDITIONS ALONG WITH SOME COOLING NEXT TUESDAY AND WEDNESDAY. && .SHORT TERM... TODAY THROUGH SATURDAY... 12Z POSITION OF CLOSED LOW WAS NEAR 30N/117W WITH SEVERAL VORTICITY CENTERS ROTATING AROUND ITS PERIMETER. NAM/GFS SOLUTIONS APPEARED TO BE SOMEWHAT SOUTH OF LATEST RUC...WITH ALL MODELS INDICATING THE STRONGEST VORT CENTER SOUTH OF THE LOW. THE 500MB WIND SPEEDS WERE ALSO STRONGEST AROUND THE SOUTHERN QUADRANTS OF THE LOW...50-70KTS. AFTER SUNRISE THE CONVECTION PICKED UP IN OUR CWA...AND CONTINUED TO DRIFT INTO YAVAPAI COUNTY. BY FAR THE HEAVIEST PRECIP WAS THROUGH SOUTHERN GILA COUNTY WHERE SPOTTERS/RAWS DATA REPORTED .30 TO .45 INCH UP TO 6 AM. SIGNIFICANT DIFFLUENCE WAS ALSO INDICATED ACROSS EASTERN AZ EARLIER TODAY. UPDATES ISSUED BY 8 AM TO COVER 88D TRENDS. WILL CONTINUE TO EXPECT STRONGEST LIFT AND LOWEST STABILITY INDICES AFTER 18Z FRIDAY...AND THAT FITS NICELY WITH OUR CURRENT FCSTS. ALTHOUGH LATEST NAM GIVES PHX A 24 HR PRECIP AMOUNT OF .38 INCH WE WILL STILL EXPECT GENERALLY LIGHTER AMOUNTS ACROSS ZONE 23. HOWEVER WE COULD SEE MUCH MORE...ACROSS ZONE 24...PER HPC OUTPUT. OUR WESTERN ZONES WILL STAY MUCH DIRER...WITH SOME PATCHY BLWG DUST TODAY. IN FACT ONE SHARP-EYED SPOTTER CALLED IN A REPORT OF BLOWING DUST NEAR A FARM FIELD WEST OF TONOPAH. MODEL TRENDS CONTINUE TO BE VERY CONSISTENT IN KEEPING THE CLOSED LOW OVER NRN MEX INTO FRIDAY NIGHT. BY 12Z SAT LATEST GFS CALLS FOR THE CENTER OF CIRCULATION TO LIFT OUT TO NEAR ABQ...WITH CSDRBL RH THROUGH A DEEP LAYER EVEN WEST OF PHX. UPPER RIDGE AND WARMER TEMPS WILL ALSO SPREAD ACROSS ENTIRE CWA FOR FRIDAY AND SATURDAY. && .LONG TERM... SATURDAY NIGHT THROUGH WEDNESDAY... WITH SLOWER EXIT OF THE SYSTEM AND POTENTIAL FOR MORE MOISTURE... ADDED SOME SLIGHT CHANCE POPS IN EASTERN PORTIONS OF THE FORECAST AREA SATURDAY NIGHT. THIS IS FOLLOWED BY RIDGE BUILDING FOR A QUICK WARMUP. IN THE LATTER PART OF THE EXTENDED...GFS AND ECWMF ARE SHOWING ANOTHER SYSTEM AFFECTING US. HOWEVER...IT LOOKS TO BE OF A DIFFERENT CHARACTER...MUCH LESS APT TO SLOW DOWN AND JOG SOUTHWARD. HOWEVER...THERE ARE SOME DIFFERENCES. THE GFS ENSEMBLE MEAN HAS A SIMILAR TRACK TO THE 12Z OPERATIONAL GFS...TAKING THE BULK OF THE SYSTEM JUST NORTH OF OUR AREA...BUT SHOWS LOWER HEIGHTS. THE ECMWF IS EVEN COOLER LOOKING THAN THE ENSEMBLE MEAN...AND A BIT SLOWER. THUS...UNDERCUT GFS-BASED TEMPERATURE GUIDANCE. TRAJECTORY OF THIS NEXT SYSTEM DOES NOT FAVOR MUCH IN THE WAY OF POPS...SO HELD OFF ON INTRODUCING ANY. IF ECMWF SOLUTION WINDS UP BEING CORRECT...THEN WE MIGHT NEED TO ADD SOME SLIGHT CHANCE POPS AT SOME POINT. ALSO...IF ECMWF SOLUTION PANS OUT...MIGHT NEED EVEN COOLER TEMPS. && .AVIATION... GENERALLY LGT SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH TODAY. WINDS IN THE 6 TO 12 THSD LAYER PROGGED TO REMAIN 180/22 THIS AFTERNOON...WITH MUCH STRONGER SPEEDS ALOFT. SOME GUSTY WINDS TO 35KTS OR SO STILL POSSIBLE IN THE KPHX AREA LATE THIS AFTERNOON AND INTO TONIGHT. WITH ADDITIONAL MOISTURE THROUGH A DEEP LAYER...WE COULD EASILY SEE LOWER CIGS LESS THAN 6-7 THSD FT. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EXPECT PERIODS OF WETTING RAINFALL OVER MUCH OF THE FORECAST AREA THURSDAY THROUGH SATURDAY...MAINLY OVER THE EASTERN ZONES...WITH THE HEAVIEST PRECIPITATION LIKELY OVER SOUTHERN GILA COUNTY AND THE RIM FRI AFTERNOON INTO SAT MORNING. DRY CONDITIONS RETURN TO THE WESTERN PORTION OF THE REGION BY SATURDAY AND THE REMAINDER OF THE FORECAST AREA BY SUNDAY. EARLY NEXT WEEK (MON NIGHT THROUGH TUE)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX 10 az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 1253 AM CDT FRI MAR 23 2007 .AVIATION... HIGH PRESSURE CONTINUES OVER THE SOUTHEAST UNITED STATES. THUNDERSTORMS ARE ONGOING IN OKLAHOMA WITH A SLOW EASTWARD PROGRESSION. EXPECT THUNDERSTORMS TO ONLY AFFECT NORTH ARKANSAS TOWARDS 12Z AND INTERMITTENTLY THROUGH 18Z. MVFR CONDITIONS ARE EXPECTED IN THE NORTH AND VFR ELSEWHERE. CEILINGS IN THE NORTH WILL DROP TO 2500 FT WITH VISIBILITIES DOWN TO 5SM. THE UPPER LEVEL DISTURBANCE TRIGGERING THE THUNDERSTORMS WILL MOVE NORTH OF THE AREA AROUND 18Z. DRY WEATHER IS THEN EXPECTED INTO SATURDAY. && .PREV DISCUSSION... /ISSUED 905 PM CDT THU MAR 22 2007/ UPDATE... SHORTWAVE EJECTING OUT OF THE SOUTHWEST CONUS UPPER LOW CONTINUES TO RIDE A STALLED OUT BOUNDARY WHICH IS POSITIONED ALONG THE NORTHERN EDGE OF MID LEVEL RIDGE BUILDING INTO THE REGION FROM GULF. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE TEXAS PANHANDLE IN RESPONSE IN AN AREA OF STRONG LIFT. NEW RUC13 AND NAM 12 KEEP AREA OF PRECIPITATION ACROSS FAR NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI OVERNIGHT. NAM12 AND WRF10 DO MOVE SOME PRECIPITATION ACROSS THE NORTHWEST PART OF THE LZK CWA AFTER 12Z BUT CONFIDENCE IS LOW THIS WILL DEVELOP AS OTHER SHORT RANGE MODELS INDICATE RIDGE BUILDING IN THE MID LEVELS THAT WILL KEEP PRECIPITATION OUT OF THE CWA. CURRENT DISTRIBUTION OF SMALL POPS OVER THE NORTHWEST PART OF THE CWA TONIGHT THROUGH PARTS OF FRIDAY LOOKS REASONABLE AND WILL BE LEFT IN PLACE. ONLY CHANGES TO ONGOING FORECAST WERE TO TWEAK SKY...DEW POINT AND RH GRIDS TO REFLECT CURRENT TRENDS. OVERNIGHT LOWS RAISED A TAD AS WELL. UPDATES OUT SHORTLY. PREV DISCUSSION... /ISSUED 629 PM CDT THU MAR 22 2007/ AVIATION... CLOUDS WILL CONTINUE TO MOVE IN FROM THE WEST WITH CEILINGS NEAR 7 THSD OR HIGHER. AREAS OF CEILINGS NEAR 35 HND WILL MOVE IN ARND 06Z. SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE NORTH AND WEST AFTER 08Z.(38) PREV DISCUSSION... /ISSUED 235 PM CDT THU MAR 22 2007/ SHORT TERM...TONIGHT THROUGH SUNDAY BLOCKING PATTERN STILL THE MAIN STORY IN THE SHORT TERM...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE GULF COAST. FRONT TO NORTH WILL TRY TO PUSH INTO ARKANSAS LATER TONIGHT/FRIDAY...BUT WILL STALL DUE TO THE HIGH AND SOUTHWEST WINDS ALOFT. EVEN SO...PUT SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS MAINLY IN AREAS NEAR THE ARKANSAS AND MISSOURI BORDER. FRONT WILL LIFT TO THE NORTH FRIDAY NIGHT/SATURDAY...WITH DRY AND WARM WEATHER TO START THE WEEKEND. LATE IN THE WEEKEND AND EARLY NEXT WEEK...LARGE STORM SYSTEM IN THE SOUTHWEST UNITED STATES WILL FINALLY ARRIVE...WITH HIGH PRESSURE SHIFTING SLOWLY TO THE EAST. BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST LATE SUNDAY INTO THE LONG TERM. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE PERIOD. (46) LONG TERM...SUNDAY NIGHT THROUGH THURSDAY REMNANTS OF A WEAKENING UPPER LOW WILL BE CROSSING ARKANSAS AS A SHORT WAVE. IT WILL BE JUST EAST OF THE STATE BY MIDDAY TUESDAY SINCE A LONG WAVE TROF WILL BE TRAVERSING THE INTERMOUNTAIN WEST ON TUESDAY. BY WEDNESDAY AFTERNOON IT WILL BE OVER THE NORTHERN PLAINS AND WEAKENING. THE SURFACE PATTERN WILL KEEP A SOUTHEAST OR SOUTH COMPONENT TO OUR WINDS THAT WILL PUMP MOISTURE NORTHWARD INTO THE PATH OF THE UPPER SYSTEM. WARMTH AND INSTABILITY WILL CAUSE SCATTERED CONVECTION TO DEVELOP SUNDAY NIGHT OVER NORTHWESTER SECTIONS. THEN...IT WILL KEEP ON MOVING EAST DURING THE DAY MONDAY. CONVECTION WILL BE OVER THE EASTERN HALF OF THE FORECAST AREA MONDAY NIGHT AND MOSTLY OUT OF THE STATE TUESDAY AFTERNOON AS THE SHORT WAVE DRIVING IT GOES ON BY ALOFT. WILL KEEP THE FORECAST DRY FROM TUESDAY NIGHT ON THROUGH THE END OF THE LONG TERM. THE UPPER SUPPORT FOR THE NEXT SYSTEM WILL BE SO FAR NORTH THAT DECIDED TO WAIT UNTIL THIS TREND GETS PICKED UP IN OTHER RUNS. NO CHALLENGE TO THE ABOVE NORMAL TRENDS WILL BE MADE DURING THIS PERIOD. (32) && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 56 76 58 76 / 20 10 10 20 CAMDEN AR 58 79 61 78 / 10 10 10 20 HARRISON AR 55 75 58 73 / 20 10 10 40 HOT SPRINGS AR 58 78 59 76 / 10 10 10 40 LITTLE ROCK AR 58 78 60 77 / 10 10 10 20 MONTICELLO AR 58 80 60 80 / 10 10 10 20 MOUNT IDA AR 57 78 59 75 / 10 10 10 40 MOUNTAIN HOME AR 54 75 56 75 / 20 10 10 40 NEWPORT AR 57 76 58 77 / 20 10 10 20 PINE BLUFF AR 59 79 61 78 / 10 10 10 20 RUSSELLVILLE AR 56 77 59 75 / 10 10 10 40 SEARCY AR 58 77 59 77 / 10 10 10 20 STUTTGART AR 59 78 60 78 / 10 10 10 20 && .LZK WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION...51 ar AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 905 PM CDT THU MAR 22 2007 .UPDATE... SHORTWAVE EJECTING OUT OF THE SOUTHWEST CONUS UPPER LOW CONTINUES TO RIDE A STALLED OUT BOUNDARY WHICH IS POSITIONED ALONG THE NORTHERN EDGE OF MID LEVEL RIDGE BUILDING INTO THE REGION FROM GULF. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE TEXAS PANHANDLE IN RESPONSE IN AN AREA OF STRONG LIFT. NEW RUC13 AND NAM 12 KEEP AREA OF PRECIPITATION ACROSS FAR NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI OVERNIGHT. NAM12 AND WRF10 DO MOVE SOME PRECIPITATION ACROSS THE NORTHWEST PART OF THE LZK CWA AFTER 12Z BUT CONFIDENCE IS LOW THIS WILL DEVELOP AS OTHER SHORT RANGE MODELS INDICATE RIDGE BUILDING IN THE MID LEVELS THAT WILL KEEP PRECIPITATION OUT OF THE CWA. CURRENT DISTRIBUTION OF SMALL POPS OVER THE NORTHWEST PART OF THE CWA TONIGHT THROUGH PARTS OF FRIDAY LOOKS REASONABLE AND WILL BE LEFT IN PLACE. ONLY CHANGES TO ONGOING FORECAST WERE TO TWEAK SKY...DEW POINT AND RH GRIDS TO REFLECT CURRENT TRENDS. OVERNIGHT LOWS RAISED A TAD AS WELL. UPDATES OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 629 PM CDT THU MAR 22 2007/ AVIATION... CLOUDS WILL CONTINUE TO MOVE IN FROM THE WEST WITH CEILINGS NEAR 7 THSD OR HIGHER. AREAS OF CEILINGS NEAR 35 HND WILL MOVE IN ARND 06Z. SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE NORTH AND WEST AFTER 08Z.(38) PREV DISCUSSION... /ISSUED 235 PM CDT THU MAR 22 2007/ SHORT TERM...TONIGHT THROUGH SUNDAY BLOCKING PATTERN STILL THE MAIN STORY IN THE SHORT TERM...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE GULF COAST. FRONT TO NORTH WILL TRY TO PUSH INTO ARKANSAS LATER TONIGHT/FRIDAY...BUT WILL STALL DUE TO THE HIGH AND SOUTHWEST WINDS ALOFT. EVEN SO...PUT SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS MAINLY IN AREAS NEAR THE ARKANSAS AND MISSOURI BORDER. FRONT WILL LIFT TO THE NORTH FRIDAY NIGHT/SATURDAY...WITH DRY AND WARM WEATHER TO START THE WEEKEND. LATE IN THE WEEKEND AND EARLY NEXT WEEK...LARGE STORM SYSTEM IN THE SOUTHWEST UNITED STATES WILL FINALLY ARRIVE...WITH HIGH PRESSURE SHIFTING SLOWLY TO THE EAST. BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST LATE SUNDAY INTO THE LONG TERM. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE PERIOD. (46) LONG TERM...SUNDAY NIGHT THROUGH THURSDAY REMNANTS OF A WEAKENING UPPER LOW WILL BE CROSSING ARKANSAS AS A SHORT WAVE. IT WILL BE JUST EAST OF THE STATE BY MIDDAY TUESDAY SINCE A LONG WAVE TROF WILL BE TRAVERSING THE INTERMOUNTAIN WEST ON TUESDAY. BY WEDNESDAY AFTERNOON IT WILL BE OVER THE NORTHERN PLAINS AND WEAKENING. THE SURFACE PATTERN WILL KEEP A SOUTHEAST OR SOUTH COMPONENT TO OUR WINDS THAT WILL PUMP MOISTURE NORTHWARD INTO THE PATH OF THE UPPER SYSTEM. WARMTH AND INSTABILITY WILL CAUSE SCATTERED CONVECTION TO DEVELOP SUNDAY NIGHT OVER NORTHWESTER SECTIONS. THEN...IT WILL KEEP ON MOVING EAST DURING THE DAY MONDAY. CONVECTION WILL BE OVER THE EASTERN HALF OF THE FORECAST AREA MONDAY NIGHT AND MOSTLY OUT OF THE STATE TUESDAY AFTERNOON AS THE SHORT WAVE DRIVING IT GOES ON BY ALOFT. WILL KEEP THE FORECAST DRY FROM TUESDAY NIGHT ON THROUGH THE END OF THE LONG TERM. THE UPPER SUPPORT FOR THE NEXT SYSTEM WILL BE SO FAR NORTH THAT DECIDED TO WAIT UNTIL THIS TREND GETS PICKED UP IN OTHER RUNS. NO CHALLENGE TO THE ABOVE NORMAL TRENDS WILL BE MADE DURING THIS PERIOD. (32) && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 59 76 56 76 / 10 20 20 10 CAMDEN AR 60 80 58 79 / 10 10 10 10 HARRISON AR 59 75 55 75 / 30 30 20 10 HOT SPRINGS AR 60 78 58 78 / 10 10 10 10 LITTLE ROCK AR 60 78 58 78 / 10 10 10 10 MONTICELLO AR 59 80 58 80 / 10 10 10 10 MOUNT IDA AR 58 78 57 78 / 10 10 10 10 MOUNTAIN HOME AR 59 75 54 75 / 30 30 20 10 NEWPORT AR 59 77 57 76 / 10 20 20 10 PINE BLUFF AR 60 79 59 79 / 10 10 10 10 RUSSELLVILLE AR 59 77 56 77 / 20 20 10 10 SEARCY AR 60 78 58 77 / 10 10 10 10 STUTTGART AR 60 79 59 78 / 10 10 10 10 && .LZK WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...56 / LONG TERM...38 ar AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 845 PM PDT THU MAR 22 2007 .UPDATE...A FEW PATCHES OF HIGH CLOUDS MOVING THRU...OTHERWISE SKIES ARE CLEAR. MID LEVEL CLOUDS WRAPPING AROUND THE NRN BAJA LOW ARE JUST EAST OF KERN CO. SOME OF THESE MID CLOUDS COULD MOVE ACROSS THE KERN DESERT FROM TIME TO TIME OVERNITE SO PTCLDY THERE LOOKS GOOD. TEMPS THIS EVE RUNNING 6-8 DEGS HIGHER THAN YESTERDAY AT THIS TIME...SO CONTINUED GOOD WARMING EXPECTED TOMORROW. CURRENT FCST ON TRACK AND NO UPDATE NEEDED THIS EVE. && .DISCUSSION...AS THE CLOSED UPPER LOW DRIFTS FURTHER OVER THE DESERT SOUTHWEST...THE WEATHER OVER CENTRAL CALIFORNIA CONTINUES TO SETTLE DOWN. WITH THE SUNSHINE...TEMPERATURES SAW ANOTHER WARMING TREND AS MANY VALLEY LOCATIONS WERE RUNNING 5 TO 10 DEG-F ABOVE THAT OF WEDNESDAY AFTERNOON. WITH THE OFFSHORE FLOW ALOFT SUPPORTING TODAY/S WARMING TEMP/S...WILL HAVE NO PROBLEM REACHING THE 70S. WHILE WRAP AROUND MOISTURE IS BEING OBSERVED OVER THE DESERT SOUTHWEST...ASSOCIATED WITH THE CLOSED UPPER LOW...AND TRACKING NORTHEAST. WHILE SOME CLOUDS SHOULD ADVANCE INTO THE DISTRICT LATE THIS AFTERNOON...RUC ANALYSIS AND VISIBLE SATELLITE IMAGERY IS SHOWING ONLY MINIMAL AMOUNTS REACHING THE AREA. THEREFORE...WILL MAINTAIN MOSTLY CLEAR CONDITIONS WITH NO POSSIBLE WEATHER. YET...THE KERN COUNTY DESERTS MAY BE CLOSER TO THE STORM THEN THE REST OF THE DISTRICT. THEREFORE...WILL MAINTAIN THE SLIGHT CHANCE POPS OVER THE DESERTS (TOKEN) JUST IN CASE THE MOISTURE IS ABLE TO MAKE IT THIS FAR NORTH. IN ADDITION...BECAUSE OF THE SLOW DRIFT OF THE UPPER LOW...STRONG WINDS WILL CONTINUE TO BE OBSERVED OVER THE DESERT AND HIGHER ELEVATIONS OF THE DISTRICT THROUGH THIS EVENING. AS THE UPPER LOW SLOWLY TRACKS EAST OVER THE NEXT SEVERAL DAYS...WILL SEE THE UPPER LEVEL RIDGE DOMINATE THE WEST THROUGH THE WEEKEND. DRY WEATHER WILL PREVAIL WITH A WARMING TREND IN TEMPERATURES THROUGH ABOUT SUNDAY. AROUND SUNDAY...SHORT RANGE MODELS BEGIN LOWERING HEIGHTS AND SWITCH TO A MORE ZONAL FLOW PATTERN BEFORE ALLOWING ANOTHER TROF TO APPROACH THE WEST COAST. LATEST TIMING STILL HAS THE NEXT TROF OVER THE WEST COAST AROUND LATE MONDAY INTO EARLY TUESDAY. ENSEMBLES SHOWING LITTLE PHASE UNCERTAINTY BUT IS SHOWING GOOD SPREAD ON THE AMPLITUDE AROUND 12Z TUESDAY. THEREFORE...WILL KEEP THE BETTER CHANCES OF MEASURABLE PRECIP NORTH OF KERN COUNTY DURING THE EVENT. IN ADDITION...DURING TROF PASSAGE...MEDIUM RANGE MODELS SHOW 500MB TEMP/S DROPPING TO AROUND MINUS 24-28 DEG-C. BEING THAT THIS MAY BE A COLD SYSTEM...WILL MAINTAIN LOW SNOW LEVELS DURING THE STORM. FURTHERMORE...WITH SUCH COLD AIR ALOFT OVER THE REGION AT THIS TIME OF THE YEAR...CONDITIONS MAY BECOME VERY UNSTABLE DURING THE STORM EVENT. LINGERING SHOWERS OVER THE MOUNTAIN TOWARD TUESDAY WILL GIVE WAY TO CLEARING BY WEDNESDAY AND THURSDAY. && .AVIATION...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 06Z SATURDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES... NONE && .HNX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ BINGHAM/MOLINA/MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 232 PM PDT THU MAR 22 2007 .DISCUSSION...AS THE CLOSED UPPER LOW DRIFTS FURTHER OVER THE DESERT SOUTHWEST...THE WEATHER OVER CENTRAL CALIFORNIA CONTINUES TO SETTLE DOWN. WITH THE SUNSHINE...TEMPERATURES SAW ANOTHER WARMING TREND AS MANY VALLEY LOCATIONS WERE RUNNING 5 TO 10 DEG-F ABOVE THAT OF WEDNESDAY AFTERNOON. WITH THE OFFSHORE FLOW ALOFT SUPPORTING TODAY/S WARMING TEMP/S...WILL HAVE NO PROBLEM REACHING THE 70S. WHILE WRAP AROUND MOISTURE IS BEING OBSERVED OVER THE DESERT SOUTHWEST...ASSOCIATED WITH THE CLOSED UPPER LOW...AND TRACKING NORTHEAST. WHILE SOME CLOUDS SHOULD ADVANCE INTO THE DISTRICT LATE THIS AFTERNOON...RUC ANALYSIS AND VISIBLE SATELLITE IMAGERY IS SHOWING ONLY MINIMAL AMOUNTS REACHING THE AREA. THEREFORE...WILL MAINTAIN MOSTLY CLEAR CONDITIONS WITH NO POSSIBLE WEATHER. YET...THE KERN COUNTY DESERTS MAY BE CLOSER TO THE STORM THEN THE REST OF THE DISTRICT. THEREFORE...WILL MAINTAIN THE SLIGHT CHANCE POPS OVER THE DESERTS (TOKEN) JUST IN CASE THE MOISTURE IS ABLE TO MAKE IT THIS FAR NORTH. IN ADDITION...BECAUSE OF THE SLOW DRIFT OF THE UPPER LOW...STRONG WINDS WILL CONTINUE TO BE OBSERVED OVER THE DESERT AND HIGHER ELEVATIONS OF THE DISTRICT THROUGH THIS EVENING. AS THE UPPER LOW SLOWLY TRACKS EAST OVER THE NEXT SEVERAL DAYS...WILL SEE THE UPPER LEVEL RIDGE DOMINATE THE WEST THROUGH THE WEEKEND. DRY WEATHER WILL PREVAIL WITH A WARMING TREND IN TEMPERATURES THROUGH ABOUT SUNDAY. AROUND SUNDAY...SHORT RANGE MODELS BEGIN LOWERING HEIGHTS AND SWITCH TO A MORE ZONAL FLOW PATTERN BEFORE ALLOWING ANOTHER TROF TO APPROACH THE WEST COAST. LATEST TIMING STILL HAS THE NEXT TROF OVER THE WEST COAST AROUND LATE MONDAY INTO EARLY TUESDAY. ENSEMBLES SHOWING LITTLE PHASE UNCERTAINTY BUT IS SHOWING GOOD SPREAD ON THE AMPLITUDE AROUND 12Z TUESDAY. THEREFORE...WILL KEEP THE BETTER CHANCES OF MEASURABLE PRECIP NORTH OF KERN COUNTY DURING THE EVENT. IN ADDITION...DURING TROF PASSAGE...MEDIUM RANGE MODELS SHOW 500MB TEMP/S DROPPING TO AROUND MINUS 24-28 DEG-C. BEING THAT THIS MAY BE A COLD SYSTEM...WILL MAINTAIN LOW SNOW LEVELS DURING THE STORM. FURTHERMORE...WITH SUCH COLD AIR ALOFT OVER THE REGION AT THIS TIME OF THE YEAR...CONDITIONS MAY BECOME VERY UNSTABLE DURING THE STORM EVENT. LINGERING SHOWERS OVER THE MOUNTAIN TOWARD TUESDAY WILL GIVE WAY TO CLEARING BY WEDNESDAY AND THURSDAY. && .AVIATION...GUSTY OFFSHORE WINDS WILL CONTINUE OVER KERN COUNTY DESERTS THROUGH EARLY EVENING THURSDAY...DIMINISHING THEREAFTER. OTHERWISE...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 00Z SATURDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES...NONE. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC:MOLINA AVIATION:MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 945 AM MST THU MAR 22 2007 .SYNOPSIS... A STRONG PACIFIC LOW PRESSURE SYSTEM WAS LOCATED JUST OFF THE NORTHERN BAJA CALIFORNIA COAST THIS MORNING. IT WILL MOVE VERY SLOWLY EAST ACROSS NORTHERN MEXICO FRIDAY INTO SATURDAY. THIS STORM SYSTEM WILL BRING INCREASING CLOUDINESS...COOLER DAYTIME HIGHS...AND PERIODS OF SHOWERS AND THUNDERSTORMS TODAY THROUGH SATURDAY...WITH THE BEST CHANCE FOR PRECIPITATION OVER SOUTH-CENTRAL ARIZONA. HIGHER PRESSURE ALOFT FROM THE PACIFIC WILL BRING DRY WEATHER WITH SOME RECOVERY OF TEMPERATURES SUNDAY AND MONDAY. ANOTHER RATHER STRONG WEATHER DISTURBANCE WILL PRODUCE BREEZY TO WINDY CONDITIONS ALONG WITH SOME COOLING NEXT TUESDAY AND WEDNESDAY. && .SHORT TERM... TODAY THROUGH SATURDAY... 12Z POSITION OF CLOSED LOW WAS NEAR 30N/117W WITH SEVERAL VORTICITY CENTERS ROTATING AROUND ITS PERIMETER. NAM/GFS SOLUTIONS APPEARED TO BE SOMEWHAT SOUTH OF LATEST RUC...WITH ALL MODELS INDICATING THE STRONGEST VORT CENTER SOUTH OF THE LOW. THE 500MB WIND SPEEDS WERE ALSO STRONGEST AROUND THE SOUTHERN QUADRANTS OF THE LOW...50-70KTS. AFTER SUNRISE THE CONVECTION PICKED UP IN OUR CWA...AND CONTINUED TO DRIFT INTO YAVAPAI COUNTY. BY FAR THE HEAVIEST PRECIP WAS THROUGH SOUTHERN GILA COUNTY WHERE SPOTTERS/RAWS DATA REPORTED .30 TO .45 INCH UP TO 6 AM. SIGNIFICANT DIFFLUENCE WAS ALSO INDICATED ACROSS EASTERN AZ EARLIER TODAY. UPDATES ISSUED BY 8 AM TO COVER 88D TRENDS. WILL CONTINUE TO EXPECT STRONGEST LIFT AND LOWEST STABILITY INDICES AFTER 18Z FRIDAY...AND THAT FITS NICELY WITH OUR CURRENT FCSTS. ALTHOUGH LATEST NAM GIVES PHX A 24 HR PRECIP AMOUNT OF .38 INCH WE WILL STILL EXPECT GENERALLY LIGHTER AMOUNTS ACROSS ZONE 23. HOWEVER WE COULD SEE MUCH MORE...ACROSS ZONE 24...PER HPC OUTPUT. OUR WESTERN ZONES WILL STAY MUCH DIRER...WITH SOME PATCHY BLWG DUST TODAY. IN FACT ONE SHARP-EYED SPOTTER CALLED IN A REPORT OF BLOWING DUST NEAR A FARM FIELD WEST OF TONOPAH. MODEL TRENDS CONTINUE TO BE VERY CONSISTENT IN KEEPING THE CLOSED LOW OVER NRN MEX INTO FRIDAY NIGHT. BY 12Z SAT LATEST GFS CALLS FOR THE CENTER OF CIRCULATION TO LIFT OUT TO NEAR ABQ...WITH CSDRBL RH THROUGH A DEEP LAYER EVEN WEST OF PHX. UPPER RIDGE AND WARMER TEMPS WILL ALSO SPREAD ACROSS ENTIRE CWA FOR FRIDAY AND SATURDAY. && .LONG TERM... SATURDAY NIGHT THROUGH WEDNESDAY... WITH SLOWER EXIT OF THE SYSTEM AND POTENTIAL FOR MORE MOISTURE... ADDED SOME SLIGHT CHANCE POPS IN EASTERN PORTIONS OF THE FORECAST AREA SATURDAY NIGHT. THIS IS FOLLOWED BY RIDGE BUILDING FOR A QUICK WARMUP. IN THE LATTER PART OF THE EXTENDED...GFS AND ECWMF ARE SHOWING ANOTHER SYSTEM AFFECTING US. HOWEVER...IT LOOKS TO BE OF A DIFFERENT CHARACTER...MUCH LESS APT TO SLOW DOWN AND JOG SOUTHWARD. HOWEVER...THERE ARE SOME DIFFERENCES. THE GFS ENSEMBLE MEAN HAS A SIMILAR TRACK TO THE 12Z OPERATIONAL GFS...TAKING THE BULK OF THE SYSTEM JUST NORTH OF OUR AREA...BUT SHOWS LOWER HEIGHTS. THE ECMWF IS EVEN COOLER LOOKING THAN THE ENSEMBLE MEAN...AND A BIT SLOWER. THUS...UNDERCUT GFS-BASED TEMPERATURE GUIDANCE. TRAJECTORY OF THIS NEXT SYSTEM DOES NOT FAVOR MUCH IN THE WAY OF POPS...SO HELD OFF ON INTRODUCING ANY. IF ECMWF SOLUTION WINDS UP BEING CORRECT...THEN WE MIGHT NEED TO ADD SOME SLIGHT CHANCE POPS AT SOME POINT. ALSO...IF ECMWF SOLUTION PANS OUT...MIGHT NEED EVEN COOLER TEMPS. && .AVIATION... GENERALLY LGT SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH TODAY. WINDS IN THE 6 TO 12 THSD LAYER PROGGED TO REMAIN 180/22 THIS AFTERNOON...WITH MUCH STRONGER SPEEDS ALOFT. SOME GUSTY WINDS TO 35KTS OR SO STILL POSSIBLE IN THE KPHX AREA LATE THIS AFTERNOON AND INTO TONIGHT. WITH ADDITIONAL MOISTURE THROUGH A DEEP LAYER...WE COULD EASILY SEE LOWER CIGS LESS THAN 6-7 THSD FT. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EXPECT PERIODS OF WETTING RAINFALL OVER MUCH OF THE FORECAST AREA THURSDAY THROUGH SATURDAY...MAINLY OVER THE EASTERN ZONES...WITH THE HEAVIEST PRECIPITATION LIKELY OVER SOUTHERN GILA COUNTY AND THE RIM FRI AFTERNOON INTO SAT MORNING. DRY CONDITIONS RETURN TO THE WESTERN PORTION OF THE REGION BY SATURDAY AND THE REMAINDER OF THE FORECAST AREA BY SUNDAY. EARLY NEXT WEEK (MON NIGHT THROUGH TUE)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX 10 ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 916 AM PDT THU MAR 22 2007 .DISCUSSION...CLOSED UPPER LOW CONTINUES TO SWINGS EASTWARD THIS MORNING AROUND BAJA CALIFORNIA...WITH CHANNELED FLOW OVER THE DISTRICT. AT THE 250MB LEVEL...RUC ANALYSIS HAS A +100KT JET MAX EXITING THE AREA WITH A GOOD DOWNWARD TRANSFER OF WINDS THIS MORNING. WHILE WINDS OVER THE MOUNTAINS AND DESERTS WERE DIMINISHING THIS MID MORNING...WINDS EARLIER WERE ABLE TO REACH 30 TO 40 MPH. AS THE JET MOVES FURTHER AWAY...WILL SEE MOUNTAIN WINDS DECREASE FURTHER AS A SHORT WAVE RIDGE SHIFTS INTO CALIFORNIA. FURTHERMORE...THE FLOW THIS MORNING HAS BEEN OFF-SHORE WHICH WILL SUPPORT THE EXPECTED WARM UP THIS AFTERNOON. OTHERWISE...AS THE CLOSED UPPER LOW MOVES FURTHER OUT...WILL SEE GENERAL CLEARING THROUGH THE END OF THE WEEK AND INTO THE WEEKEND WITH A CONTINUAL WARMING OF TEMPERATURES. NO UPDATES NEEDED. && .AVIATION...LOCAL MVFR CEILINGS AND VISIBILITIES WILL PERSIST ALONG THE EAST SIDE AND SOUTH END OF THE SAN JOAQUIN VALLEY AS WELL AS THE NORTH FACING SLOPES OF THE TEHACHAPI MOUNTAINS UNTIL 17Z. LOCALLY STRONG WINDS WILL ALSO BUFFET THE HIGHER ELEVATIONS OF THE SIERRA NEVADA AND THE INDIAN WELLS VALLEY THIS MORNING. OTHERWISE...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 12Z FRIDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES...NONE. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC:MOLINA AVIATION:MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 437 AM MDT FRI MAR 23 2007 .SHORT TERM... (TODAY AND TONIGHT) ...ISOLD-SCT SHOWERS AND A FEW THUNDERSTORMS POSSIBLE TODAY... CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES HAD A MATURING CLOSED LOW OVER THE CA BAJA WITH AN EXPANDED SYNOPTIC SCALE PRECIPITATION SHIELD IN THE NORTH-EAST QUADRANTS ACROSS AZ/WRN NM. SOME OF THE MIDDLE/HIGH LEVEL CLOUD SHIELD WAS MOVING INTO EXTREME SWRN CO. THERE WAS A ROGUE SMALL CLUSTER OF SHRA/TSRA OVER E CNTRL NM MOVING NWD...BUT IT CONTINUES TO DISSIPATE AS TO MOVES AWAY FROM ITS LOW LEVEL FORCING AND NO UPPER AIR SUPPORT. ISENTROPIC ASCENT DRIVEN ISOLD-SCT TSRA WAS ACROSS SRN NM JUST NORTH OF THE SURFACE WARM FRONT. THIS NEW MINI-MESOSCALE CONVECTIVE SYSTEM MAY FALL APART ONCE IT GETS INTO NERN NM EARLY THIS MORNING. BASICALLY...JUST SOME HIGH CLOUDS MOVING INTO OUR WRN CWFA/CONTDVD AND IN EXTREME SERN CO. TEMPERATURES ARE RELATIVELY MILD WITH 40S/LOWER 50S ACROSS SERN CO AND 20S/30S IN THE MOUNTAINS/ HIGH VALLEYS. TODAY...WE WILL BE WAITING FOR THE OLD CLOSED LOW TO EJECT LATER TONIGHT...SO NOT ANTICIPATING MUCH "SIGNIFICANT" WEATHER UNTIL LATER TONIGHT. THERE WILL BE ENOUGH MIDLEVEL MOISTURE AND INSTABILITY LATER THIS AFTERNOON TO TRIGGER SOME SHRA/TSRA OVER THE MOUNTAINS. ACROSS SERN CO...PRECIP MIGHT HAVE A TOUGH TIME REACHING THE GROUND...INITIALLY...GIVEN INVERTED-V THERMAL STRUCTURE SUPPORTING VIRGA AND LOCALLY GUSTY WINDS. SOME OF THE PRECIPITATION SHAFTS...IF THEY FORM...MAY MAKE IT TO THE GROUND BY MIDDLE TO LATE AFTERNOON ACROSS SERN CO. ANY SNOW POTENTIAL WOULD BE AT OR ABOVE 10K FT MSL LATER TODAY. CURRENT TEMPERATURES LOOK FAIRLY DOABLE AND BLENDED WITH LATEST MOS GUIDANCE. TONIGHT...06Z/23 WRF IS INTERESTING COMPARED TO THE 00Z/23 RUN. THE 00Z/23 RUN HAD THE TYPICAL DIURNAL CONVECTIVE PRECIPITATION DISSIPATING AFTER SUNSET WHILE WE WAIT FOR THE LOW AND ANY POTENTIAL SYNOPTIC SCALE ASCENT PRECIPITATION TO GENERATE TOWARDS SAT AM. WELL...NOW IT "BLOWS" UP SOME PRECIPITATION OVER THE SANGRE DE CRISTO MOUNTAINS AFTER MIDNIGHT...WHILE THE 00Z/23 DID NOT "BLOW UP" PRECIPITATION IN THIS AREA. ONE CONSISTENT PRECIPITATION ZONE DEVELOPING MAY BE ACROSS ERN NM/WRN TX/WRN OK INTO EXTREME SERN CO LATE TONIGHT. AS THE OLD CLOSED LOW LIFTS N-NEWD OUT OF AZ/WRN NM...RELATIVELY DEEP SLY FLOW BEGINS TO TRANSPORT MOISTURE PER H7 MOISTURE TRANSPORT VECTORS/MAG. THIS WILL HELP DESTABILIZE THE AIR MASS TO GENERATE NOCTURNAL THUNDERSTORMS ACROSS JUST S OF EXTREME SERN CO AND POSSIBLY MOVING INTO SERN CO AFTER MIDNIGHT. WRF SUGGESTING A LINEAR MESOSCALE CONVECTION SYSTEM JUST AHEAD OF THE CLOSED LOW IN THE AFOREMENTIONED AREA. MIGHT SEE SOME MODERATE TO HEAVY RAIN ACROSS EXTREME SERN CO AND SWD GIVEN GEORGE/S K-INDICES OF 35-40C AND H7-H5 SPECIFIC HUMIDITY AROUND 5 G/KG AND MORE IMPORTANTLY ANY PRECIPITATION TRAINING GIVEN A DEEP SLY FLOW. THE GREATER THREAT FOR MODERATE TO HEAVY RAIN WOULD BE S-SE OF EXTREME SERN CO...BUT IT MIGHT MOVE INTO BACA COUNTY IF CELLS CAN HOLD TOGETHER. INCREASED POPS ACROSS EXTREME SERN CO TO LIKELY FOR LATER TONIGHT. ANY SNOW POTENTIAL WOULD BE AT OR ABOVE 9K FT MSL. METZE .LONG TERM... (SATURDAY THROUGH THURSDAY) MODELS FINALLY COMING INTO BETTER CONSENSUS LIFTING CLOSED LOW FROM CENTRAL NM AND THE 4 CORNERS REGION THROUGH CENTRAL CO...AND INTO NE CO/SW NE BY 00Z SUNDAY. THIS BRINGS FCST AREA UNDER FAIRLY STRONG QG FORCING BY SAT MORNING...SPREADING NORTHWARD QUICKLY DURING THE LATE MORNING/EARLY AFTN. ATMOS BECOMES CONVECTIVELY UNSTABLE AS COLD CORE ALOFT MOVES OVER THE REGION BY AFTN...SO SHOULD SEE SOME EMBEDDED THUNDERSTORMS AS WELL. LOW LEVELS STILL LOOK FAIRLY WARM WITH THIS SYSTEM...WITH SNOW LEVELS STARTING AROUND 9KFT...DROPPING TO 8KFT BY LATE AFTN. BEST LIFT ACCORDING TO 00Z RUNS WILL AFFECT CEN CO UNDER DEFORMATION BAND AND MID LEVEL TROWAL. HOWEVER...WITH CONVECTIVE INSTABILITY...COULD SEE BOUTS OF HEAVY SNOW ACROSS JUST ABOUT ANY OF THE MTS. FOR THE SOUTHEAST PLAINS/ADJACENT INTERSTATE 25 CORRIDOR...SHOULD SEE SNOW SHOWERS RAMPING UP IN THE MID TO LATE MORNING AS H7 WINDS BRIEFLY BECOME EASTERLY AS H7 CLOSED LOW LIFTS NORTHWARD. FAR EASTERN PLAINS QUICKLY BECOME DRY SLOTTED BY MID/LATE MORNING THOUGH AS 90 KT UPPER JET CORE LIFTS NORTH INTO SE CO...SO COULD SEE A LULL IN THE SHOWERS LATE SAT MORNING...BEFORE THEY REDEVELOP ALONG THE FRONT DURING THE AFTN. NAM/GFS HAVE THE FRONT POSITIONED ALONG THE PALMER DIVIDE BY MID AFTN...WITH AROUND 800 J/KG OF CAPE ALONG/NORTH OF THE BOUNDARY. SOUTH OF A LINE FROM PUEBLO TO EADS...WESTERLY DOWNSLOPE FLOW QUICKLY MIXES OUT LOW LEVEL MOISTURE...WHICH SHOULD LIMIT AFTERNOON SHOWERS/THUNDERSTORMS POTENTIAL. WILL STILL HAVE TO MONITOR POTENTIAL FOR STRONG STORMS...MAINLY ACROSS KIOWA COUNTY...HOWEVER LATEST RUNS APPEAR TO KEEP BEST SVR POTENTIAL JUST TO THE EAST AND NORTHEAST. OF COURSE BIGGEST CHALLENGE WILL BE SNOW AMOUNTS ACROSS THE MOUNTAINS. NAM PAINTS A GENEROUS 4-8 INCHES OF SNOW FOR SAT ACROSS ALL BUT THE SRN SANGRES (IN PROXIMITY OF DRY SLOT)...WITH AN ADDITIONAL 3 INCHES OF SNOWFALL ACROSS THE CENTRAL MTS SAT NIGHT. GFS ON THE OTHER HAND HAS UP TO A FOOT OF SNOWFALL ACROSS THE CEN/SW MTS UNDER DEFORMATION BAND ON SAT...WITH UP TO AN ADDITIONAL 3 INCHES POSSIBLE ACROSS THE CENTRAL MTS SAT NIGHT. GFS MAY BE A LITTLE OVERDONE GIVEN CONVECTIVE NATURE...BUT WOULDNT BE SURPRISED TO SEE AROUND 4-8 INCHES OF SNOW FOR THE HIGHER MTN AREAS...WITH LOCALLY HEAVIER AMOUNTS POSSIBLE GIVEN CONVECTIVE POTENTIAL. ALL IN ALL...STILL LOOKS LIKE A POTENTIAL ADVISORY EVENT. DEPENDING ON WESTWARD EXTENT OF DRY SLOT...PIKES PEAK AND THE WET MTS COULD ALSO SEE LOW END ADVISORY NUMBERS...THOUGH BREVITY OF UPSLOPE MAY KEEP THEM JUST SHY. STILL SOME UNCERTAINTIES WITH THE POSITION OF DRY AIR WRAPPING AROUND UPPER LOW...WHICH COULD MAKE/BREAK THE SNOW AMOUNT FCST. SO WILL NOT HOIST ANY HIGHLIGHTS JUST YET. WILL LET DAY SHIFT GET A LOOK AT ANOTHER SET OF RUNS. SYSTEM PULLS EAST OF THE AREA BY SUN WITH SNOW SHOWERS QUICKLY WINDING DOWN. TEMPS REBOUND NICELY FOR THE EARLY PART OF NEXT WEEK...THEN GFS BRINGS ANOTHER CLOSED LOW ACROSS NRN CO/WY TUES NIGHT. THIS WILL BRING WARM AND WINDY CONDITIONS TO THE AREA ON TUES AHEAD OF THE SYSTEM...THEN INCREASING CHANCES FOR PRECIPITATION FOR THE MTS ALONG/WEST OF THE CONTINENTAL DIVIDE FOR TUES NIGHT/EARLY WED. THIS COULD POSE PROBLEMS FOR FIRE WEATHER CONCERNS GIVEN THE STRONG WINDS/LOW RH POTENTIAL ON FOR MID WEEK. NO CHANGES MADE TO GRIDS BEYOND TUES. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/31 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 328 AM EDT FRI MAR 23 2007 .SYNOPSIS...SFC HIGH PRES RIDGE JUST OUR N WITH PREVAILING LOW LEVEL NE TO E FLOW OVER THE FORECAST AREA. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW THE MID-UPPER RIDGE FROM CENTRAL GOMEX NEWD INTO THE SE STATES. MOIST BOUNDARY LAYER...CLEAR SKIES AND CALM WINDS OVER SE GA SUPPORTING FOG DEVELOPMENT WITH ALMA OCCASIONAL REPORTING VIS BELOW 1SM. EXPECT MORE FOG DEVELOPMENT OVER ENTIRE CWA NEXT FEW HOURS WITH THE DENSE FOG MAINLY CONFINED IN INTERIOR SE GA. && .SHORT TERM...HIGH PRES SFC AND ALOFT WILL DOMINATE THE REGION WITH A 1026 MB SFC HIGH PINCHING OFF OVER SRN AL AND GA SAT-SUN. STRONG RIDGING ALOFT WILL ENSURE A DEFINITE WARMING TREND FOR MOST AREAS TODAY THROUGH SUNDAY. TODAY...PATCHY DENSE FOG EXPECTED THROUGH EARLY MORNING OVER SE GA WITH PATCHY FOG MOST OTHER AREAS. FOR MAX TEMPS PREFERRED A BLEND BUT MOSTLY LIKED THE MAV GUIDANCE AS MET VERIFYING A BIT TOO COOL. MID 80S ARE POSSIBLE INLAND SECTIONS. WEAKER PRES GRADIENT WILL PROVIDE MOSTLY ELY 10-15 MPH WINDS BUT STILL SOME GUSTINESS IN AFTERNOON BUT LOWER THAN PREVIOUS DAYS. TONIGHT...STRONGER HIGH PRES ALOFT WITH WEAKER BOUNDARY LAYER WINDS SPELLS FOR ANOTHER ROUND OF AREAS OF FOG AFTER MIDNIGHT LESS THAN 1SM AT TIMES BUT OTHERWISE MOSTLY CLEAR SKIES. LOWS MOSTLY IN THE MID 50S. SAT...MORNING FOG DISSIPATES GIVING WAY TO PARTLY TO MOSTLY SUNNY SKIES AND WARM TEMPS WITH MID 80S INLAND...UPPER 70S NEAR THE COAST. SAT NIGHT...MOSTLY CLEAR SKIES AND PATCHY TO AREAS OF FOG EXPECTED. LOWS CONTINUE TO BE MOSTLY MID 50S. SUNDAY...SFC HIGH PRES CONTINUES WITH WARM TEMPS FROM MID 80S TO UPPER 70S AGAIN. WILL BE SEEING A BACK-DOOR COLD FRONT SLIDE DOWN THE E COAST THROUGH CAROLINAS LATE IN THE DAY. .LONG TERM...SUN NIGHT-THU. MODEL GUIDANCE FASTER THAN YESTERDAY`S RUN SHOWING BACK-DOOR FRONT MOVING INTO THE FORECAST AREA. NAM AND GFS SHOWING FRONT MOVING INTO SE GA BETWEEN 06Z-12Z MON WITH POSSIBLE LIGHT SHOWERS ACCOMPANYING THE FRONT. FRONT PUSHES THROUGH ALL THE CWA WITH TEMPS A BIT COOLER ON NE FLOW THANKS TO 1033 MB HIGH OFF THE MID ATLC. PRES GRADIENT WILL HAVE INCREASED MON WITH BREEZY CONDS DEVELOPING OVER ERN ZONES. HAVE MOVED UP POPS TO MON AT 20% FOR PORTIONS OF SE GA AND NE FL AS ASSOCD MOISTURE WITH FRONT PUSHES THROUGH. SFC HIGH PRES RIDGE BUILDS SWD TUE-THU WITH NO MENTION OF POPS WITH SLIGHTLY WARMER TEMPS ANTICIPATED. && .AVIATION...WILL SEE TEMPO MVFR AT ALL TAF SITES BETWEEN 09Z AND 12Z DUE MAINLY TO VSBY. OTHERWISE VFR. EAST WINDS INCREASE BY EARLY THIS AFTERNOON WITH GUSTS TO NEAR 20 KNOTS AFTER 16Z. && .MARINE...WITH RIDGE BUILDING IN...WINDS AND EASTERLY SWELLS WILL SUBSIDE TODAY AND THROUGH THE WEEKEND. WILL KEEP THE ADVISORY FOR SEAS GOING THROUGH SATURDAY AND DROP ON SUNDAY. A STRONG BACK DOOR FRONT MOVES DOWN THE COAST MONDAY AND WILL PROBABLY SEE SCA CONDITIONS RETURN AGAIN. && .FIRE WX...BRIEF DURATIONS OF RH`S AOB 35% POSSIBLE TODAY AND SAT AFTN ACROSS THE SUWANNEE RIVER VALLEY IN NE FL. OTHERWISE NO MAJOR CONCERNS THROUGH THE WEEKEND. WINDS ARE EXPECTED TO INCREASE TO 15 MPH INLAND AND 15 TO 20 MPH ALONG THE COAST MONDAY WHEN A BACK DOOR FRONT SWEEPS THROUGH THE AREA. && .PRELIMINARY POINT TEMPS/POPS... AMG 83 54 85 53 / 10 10 10 10 SSI 74 58 76 57 / 0 0 0 10 JAX 79 55 81 55 / 10 10 10 10 SGJ 74 59 75 60 / 10 10 0 10 GNV 83 53 83 55 / 10 10 0 10 OCF 83 55 83 55 / 10 10 0 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 3 PM EDT SATURDAY FOR ALTAMAHA SOUND GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE-FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE-ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 PM EDT THIS EVENING FOR FERNANDINA BEACH TO ST AUGUSTINE FL OUT 20 NM- ST AUGUSTINE TO FLAGLER BEACH FL OUT 20 NM. && $$ SHASHY/PETERSON fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 940 PM EDT WED MAR 21 2007 .SHORT TERM UPDATE /TONIGHT/... PER RADAR/SATELLITE TRENDS...DEPICTING CLOUDS/SHOWERS PUSHING TOWARD SHORE ON THE SOUTHERN PERIPHERY OF HIGH PRES CENTERED EAST OF NEW ENGLAND...EXPANDED ISOLATED SHOWERS INTO GA COUNTIES OVERNIGHT. 18Z NAM12/WRF AND 0Z RUC40 SUGGEST THAT PRECIP WILL STRUGGLE TO PUSH ONSHORE OVERNIGHT...SO WILL NOT RAISE POPS. HOWEVER...WILL CONTINUE TO MONITOR TRENDS AND MAY YET RAISE POPS IF NEEDED...ESP ACROSS SC COUNTIES. OTHERWISE...DEWPOINTS IN THE 50S AND BREAKS IN THE CLOUD COVER SUPPORT THE ONGOING FORECAST OF PATCHY FOG. && .MARINE... RECENT REPORTS FROM AREA BUOYS AND FROM THE CHARLESTON AND SAVANNAH PILOT BOATS SUGGEST THAT SEAS ARE BUILDING AHEAD OF SCHEDULE...AND CURRENT TRENDS SUGGEST THAT 6 FT SEAS WILL PROBABLY SLIP INTO NEARSHORE WATERS OVERNIGHT. THUS...MOVED UP START TIME OF ONGOING SCAS FOR SC/GA NEARSHORE WATERS FROM NOON THU TO 2 AM THU. && .AVIATION /02Z-24Z/...VFR CONDITIONS WILL PREVAIL UNTIL AFTER 8Z...WHEN AT LEAST MVFR VISIBILITY SHOULD DEVELOP AT KCHS...WHILE OCCASIONAL IFR CIGS/VSBYS SHOULD DEVELOP AT KSAV AROUND DAYBREAK. THEN...AFTER 12Z...VFR CONDITIONS SHOULD PREVAIL FOR THE REMAINDER OF THE FORECAST PERIOD. MEANWHILE...TAFS INDICATE SHOWERS IN THE VICINITY UNTIL 9Z...WILL AMEND AS NEEDED FOR TIMING OF INDIVIDUAL SHOWERS. && .RIP CURRENTS... PERSISTENT ONSHORE FLOW AND DEVELOPING LONG PERIOD EASTERLY SWELL WILL RESULT IN A MODERATE RISK OF RIP CURRENTS THURSDAY. THE INCREASED THREAT OF RIP CURRENTS MAY CONTINUE UNTIL THE SWELL SUBSIDES SATURDAY. && .COASTAL FLOODING/HIGH SURF... GIVEN PERSISTENT ONSHORE FLOW...BUILDING E SWELL AND ASTRONOMICAL COMPONENT OF TIDES...STILL CLOSE TO THE MARCH 19 NEW MOON...WILL CONTINUE TO CLOSELY MONITOR WATER LEVELS AROUND THE TIMES OF HIGH TIDE TONIGHT AND AGAIN THURSDAY NIGHT. ALSO...WILL NEED TO ASSESS NEED FOR A HIGH SURF ADVISORY THU...AS WAVES IN SURF ZONE COULD BE CLOSE TO 5 FT. THIS COULD ALSO CONTRIBUTE TO MINOR BEACH EROSION AT HIGH TIDE...ESPECIALLY THU AND THU NIGHT. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM THURSDAY TO 6 AM EDT FRIDAY FOR AMZ350-352-354. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT SUNDAY FOR AMZ374. && $$ SPR ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 130 PM CDT THU MAR 22 2007 .DISCUSSION FOR ZONES/GRIDS... 11AM...SKIES ARE CLEARING OVER MUCH OF FCST AREA AT LATE MRNG AS WINDS TURN NW AND TEMPS STEADY OUT. COLD ADVECTION ON NW WINDS WILL HOLD TEMPS WITHIN FEW DEG OF CURRENT LEVELS THROUGH THE AFTERNOON. HIGH PERS OVER NW IOWA SHOULD DRIFT ACROSS TONIGHT FOR SOMEHWAT COOLER TEMPS. RETURN MOISTURE AND CLOUDS ETC LKLY TO BEGIN LATER TONIGHT AND CONTINUE FRIDAY. CHARACTER OF THAT RETURN REMAINS TO BE SEEN AND WILL TRIM/DELAY RETURN A LITTLE IN UPDATED GRIDS. FAIRLY MARKED DIFFERENCES IN GFS AND NAM IN GROWING AMPLITUDE OF EJECTING WESTERN TROUGH NEXT 48HRS IS ONE SOURCE OF UNCERTAINTY. KL PREVIOUS DISCUSSION 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... THE COLD FRONT HAS MOVED SOUTH OF THE TAF FORECAST AREA OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA. THE WIND PROFILER DATA SHOWS A WEST WIND IN ILLINOIS AT 700 MB AND AT 850 MB. WITH THIS WIND PATTERN ALOFT THE FRONT WILL PROBABLY STALL OVER CENTRAL ILLINOIS. A HIGH WILL MOVE ACROSS THE NORTH CENTRAL PART OF THE STATE THIS EVENING. THE WIND WILL BECOME SOUTHERLY AND THE FRONT WILL MOVE NORTH INTO NORTH CENTRAL ILLINOIS AND NORTHWEST INDIANA LATE TONIGHT. WE WILL ADD THUNDERSTORMS TOWARD FROM 11 TO 12 UTC. THIS IS THE TIME OF MAXIMUM CONVERGENCE AS THE FRONT MOVES THROUGH. WE WILL HAVE LIGHT RAIN THROUGH THE MORNING ACROSS THE FORECAST AREA. WE EXPECT A SOUTHEAST WIND AFTER MIDNIGHT TONIGHT. WE USED THE NAM AND A LOCALLY RUN WRF MODEL. && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1100 AM CDT THU MAR 22 2007 .DISCUSSION FOR ZONES/GRIDS... 11AM...SKIES ARE CLEARING OVER MUCH OF FCST AREA AT LATE MRNG AS WINDS TURN NW AND TEMPS STEADY OUT. COLD ADVECTION ON NW WINDS WILL HOLD TEMPS WITHIN FEW DEG OF CURRENT LEVELS THROUGH THE AFTERNOON. HIGH PERS OVER NW IOWA SHOULD DRIFT ACROSS TONIGHT FOR SOMEHWAT COOLER TEMPS. RETURN MOISTURE AND CLOUDS ETC LKLY TO BEGIN LATER TONIGHT AND CONTINUE FRIDAY. CHARACTER OF THAT RETURN REMAINS TO BE SEEN AND WILL TRIM/DELAY RETURN A LITTLE IN UPDATED GRIDS. FAIRLY MARKED DIFFERENCES IN GFS AND NAM IN GROWING AMPLITUDE OF EJECTING WESTERN TROUGH NEXT 48HRS IS ONE SOURCE OF UNCERTAINTY. KL PREVIOUS DISCUSSION 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 650 AM CDT MID LVL S/WV TROF CONTINUES TO PLOW INTO WRN GRTLKS REGION THIS MORNING...COLD FRONT PUSHING THRU FCST AREA AT 12Z. BAND OF ELEVATED CONVECTION ASSOCIATED WITH 55 KT LLJ NOW PUSHING OFF TO THE EAST OF FCST AREA AS 950-850 HPA FLOW BECOMING A BIT MORE WESTERLY WITH APPROACH OF TROF...THOUGH A FEW ISOLATED CELLS STILL DVLPG GENERALLY ALONG/SOUTH OF A KVYS...KLOT...KGYY LINE ASSOCIATED WITH ELEVATED INSTABILITY PLUME/LLJ AXIS. EXPECT THESE TO REMAIN SOUTH OF TERMINALS WITH EXCEPTION OF KGYY FIRST COUPLE OF HOURS OF TAF PERIOD EARLY THIS MORNING. OTHERWISE...COLD FROPA HAS OCCURRED AT KRFD AND WILL BE INTO CHI AREA TERMINALS NEXT 1-2 HRS. PATCHY MVFR CIGS IN 1500-2000 FT RANGE IMMEDIATELY BEHIND FRONT...THOUGH STRONG LLVL DRY ADVECTION DVLPG POST FRONTAL SHOULD CLR THIS OUT BY LATE MORNING. STRONG ISALLOBARIC GRADIENT WITH PRESSURE RISES BEHIND FRONT...SO WITH WSFT TO NW XPCT TO CONTINUE TO SEE GUSTS INTO THE LOW/MID 20 KT RANGE THIS MORNING. SFC HIGH PRESSURE BUILDS IN RAPIDLY THIS AFTN/THIS EVE ALLOWING WINDS TO DECREASE QUICKLY...GOING VRBL THIS EVE. WILL LIKELY SEE A BIT OF A LAKE BREEZE TOWARD EVE ALONG IL/IND LAKE MICH SHORE AS GRADIENT RELAXES. NEXT S/WV PROPAGATES ACROSS UPPER MIDWEST TONIGHT...WITH ANOTHER ROUND OF WAA/UPGLIDE DVLPG ACROSS BAROCLINIC FRONTAL ZONE TO SOUTH OF FCST AREA OVRNGT. 06Z NAM/GFS RUNS BOTH FOCUS PCPN SOUTH OF TERMINALS WITH VFR CIG DVLPG. COULD SEE PCPN FARTHER NORTH INTO TERMINAL SITES AFTER 06Z TONIGHT...THOUGH CONFIDENCE THAT FAR NORTH IS LOW ATTM. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 650 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 650 AM CDT MID LVL S/WV TROF CONTINUES TO PLOW INTO WRN GRTLKS REGION THIS MORNING...COLD FRONT PUSHING THRU FCST AREA AT 12Z. BAND OF ELEVATED CONVECTION ASSOCIATED WITH 55 KT LLJ NOW PUSHING OFF TO THE EAST OF FCST AREA AS 950-850 HPA FLOW BECOMING A BIT MORE WESTERLY WITH APPROACH OF TROF...THOUGH A FEW ISOLATED CELLS STILL DVLPG GENERALLY ALONG/SOUTH OF A KVYS...KLOT...KGYY LINE ASSOCIATED WITH ELEVATED INSTABILITY PLUME/LLJ AXIS. EXPECT THESE TO REMAIN SOUTH OF TERMINALS WITH EXCEPTION OF KGYY FIRST COUPLE OF HOURS OF TAF PERIOD EARLY THIS MORNING. OTHERWISE...COLD FROPA HAS OCCURRED AT KRFD AND WILL BE INTO CHI AREA TERMINALS NEXT 1-2 HRS. PATCHY MVFR CIGS IN 1500-2000 FT RANGE IMMEDIATELY BEHIND FRONT...THOUGH STRONG LLVL DRY ADVECTION DVLPG POST FRONTAL SHOULD CLR THIS OUT BY LATE MORNING. STRONG ISALLOBARIC GRADIENT WITH PRESSURE RISES BEHIND FRONT...SO WITH WSFT TO NW XPCT TO CONTINUE TO SEE GUSTS INTO THE LOW/MID 20 KT RANGE THIS MORNING. SFC HIGH PRESSURE BUILDS IN RAPIDLY THIS AFTN/THIS EVE ALLOWING WINDS TO DECREASE QUICKLY...GOING VRBL THIS EVE. WILL LIKELY SEE A BIT OF A LAKE BREEZE TOWARD EVE ALONG IL/IND LAKE MICH SHORE AS GRADIENT RELAXES. NEXT S/WV PROPAGATES ACROSS UPPER MIDWEST TONIGHT...WITH ANOTHER ROUND OF WAA/UPGLIDE DVLPG ACROSS BAROCLINIC FRONTAL ZONE TO SOUTH OF FCST AREA OVRNGT. 06Z NAM/GFS RUNS BOTH FOCUS PCPN SOUTH OF TERMINALS WITH VFR CIG DVLPG. COULD SEE PCPN FARTHER NORTH INTO TERMINAL SITES AFTER 06Z TONIGHT...THOUGH CONFIDENCE THAT FAR NORTH IS LOW ATTM. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 330 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 1254 AM CDT VIGOROUS S/WV TROF PROPAGATING ACROSS NRN PLAINS AND UPPER MIDWEST EARLY THIS MORNING...WITH ASSOCIATED SFC TROF/COLD FRONT FROM NRN WI TO ERN IA AT 05Z. REGIONAL PROFILER DATA...AND 0445Z ACARS SOUNDING OUT OF KRFD INDICATE 55 KT SOUTHWESTERLY LLJ IN 930-850 HPA LAYER AHEAD OF LOW LEVEL TROF/FRONT. SOUNDING ALSO INDICATES STEEP LAPSE RATES IN THIS LAYER...THOUGH A BIT OF A CAP NOTED AROUND 670 MB. ISOLATED WEAK ELEVATED CONVECTIVE CELLS HAVE BEEN TRYING TO INITIATE IN THIS REGION OF MOIST/WAA ACROSS FAR NRN IL...THOUGH APPEARS THEY ARE FIGHTING CAP. NAM FCST SOUNDINGS DEPICT COOLING OF MID/UPR LVLS WITH APPROACH OF S/WV EARLY THIS MORNING HOWEVER...WITH ELEVATED CAPE INCREASING TO 550-650 J/KG FOR PARCELS BASED 875-900 HPA. THIS ALONG WITH INCREASING LLVL CONVERGENCE AHEAD OF FRONT SHOULD BE SUFFICIENT TO RESULT IN SCATTERED TRW AS BOUNDARY ADVANCES ACROSS FCST IL. CURRENT REGIONAL RADAR TRENDS INDICATE STRONG CONVECTION IN SWRN WI AND SRN IA...WITH SOME INCREASE IN CELL DEVELOPMENT ACROSS ERN IA. GIVEN STRONG FAIRLY UNIDIRECTIONAL WIND FIELD MAY SEE SOME GUSTS IN 40 KT RANGE WITH TSTMS...AND PERHAPS SOME SMALL HAIL GIVEN MARGINAL CAPE PROFILES. THUS WILL MAINTAIN TS IN TERMINALS THIS MORNING...MAINLY DURG 09-13Z PERIOD FROM WEST TO EAST AS FRONT MOVES THRU. MAY SEE BRIEF PERIOD OF MVFR CIGS IN FRONTAL ZONE...THOUGH STRONG LLVL DRYING BEHIND FRONT SHOULD DECREASE CLOUDS FAIRLY RAPIDLY WITH VFR CONDITIONS PREVAILING WITHIN A FEW HOURS OF SUNRISE. STRONG SW LLVL WIND FIELD IN TIGHT PRES GRADIENT AHEAD OF COLD FRONT RESULTING IN GUSTY 20-30 KT WINDS ATTM. WILL SEE GRADIENT DECREASE JUST A BIT WITHIN TROF AXIS TOWARD SUNRISE...THEN WSHFT TO NWLY DIRECTION. SOME GUSTINESS AS SFC PRES RISE BUILDS IN EARLY MORNING...THEN DECREASING WINDS THIS AFTN AS WEAK SFC HIGH BUILDS IN. DVLPMNT OF NE WINDS OFF LAKE A GOOD PROBABILITY VERY LATE AFTN/EARLY EVE AS GRADIENT WINDS DECREASE. NEXT S/WV AND ELEVATED PCPN THREAT BEYOND 06Z TONIGHT...MORE ON THAT WITH NEXT FCST ISSUANCE. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 745 PM EDT WED MAR 21 2007 .DISCUSSION FOR 00Z TAFS...WARM SECTOR AIR OVER TAF ROUTES WITH SCT AC AND CI OVR INDIANA WHILE CONVECTION OCCURRING NEAR WRM FNT ACRS SRN GRTLKS. PATCHY MID CLOUD EMBEDDED IN SW FLOW AHEAD OF CDFNT MEANS VFR TO CONTINUE TIL DAYBREAK WHILE GUSTY WINDS AT SUNSET TODAY BECOME STEADY OVRNGT. MODELS TIMING OF CDFNT THU FAIRLY SIMILAR AND APPEARS BEST LIFT WILL OCCUR JUST PRIOR TO AND DURING FROPA SO HAVE KEPT PCPN OUT OF FCST TIL THEN. EXPECT PERIOD OF MVFR VSBY WITH SHRA AND CB DURING CDFNT PASSAGE AND TREND TO MVFR CIGS OVC020 IN COLD AIR BEHIND FNT. INCREASED STABILITY SHOULD LEAD TO END OF TSHRA SHORTLY AFT FROPA. && .PREV DISCUSSION...SURFACE FRONT CURRENTLY LOCATED OVER NORTHERN PLAIN/UPPER MIDWEST WILL MOVE SOUTH INTO THE AREA THURSDAY. HAVE ADJUSTED PRECIP TIMING ACCORDINGLY. HAVE KEPT A CHANCE IN MOST AREAS DURING THE OVERNIGHT HOURS TO ACCOUNT FOR ANY PRE-FRONTAL ELEVATED CONVECTION THAT MAY FIRE AS S/W OVER S. MO AND N. AR MOVES INTO AREA ALONG WITH INCREASING ISENTROPIC LIFT FROM THE LLJ. THE MID LEVEL FORCING ASSOCIATED WITH THE ACCOMPANYING S/W IS FCST TO MOVE ACRS THE UPPER MIDWEST AND LAKES REGION SHOULD REMAIN DISPLACED AWAY FROM CENTRAL INDIANA. THIS WILL TEND TO LIMIT DESTABILIZATION OVERTOP MOIST TONGUE ADVECTING INTO THE REGION TONIGHT AND EARLY TOMORROW. MODEL CONSENSUS FCST SOUNDINGS INDICATING MODEST LOW LEVEL FLOW DURING THE AFTERNOON HOURS TOMORROW BUT SEVERE POTENTIAL WILL BE LIMITED MAINLY BY VERY WEAK INSTABILITY. FRONTOGENESIS MOVES INTO AREA BY THURS MORNING AND REMAINS QUASI STATIONARY OVER THE OH VALLEY THRU SATURDAY ACCORDING TO NAM/GFS. ADDITIONAL EMBEDDED SHORTWAVES IN MEAN FLOW WILL HELP TO TRIGGER OCCASL CONVECTIVE SHOWERS/TSTMS IN CONJUNCTION WITH FRONTAL LIFTING IN REGION. PWATS VALUES WILL BE ON THE ORDER OF 1.2 TO 1.5 INCHES OVERNIGHT AND THURSDAY AS LLJ MOVES INTO THE AREA AND ACTS AS MSTR TRANSPORT MECHANISM...THEREFORE POTENTIAL EXISTS FOR HEAVY RAIN AMOUNTS. HPC GUIDANCE CURRENTLY HAS ROUGHLY 1.5 INCHES ACCUMULATING OVER THE ENTIRE FCST AREA...WITH POTENTIAL FOR UP TO 3 INCH AMOUNTS IN ISOLATED AREAS IN THE NEXT 48-60 HRS. AT THIS TIME...1 TO 2 INCH AMTS APPEAR TO BE THE MORE PROBABLE SCENARIO. WILL ISSUE AN ESF TO INCREASE AWARENESS ABOUT THE WATER THREAT BUT WILL HOLD OFF ON ANYTHING ELSE WHEN/IF FOCUS FOR LIFT BECAUSE MORE APPARENT. HAVE ADJUSTED TEMPS SLIGHTLY TO ALIGN THEM IN A NORTH-SOUTH GRADIENT AS THE MODEL CONSENSUS INDICATES AN EAST-WEST FRONTAL POSITION OVER THE TONIGHT THRU FRIDAY NIGHT PERIOD. LONG TERM...AFT 12Z ON MARCH 24...CONSENSUS IS WARM AND OFTEN WET WITH STRONG SW FLOW AND FRONT WEAVING BACK AND FORTH ACROSS AREA. HOWEVER JUST HOW THE FRONT AND SHORT WAVES MOVING THROUGH AREA INTERACT COULD MAKE A BIG DIFFERENCE IN JUST HOW WARM AND HOW WET WE GET. FOR NOW WILL STICK CLOSE TO NCEP GUIDANCE BECAUSE DONT HAVE A BETTER IDEA...BUT THIS IS NOT A HIGH CONFIDENCE FCST. && .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...SMITH/JK AVIATION...TUCEK in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 410 PM EDT WED MAR 21 2007 .DISCUSSION...SURFACE FRONT CURRENTLY LOCATED OVER NORTHERN PLAIN/UPPER MIDWEST WILL MOVE SOUTH INTO THE AREA THURSDAY. HAVE ADJUSTED PRECIP TIMING ACCORDINGLY. HAVE KEPT A CHANCE IN MOST AREAS DURING THE OVERNIGHT HOURS TO ACCOUNT FOR ANY PRE-FRONTAL ELEVATED CONVECTION THAT MAY FIRE AS S/W OVER S. MO AND N. AR MOVES INTO AREA ALONG WITH INCREASING ISENTROPIC LIFT FROM THE LLJ. THE MID LEVEL FORCING ASSOCIATED WITH THE ACCOMPANYING S/W IS FCST TO MOVE ACRS THE UPPER MIDWEST AND LAKES REGION SHOULD REMAIN DISPLACED AWAY FROM CENTRAL INDIANA. THIS WILL TEND TO LIMIT DESTABILIZATION OVERTOP MOIST TONGUE ADVECTING INTO THE REGION TONIGHT AND EARLY TOMORROW. MODEL CONSENSUS FCST SOUNDINGS INDICATING MODEST LOW LEVEL FLOW DURING THE AFTERNOON HOURS TOMORROW BUT SEVERE POTENTIAL WILL BE LIMITED MAINLY BY VERY WEAK INSTABILITY. FRONTOGENESIS MOVES INTO AREA BY THURS MORNING AND REMAINS QUASI STATIONARY OVER THE OH VALLEY THRU SATURDAY ACCORDING TO NAM/GFS. ADDITIONAL EMBEDDED SHORTWAVES IN MEAN FLOW WILL HELP TO TRIGGER OCCASL CONVECTIVE SHOWERS/TSTMS IN CONJUNCTION WITH FRONTAL LIFTING IN REGION. PWATS VALUES WILL BE ON THE ORDER OF 1.2 TO 1.5 INCHES OVERNIGHT AND THURSDAY AS LLJ MOVES INTO THE AREA AND ACTS AS MSTR TRANSPORT MECHANISM...THEREFORE POTENTIAL EXISTS FOR HEAVY RAIN AMOUNTS. HPC GUIDANCE CURRENTLY HAS ROUGHLY 1.5 INCHES ACCUMULATING OVER THE ENTIRE FCST AREA...WITH POTENTIAL FOR UP TO 3 INCH AMOUNTS IN ISOLATED AREAS IN THE NEXT 48-60 HRS. AT THIS TIME...1 TO 2 INCH AMTS APPEAR TO BE THE MORE PROBABLE SCENARIO. WILL ISSUE AN ESF TO INCREASE AWARENESS ABOUT THE WATER THREAT BUT WILL HOLD OFF ON ANYTHING ELSE WHEN/IF FOCUS FOR LIFT BECAUSE MORE APPARENT. HAVE ADJUSTED TEMPS SLIGHTLY TO ALIGN THEM IN A NORTH-SOUTH GRADIENT AS THE MODEL CONSENSUS INDICATES AN EAST-WEST FRONTAL POSITION OVER THE TONIGHT THRU FRIDAY NIGHT PERIOD. LONG TERM...AFT 12Z ON MARCH 24...CONSENSUS IS WARM AND OFTEN WET WITH STRONG SW FLOW AND FRONT WEAVING BACK AND FORTH ACROSS AREA. HOWEVER JUST HOW THE FRONT AND SHORT WAVES MOVING THROUGH AREA INTERACT COULD MAKE A BIG DIFFERENCE IN JUST HOW WARM AND HOW WET WE GET. FOR NOW WILL STICK CLOSE TO NCEP GUIDANCE BECAUSE DONT HAVE A BETTER IDEA...BUT THIS IS NOT A HIGH CONFIDENCE FCST. && .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...SMITH/JK AVIATION...KOCH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 100 PM EDT WED MAR 21 2007 .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .DISCUSSION...SPLIT UPPR FLOW DVLPG ACRS THE COUNTRY OVR THE NEXT COUPLE OF DAYS. WK DISTURBANCES WL BE EJECTING OUT OF THE SRN PLAINS...WHILE A STRONGER NRN STREAM SYS CURRENTLY LOCATED OVR THE NRN ROCKIES PUSHES EWD INTO THE UPPR GRTLKS ON THURS. THIS SYS WL BRING A CDFNT INTO THE LOCAL AREA BY THURS AFT/NIGHT. MODELS IN RELATIVELY GOOD AGREEMENT ON THE MAIN DETAILS. FCST FOCUS CENTERS ON POPS. LIFT AHEAD OF WK SHORT WV TROF OVR WRN IL CAUSING SHWRS TO BREAK OUT ACRS THE AREA. 21/00Z UA INDICATES NOSE OF LLJ POINTED MORE TOWARDS SRN LI MI...SO WOULD XPCT THE BULK OF THE HVR PCPN TO STAY NW OF THE LOCAL AREA EARLY THIS MORN. BASED ON MODEL DATA...WV SHOULD PUSH OFF TO THE NE BY SUNRISE...SO PCPN THREAT SHOULD DIMINISH BY THAT TIME. H20 LOOP LOOKS PRETTY MESSY IN THE SRN STREAM...WITH INDICATIONS OF ADDITIONAL DISTURBANCES PSBLY OVR NEBRASKA AND ERN OK. CONSIDERING ABV AND THE FACT THAT LLJ WL REMAIN IN THE GENERAL AREA THRU TONIGHT...DECIDED TO LEAVE CHC POPS IN THE FCST THRU TONIGHT. APPEARS CDFNT WL BE MOVG INTO THE NWRN ZONES BY THURS AFT. GOOD INFLOW INTO THE FNT WITH 850MB WNDS PROGGED ARND 40KTS. THIS SUGGESTS FAIRLY WIDESPREAD PCPN SHOULD DVLP INVOF FNT. WL GO WITH HI POPS BY THURS AFT AS A RESULT. MODELS INDICATE FNT MAY STALL OUT NEARBY TOWARDS THE END OF THE WEEK. 850MB FLOW INTO THE FNT REMAINS RATHER HEALTHY AS WELL...SUGGESTING HVY RAINFALL TOTALS PSBL LT IN THE WEEK IF MODEL SOLUTIONS COME TO PASS. BASED ON PROGGED LO LVL THICKNESSES...NGM MOS GUIDANCE TEMPS LOOK REASONABLE AT THIS PT...SO WON/T STRAY TOO FAR FM THEM. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...JAS AVIATION...KOCH in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 309 PM CST WED MAR 21 2007 .SYNOPSIS... CONVECTION ONGOING OVER THE NW FOURTH OF THE CWA THIS AFTERNOON. TSRA MOVED INTO THE WRN COUNTIES AHEAD OF H5 S/W MVNG THROUGH CENTRAL IA...THEN REFORMED INTO AN E/W LINE ALONG INSTABILITY GRADIENT OVER SE IA. SO FAR JUST SOME ISOLATED SEVERE HAIL REPORTS AND WIND GUSTS AROUND 35KTS. COLD FRONT WAS LOCATED FROM THE WRN MN THROUGH ERN NE EARLY THIS AFTERNOON. 12Z UA ANALYSIS SHOWED A POTENT NRN ROCKIES UPPER TROF ASSOCIATED WITH THE FRONT. SO FAR NOT MUCH IN THE WAY OF CONVECTION WAS NOTED WITH SURFACE FRONT WITH STRONG CAP NOTED ON KOAX 18Z SOUNDING...SUPPRESSING DEVELOPMENT. && .SHORT TERM...TONIGHT AND THURSDAY... CONVECTION CURRENTLY OVER THE NRN CWA SHOULD BE EAST OF THE CURRENT WATCH AND ANTICIPATE CANCELLING THE SEVERE WATCH EARLY FOR MOST OF THE WATCH AREA. COLD FRONT PROGGED TO MOVE THROUGH CWA LATE THIS EVENING AND EARLY THURSDAY MORNING AS MID LEVEL S/W CROSSES THE NCNTRL STATES. LOOKING AT A RUC FCST NR KOMA FOR THIS AFTERNOON...IT SHOWS THE STRONG CAP DISSIPATING BY 00Z...SO EXPECT CONVECTION TO FORM IN WRN IA BY EARLY EVENING ON THE FRONT AND REACH THE NWRN CWA AROUND 03Z ...THEN MOVING THROUGH THE SERN CWA BTWN 09Z AND 12Z. FRONT IS THEN EXPECTED TO STALL OVER CENTRAL MO/IL THURSDAY AFTN/EVE. HAVE CONTINUED CATEGORICAL POPS FROM THE PREV FCST FOR TONIGHT. SEVERE THREAT REMAINS WITH SOME MODEST CAPE AROUND 1000J/KG PROGGED TO REMAIN OVER ERN IA THROUGH THE EVENING. BELIEVE SYSTEM WILL BE PROGRESSING EAST FAST ENOUGH TO LIMIT ANY RAINFALL THREAT IN ANY ONE AREA. PROBABLY THE MOST VULNERABLE AREA WILL BE THE SRN MOST COUNTIES WAS THE FRONT SLOWS AS IT BECOMES MORE ALIGNED WITH THE MID LEVEL FLOW. && .LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY... THE GFS/NAM/UKMET ARE IN GOOD AGREEMENT LIFTING THE BOUNDARY BACK NORTH INTO NRN MO/CNTRAL IL LATE THURSDAY NIGHT SETTING UP THE POTENTIAL FOR A HEAVY RAIN AS STRONG/MOIST SLWY LOW LEVEL FLOW INTERSECTS THE BOUNDARY...AND FUELING STORMS ON THE COOL SIDE. REPEAT CONVECTION WILL BE POSSIBLE WITH THE FRONT ORIENTED PARALLEL TO THE MID LEVEL FLOW AND A SWLY LLJ POINTED AT NW MO/SW IA MOST OF THE NIGHT. MODELS DIVERGE FRIDAY INTO THE SATURDAY HANDLING THE WARM FRONT. THE GFS PULLS THE BOUNDARY NORTH WELL INTO IA WHILE THE NAM/UKMET KEEP SOUTH AS THEY BRING S/W ENERGY THROUGH NRN STREAM. SINCE THE GFS IS THE OUTLIER...HAVE LIMITED CHANCE POPS TO THE SRN COUNTIES. FOR SATURDAY NIGHT THROUGH MONDAY THE LONG RANGE MODELS ARE IN BETTER AGREEMENT HANDLING THE SRN STREAM CUT OFF LOW...LIFTING IT NE THROUGH THE MID MS VALLEY BY EARLY MONDAY. BASED ON THIS HAVE STARTED TO TREND POPS HIER ESPECIALLY IN ADVANCE OF THE SYSTEM SATURDAY NIGHT THROUGH SUNDAY NIGHT. LONG RANGE MODELS THEN DEVELOP DEEP LOW PRESSURE OVER THE CENTRAL PLAINS FOR MID WEEK. HAVE OPTED TO KEEP FCST DRY TO MODELS ESTABLISH SOME RUN TO RUN CONTINUITY. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. $$ ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 924 AM MDT FRI MAR 23 2007 .UPDATE...ZONES HAVE BEEN UPDATED TO EXTEND THE DENSE FOG ADVISORY FOR THE KANSAS AND SOUTHWEST NEBRASKA COUNTIES UNTIL 11 AM MDT/ NOON CDT. LATEST RUC SOUNDINGS SHOW INVERSION TO TAKE A LITTLE LONGER TO BREAK WITH GOOD AMOUNT OF LOW LEVEL MOISTURE. SURFACE OBSERVATIONS STILL AT A QUARTER OF A MILE REPORTED AT SOME LOCATIONS INCLUDING GOODLAND...COLBY AND MCCOOK. EXPECT FOG TO LIFT BY LATER IN THE MORNING. REST OF FORECAST STILL ON TRACK. WILL BE WATCHING HIGH TEMPERATURES TODAY CLOSELY WHICH MAY BE DEPENDENT ON AMOUNT OF CLOUDINESS THROUGHOUT THE DAY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 11 AM MDT /NOON CDT/ THIS MORNING FOR KSZ001>004-013>016-027>029-041-042. NE...DENSE FOG ADVISORY UNTIL 11 AM MDT /NOON CDT/ THIS MORNING FOR NEZ079>081. CO...NONE. && $$ LAMMERS ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1038 AM CDT THU MAR 22 2007 .UPDATE... SURFACE FRONT HAD BECOME QUASI-STATIONARY GENERALLY JUST SOUTH OF HIGHWAY 50 AT MID-MORNING...WITH THE LATEST NAM AND RUC SUGGESTING A SLIGHT NORTHWARD MOVE INTO THE AFTERNOON. THIS IS SLIGHTLY NORTH OF EARLY MORNING GRID PACKAGE...SO HAVE REFLECTED THE CHANGES IN THE LATEST GRID/FORECAST UPDATE. AS FOR CONVECTIVE CHANCES FOR THIS AFTERNOON...A LOT WILL DEPEND ON DIURNAL HEATING (IE. CLOUD TRENDS) ALONG AND SOUTH OF SURFACE FRONTAL BOUNDARY. DESPITE SOME HOLES INTO MIDDAY...HIGHER LEVEL CLOUDS LOOK TO ENCROACH SOUTH CENTRAL KANSAS DURING THE EARLY AFTERNOON. CONVERGENCE ALONG THE BOUNDARY LOOKS SUFFICIENT TO FOCUS CONVECTION WITH POTENTIAL ML CAPES OF AROUND 1800 J/KG LATER THIS AFTERNOON. SO LITTLE CHANGE TO THE GOING POP FORECAST AND FLOOD WATCH HEADLINE. BETTER CHANCES FOR ELEVATED CONVECTION APPEAR TO BE IN THE OFFING LATE THIS EVENING OR OVERNIGHT...ALONG AND NORTH OF SURFACE FRONT. KED && .PREV DISCUSSION... /ISSUED 328 AM CDT THU MAR 22 2007/ DISCUSSION... FORECAST CONCERNS TODAY ARE TSRA CHANCES FOR TODAY THROUGH THE WEEKEND AND ALSO TEMPS. TODAY: WAVY FRONTAL BOUNDARY MAKING SLOW PROGRESS INTO THE SOUTHERN KS AT THIS TIME. SOME WIDELY SCATTERED TSRA FINALLY HAVE DEVELOPED ALONG THE BOUNDARY AS LOW LEVEL JET INCREASES OVER THE TOP OF THE FRONT HELPING TO GET ELEVATED STORMS GOING. QUESTION TODAY IS HOW FAR SOUTH /IF AT ALL/ THIS FRONT WILL MAKE IT BEFORE STALLING OUT LATER THIS MORNING. SOME PRESSURE RISES STILL NOTED BEHIND THE BOUNDARY SO PREFER THE NAM-WRF FOR FRONTAL PLACEMENT GENERALLY ALONG AN EMP-HUT LINE BEFORE IT STALL. WHERE THE BOUNDARY WILL ULTIMATELY STALL OUT IS THE BIG PROBLEM TODAY AS THIS BOUNDARY WILL PROVIDE THE FOCUS FOR CONVECTION AND POSSIBLE TRAINING ECHOES. EXPECT SOME CONVECTION TO BE ONGOING EARLY IN THE PERIOD...BUT MAIN TSRA CHANCE WILL BE THIS AFTERNOON AS A MID LEVEL IMPULSE IN THE SOUTHWEST FLOW AND INCREASING ISENTROPIC LIFT IN THE 305K LAYER WILL STEEPEN LAPSE RATES ENOUGH FOR A MORE WIDESPREAD CONVECTION CHANCE. INSTABILITY IS MODEST WITH MUCAPE VALUES THIS AFTERNOON ONLY AROUND 1000 J/KG...BUT 0-6KM SHEAR VALUES STILL SUGGEST A POSSIBLE LARGE HAIL THREAT FOR AREAS WHERE SURFACE HEATING CAN BE MAXIMIZED. WITH SOME SURFACE BASED CONVECTION POSSIBLE SOUTH OF THE BOUNDARY OVER AREAS WITH SATURATED GROUNDS...WILL LEAVE THE FLOOD WATCH GOING FOR SOUTH CENTRAL AND SOUTHEAST KS BUT DAY SHIFT WILL PROBABLY HAVE TO BETTER DEFINE THIS ONCE BOUNDARY DECIDES TO STOP ITS SOUTHERN PROGRESS. WILL RAISE MAX TEMPS IN SOUTHERN KS AS BOUNDARY JUST TO THE NORTH OF THIS AREA WILL ALLOW TEMPS TO CLIMB INTO THE LOWER 70S. TONIGHT: BOUNDARY DRIFTS TO THE NORTH SOME AS THE NIGHT PROGRESSES...WITH SOME ISENTROPIC LIFT STILL LOCATED SOUTH OF THE BOUNDARY. SO EXPECT SOME CONVECTION IN SOUTHEAST KS EARLY BUT PROBABLY DIMINISHING OVERNIGHT. THIS LIFT WILL PROBABLY LEAD TO SOME TRANING STORMS IN AND NEAR THE BOUNDARY...SO FLOODING THREAT WILL DEFINATELY HAVE TO BE WATCHED. FRI-FRI NIGHT: NOT ALOT OF CONFIDENCE IN FRONTAL PLACEMENT AND POSSIBLE CONVECTION FOR FRI. MODELS ALSO DIFFER ON MID LEVEL IMPULSES EXPECTED TO MOVE ACROSS THE AREA IN THE SOUTHWEST FLOW. WITH THE BOUNDARY STILL EXPECTED TO BE IN THE AREA WILL LEAVE CHANCE POPS IN MOST LOCATIONS AS ANY WEAK IMPULSE COULD LEAD TO DEVELOPMENT...BUT DO NOT EXPECT TSRA CHANCE TO BE WIDESPREAD. BETTER DEVELOPMENT LOOKS TO BE FRI NIGHT AS ISENTROPIC LIFT AGAIN INCREASES ACROSS THE AREA. WILL STILL ONLY GO CHANCE POPS FOR NOW AS PLACEMENT OF THE BOUNDARY IN LATER RUNS WILL BETTER DEFINE HIGHEST POP AREAS. SAT-SUN: CONFIDENCE REMAINS LOW DURING THIS TIME FRAME AS BOUNDARY REMAINS SOMEWHAT STATIONARY ON SAT FOR BEGINNING TO LIFT TO THE NORTH AGAIN AS A WARM FRONT ON SUN AND MAIN SHORTWAVE REMAINS SOUTHWEST OF THE AREA UNTIL SUN EVENING. WITH LOTS OF LOW LEVEL MOISTURE AROUND HEAVY RAINFALL THREAT WILL ALSO CONTINUE. WILL HAVE TO KEEP AN EYE ON SEVERE THREAT ON SAT AS SHEAR VALUES LOOK FAVORABLE BUT INSTABILITY LOOKS MODEST. MONDAY-WEDNESDAY: PRECIP CHANCES LOOK TO COME TO AN END ON MONDAY AS MED RANGE MODELS FINALLY MOVE THE MAIN SHORTWAVE ACROSS THE AREA. LOOKS LIKE TUESDAY WILL BE A DAY TO DRY OUT WITH WEAK RIDGING IN THE MID LAYERS. A RATHER RIGOROUS SHORTWAVE MOVES INTO THE PLAINS ON WED FOR ANOTHER POSSIBLE ROUND OF CONVECTION. KETCHAM && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 74 59 72 58 / 50 60 40 40 HUTCHINSON 70 58 72 57 / 40 50 40 40 NEWTON 71 58 71 57 / 50 60 40 40 ELDORADO 73 59 72 58 / 60 60 40 40 WINFIELD-KWLD 73 60 73 59 / 60 60 40 40 RUSSELL 61 51 71 53 / 20 30 40 40 GREAT BEND 64 53 71 55 / 30 40 40 40 SALINA 63 52 69 54 / 30 50 40 40 MCPHERSON 67 56 71 56 / 40 50 40 40 COFFEYVILLE 76 61 73 59 / 60 60 40 30 CHANUTE 74 60 72 59 / 60 60 40 30 IOLA 73 59 72 58 / 60 60 40 30 PARSONS-KPPF 74 61 73 59 / 60 60 40 30 && .ICT WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH FRIDAY MORNING FOR KSZ069>072-083-092>096- 098>100. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 440 AM CDT THU MAR 22 2007 .DISCUSSION... THE UNSETTLED PATTERN CONTINUES. INTERESTING SET UP TODAY WITH SFC BNDRY TO THE SOUTH AND GOOD OVER-RUNNING PATTERN DEVELOPING. LATEST RUC SOUNDINGS SHOW GOOD ELEVATED LIFT DEVELOPING NORTH OF THE SFC BNDRY BY MIDDAY ALONG OR JUST SOUTH OF INTERSTATE 70. OPTIMUM ELEVATED LIFT WITH FAIRLY GOOD CHANCE FOR THUNDERSTORMS MOVES SLOWLY NORTH THROUGH THE AFTERNOON AND OVERNIGHT...REACHING THE NORTHERN BORDER AFTER MIDNIGHT. PATTERN SUPPORTIVE OF LOCALLY HEAVY RAINS WITH TRAINING OVER SAME AREAS. NO FLOOD WATCH ISSUED YET...BUT BEARS WATCHING IN 12Z RUN. PRECIPITABLE WATER VALUES EXCEEDINGLY HIGH FOR THIS TIME OF YEAR...RUNNING NEARLY 250% OF NORMAL! THIS HIGH WATER CONTENT CONTINUES INTO THE WEEKEND AND DOES NOT REALLY GET MODIFIED TO ANY GREAT EXTENT UNTIL UPPER SYSTEM FINALLY LIFTS THROUGH FROM THE SOUTHWEST STATES EARLY NEXT WEEK. UNTIL THEN, PERIODIC CHANCES FOR CONVECTION...SOME OF WHICH MAY BE STRONG TO SEVERE. SETUP FOR SEVERE TODAY IS MAXIMIZED ALONG AND NORTH OF THE WARMFRONT. CONSIDERABLE HIGH CLOUDINESS WILL LIMIT SOLAR INSOLATION TO FRONTAL AREA OTHERWISE TEMPERATURES WOULD BE WARMER AND THE THREAT FOR SEVERE HAIL WOULD BE EVEN GREATER. SHEAR SEEMS TO BE SUFFICIENT FOR LARGE HAIL LATER TODAY AS WELL. TEMPERATURES IN TURN A REAL CHALLENGE WITH CLOUDS HANGING TOUGH TO THE NORTH OF THE FRONT. HAVE FOLLOWED NAM CLOSELY WITH IT`S SFC TEMPERATURE FCST. THUS COULD RANGE FROM THE UPPER 40S NORTH TO THE LOWER 70S SOUTH. BY FRIDAY THE FRONT SHOULD RESIDE ALONG THE NORTHERN BORDER WAITING FOR AN UPPER WAVE TO EJECT OUT OF MEAN WESTERN TROF POSITION. THIS COULD TRIGGER ANOTHER ROUND OF CONVECTION FRIDAY NIGHT. BETTER CHANCE APPEARS SATURDAY NIGHT INTO SUNDAY NIGHT AS UPPER SYSTEM LIFTS NORTHEAST INTO THE PLAINS. LATER PERIODS OF THE FORECAST NOT CHANGED MUCH AS IS IMPOSSIBLE TO ADD MUCH DETAIL OR FIND REASONS TO MAKE CHANGES IN SUCH AN UNSETTLED PATTERN. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 358 AM CDT THU MAR 22 2007 .DISCUSSION... DAYS 1-2... A NORTHERN STREAM SHORTWAVE TROUGH PASSED ACROSS THE NORTHERN PLAINS AND INTO THE GREAT LAKES OVERNIGHT. THIS HELPED PUSH A COLD FRONT THROUGH MOST OF SW KS. THE FRONT AS OF 3 AM STRETCHED FROM NORTH OF HUGOTON TO HUTCHINSON. SFC TEMPS WERE VERY BALMY SOUTH OF THE FRONT(71 AT BUFFALO,OK AND 65 AT LIBERAL). THE SFC DRYLINE WAS CURRENTLY MOVING NW THROUGH WEST TEXAS. AN UPPER LOW WAS SITUATED JUST OFF THE SOUTHERN CA COAST. 500MB TEMPS HAVE TURNED OUT TO BE WARMER THAN THE MODELS WERE FORECASTING A FEW DAYS AGO. IN FACT THE NAM HAS 500MB TEMPS AROUND -13C THIS AFTERNOON. SURFACE DEWPOINTS HAVE CLIMBED INTO THE UPPER 50S AND LOWER 60SF ACROSS OK/SOUTHERN KS. A LARGE AREA OF MID TO HIGH LEVEL CLOUD WAS MOVING NE INTO NM AND WEST TX. IN THE ABSENCE OF STRONG SYNOPTIC SCALE DYNAMICS TODAY...THE LOCATION OF SFC BOUNDARIES WILL DETERMINE THE PLACEMENT OF SHOWER/THUNDERSTORM INITIATION. THE NAM/GFS AND SOME OF THE RUC MEMBERS SURGE THE FRONT BACK TO THE NORTH TODAY TO A GCK TO HAYS LINE. I HAVE CHOSEN TO GO WITH THE RUC13 SOLUTION FOR TODAY. THIS MODEL KEEPS THE FRONT NEARLY STATIONARY ALL DAY. WITH BROKEN MID TO HIGH CLOUDS AND LOW LEVEL UPSLOPE FLOW... TEMPS WILL STAY IN THE 60S NORTH OF THE FRONT. BUT LOCATIONS ALONG THE OK STATE LINE COULD REACH THE UPPER 70S. I EXPECT THE SFC DRYLINE TO STRETCH FROM DALHART TO CARLSBAD,NM BY THIS AFTERNOON. THE DRYLINE WILL INTERSECT THE FRONT CLOSE TO DALHART. FAIRLY WEAK CAPPING...SOME ELEVATED HEATING ON THE HIGH PLAINS... AND CONVERGENCE ALONG THE DRYLINE AND NEAR THE FRONT/DRYLINE INTERSECTION WILL ALLOW STORMS TO DEVELOP BY 21Z. LOCAL POOLING OF MOISTURE MAY ALLOW FOR SFC BASED CAPES AS HIGH AS 1000-1500 J/KG FROM P28 TO ENGLEWOOD. AS STORMS MOVE INTO THIS AREA...A FEW OF THEM COULD BECOME SEVERE. VERTICAL SHEAR PROFILES WILL BE FAVORABLE FOR SEVERE STORMS. BUT THE MAIN LIMITING FACTOR FOR SEVERE STORMS WILL BE THE MARGINAL INSTABILITY. BUT AS WE HAVE SEEN IN THE RECENT PAST...STRONG VERTICAL WIND SHEAR AND CAPES AROUND 1000 J/KG CAN BE ENOUGH FOR SEVERE STORMS. ANY STORMS THAT DEVELOP THIS AFTERNOON WILL PROBABLY LINGER INTO TONIGHT. BUT THE STORM ACTIVITY WILL SHIFT OFF TO THE NE BY FRIDAY BEFORE THE MAIN UPPER LOW EJECTS INTO THE PLAINS ON SATURDAY. SOME POPS WERE MAINTAINED FOR FRIDAY FOR CONSISTENCY SAKE AND SINCE THERE IS SOME UNCERTAINTY. DAYS 3-7... NOT GOING TO CHANGE MUCH IN THE GOING EXTENDED. BOTH THE UKMET AND GFS BRING AN ORGANIZED SYSTEM UP FROM SOUTHERN BAHA CALIFORNIA TO WESTERN KANSAS FROM FRIDAY INTO SUNDAY. THE BEST CHANCES FOR PRECIPITATION LOOK TO BE ON SATURDAY AFTERNOON...WHERE WE HAVE 40 POPS GOING NOW. THESE POPS MAY HAVE TO BE RAISED IF THE TRACK OF THE UPPER SYSTEM BEARS OUT. TEMPERATURES LOOKED REASONABLE AND IN LINE WITH SURROUNDING WFO GRIDS. TUESDAY LOOKS TO BE WARM...PERHAPS WITH 80S SOMEWHERE IN OUR CWA. LEFT TUES MAX T`S ALONE FOR NOW...AS OUR SW HAS MID 70S GOING. && .AVIATION... AS LOW LEVEL MOISTURE CONTINUES TO CONVERGE ALONG AND SOUTH OF A FRONTAL BOUNDARY LYING ACROSS SOUTHERN KANSAS...STRATUS WILL LIKELY FORM AT DDC AND GCK IN THE 012 TO 015 FEET RANGE BY 11Z THIS MORNING. DO NOT EXPECT THE STRATUS TO LINGER MUCH BEYOND 15-16Z. ALSO...FOG WITH VSBYS IN THE 4-5SM RANGE WILL FORM AT DDC...GCK AND HYS AND LAST THROUGH 15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 53 71 56 / 20 30 20 20 GCK 64 45 72 53 / 20 20 20 20 EHA 71 47 71 53 / 20 20 20 20 LBL 73 51 71 56 / 20 30 20 20 HYS 61 48 72 55 / 20 20 20 20 P28 76 59 70 61 / 30 30 30 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN24/12 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 200 AM MDT THU MAR 22 2007 .DISCUSSION... PRIMARY UPPER FEATURE FOR THE SHORT TERM PERIOD WILL BE CUT OFF LOW OVER THE DESERT SOUTHWEST. FORECAST AREA TO REMAIN UNDER THE SOUTHWEST FLOW AHEAD OF THE MAIN LOW FOR THE NEXT SEVERAL DAYS. THE UPPER LOW WILL THEN BEGIN TO LIFT NORTH/NORTHEAST OVER THE WEEKEND. UNFORTUNATELY MODELS IN POOR AGREEMENT ON FINER DETAILS. EVEN AS EARLY AS TODAY...NAM BRINGING A FAIRLY WELL DEFINED VORT MAX OVER THE AREA/WHEREAS GFS SHOWS LITTLE IF ANYTHING. WATER VAPOR IMAGERY INCONCLUSIVE...SINCE JUST SEE A BROAD SOUTHWEST FLOW WITH DEEP TROPICAL PLUME AHEAD OF THE MAIN LOW. WITH LITTLE TO GO ON WILL PLAY THE PERCENTAGES AND HAVE SOME SLIGHT/LOW CHANCE POPS THIS AFTERNOON AND EVENING ACROSS SOUTHEAST COUNTIES. SOMEWHAT RELIABLE RUC CEILING FORECAST SHOWS 2KFT BROKEN DECK OVERSPREADING THE CWA FROM THE SOUTH THIS AFTERNOON...WILL FAVOR COOLER GUIDANCE FOR HIGHS AS A RESULT. FRIDAY WILL BE A VIRTUAL REPEAT...THOUGH MODELS SWITCH PLACES WITH GFS WET AND NAM DRY. IT DOES APPEAR THE AREA WILL COME UNDER FAVORABLE RIGHT ENTRANCE REGION OF JET WHICH DEVELOPS FRIDAY NIGHT/SATURDAY MORNING OVER THE MIDWEST. SURFACE FRONT WILL ALSO BE SURGING NORTH INTO THE AREA. NONETHELESS...ISC CONSTRAINTS WILL DICTATE LOW CHANCE POPS. THEN WILL HAVE TO DEAL WITH THE MAIN LOW OVER THE WEEKEND. MODELS ALL OVER THE PLACE...WHICH LENDS LITTLE TO NO CONFIDENCE TO THE PRECIPITATION CHANCES. GFS ENSEMBLE AVERAGES GIVE SOLID CHANCE POPS THROUGH SATURDAY...GRADUALLY DIMINISHING SATURDAY NIGHT AND SUNDAY TO SLIGHT CHANCES. THE ENSEMBLE APPROACH SEEMS REASONABLE GIVEN THE UNCERTAINTIES. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JDK ks AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE DODGE CITY KS 258 PM CDT WED MAR 21 2007 .DISCUSSION... DAYS 1-2... MAIN CONCERN THIS AFTERNOON WILL BE IF/WHEN CONVECTION WILL DEVELOP ALONG A DRYLINE WHICH WAS SLOWLY MOVING EAST ACROSS OUR EASTERN CWA. AT THIS TIME NOT SEEING ANY GOOD UPPER LEVEL DYNAMICS AND BASED ON NAM SOUNDINGS THE CONVECTIVE TEMPS ALONG THE DRYLINE WERE BETWEEN 82-86F. ALSO NOTICING CAPES ALONG AND AHEAD OF THIS FRONT WERE AT 15-2K J/KG WITH IMPROVING MOIST CONV. THE RUC40 ALSO WAS FORECASTING 0-6KM SHEAR OF 30 TO 35KTS. IF THE CONVECTIVE TEMPERATURE CAN BE REACHED LATE TODAY SHOULD SEE A FEW STORMS GO UP QUICKLY WITH THE MAIN HAZARD BEING HAIL. DOES NOT LOOK LIKE ANYTHING WIDESPREAD SO WILL KEEP SLT CHC POPS AND ADJUST AS NEEDED AS WE APPROACH 4 PM BASED ON LATEST OBSERVATIONS/CU DEVELOPMENT. FOR TONIGHT A COLD FRONT MOVES SOUTH ACROSS KANSAS AS A NORTHERN BRANCH S/W TROF MOVES ACROSS THE NORTHERN PLAINS INTO THE MISSISSIPPI VALLEY. THE BETTER DYNAMICS FROM THIS SYSTEM WILL REMAIN WELL TO OUR EAST BUT WITH SOME MOISTURE POOLING BEHIND THE FRONT AND WEAK LIFT OVERNIGHT IN OUR EAST AM UNABLE TO COMPLETELY RULE OUT PCPN CHANCES. WILL THEREFORE KEEP SMALL POPS GOING DURING THE OVERNIGHT HOURS. THE FORECAST THURSDAY THROUGH FRIDAY WILL MAINLY BE DEPENDANT ON WHERE OUR FRONT WILL BE. THROUGH FRIDAY MORNING OUR SURFACE FRONT IS EXPECTED TO REMAIN NEARLY STATIONARY ALONG THE KS/OK BORDER. MUCH LIKE OUR LAST SYSTEM GOOD ISENTROPIC LIFT, MOISTURE AND ISENTROPIC LIFT DEVELOPS ALONG AND NORTH OF THIS BOUNDARY. WILL THEREFORE KEEP HIGH CHC POPS IN OUR SE CWA AND TAPER POPS OFF FURTHER NW AND HIGHLIGHT THE BETTER CHANCE OF PCPN THURSDAY NIGHT. BY FRIDAY THE BULK OF THE PCPN WILL BE MOVING OUT OF SW KS. HOWEVER WILL HAVE TO WATCH LOW LEVEL MOISTURE AND UPSLOPE FLOW EARLY FRIDAY. AT THIS TIME WILL GO WITH AREAS OF FOG AND DRIZZLE EARLY WITH SOME CLEARING LATE IN THE DAY. GIVEN THE CLOUDS AND UPSLOPE FLOW WILL ALSO LEAN TOWARDS THE COOLER MET NUMBERS FOR HIGHS FRIDAY. DAYS 3-7... AFTER LOOKING AT THE OVERALL PICTURE THIS MORNING THE GFS/ECMWF ARE VERY SIMILAR WITH THE NEXT FRONT MOVING INTO THE REGION OVER THE WEEKEND. THE ONSET OF OUR NEXT COLD FRONT MOVING IN FRIDAY NIGHT INTO SATURDAY WILL HELP SET THE SCENCE FOR CONVECTIVE ACTIVITY WITH ANOTHER DRY LINE OVER SOUTHWESTERN KANSAS. LOW LEVEL JET WILL PUSH AMPLE MOISTURE INTO THE REGION...MODELS HAVE ALSO INDICATED THE PRESENCE OF VERY STRONG CONVERGENCE WITHIN THE VICINITY OF THE DRY LINE. WITH UPPER LEVEL SUPPORT TO KICK OFF CONVECTIVE ACTIVITY WILL NOT BE ABLE TO RULE OUT THE CHANCES FOR SEVERE THUNDERSTORMS. AS THE SYSTEM BEGINS TO PUSH OUT OF THE REGION BY MONDAY MUCH DRIER AIR WILL TAKE PLACE OVER SOUTHWESTERN KANSAS FOR THE BEGINNING OF THE WEEK. DECIDED TO TWEAK TEMPERATURES UP A FEW DEGREES FOR THE FIRST PART OF THE WEEK. THEN ON WEDNESDAY LOOKS LIKE MOISTURE RETURNING TO OUR PART OF THE WORLD. HOWEVER JUST TOO EARLY TO SEE IF THIS WILL BECOME A MID WEEK MOISTURE PRODUCER. && .AVIATION... AREAS OF SCT HIGH LVL CLOUDS EXPECTED OVER MOST THE FORECAST AREA. BETWEEN 09-12Z LOW STRATUS CAN BE EXPECTED WITH VSBYS OF 5SM BR AND LGT AND VARIABLE WINDS ARE FORECAST SO CANNOT RULE OUT THE CHANCES FOR THE DEVELOPMENT OF FOG BETWEEN 09-15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 49 63 48 68 / 20 20 20 0 GCK 45 64 46 68 / 20 10 10 0 EHA 47 66 51 72 / 10 10 10 0 LBL 50 68 51 72 / 10 20 20 0 HYS 47 57 47 66 / 30 10 10 0 P28 56 66 54 68 / 30 50 50 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN18/31 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 242 PM CDT WED MAR 21 2007 .DISCUSSION... DAYS 1-2... MAIN CONCERN THIS AFTERNOON WILL BE IF/WHEN CONVECTION WILL DEVELOP ALONG A DRYLINE WHICH WAS SLOWLY MOVING EAST ACROSS OUR EASTERN CWA. AT THIS TIME NOT SEEING ANY GOOD UPPER LEVEL DYNAMICS AND BASED ON NAM SOUNDINGS THE CONVECTIVE TEMPS ALONG THE DRYLINE WERE BETWEEN 82-86F. ALSO NOTICING CAPES ALONG AND AHEAD OF THIS FRONT WERE AT 15-2K J/KG WITH IMPROVING MOIST CONV. THE RUC40 ALSO WAS FORECASTING 0-6KM SHEAR OF 30 TO 35KTS. IF THE CONVECTIVE TEMPERATURE CAN BE REACHED LATE TODAY SHOULD SEE A FEW STORMS GO UP QUICKLY WITH THE MAIN HAZARD BEING HAIL. DOES NOT LOOK LIKE ANYTHING WIDESPREAD SO WILL KEEP SLT CHC POPS AND ADJUST AS NEEDED AS WE APPROACH 4 PM BASED ON LATEST OBSERVATIONS/CU DEVELOPMENT. FOR TONIGHT A COLD FRONT MOVE SOUTH ACROSS KANSAS AS A NORTHERN BRANCH S/W TROF MOVES ACROSS THE NORTHERN PLAINS INTO THE MISSISSIPPI VALLEY. THE BETTER DYNAMIC FROM THIS SYSTEM WILL REMAIN WELL TO OUR EAST BUT WITH SOME MOISTURE POOLING BEHIND THE FRONT AND WEAK LIFT OVERNIGHT IN OUR EAST AM UNABLE TO COMPLETELY RULE OUT PCPN CHANCES. WILL THEREFORE KEEP SMALL POPS GOING DURING THE OVERNIGHT HOURS. THE FORECAST THURSDAY THROUGH FRIDAY WILL MAINLY BE DEPENDANT ON WHERE OUR FRONT WILL BE. THROUGH FRIDAY MORNING OUR SURFACE FRONT IS EXPECTED TO REMAIN NEARLY STATIONARY ALONG THE KS/OK BORDER. MUCH LIKE OUR LAST SYSTEM GOOD ISENTROPIC LIFT, MOISTURE AND ISENTROPIC LIFT DEVELOPS ALONG AND NORTH OF THIS BOUNDARY. WILL THEREFORE KEEP HIGH CHC POPS IN OUR SE CWA AND TAPER POPS OFF FURTHER NW AND HIGHLIGHT THE BETTER CHANCE OF PCPN THURSDAY NIGHT. BY FRIDAY THE BULK OF THE PCPN WILL BE MOVING OUT OF SW KS. HOWEVER WILL HAVE TO WATCH LOW LEVEL MOISTURE AND UPSLOPE FLOW EARLY FRIDAY. AT THIS TIME WILL GO WITH AREAS OF FOG AND DRIZZLE EARLY WITH SOME CLEARING LATE IN THE DAY. GIVEN THE CLOUDS AND UPSLOPE FLOW WILL ALSO LEAN TOWARDS THE COOLER MET NUMBERS FOR HIGHS FRIDAY. DAYS 3-7... AFTER LOOKING AT THE OVERALL PICTURE THIS MORNING SHOWS THE GFS/ECMWF/NAM TO BE VERY SIMILAR WITH THE NEXT FRONT MOVING INTO THE REGION OVER THE WEEKEND. THE ONSET OF OUR NEXT COLD FRONT MOVING IN FRIDAY NIGHT INTO SATURDAY WILL HELP SET THE SCENCE FOR CONVECTIVE ACTIVITY WITH ANOTHER DRY LINE OVER SOUTHWESTERN KANSAS. LOW LEVEL JET WILL PUSH AMPLE MOISTURE INTO THE REGION...MODELS HAVE ALSO INDICATED THE PRESENCE OF VERY STRONG CONVERGENCE WITHIN THE VICINITY OF THE DRY LINE. WITH UPPER LEVEL SUPPORT TO KICK OFF CONVECTIVE ACTIVITY WILL NOT BE ABLE TO RULE OUT THE CHANCES FOR SEVERE THUNDERSTORMS. AS THE SYSTEM BEGINS TO PUSH OUT OF THE REGION BY MONDAY MUCH DRIER AIR WILL TAKE PLACE OVER SOUTHWESTERN KANSAS FOR THE BEGINNING OF THE WEEK. DECIDED TWEAK TEMPERATURES UP A FEW DEGREES FOR THE FIRST PART OF THE WEEK. THEN ON WEDNESDAY LOOKS LIKE MOISTURE RETURNING TO OUR PART OF THE WORLD. HOWEVER JUST TOO EARLY TO SEE IF THIS WILL BECOME A MID WEEK MOISTURE PRODUCER. && .AVIATION... AREAS OF SCT HIGH LVL CLOUDS EXPECTED OVER MOST THE FORECAST AREA. BASED ON SATELLITE IMAGRY CIGS AND VSBYS ARE NOT EXPECTED TO DROP BELOW VFR CONDITIONS. BETWEEN 09-12Z LOW STRATUS CAN BE EXPECTED WITH VSBYS OF 5SM BR AND LGT AND VARIABLE WINDS ARE FORECAST SO CANNOT RULE OUT THE CHANCES FOR THE DEVELOPMENT OF FOG BETWEEN 09-15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 49 63 48 68 / 20 20 20 0 GCK 45 64 46 68 / 20 10 10 0 EHA 47 66 51 72 / 10 10 10 0 LBL 50 68 51 72 / 10 20 20 0 HYS 47 57 47 66 / 30 10 10 0 P28 56 66 54 68 / 30 50 50 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN18/31 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 100 AM EDT FRI MAR 23 2007 AVIATION (06Z TAFS)... NO AVIATION CONCERNS THROUGH THE MORNING HOURS FRIDAY EXCEPT FOR SOME HIGH CLOUDINESS EXPECTED AT SDF AND LEX. THESE HIGH CLOUDS ARE CONVECTIVE DEBRIS CLOUDS DOWNSTREAM FROM WIDESPREAD CONVECTION ACROSS CENTRAL INDIANA AND ILLINOIS. SKIES WILL REMAIN CLEAR AT BWG OVERNIGHT. FOG FORMATION WILL NOT BE A FACTOR AS DECENT SOUTHERLY WINDS AT 1500FT (25KT) WILL KEEP THE BOUNDARY LAYER SOMEWHAT MIXED. ALSO NOTED THAT A 10-15 DEGREE DEWPOINT DEPRESSIONS ARE PRESENT EVEN NOW WITH THE LATEST SURFACE OBS. SKIES WILL BECOME INCREASINGLY CLOUDY LATE THIS AFTERNOON. SCATTERED SHOWER MAY DEVELOP AFTER 18Z ACROSS LEX AND SDF. CEILINGS WILL STAY VFR TOMORROW AFTERNOON EXCEPT UNDERNEATH ANY LOCAL SHOWERS. JSD && .PREV DISCUSSION... /ISSUED 729 PM EDT THU MAR 22 2007/ EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIFY CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 902 PM CDT THU MAR 22 2007 .UPDATE... FORECAST UPDATED MAINLY TO REMOVE EVENING WORDING. ADDED A SLIGHT CHANCE POP FOR SW INDIANA OVERNIGHT DUE TO THE CLOSE PROXIMITY OF THE SURFACE BOUNDARY. GRADUAL INCREASE IN CONVECTION NOTED OVER CENTRAL IL/CENTRAL MO/EASTERN KS OVER THE PAST COUPLE OF HOURS. THIS CONVECTION IS ALONG THE FRONT...WHICH THE MODELS KEEP QUASI STATIONARY FOR THE NEXT FEW DAYS. THIS CONVECTION MAY PROPAGATE SOUTHEAST AWAY FROM THE BOUNDARY INTO SRN ILLINOIS AND SE MISSOURI OVERNIGHT. RUC MODEL CORFIDI VECTORS INDICATE A SE MOVEMENT TO ANY ORGANIZED MCS THAT DEVELOPS. && .PREVIOUS DISCUSSION... MAIN CONCERNS FOR THIS FORECAST CONTINUE TO BE POPS THROUGH THE ENTIRE PERIOD...AS TEMPERATURES WILL REMAIN MILD THROUGHOUT. ELEVATED CONVECTION HAS SHRUNK DOWN TO A NARROW BAND OF SHOWERS RIGHT THROUGH THE MID-SECTION OF THE AREA...AND IT APPEARS TO BE WEAKENING AND FINALLY PUSHING OFF TO THE EAST. WITH THE AIRMASS THOROUGHLY WORKED OVER...AND THE SURFACE BOUNDARY WELL NORTH OF THE AREA...SEE LITTLE REASON TO HAVE MUCH POP IN THE AREA THIS EVENING. WILL HOWEVER...INCLUDE A SMALL CHANCE IN THE NORTHEAST IN AN ATTEMPT TO FIT IN TO SOME DEGREE WITH NEIGHBORS. OVERNIGHT...THE GFS IS A BIT FASTER BRINGING ANOTHER ROUND OF ELEVATED CONVECTION EASTWARD INTO THE REGION...AS ANOTHER MID-LEVEL DISTURBANCE BRINGS AN AREA OF LOW-LEVEL THETA-E ADVECTION INTO THE REGION. IF THE NAM IS RIGHT...THE CONVECTION WILL STAY TO OUR WEST THROUGH 12Z...BUT THE GFS BRINGS INTO OUR WEST JUST BEFORE 12Z. WILL MENTION A CHANCE OVERNIGHT IN THE WEST...AND THEN RAMP UP TO 50-60 POPS SOUTH TO NORTH ON FRIDAY. THIS SIGNAL HAS BEEN THERE FOR A COUPLE OF DAYS...HOWEVER...IF IT IS AS FOCUSED AS TODAYS CONVECTION HAS BEEN...SOME AREAS MAY NOT GET WET. THEREFORE WILL NOT GO HIGHER THAN 60S FOR NOW. THOSE 60S WILL BE IN THE NORTH WHERE THE MODELS ARE IN BETTER AGREEMENT WITH THE QPF. THE NAM IS NOT SURE ABOUT OUR SOUTHERN ZONES GETTING WET. MAY SEE SOME LINGERING CONVECTION FRIDAY NIGHT MAINLY NORTHEAST...SO WILL LEAVE A 20-30 POP ACROSS MUCH OF THE AREA. ON SATURDAY...THE FRONT RE-LOCATES WELL NORTH OF THE AREA...AND WILL KEEP THE FOCUS FOR CONVECTION TO OUR NORTH AS WELL. THE 12Z NAM TRIES TO REGENERATE CONVECTION ALL OVER THE AREA ON SATURDAY...BUT IT IS THE LONE MODEL THAT DOES NOT BUILD A MID/UPPER-LEVEL RIDGE THROUGH THE AREA. WILL THEREFORE IGNORE ITS SOLUTION FOR NOW. THE WEEKEND SHOULD BE QUITE GLORIOUS WITH TEMPS PUSHING 80 EACH AFTERNOON AND LOWS IN THE 50S. IN THE MEDIUM RANGE...EVEN THE ECMWF IS NOW TRYING TO DRAG SOME REMNANT OF THE SW U.S. CUT OFF LOW ACROSS THE AREA SOMETIME MONDAY OR TUESDAY. WILL THROW IN 20-30 POPS FOR THIS PERIOD WITH THE BEST CHANCES MONDAY NIGHT INTO TUESDAY. TUESDAY NIGHT AND WEDNESDAY LOOK DRY...BUT A MORE SIGNIFICANT SYSTEM MAY BEGIN TO EFFECT THE AREA ON THURSDAY OR FRIDAY. TEMPERATURES WILL CONTINUE TO BE WELL ABOVE NORMAL THROUGH THE ENTIRE 7 DAY PERIOD...WITH HIGHS IN THE 70S OR LOWER 80S AND LOWS IN THE 50S OR LOWER 60S. THE EXCEPTION WILL BE TOMORROW WHERE THE CONVECTION MAY HOLD TEMPS IN THE 60S. HOWEVER...IT IS NOT CERTAIN WHERE THE PRECIPITATION WILL BE FOCUSED ACROSS THE AREA TOMORROW. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ UPDATE...MY PREVIOUS...DRS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 953 PM EDT THU MAR 22 2007 .UPDATE... SMALL UPDATE TO SLIGHTLY LOWER OVERNIGHT LOWS A DEGREE OR TWO ACROSS PORTIONS OR THE NORTHERN AREA AROUND SDF AND LEX...NOT SO MUCH ACROSS THE SOUTHERN HALF OF THE AREA. -SCHOTT && .PREV DISCUSSION... /ISSUED 729 PM EDT THU MAR 22 2007/ EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT AVIATION DISCUSSION (00Z TAFS)... GRADUAL CLEARING APPEARS TO BE DEVELOPING IN THE LATEST VIS SAT LOOP...NOTHING OF ANY SIGNIFICANCE LOOKS TO EFFECT AVIATION CONCERNS THROUGH DAYBREAK FRIDAY. MODEST LOW LEVEL JET DEVELOPS TONIGHT BUT DOESN`T REACH THE 20 KNOTS GREATER THAN SFC WINDS TO MENTION IN THE TAFS...BUT 20 TO 25 KTS AROUND 1500 TO 2000 FEET LOOKS LIKELY OVERNIGHT. VFR CONDITIONS AT ALL THREE TAFS SITES LOOKS AS A GOOD BET THROUGH THE PERIOD...SOME SCATTERED SHOWER AND THUNDERSTORM ACTIVITY LOOKS TO PUSH SOUTH INTO THE NORTHERN TAF SITES OF SDF AND LEX AFTER 14 TO 18Z...WITH SHRA POSSIBLE AT BWG AFTER 22Z. --SCHOTT PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIF CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ AVIATION (18Z TAFS)... SCT TO NUMEROUS SHOWERS WILL STREAM EWD THRU THE AFTN ALONG AND EITHER SIDE OF OH RIVER. STILL A CONVECTIVE THREAT BUT CG LIGHTNING ACTIVITY GRADUALLY DIMINISHING AT THIS TIME. KLVX VWP PROFILE SHOWS UNIFORM SWLY FLOW IN LOW-LEVELS WITH ONLY MODEST INCREASE IN SPEED WITH HEIGHT...THUS LOW-LEVEL WIND SHEAR NO LONGER A SIGNIFICANT HAZARD. CIGS MAY OCCASIONALLY FALL INTO MVFR CATEGORY BUT GENERALLY CIGS EXPECTED ABOVE 3KFT (VFR) DURING FCST PD. AS SHORTWAVE TO OUR N PULLS OUT...PRECIP SHOULD BE MORE SCT LATE TNGT AND EARLY FRI...BEFORE MODELS SHOW NEXT SURGE OF MOISTURE AND PRECIP ARRIVING FRI AFTN. TWF LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 729 PM EDT THU MAR 22 2007 .EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT && .AVIATION DISCUSSION (00Z TAFS)... GRADUAL CLEARING APPEARS TO BE DEVELOPING IN THE LATEST VIS SAT LOOP...NOTHING OF ANY SIGNIFICANCE LOOKS TO EFFECT AVIATION CONCERNS THROUGH DAYBREAK FRIDAY. MODEST LOW LEVEL JET DEVELOPS TONIGHT BUT DOESN`T REACH THE 20 KNOTS GREATER THAN SFC WINDS TO MENTION IN THE TAFS...BUT 20 TO 25 KTS AROUND 1500 TO 2000 FEET LOOKS LIKELY OVERNIGHT. VFR CONDITIONS AT ALL THREE TAFS SITES LOOKS AS A GOOD BET THROUGH THE PERIOD...SOME SCATTERED SHOWER AND THUNDERSTORM ACTIVITY LOOKS TO PUSH SOUTH INTO THE NORTHERN TAF SITES OF SDF AND LEX AFTER 14 TO 18Z...WITH SHRA POSSIBLE AT BWG AFTER 22Z. --SCHOTT && .PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIF CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ AVIATION (18Z TAFS)... SCT TO NUMEROUS SHOWERS WILL STREAM EWD THRU THE AFTN ALONG AND EITHER SIDE OF OH RIVER. STILL A CONVECTIVE THREAT BUT CG LIGHTNING ACTIVITY GRADUALLY DIMINISHING AT THIS TIME. KLVX VWP PROFILE SHOWS UNIFORM SWLY FLOW IN LOW-LEVELS WITH ONLY MODEST INCREASE IN SPEED WITH HEIGHT...THUS LOW-LEVEL WIND SHEAR NO LONGER A SIGNIFICANT HAZARD. CIGS MAY OCCASIONALLY FALL INTO MVFR CATEGORY BUT GENERALLY CIGS EXPECTED ABOVE 3KFT (VFR) DURING FCST PD. AS SHORTWAVE TO OUR N PULLS OUT...PRECIP SHOULD BE MORE SCT LATE TNGT AND EARLY FRI...BEFORE MODELS SHOW NEXT SURGE OF MOISTURE AND PRECIP ARRIVING FRI AFTN. TWF LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 144 PM EDT WED MAR 21 2007 .SHORT TERM.../TODAY THROUGH FRIDAY NIGHT/ ISOLATED SHOWERS MOVED ALONG THE KY/TN BORDER THIS MORNING. RADAR HOWEVER CURRENTLY SHOWS THESE HAVE DISSIPATED. SOME ADDITIONAL SHOWERS ATM ARE JUST NORTH OF OUR NW COUNTIES MOVING W TO EAST JUST SOUTH OF THE OH RIVER. RUC AND WRF-NAM BOTH KEEP PRECIP OUT OF FORECAST AREA FOR MOST OF THE REMAINDER OF 1ST PERIOD. BOTH MODELS ARE SHOWING POSSIBILITY OF SOME ADDITIONAL DEVELOPMENT LATER THIS AFTERNOON..IN ASSOCIATION WITH WEAK UPPER-LEVEL SHORT WAVE. THIS IS CONFINED PRIMARILY IN OUR FAR EASTERN ZONES AND ALONG THE SPINE OF THE APPALACHIANS. BELIEVE THIS IS WAY OVERDONE. HAVE THEREFORE KEPT POPS BELOW SLIGHT CHANCE ENTIRE PERIOD. IF RUC/NAM FORECAST DOES PAN OUT...WE`LL ADDRESS ACTIVITY WITH SHORT-TERM FORECASTS. LOCAL OBSERVATIONS SHOW TEMPERATURES ARE CURRENTLY ON TRACK WITH FORECAST GRIDS. UPDATE ALREADY OUT TO REMOVE DENSE FOG ADVISORY...POPS...AND MORNING WORDING. NEAR TERM WINDS WERE REFRESHED USING RUC GUIDANCE. ...REMAINDER OF EARLIER DISCUSSION FOLLOWS. THE MODELS ARE EXHIBITING SIMILAR DIFFERENCES ALOFT AS THEY WERE LAST NIGHT. THEY ALL HAVE A LONGWAVE PATTERN THAT FEATURES A CLOSING LOW OVER THE DESERT SOUTHWEST...FAST NORTHERN STREAM FLOW WITH A WAVE CROSSING THE GREAT LAKES EARLY THURSDAY AND SOME RIDGING ACROSS THE SOUTHEAST. THE FIRST ITEM OF CONCERN FOR EAST KENTUCKY WILL BE THE WAVE PASSING BY TO THE NORTH. WITH THIS...THE NAM IS A TAD FASTER AND STRONGER THAN THE GFS. AS FOR THE DEVELOPING BAJA LOW THE GFS REMAINS FURTHER EAST THAN THE NAM. IN THE WAKE OF THE NORTHERN STREAM WAVE PASSING AND THE BAJA LOW OPENING UP TOWARD THE END OF THE WORK WEEK...KENTUCKY WILL FIND ITSELF AWASH IN FAST MOVING MINOR WAVES. THESE WILL BE RUNNING EAST FROM THE SOUTHERN PLAINS IN THE ZONAL FLOW FOUND ON THE NORTHERN FRINGE OF THE SOUTHERN RIDGE. DESPITE THE NAM HAVING MORE SUPPORT WITH ITS SOLUTION FOR THE NORTHERN STREAM WAVE EARLY ON...THE GFS IS FAVORED FROM THURSDAY AFTERNOON ON GIVEN ITS APPARENT BETTER HANDLING OF THE OPENING LOW OVER THE SOUTHWEST. FOR FORECAST SPECIFICS HAVE LEANED TOWARD THE GFS FRONTAL POSITION ...BUT FOLLOWED THE NAM/S EVOLUTION AND TIMING OF THE INDIVIDUAL WAVES THAT PASS OVERHEAD AND AMPLIFY THE FRONT THROUGH THE LATTER PART OF THE WORK WEEK. SENSIBLE WEATHER WILL FEATURE AREAS OF DENSE FOG BURNING OFF AND MIXING OUT LATER THIS MORNING REVEALING A PARTLY SUNNY SKY AND ONLY AN SMALL CHANCE FOR A POP-UP SHOWER. HAVE LEFT THUNDER OUT OF THE FORECAST FOR TODAY GIVEN THE LOW POPS AND MARGINAL INSTABILITY. TONIGHT SHOULD BE MORE OF THE SAME WITH THE MOIST BOUNDARY LAYER... AND ONLY PARTIAL CLOUDINESS...RESULTING IN RADIATIONAL FOG. A WAVE SEEN IN THE GFS THAT PASSES BY TO THE NORTHEAST WILL PROBABLY BE TOO FAR AWAY TO WARRANT EVEN SLIGHT CHANCE POPS. NEXT...A COLD FRONT FROM THAT NORTHERN STREAM WAVE WILL SAG TOWARD KENTUCKY ON THURSDAY BEFORE STRETCHING OUT AND BECOMING STATIONARY OVER THE NORTHERN HALF OF THE STATE LATER THAT NIGHT. THIS WILL RESULT IN A PROLONGED AND PERSISTENT PERIOD OF DECENT POPS FOR SHOWERS AND THUNDERSTORMS LASTING INTO FRIDAY NIGHT AS IMPULSES MOVE EAST ALONG THE BOUNDARY... SPURNED ALONG BY THE MINOR UPPER WAVES SPINNING OUT OF THE OPENING SOUTHWESTERN LOW. WITH THE TEMPERATURES...WENT WITH THE WARMER MET NUMBERS TODAY AND THURSDAY...THOUGH HELD THE DIURNAL RISE BACK A BIT THIS MORNING UNTIL THE FOG BURNS OFF. FOR HIGHS FRIDAY...FOLLOWED MORE OF A BLEND. AT NIGHT...THE NUMBERS WERE SIMILAR SO WENT WITH A BLEND...ALONG WITH SOME SITE SPECIFIC TWEAKING. THE POPS ENDED UP CLOSEST TO THE MET NUMBERS THROUGH THE SHORT TERM PART OF THE FORECAST. .LONG TERM.../SATURDAY THROUGH TUESDAY/ A FRONTAL BOUNDARY WILL LINGER ACROSS THE AREA TO END THE WORKWEEK...WITH THE BEST CHANCE OF RAIN REMAINING ALONG AND NORTH OF THE MOUNTAIN PARKWAY. ECMWF AND GFS CONTINUE TO DIFFER WITHIN THE DETAILS OF THE FORECAST INTO EARLY NEXT WEEK. TWO MAIN FEATURES OF INFLUENCE WILL BE A BUILDING SOUTHEASTERN CONUS RIDGE...WITH AN EJECTING UPPER LEVEL LOW APPROACHING OUT OF THE SOUTHWEST. ECMWF WASHES THE AFOREMENTIONED FRONT OUT TO THE SOUTH...WITH A LARGE AREA OF HIGH PRESSURE LENDING IT`S INFLUENCE ACROSS THE AREA THROUGH THE WEEKEND. THE PROGGED RIDGE THEN SLOWS AS WELL DAMPENS THE UPPER LEVEL LOW SIGNIFICANTLY BY EARLY NEXT WEEK. GFS STARTS OUT WITH A MUCH WEAKER AREA OF HIGH PRESSURE PUSHING IN FOR THE BEGINNING OF THE WEEKEND...GENERALLY KEEPING THE FRONT AROUND LONGER AND LINGERING PRECIPITATION INTO EARLY SATURDAY...BEFORE PUSHING BACK NORTH BY SATURDAY AFTERNOON AS MORE MODEST RIDGING TAKES PLACE THROUGH SUNDAY. A MUCH MORE ROBUST PROGGED UPPER LEVEL LOW LIFTS THROUGH MONDAY INTO TUESDAY...WITH SCATTERED PRECIPITATION ASSOCIATED WITH THIS FEATURE. HAVE COMPROMISED BETWEEN THE MODELS. ECMWF HAS BEEN MORE CONSISTENT LATELY...HOWEVER FEEL THAT IT DOES DAMPEN THE UPPER LEVEL LOW A BIT TOO MUCH AS IT BRINGS IT IN. ON THE OTHER HAND...THE GFS SEEMS A BIT OVERDONE WITH THE UPPER LEVEL FEATURE. AS SUCH...WILL KEEP THE MAJORITY OF THE WEEKEND DRY UNDER THE INFLUENCE OF UPPER LEVEL RIDGING...WHILE INTRODUCING CHANCE POPS BY MONDAY AFTERNOON AS THE WAVE APPROACHES. TEMPERATURES CONTINUE TO LOOK ABOVE NORMAL THROUGHOUT THE PERIOD AS WELL. GENERALLY STAYED A BIT WARMER THAN MOS...THINKING THAT THE NUMBERS ARE A BIT COOL WITH THE OVERPLAYED CLOUD COVER AND PRECIPITATION. && .AVIATION.../18Z TO 18Z/...UPDATED WARM FRONT HAS EDGED NORTH TODAY AND IS CURRENTLY LOCATED ALONG OUR NORTHERN TIER OF COUNTIES. A FEW WIDELY SCATTERED SHOWERS KICKED UP EARLIER NORTH OF THE BOUNDARY...BUT SATELLITE CURRENTLY SHOWS NO ACTIVITY. SHORT RANGE FORECAST MODELS SHOW HIGH PRESSURE...LOCATED TO OUR SOUTHEAST HOLDING IN PLACE THROUGH MOST OF THE FORECAST PERIOD. THURSDAY AFTERNOON HOWEVER A COLD FRONTAL BOUNDARY WILL DROP OUT OF THE NORTHWEST...BRINGING SHOWERS AND MVFR CEILINGS BACK INTO THE REGION. TIMING RIGHT NOW LOOKS TO BE OUTSIDE THE 24-HOUR TAF PERIOD...SO CONDITIONS ARE NOT REFLECTED IN THIS 18Z-18Z TAF. SUBSEQUENT ISSUANCES THOUGH WILL NEED TO CONSIDER INCLUDING SHOWERS / LOWERING CEILINGS IN ANOTHER CHANGE GROUP. FOR NOW...CEILINGS/ VISIBILITIES WILL REMAIN VFR...WITH CLOUD BASES GRADUALLY LOWERING THIS EVENING FROM HIGH CIRRUS DECK THIS AFTERNOON TO MID-LEVELS THIS EVENING. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE && $$ SHORT TERM...MCLANE/GREIF LONG TERM....GEOGERIAN AVIATION...MCLANE ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1048 AM EDT THU MAR 22 2007 .SHORT TERM /REST OF TODAY/... AREA MORNING UPPER AIR SOUNDINGS SHOW LAYERED MOISTURE THROUGH MUCH OF THE COLUMN. SFC OBS/SATL DATA CONFIRMS SCT-BKN MULTILAYERED CLOUDS ACRS FORECAST AREA THIS LATE MORNING BUT THE CLOUD PATCHES APPEAR TO BE BREAKING AND THINNING. THEREFORE EXPECT SKY CONDITION WILL AVERAGE PTSUNNY DURING THE AFTN. INSOLATION SHUD BE SUFFICIENT TO ALLOW TEMPS TO REACH FCSTD VALUES RANGING FROM M60S ACRS THE EASTERN SHORE TO M70S OVER PIEDMONT...BUT OF COURSE COOLER WHERE FLOW IS ONSHORE. LTL IF ANY CHANGES NEEDED TO FCST ATTM BUT UPDATED FCST TO REFRESH PRODUCTS. .MARINE UPDATE... DECIDED TO ADD SCA FOR THE CHESAPEAKE BAY WTRS FROM SMITH POINT TO NEW POINT COMFORT...WITH 15-20 KT WINDS AND 2-3 FT WAVES. RUC AND NAM MODELS SUGGEST INCRSG SFC WINDS AFTER 18Z. SOUNDINGS SHOW AROUND 15 KT AT SFC UNDER WEAK INVERSION WITH 25-30 KTS ABOVE INVERSION. EXPECT ENOUGH MIXING TO ALLOW 20 KT GUSTS DOWN TO SFC. STRONGER LOW LEVEL INVERSION TO SOUTH OF NEW POINT COMFORT SO OPTED NOT TO GO FOR SCA FOR SOUTHERN BAY BUT STEADY 15 KT. ON CSTL WTRS...EXPECT 15-20 KT SOUTH WINDS FROM FENWICK DOWN TO PARRAMORE WITH LONGER FETCH BUILDING SEAS TO SCA CRITERIA AFTER 2 PM. DIFFICULT FCST FOR THE WEEKEND WITH BACKDOOR COLD FRONT SAT/SAT NGT. HAVE DECIDED TO GO CLOSER TO NAM/UKMET (GFS IS OUTLIER)...KEEPING SW FLOW SRN ZONES ON SAT...ELY FLOW ACRS THE NORTH. THEN...FRONT CLEARS ENTIRE MARINE AREA SAT NGT/SUN...WITH NNE FLOW AND POSSIBLE SMALL CRAFT CONDITIONS AT THAT TIME. && .PREV DISCUSSION... /ISSUED 513 AM EDT THU MAR 22 2007/ SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... CURRENTLY...HIGH PRESSURE CONTINUES TO PUSH OFFSHORE WHILE A COLD FRONT ADVANCES EAST THROUGH THE WESTERN GREAT LAKES AND MIDWEST REGIONS. THE MAIN FORECAST CONERN TODAY WILL BE WITH CLOUD COVER EXTENT (DEPTH) AND THUS IMPACT ON TEMPS. GFS/NAM ARE IN FAIRLY CLOSE ACCORD IN THE SHORT TERM (THROUGH TONIGHT). BOTH INDICATE THE COLD FRONT DROPPING TO NEAR THE MASON- DIXON LINE BY MIDNIGHT TONIGHT...BECOMING MORE W-E ORIENTED AS THE ASSOCIATED UPPER LEVEL VORT LOBE ENCOUNTERS A ZONAL/FLAT UPPER RIDGE. PRE-FRONTAL FORCING/MOISTURE IS INSUFFICIENT FOR POPS ACROSS THE FCST AREA TODAY. AS FOR SKY COVER...EXPECT THE LOWER CLOUDS TO SCOUR OUT LATER THIS MORNING/AFTN AS THE LOW LEVEL FLOW VEERS TOWARD THE S-SW RESULTING IN MORE APPRECIABLE WARMING (AND RELATIVE DRYING) WITHING THE 1000-850 MB LAYER. STILL EXPECT PERIODIC WAVES OF HIGHER BASED CLOUDS IN THE AFTN AS WE GET INTO THE WARM SECTOR...THUS HAVE WORDED PARTLY SUNNY. BASED ON RECENT TRENDS (YDAY)...HAVE GONE A FEW DEGREES HIGHER THAN MOS TODAY FOR HIGH TEMPS. THIS BASED ON THE LOW LEVEL WAA AND INCREASED SUNSHINE THIS AFTN (ANTICIPATED DEEPER MIXING WITH THE LATE MARCH SUN ANGLE). TONIGHT...FRONT DIPS INTO NRN VA AND THE NRN PTN OF THE DELMARVA. HAVE INCLUDED LOW (30-40%) POPS OVER THE NRN THIRD OF THE CWA CLOSEST TO THE FRONT...THOUGH ONCE AGAIN WITH THE FLATTENING UPPER FLOW (AND NEGLIGIBLE STRAIGHT UPPER JET FORCING)...DYNAMICS AND THUS MOISTURE DEPTHS REMAIN LACKING. S OF FVX-RIC-MFV...MOISTURE IS JUST TOO SHALLOW (PARTICULARLY IN LOW LEVELS) FOR POPS. FRIDAY...COMPARED TO THE NAM/UKMET/ECMWF...THE 00Z GFS IS TOO QUICK WITH THE INITIAL IMPULSE TRACKING FROM THE UPPER MIDWEST- OH VLY-MID ATLC REGION. SIDING MORE TOWARD A NAM/ECMWF BLEND... EXPECT A NW-SE DRAPED SURFACE FRONTAL BNDRY ACROSS THE FCST AREA... WITH THE FRONT TAKING ON THE TYPICAL "SAG" EAST TOWARD THE COOLER COASTAL WATERS. AS A RESULT EXPECT A LARGE TEMP GRADIENT FROM SW-NE... I.E. AROUND 80/LOWER 80S INLAND TO AROUND 60 ALONG THE LOWER ERN SHORE. WILL ALSO MAINTAIN MORE EXTENSIVE CLOUD COVER/LOW POPS OVER THE N-NE ZONES ALONG AND N OF THE PROJECTED FRONTAL ZONE. SATURDAY...GFS IS MUCH COOLER WITH THE LOWER LEVELS COMPARED TO THE OTHER MODELS...BASICALLY A CONSEQUENCE OF THIS MODEL BEING TOO PROGRESSIVE WITH THE INITIAL UPPER SHORTWAVE/WEAK SURFACE LOW ALONG THE STATIONARY FRONT. GFS (MAV) MOS GUIDANCE IN FACT IS SOME 20+ DEGREES COOLER WITH HIGH TEMPS OVER INLAND LOCALES COMPARED TO THE NAM (MET) GUIDANCE! FOR NOW WILL CONTINUE TO LEAN MORE TOWARD THE NAM/ ECMWF...WHICH DOES NOT DROP THE FRONT S OF THE LOWER DELMARVA UNTIL LATE IN THE DAY. BASED ON THESE PROJECTIONS...EXPECT ANOTHER DAY WITH A SIGNIFICANT TEMPERATURE GRADIENT FROM SW (80-85) TO AREAS ALONG THE ATLANTIC SIDE OF THE LOWER MD ERN SHORE (LOW-MID 50S). LONG TERM /SUNDAY THROUGH WEDNESDAY/... BASED ON THE LATEST NAM/ECWMF TRENDS...AND WITH THE LOWER CONFIDENCE IN THE GFS SAT-SUN...DID NOT MAKE TOO MANY CHANGES TO THE FCSTS DURING THE EXTENDED PERIODS. HIGH PRESSURE BUILDING FROM THE N AND EVENTUALLY NE (OFFSHORE) ON SUNDAY WILL MAKE FOR A COOLER DAY OVER THE NERN PTNS OF THE FCST AREA...THOUGH AGAIN EXPECT TEMPS TO REMAIN MUCH MILDER AS YOU HEAD FARTHER SW. TOWARD PETERSBURG/FARMVILLE/SOUTH HILL. AVIATION...VARIABLE CONDITIONS EARLY THIS MORNING...HAVE MVFR CIGS NORTH AND WEST...VFR SOUTH. FLOW TURNS TO S OR SW LATER TODAY WITH INCREASING WIND SPEEDS BY AFTN...AND MAINLY VFR CONDS. MVFR CIGS MAY HANG TOUGH ON THE ERN SHORE THRU 16-18Z. CONTINUED VFR TONIGHT AS MIXING SHOULD INHIBIT SIGNIFICANT FOG FORMATION. MARINE...GRADIENT INCREASES FROM SOUTH TO SOUTHWEST LATER TODAY. CHILLY BAY WATERS WILL MAKE IT DIFFICULT TO EFFICIENTLY MIX THESE WINDS DOWN TO THE SFC...SO OPTED TO KEEP CONDITIONS ON THE BAY & SOUND BELOW SMALL CRAFT (ALTHOUGH IT WILL BE CLOSE LATER THIS AFTN). ON COASTAL WATERS...INCREASING SOUTHERLY FLOW (NEAR 20 KTS BY AFTN) WILL LIKELY BRING SEAS TO MARGINAL SMALL CRAFT CONDITIONS (5 FT WAVES OFFSHORE) N OF PARRAMORE ISL...FROM LATER IN THE AFTN THROUGH ERLY MRNG THU. DIFFICULT FCST FOR THE WEEKEND WITH BACKDOOR COLD FRONT SAT/SAT NGT. HAVE DECIDED TO GO CLOSER TO NAM/UKMET (GFS IS OUTLIER)...KEEPING SW FLOW SRN ZONES ON SAT...ELY FLOW ACRS THE NORTH. THEN...FRONT CLEARS ENTIRE MARINE AREA SAT NGT/SUN...WITH NNE FLOW AND POSSIBLE SMALL CRAFT CONDITIONS AT THAT TIME. FIRE WEATHER...LIGHT SE TO S FLOW THIS MRNG...WITH GUSTY SOUTH...SOUTHWEST WINDS INCREASING BY AFTN FOR MUCH OF INLAND VA. HOWEVER...NOT REALLY A DOWNSLOPE FLOW SO RH VALUES DO NOT DROP OFF THAT MUCH...WITH MOST LOCATIONS BOTTOMING OUT 35-45% AT THE DRIEST. FARTHER EAST...COOLER TEMPERATURES WILL TEND TO INHIBIT MIXING SOMEWHAT SO WINDS LIKELY STAY MORE FROM DUE SOUTH AT 15 KTS OR LESS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM EDT FRIDAY FOR ANZ630-631-650-652. && $$ SHORT TERM UPDATE...CULLEN/FOSTER md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1100 AM EDT FRI MAR 23 2007 .UPDATE... MID CLOUDS CONTINUE TO LINGER LATE THIS MORNING OVER THE ERN FCST AREA...AND NEW CLOUD DEVELOPMENT IS OCCURRING OVER NCNTRL UPPER MI. CLOUDS ARE DEVELOPING IN AN AREA OF PERSISTENT ISENTROPIC ASCENT AS VIEWED ON 290K SFC (ROUGHLY 750-800MB) PER 12Z RUC. ASCENT SLACKENS DURING THE AFTN...SO CLOUDS SHOULD TEND TO THIN OUT SOME LATER IN THE AFTN. AS FOR TEMPS...12Z KINL/KGRB SOUNDINGS AND MORNING TAMDAR SOUNDING FROM KSAW SUPPORT RAISING HIGH TEMPS. KINL/KGRB SOUNDINGS YIELD HIGHS IN THE MID 50S TO AROUND 60F IF MIXED LAYER BUILDS TO 850MB WHILE KSAW SOUNDING SUPPORTS HIGHS IN THE LWR 50S. RAISED HIGHS TO THE LWR END OF THOSE VALUES GIVEN SOME CLOUD COVER. TEMPS WILL BE CONSIDERABLE COOLER NEAR LAKE MICHIGAN UNDER LIGHT SRLY FLOW...AND THE COOLING SHOULD EXTEND ACROSS ALL OF THE ERN FCST AREA. LAKE BREEZE SHOULD DEVELOP OFF LAKE SUPERIOR EXCEPT FOR AREAS E OF MARQUETTE AS SRLY FLOW SHOULD BE SUFFICIENT THRU THE AFTN TO PREVENT DEVELOPMENT THERE. && .PREV DISCUSSION (ISSUED AT 530 AM EDT)... MAIN FCST CONCERNS IN SHORT TERM ARE CLOUDS/TEMPS THEN FOCUS WILL BE ON TIMING OF NEXT CHC OF RAIN/THUNDERSTORMS FOR SUN AFTERNOON. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. ONE SHORTWAVE IS MOVING THROUGH THE UPR GREAT LAKES EARLY THIS MORNING WHILE ANOTHER IS UPSTREAM OVER SRN ALBERTA. SHORTWAVE MOVING THROUGH UPR GREAT LAKES PRODUCED A FEW FLURRIES THIS MORNING NORTH OF LAKE SUPERIOR IN AREA OF WEAK Q-VECT CONV AND ISENTROPIC ASCENT. MODEL SNDGS CONSISTENT IN SHOWING LINGERING MOISTURE AROUND 850 MB IN WAKE OF SHORTWAVE SO KEPT IN A BIT MORE CLOUD COVER TODAY IN ANTICIPATION OF STRATOCU DEVELOPING DURING THE DAY. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE LOW/MID 50S OVER THE WRN INTERIOR. SRLY FLOW WILL KEEP TEMPS MUCH COOLER OVER THE ERN FCST AREA NEAR AND DOWNWIND OF LAKE MICHIGAN. LOCAL COOLING SHOULD ALSO OCCUR NEAR LAKE SUPERIOR OVER THE W AND NCNTRL AREAS MID/LATE AFTN WHERE BOUNDARY LAYER WINDS WILL BE LIGHTER. FROM MUNISING EWD...SRLY FLOW MAY STRONG ENOUGH 10-15 KT TO SUPRESS LAKE BREEZE DEVELOPMENT. NEXT SHORTWAVE FROM ALBERTA IS DUE TO MOVE INTO THE UPR GREAT LAKES LATE FRI NIGHT AND SAT. UPR DIV IN RRQ OF 100 KT 3H JET SHOULD PRODUCE SOME MID CLOUDS PER MODEL SNDGS BUT OTHERWISE MODEL SNDGS LOOK PRETTY DRY AT LOW LEVELS. WEAK PRES GRADIENTS WITH SFC HIGH OVERHEAD WILL ALLOW FOR LAKE BREEZES TO DEVELOP SAT OFF BOTH LAKES SUPERIOR AND MICHIGAN...KEEPING TEMPS COOLER (40S) ALONG LAKESHORE AREAS. MIXING TO AROUND 850 MB OVER THE WESTERN INTERIOR WILL ALLOW MAX TEMPS TO REACH NEAR TO MID 50S. SAT NIGHT...INFLUENCE OF SFC HIGH JUST TO THE NE OF LAKE SUPERIOR WILL ALLOW FOR LIGHT WIND AND GENERALLY CLEAR TO PARTLY CLOUDY SKIES. EXPECT LOWS TO REACH INTO THE 20S OVER THE INTERIOR...CLOSER TO COOLER GFS MOS GUIDANCE. MODELS STILL IN GOOD AGREEMENT SHOWING UPR LOW EJECTING OUT OF THE PLAINS AND INTO THE UPR GREAT LAKES SUN NIGHT INTO MON. AN INCREASING RIBBON OF MOISTURE/ISENTROPIC ASCENT ON THE 300K SFC... A 40KT H85 JET...AND PWATS AROUND AN INCH ARE MAIN TRIGGERS FOR SHOWERS LATE SUN INTO SUN NIGHT. NEG 850-500 MB THETA-E LAPSE RATES COULD ALSO RESULT IN THUNDER. BUMPED UP POPS TO LIKELY SUN NIGHT WITH ARRIVAL OF SFC WARM FRONT AND UPR TROUGH. DEPARTURE OF SHORTWAVE AND ASSOC SFC TROF/WARM FRONT SHOULD TAPER OFF RAIN CHCS BY MON AFTERNOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON (UPDATE) VOSS (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 530 AM EDT FRI MAR 23 2007 .DISCUSSION... MAIN FCST CONCERNS IN SHORT TERM ARE CLOUDS/TEMPS THEN FOCUS WILL BE ON TIMING OF NEXT CHC OF RAIN/THUNDERSTORMS FOR SUN AFTERNOON. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. ONE SHORTWAVE IS MOVING THROUGH THE UPR GREAT LAKES EARLY THIS MORNING WHILE ANOTHER IS UPSTREAM OVER SRN ALBERTA. SHORTWAVE MOVING THROUGH UPR GREAT LAKES PRODUCED A FEW FLURRIES THIS MORNING NORTH OF LAKE SUPERIOR IN AREA OF WEAK Q-VECT CONV AND ISENTROPIC ASCENT. MODEL SNDGS CONSISTENT IN SHOWING LINGERING MOISTURE AROUND 850 MB IN WAKE OF SHORTWAVE SO KEPT IN A BIT MORE CLOUD COVER TODAY IN ANTICIPATION OF STRATOCU DEVELOPING DURING THE DAY. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE LOW/MID 50S OVER THE WRN INTERIOR. SRLY FLOW WILL KEEP TEMPS MUCH COOLER OVER THE ERN FCST AREA NEAR AND DOWNWIND OF LAKE MICHIGAN. LOCAL COOLING SHOULD ALSO OCCUR NEAR LAKE SUPERIOR OVER THE W AND NCNTRL AREAS MID/LATE AFTN WHERE BOUNDARY LAYER WINDS WILL BE LIGHTER. FROM MUNISING EWD...SRLY FLOW MAY STRONG ENOUGH 10-15 KT TO SUPRESS LAKE BREEZE DEVELOPMENT. NEXT SHORTWAVE FROM ALBERTA IS DUE TO MOVE INTO THE UPR GREAT LAKES LATE FRI NIGHT AND SAT. UPR DIV IN RRQ OF 100 KT 3H JET SHOULD PRODUCE SOME MID CLOUDS PER MODEL SNDGS BUT OTHERWISE MODEL SNDGS LOOK PRETTY DRY AT LOW LEVELS. WEAK PRES GRADIENTS WITH SFC HIGH OVERHEAD WILL ALLOW FOR LAKE BREEZES TO DEVELOP SAT OFF BOTH LAKES SUPERIOR AND MICHIGAN...KEEPING TEMPS COOLER (40S) ALONG LAKESHORE AREAS. MIXING TO AROUND 850 MB OVER THE WESTERN INTERIOR WILL ALLOW MAX TEMPS TO REACH NEAR TO MID 50S. SAT NIGHT...INFLUENCE OF SFC HIGH JUST TO THE NE OF LAKE SUPERIOR WILL ALLOW FOR LIGHT WIND AND GENERALLY CLEAR TO PARTLY CLOUDY SKIES. EXPECT LOWS TO REACH INTO THE 20S OVER THE INTERIOR...CLOSER TO COOLER GFS MOS GUIDANCE. MODELS STILL IN GOOD AGREEMENT SHOWING UPR LOW EJECTING OUT OF THE PLAINS AND INTO THE UPR GREAT LAKES SUN NIGHT INTO MON. AN INCREASING RIBBON OF MOISTURE/ISENTROPIC ASCENT ON THE 300K SFC... A 40KT H85 JET...AND PWATS AROUND AN INCH ARE MAIN TRIGGERS FOR SHOWERS LATE SUN INTO SUN NIGHT. NEG 850-500 MB THETA-E LAPSE RATES COULD ALSO RESULT IN THUNDER. BUMPED UP POPS TO LIKELY SUN NIGHT WITH ARRIVAL OF SFC WARM FRONT AND UPR TROUGH. DEPARTURE OF SHORTWAVE AND ASSOC SFC TROF/WARM FRONT SHOULD TAPER OFF RAIN CHCS BY MON AFTERNOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 PM EDT THU MAR 22 2007 .SHORT TERM (TONIGHT AND FRIDAY)... MAIN FCST ISSUE IN THE SHORT TERM IS POSSIBILITY OF SOME -SN TONIGHT. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. SHORTWAVE THAT PASSED ACROSS THE UPPER LAKES EARLIER TODAY IS NOW OVER THE ONTARIO/QUEBEC BORDER. NEXT SHORTWAVE IN THE FAST FLOW IS OVER NW ND. MID CLOUDS ASSOCIATED WITH SHORTWAVE WERE SPREADING ACROSS NRN MN...AND HIGH CLOUDS HAVE ALREADY SPREAD ACROSS ALL OF UPPER MI THIS AFTN. RADARS SHOW A DECENT AREA OF RETURNS ACROSS FAR NE ND/NW MN AND SRN MANITOBA. SFC OBS THAT REPORT VSBY ARE SPARSE IN THAT AREA...SO DIFFICULT TO KNOW HOW MUCH PCPN IS REACHING THE GROUND. HOWEVER...IN THE LAST FEW HRS...A COUPLE OF OBS IN SRN MANITOBA HAVE REPORTED 1-4SM IN -SN. WELL TO THE W...SHORTWAVE THAT DROPPED OUT OF THE WESTERLIES A DAY OR TWO AGO OVER THE W COAST HAS CLOSED OFF INTO A MIDLEVEL LOW CENTERED JUST S OF CA. THIS SYSTEM WILL BE OF INTEREST TO FCST HERE LATE IN THE UPCOMING WEEKEND AS IT GETS KICKED NE BY NEXT TROF APPROACHING THE W COAST. UPSTREAM SHORTWAVE WILL RACE E...CROSSING UPPER MI/LAKE SUPERIOR BTWN 03Z-09Z. BASED ON THE DARKENING SEEN ON WATER VAPOR IMAGERY... THE GFS HAS A BETTER HANDLE ON SHORTWAVE THAN THE WEAKER NAM. LATEST RUC AND 12Z REGIONAL CANADIAN ALSO SUPPORT THE GFS. OVERLAP OF MODEST DEEP LAYER QVECTOR CONVERGENCE AND MOIST ISENTROPIC ASCENT (CONDENSATION PRES DEFICITS UNDER 20MB) ON THE 290K SFC (AROUND 700MB) LINES UP WELL WITH WHERE RADAR RETURNS ARE PRESENT IN NE ND/NW MN AND SRN MANITOBA. STRONGER ISENTROPIC ASCENT IS INDICATED FARTHER S...BUT AIRMASS IS DRIER THERE. LATEST RUC IS VERY SIMILAR TO THE GFS WITH REGARD TO PROGRESSION OF QVECTOR CONVERGENCE/ISENTROPIC ASCENT THRU 06Z. FORCING/ISENTROPIC ASCENT IS TO SHIFT THRU NE MN BEFORE WEAKENING AS IT CROSSES UPPER MI/LAKE SUPERIOR TONIGHT. WITH ANTECEDENT DRY AIR TO OVERCOME...THE WEAKENING FORCING SUGGESTS PCPN THAT IS OCCURRING UPSTREAM WILL TEND TO DISSIPATE AS IT NEARS AND THEN MOVES ACROSS THE FCST AREA. ON THE OTHER HAND...GIVEN THE APPEARANCE ON WATER VAPOR IMAGERY...SHORTWAVE MAY NOT WEAKEN AS FAST AS MODELS INDICATE. SO...SITUATION IS CERTAINLY STILL WORTHY OF SLIGHT CHC/LOW CHC POPS OVER NW LAKE SUPERIOR AND ACROSS THE KEWEENAW. FCST WETBULB ZERO PROFILES INDICATE ANY PCPN THAT OCCURS WILL BE SNOW. FOLLOWING SHORTWAVE...CANADIAN/GFS SHOW MOISTURE LINGERING AROUND 850MB ON FRI...ESPECIALLY OVER THE CNTRL/ERN FCST AREA. SO THERE SHOULD BE A FAIR AMOUNT OF STRATOCU DEVELOPING DURING THE DAY. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE LOW/MID 50S. HOWEVER...SRLY FLOW WILL KEEP TEMPS MUCH COOLER NEAR AND DOWNWIND OF LAKE MICHIGAN. LOCAL COOLING SHOULD ALSO OCCUR NEAR LAKE SUPERIOR OVER THE W AND OVER THE NCNTRL MID/LATE AFTN AS BOUNDARY LAYER WINDS SLACKEN. FROM MUNISING EWD...SRLY FLOW MAY BE SUFFICIENT THRU THE DAY TO PREVENT LAKE BREEZE DEVELOPMENT. .LONG TERM (FRIDAY NIGHT THROUGH NEXT THURSDAY)... CONTINUITY IN MODEL SOLUTIONS IS POOR CURRENTLY MAINLY DUE TO ZONAL WEST TO EAST UPPER FLOW ALONG CANADA/UNITED STATES BORDER. IN RECENT MODEL RUNS...IT APPEARED SHORTWAVE CURRENTLY OFF SHORE OF BRITISH COLUMBIA WAS TO MOVE EAST AND ARRIVE OVR ONTARIO AND UPR LAKES FRI NIGHT INTO EARLY SAT. ALSO...THE WAVE WAS PROGGED TO SHEAR OUT AS IT CAME EAST. NOW...A TREND IS EMERGING THAT RESULTS IN STRONGER WAVE NOT COMING THROUGH UNTIL SAT. NAM MOST EMPHATIC WITH THIS IDEA WHILE UKMET/GFS AND LATEST ECMWF ARE WEAKER. SHORTWAVE ALONG WITH DIVERGENCE FM RRQ OF H3 OVR ONTARIO SHOULD PRODUCE CONSIDERABLE MID CLOUDS. HOWEVER...SOUNDINGS FM GFS AND EVEN NAM ARE VERY DRY BLO H85 SO HAVE KEPT A DRY FCST. MIXING HEIGHTS MAY BE LIMITED DUE TO CLOUDS AND LIGHT WINDS SO LOWERED TEMPS SLIGHTLY. AT THE SFC...RIDGE DRIFTING OVER UPR LAKES WILL MOVE TO THE LOWER GREAT LAKES SAT NIGHT INTO SUN. RETURN FLOW AS HIGH DEPARTS WILL ONLY STRENGTHEN THROUGH MOST OF THE UPCOMING WEEK. IT IS FEASIBLE THAT SAT NIGHT WILL BE THE LAST ONE FOR A WHILE WITH A GOOD PORTION OF CWA EXPERIENCING MIN TEMPS BLO FREEZING. UPR LOW OVR SOUTHWEST EJECTS INTO PLAINS SUN AND LIFTS TOWARD UPR GREAT LAKES SUN NIGHT INTO MON. UKMET/GFS/ECMWF IN GOOD AGREEMENT HERE. NAM IS MUCH SLOWER WITH TROUGH EJECTION AND WAS NOT PREFERRED DUE TO EVEN STRONGER KICKER SHORTWAVE TROUGH BARRELLING INTO WEST COAST AS EARLY AS SUN. LARGE AREA OF H85-H7 WARM AIR ADVECTION... 40KT H85 JET...AND PWATS ECLIPSING AN INCH (250-300 PCT OF NORMAL) ARE MAIN TRIGGERS FOR PCPN SUN INTO SUN NIGHT. WARMING H85 TEMPS COMBINED WITH COOL H5 TEMPS AROUND -15C RESULT IN STEEPENING MID LEVEL LAPSE RATES AND POSSIBILITY OF THUNDER. MAIN SFC WARM FRONT AND UPR TROUGH DO NOT ARRIVE UNTIL LATE SUN NIGHT INTO MON WHICH IS WHEN BEST COVERAGE TO SHOWERS/THUNDERSTORMS IS EXPECTED. 00Z GFS EVEN INDICATED SOME SFC BASED INSTABILITY AHEAD OF PRIMARY COLD FRONT MOVING THROUGH MON EVENING. ECMWF MUCH QUICKER WITH FROPA. ALTHOUGH MOST PCPN WILL BE DONE BY MON NIGHT...KEPT A SMALL CHANCE IN GRIDS FOR TUE AS SECONDARY SFC TROUGH MOVES THROUGH PER HPC AND H5 COLD POOL (-20C AT H5) ALSO ROTATES THROUGH. BRIEF RIDGING BOTH ALOFT AND AT SFC FOR WED...THEN DEEP TROUGH CONTINUES TO DEVELOP OVR MUCH OF WESTERN CONUS. SW FLOW DEVELOPING ALOFT...AND EVENTUALLY AT SFC...LEADS TO AN INCREASE IN RAIN CHANCES LATE NEXT WEEK. TEMPS WILL REMAIN ABOVE NORMAL. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1037 AM EDT THU MAR 22 2007 .UPDATE... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A POTENT SHORTWAVE RACING E ACROSS ERN LAKE SUPERIOR AND ONTARIO. SHARP DRYING/SUBSIDENCE IN THE WAKE OF SHORTWAVE IS LEADING TO A DECREASE IN CLOUD COVER ACROSS THE FCST AREA THIS MORNING. 00Z/12Z KINL SOUNDINGS SHOWED THE INCOMING DRY AIR NICELY AS PRECIPITABLE WATER DROPPED FROM 0.68 TO 0.15 INCHES...AND 12Z SOUNDING INDICATED DWPT DEPRESSIONS OF 15-25C FROM 840MB TO 550MB. A PERIOD OF GUSTY WINDS IS ALSO FOLLOWING THE STRONG SHORTWAVE. WINDS WERE BEING AIDED BY 4-5MB/3HR PRES RISE MAX THAT WAS QUICKLY MOVING E ACROSS THE UPPER LAKES. CORE OF PRES RISES IS NOW OVER CNTRL LAKE SUPERIOR/CNTRL UPPER MI...SO STRONGEST WINDS HAVE JUST ABOUT PASSED THE AREA. NEXT SHORTWAVE IS HEADING ESE THRU SRN SASKATCHEWAN. MID/HIGH CLOUDS ASSOCIATED WITH SHORTWAVE ARE ALREADY STREAMING E THRU ND INTO NRN MN. INHERITED FCST IS IN GOOD SHAPE FOR THE AFTN AND ONLY REQUIRES MINOR ADJUSTMENTS BASED ON MORNING TRENDS. SOME STRATOCU WILL BE AROUND FOR A FEW MORE HRS...MAINLY ACROSS THE N...ASSOCIATED WITH 850MB THERMAL TROF AND LINGERING LOW-LEVEL MOISTURE. STRATOCU SHOULD BE GONE BY MID/LATE AFTN...BUT ALREADY MID/HIGH CLOUDS ASSOCIATED WITH NEXT SHORTWAVE WILL BE SLIPPING INTO THE FCST AREA FROM THE W. AS FOR TEMPS...MIXING TO 800-850MB ON 12Z KINL SOUNDING SUGGESTS HIGH TEMPS IN THE UPPER 30S/LWR 40S ARE ON TRACK OVER THE W AND N. WNW DOWNSLOPING WIND WILL RESULT IN MAX TEMPS SEVERAL DEGREES HIGHER OVER PORTIONS OF THE CNTRL FCST AREA...ESPECIALLY SCNTRL. AS FOR WINDS...WILL MAINTAIN GALE WARNING OVER ERN LAKE SUPERIOR FOR A FEW MORE HRS WITH EXPECTATION OF GALE FORCE GUSTS. OTHERWISE...WINDS WILL CONTINUE TO DIMINISH OVER THE ENTIRE FCST AREA THRU THE DAY AS PRES RISE SHIFTS E OF THE AREA AND SFC HIGH PRES RIDGE OVER MN DRIFTS E. && .PREV DISCUSSION (ISSUED AT 400 AM EDT)... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STRG SHRTWV NEAR LK WINNIPEG EMBEDDED IN ZONAL FLOW ALF ALG THE CNDN BORDER...WITH ANOTHER SHRTWV PRESENT OVER ND. THREE DISTINCT AREAS OF PCPN NOTED AT THE START OF SHIFT. THE FIRST WAS A BAND OF SHRA MOVING INTO WRN LK SUP JUST AHEAD OF COLD FNT IN DPVA/DEEP LYR H85-3 QVECTOR CNVGC ASSOCIATED WITH ND SHRTWV. LLVL MSTR LINGERS BEHIND THIS FNT WITH SC CIGS OBSVD BACK TO THE RED RIVER VALLEY...WHERE DRIER AIR NOTED ON THE BIS SDNG IS WORKING EWD. STRONGER COLD FNT ASSOCIATED WITH SHRTWV OVER LK WINNIPEG MOVING TOWARD THE MN AT 03Z...BUT LTL PCPN OBSVD ALG THIS BNDRY DESPITE SHARPER THERMAL CONTRAST. SECOND CLUSTER OF SHRA WITH EMBEDDED TSRA EXTENDS FM NW WI INTO IA WHERE DPVA/DEEP LYR H85-3 QVECTOR CNVGC/SFC COLD FNT INTERSECTING HIER H85 DWPTS AOA 8C SURGING NEWD IN ADVANCE OF FNT...MSTR NOT AVBL TO BAND FARTHER N IN WRN LK SUP. RAOBS/PROFILERS SHOW H85 SW WINDS AOA 50 KTS AHEAD OF THIS CLUSTER. LARGEST AREA OF SHRA PRESENT OVER ERN WI/LK MI/NW LWR MI AT NOSE OF STRONGEST H85-7 WINDS JUST AHEAD OF WEAK SHRTWV NOTED ON RUC ANALYSIS. SCT SHRA/TSRA ON NRN FRINGE OF THIS AREA ARE IMPACTING THE ERN CWA...BUT FOR THE MOST PART THESE SHRA/TSRA ON TRACK TO MISS THE FA. OTRW...LTL PCPN NOTED OVER THE FA RIGHT NOW...BUT RETURN OF HIER LLVL MSTR OVER MELTING SN HAS CAUSED QUITE A BIT OF ST/FOG...WITH VSBYS AOB 1/4SM AT PLACES ACRS MAINLY THE SCNTRL AND E. UPSTREAM...ANOTHER SHRTWV MOVING THRU BRITISH COLUMBIA. MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND EVOLUTION OF PCPN AREAS AS LATEST RUC/LARGER SCALE MODELS SHOW SHRTWVS OVER ND AND LK WINNIPEG PHASING OVERNGT. FOCUS AFTER COLD FROPA EARLY THIS MRNG SHIFTS TO WINDS/TEMPS. AS SHRTWVS BEGIN TO MERGE TO A 40-UNIT VORT MAX OVER FAR NRN LK SUP BY 12Z THU...EXPECT SHRA AREAS OVER WRN LK SUP/WI TO MERGE OVER THE SCNTRL/ERN CWA WITH SOME LOCALLY HEAVY RA THERE WHERE MSTR CNVGC PHASES BETTER WITH DPVA/FALLING HGTS/DEEP QVECTOR CVNGC BEFORE ACCELERATING INCRSGLY KATAFNT TYPE COLD FNT DRIVES E UNDER JET SURGE REGION OF DEEPENING SHRTWV. WITH RAPID INFLUX OF DRY AIR EXPECTED AS H85 W WINDS INCRS UP TO 50KT...LOOK FOR PCPN/DENSE FOG TO END SOON AFTR COLD FROPA WITH INTENSE DRY ADVCTN/SUBSIDENCE. 00Z RUC/NAM INDICATE DRYING WL REACH ERY ARND 12Z...SO MOST IF NOT ALL PCPN WL BE OVER BY EARLY TDAY. WL CARRY LINGERING SHRA OVER THE ERN COUNTIES EARLY...OTRW HAVE REMOVED POPS ALTOGETHER AS NAM/RUC FCST SDNGS FOLLOWING THE FROPA ARE QUITE DRY. WL EVALUATE NEED TO KEEP GOING DENSE FOG ADVY GOING CLOSE TO FCST ISSUANCE...BUT ANTICIPATE DROPPING ADVY FOR MOST OF THE FA BY FCST ISSUANCE. GFS FCST SDNGS SHOW MORE LLVL MSTR...BUT PREFER THE DRIER LOOK TO THE RUC/NAM FCSTS GIVEN MORE DRYING OBSVD UPSTREAM OVER NW MN/ANTICIPATED DRY SURGE BEHIND DEEPENING SHRTWV. OTRW...LOOK FOR GUSTY WINDS THIS MRNG BEHIND THE BNDRY WITH 35KT WINDS WITHIN THE MIXED LYR TO DIMINISH A BIT THIS AFTN WITH ARRIVAL OF HI PRES RDG. ALTHOUGH PRES GRADIENT SEEMS TO DIMINISH WITH APRCH OF RDG...MIXING/DEEPENING PBL WITH PLENTY OF SUNSHINE IN LLVL CAD SHOULD TAP STRONGER WINDS ALF TO MAINTAIN GUSTINESS THRU THE DAY. MIXING TO H85 ON NAM FCST SDNGS SUGS HI TEMPS WL REACH ARND 45 OVER THE SE COUNTIES...WHERE NW FLOW WL BE DOWNSLOPING. LOOK FOR AN INCRS IN HI CLD LATE TDAY IN ADVANCE OF NEXT SHRTWV NOW MOVING INTO BRITISH COLUMBIA FCST TO MOVE TOWARD NW MN LATE TDAY. FOR TNGT...SHRTWV OVER THE NRN PLAINS PROGGED TO DRIFT ACRS THE UPR GRT LKS...AND GFS/NAM/UKMET SHOW INCRSG MID LVL MSTR. ALTHOUGH LLVLS APPEAR WL BE TOO DRY FOR ANY PCPN...GFS AND ESPECIALLY THE NAM GENERATE SOME GENERALLY LGT QPF OVER THE NW AND LK SUP. NAM ACTUALLY SHOWS SOME SHARP H85-7 FGEN WITH SOME MODEST ISENTROPIC LIFT IN ADVANCE OF THE SHRTWV. SINCE GFS/UKMET ARE MUCH WEAKER WITH FCST DYNAMICS BUT WV IMAGERY INDICATES A WELL DEFINED SHRTWV IN BRITISH COLUMBIA...WL CARRY SLGT CHC -SHSN (FCST WBZ PROFILES SUG ANY PCPN WOULD BE SN) ACRS THE NW CWA ON CYC SIDE OF NAM FCST H3 JET MAX/BEST H85-7 FGEN. EXPECT THE LOWEST MIN TEMPS OVER THE SCNTRL WHERE THE CLDS WL BE THINNEST. FOLLOWING DEPARTURE OF SHRTWV EARLY FRI...SFC-H85 RDG AXIS/MID LVL DRYING FCST TO DOMINATE. GFS/NAM BOTH SHOW SOME HIER DWPTS AT H85 LINGERING HOWEVER...SO EXPECT BKN DIURNAL SC TO DVLP DURING DAY. MIXING TO H85 ON GFS/NAM FCST SDNGS YIELDS HI TEMPS NEAR 55. WITH LGT SW FLOW...EXPECT LK BREEZES/AFTN COOLING TO DVLP MAINLY NEAR LK MI. SOME CONSIDERABLE MODEL DISAGREEMENTS BEGIN TO SHOW IN THE FRI NGT/SAT PDS...NOT SURPRISING CONSIDERING FAST ZONAL FLOW FCST TO PREVAIL. GFS SHOWS A MUCH DEEPER SHRTWV ARRIVING LATE FRI NGT AND GENERATING SGNFT PCPN ON SAT. WL SIDE WITH THE MAJORITY UKMET/ ECWMF/CNDN/NAM THAT SHOW A MUCH WEAKER SHRTWV SHEARING BY ON FRI NGT FOLLOWED BY RDGING ON SAT. OPTED TO REMOVE POPS FRI NGT AND KEEP SAT DRY. WITH H85 TEMPS APRCHG 6C ON SAT...EXPECT TEMPS OVER THE INLAND TO RISE WELL INTO THE 50S TO NEAR 60 PER MIXING TO H8 ON NAM FCST SDNGS. WITH SFC HI CENTER TO THE SE AND CWA IN SYNOPTIC SW FLOW... EXPECT THE MOST SGNFT LK MODERATION OFF LK MI. BUT RELATIVELY WEAK FLOW AND SFC HTG INLAND SHOULD ALLOW LK BREEZES OFF SUPERIOR AS WELL. COORDINATED WITH GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING E HALF OF LAKE SUPERIOR. && $$ ROLFSON (UPDATE) KC (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 AM EDT THU MAR 22 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STRG SHRTWV NEAR LK WINNIPEG EMBEDDED IN ZONAL FLOW ALF ALG THE CNDN BORDER...WITH ANOTHER SHRTWV PRESENT OVER ND. THREE DISTINCT AREAS OF PCPN NOTED AT THE START OF SHIFT. THE FIRST WAS A BAND OF SHRA MOVING INTO WRN LK SUP JUST AHEAD OF COLD FNT IN DPVA/DEEP LYR H85-3 QVECTOR CNVGC ASSOCIATED WITH ND SHRTWV. LLVL MSTR LINGERS BEHIND THIS FNT WITH SC CIGS OBSVD BACK TO THE RED RIVER VALLEY...WHERE DRIER AIR NOTED ON THE BIS SDNG IS WORKING EWD. STRONGER COLD FNT ASSOCIATED WITH SHRTWV OVER LK WINNIPEG MOVING TOWARD THE MN AT 03Z...BUT LTL PCPN OBSVD ALG THIS BNDRY DESPITE SHARPER THERMAL CONTRAST. SECOND CLUSTER OF SHRA WITH EMBEDDED TSRA EXTENDS FM NW WI INTO IA WHERE DPVA/DEEP LYR H85-3 QVECTOR CNVGC/SFC COLD FNT INTERSECTING HIER H85 DWPTS AOA 8C SURGING NEWD IN ADVANCE OF FNT...MSTR NOT AVBL TO BAND FARTHER N IN WRN LK SUP. RAOBS/PROFILERS SHOW H85 SW WINDS AOA 50 KTS AHEAD OF THIS CLUSTER. LARGEST AREA OF SHRA PRESENT OVER ERN WI/LK MI/NW LWR MI AT NOSE OF STRONGEST H85-7 WINDS JUST AHEAD OF WEAK SHRTWV NOTED ON RUC ANALYSIS. SCT SHRA/TSRA ON NRN FRINGE OF THIS AREA ARE IMPACTING THE ERN CWA...BUT FOR THE MOST PART THESE SHRA/TSRA ON TRACK TO MISS THE FA. OTRW...LTL PCPN NOTED OVER THE FA RIGHT NOW...BUT RETURN OF HIER LLVL MSTR OVER MELTING SN HAS CAUSED QUITE A BIT OF ST/FOG...WITH VSBYS AOB 1/4SM AT PLACES ACRS MAINLY THE SCNTRL AND E. UPSTREAM...ANOTHER SHRTWV MOVING THRU BRITISH COLUMBIA. MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND EVOLUTION OF PCPN AREAS AS LATEST RUC/LARGER SCALE MODELS SHOW SHRTWVS OVER ND AND LK WINNIPEG PHASING OVERNGT. FOCUS AFTER COLD FROPA EARLY THIS MRNG SHIFTS TO WINDS/TEMPS. AS SHRTWVS BEGIN TO MERGE TO A 40-UNIT VORT MAX OVER FAR NRN LK SUP BY 12Z THU...EXPECT SHRA AREAS OVER WRN LK SUP/WI TO MERGE OVER THE SCNTRL/ERN CWA WITH SOME LOCALLY HEAVY RA THERE WHERE MSTR CNVGC PHASES BETTER WITH DPVA/FALLING HGTS/DEEP QVECTOR CVNGC BEFORE ACCELERATING INCRSGLY KATAFNT TYPE COLD FNT DRIVES E UNDER JET SURGE REGION OF DEEPENING SHRTWV. WITH RAPID INFLUX OF DRY AIR EXPECTED AS H85 W WINDS INCRS UP TO 50KT...LOOK FOR PCPN/DENSE FOG TO END SOON AFTR COLD FROPA WITH INTENSE DRY ADVCTN/SUBSIDENCE. 00Z RUC/NAM INDICATE DRYING WL REACH ERY ARND 12Z...SO MOST IF NOT ALL PCPN WL BE OVER BY EARLY TDAY. WL CARRY LINGERING SHRA OVER THE ERN COUNTIES EARLY...OTRW HAVE REMOVED POPS ALTOGETHER AS NAM/RUC FCST SDNGS FOLLOWING THE FROPA ARE QUITE DRY. WL EVALUATE NEED TO KEEP GOING DENSE FOG ADVY GOING CLOSE TO FCST ISSUANCE...BUT ANTICIPATE DROPPING ADVY FOR MOST OF THE FA BY FCST ISSUANCE. GFS FCST SDNGS SHOW MORE LLVL MSTR...BUT PREFER THE DRIER LOOK TO THE RUC/NAM FCSTS GIVEN MORE DRYING OBSVD UPSTREAM OVER NW MN/ANTICIPATED DRY SURGE BEHIND DEEPENING SHRTWV. OTRW...LOOK FOR GUSTY WINDS THIS MRNG BEHIND THE BNDRY WITH 35KT WINDS WITHIN THE MIXED LYR TO DIMINISH A BIT THIS AFTN WITH ARRIVAL OF HI PRES RDG. ALTHOUGH PRES GRADIENT SEEMS TO DIMINISH WITH APRCH OF RDG...MIXING/DEEPENING PBL WITH PLENTY OF SUNSHINE IN LLVL CAD SHOULD TAP STRONGER WINDS ALF TO MAINTAIN GUSTINESS THRU THE DAY. MIXING TO H85 ON NAM FCST SDNGS SUGS HI TEMPS WL REACH ARND 45 OVER THE SE COUNTIES...WHERE NW FLOW WL BE DOWNSLOPING. LOOK FOR AN INCRS IN HI CLD LATE TDAY IN ADVANCE OF NEXT SHRTWV NOW MOVING INTO BRITISH COLUMBIA FCST TO MOVE TOWARD NW MN LATE TDAY. FOR TNGT...SHRTWV OVER THE NRN PLAINS PROGGED TO DRIFT ACRS THE UPR GRT LKS...AND GFS/NAM/UKMET SHOW INCRSG MID LVL MSTR. ALTHOUGH LLVLS APPEAR WL BE TOO DRY FOR ANY PCPN...GFS AND ESPECIALLY THE NAM GENERATE SOME GENERALLY LGT QPF OVER THE NW AND LK SUP. NAM ACTUALLY SHOWS SOME SHARP H85-7 FGEN WITH SOME MODEST ISENTROPIC LIFT IN ADVANCE OF THE SHRTWV. SINCE GFS/UKMET ARE MUCH WEAKER WITH FCST DYNAMICS BUT WV IMAGERY INDICATES A WELL DEFINED SHRTWV IN BRITISH COLUMBIA...WL CARRY SLGT CHC -SHSN (FCST WBZ PROFILES SUG ANY PCPN WOULD BE SN) ACRS THE NW CWA ON CYC SIDE OF NAM FCST H3 JET MAX/BEST H85-7 FGEN. EXPECT THE LOWEST MIN TEMPS OVER THE SCNTRL WHERE THE CLDS WL BE THINNEST. FOLLOWING DEPARTURE OF SHRTWV EARLY FRI...SFC-H85 RDG AXIS/MID LVL DRYING FCST TO DOMINATE. GFS/NAM BOTH SHOW SOME HIER DWPTS AT H85 LINGERING HOWEVER...SO EXPECT BKN DIURNAL SC TO DVLP DURING DAY. MIXING TO H85 ON GFS/NAM FCST SDNGS YIELDS HI TEMPS NEAR 55. WITH LGT SW FLOW...EXPECT LK BREEZES/AFTN COOLING TO DVLP MAINLY NEAR LK MI. SOME CONSIDERABLE MODEL DISAGREEMENTS BEGIN TO SHOW IN THE FRI NGT/SAT PDS...NOT SURPRISING CONSIDERING FAST ZONAL FLOW FCST TO PREVAIL. GFS SHOWS A MUCH DEEPER SHRTWV ARRIVING LATE FRI NGT AND GENERATING SGNFT PCPN ON SAT. WL SIDE WITH THE MAJORITY UKMET/ ECWMF/CNDN/NAM THAT SHOW A MUCH WEAKER SHRTWV SHEARING BY ON FRI NGT FOLLOWED BY RDGING ON SAT. OPTED TO REMOVE POPS FRI NGT AND KEEP SAT DRY. WITH H85 TEMPS APRCHG 6C ON SAT...EXPECT TEMPS OVER THE INLAND TO RISE WELL INTO THE 50S TO NEAR 60 PER MIXING TO H8 ON NAM FCST SDNGS. WITH SFC HI CENTER TO THE SE AND CWA IN SYNOPTIC SW FLOW... EXPECT THE MOST SGNFT LK MODERATION OFF LK MI. BUT RELATIVELY WEAK FLOW AND SFC HTG INLAND SHOULD ALLOW LK BREEZES OFF SUPERIOR AS WELL. COORDINATED WITH GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING LAKE SUPERIOR. && $$ KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 221 PM EDT WED MAR 21 2007 .UPDATE...TEMPERATURES STILL STRUGGLING TO GET ABOVE THE FREEZING MARK OVER THE HIGHER TERRAIN AREAS AROUND HTL...WEST BRANCH. WITH ADDITIONAL SHOWERS MOVING THROUGH...FELT COMPELLED TO EXTEND FREEZING RAIN ADVISORY OUT A FEW MORE HOURS. WARM AIR GETTING CLOSER AS WELL AS SFC DEWPOINTS HEADING TOWARD FREEZING. SO HOPEFULLY WE CAN DROP THE ADVISORY WITH THE 4 PM FORECAST. ADAM && .AVIATION...ISSUED AT 144 PM. AN INTERESTING SITUATION AS THE WARM FRONT IS STILL HUNG UP ALONG THE INDIANA/OHIO BORDER. BECAUSE OF THIS, THERE IS A SIZABLE SFC BASED INVERSION THAT WILL CONTINUE THROUGH 12Z THURSDAY WHEN THE COLD FRONT MOVES THROUGH. THE WARM FRONT IS CAUSING LOW LEVEL WIND SHEAR THAT THE KAPX RADAR IS PEGGING AROUND 35 KTS AROUND 1500 FT. THE MODELS SHOW THAT A LOW LEVEL JET MOVES THROUGH AHEAD OF THE COLD FRONT AND BRINGS IN THE POSSIBILITY OF 50+KTS OVERNIGHT AROUND 1500 TO 2000 FEET. OTHERWISE, THE THUNDERSTORMS LOOK TO BE TIMED MORE WITH THE COLD FRONT PASSING THROUGH THE REGION. SO HAVE THE THUNDERSTORMS IN THE HOURS JUST PRIOR TO FROPA. SFC TEMPERATURES ARE ABOVE FREEZING AT THE TAF SITES SO IT LOOKS LIKE AT THE SFC THE FREEZING RAIN IS NO LONGER AN ISSUE. && .UPDATE...ISSUED 1121 AM. OCCLUDED LOW PRESSURE SYSTEM MOVING INTO WESTERN ONTARIO THIS MORNING. ASSOCIATED OCCLUDED FRONT EXTENDS TO A TRIPLE POINT LOW OVER SOUTH DAKOTA...WARM FRONT STRETCHING SE INTO THE OHIO VALLEY. STRONG WARM/MOIST ADVECTION UNDERWAY ACROSS THE WESTERN GREAT LAKES ALONG AND AHEAD OF THE WARM FRONT. 12Z APX SOUNDING REVEALING ABOVE FREEZING WARM NOSE BETWEEN 940 AND 740 MB WITH A MAX TEMP OF +5C WITHIN THE LAYER...A +6C CHANGE IN THE LAST 12 HOURS. LOW LEVEL MOISTURE GRADIENT SITTING BETWEEN APX AND GRB PER 12Z SOUNDINGS AND INITIAL ROUND OF CONVECTIVE SHOWERS HAVE DEVELOPED ALONG THE MOISTURE AXIS (PER MOIST CONVERGENCE PROCESSES) AND NOW PASSING THROUGH NORTHERN LOWER MICHIGAN ATTM. ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOPING UPSTREAM IN THE IOWA/WISCONSIN/ILLINOIS AREA SPURRED ON BY BETTER CONDITIONAL INSTABILITY ALOFT SPREADING EASTWARD OUT OF THE PLAINS AND EXPECTED TO IMPACT THE REGION LATER IN THE AFTERNOON THROUGH TONIGHT. PER RADAR TRENDS...INITIAL ROUND OF SHOWERS LOOKING TO PASS THROUGH NORTHERN LOWER MICHIGAN THROUGH EARLY AFTERNOON WITH THE HEAVIEST QPF FALLING OVER THE SE QUARTER OF THE CWA. SFC TEMPS ACROSS THIS AREA STILL AT OR BELOW FREEZING PARTICULARLY OVER THE HIGHER TERRAIN. A BIT ON THE FENCE WITH THIS ONE...BUT SPOTTER REPORTS FROM GRAND RAPIDS CWA INDICATE SOME ROADWAY ICING OCCURRING IN COUNTIES JUST UPSTREAM AND THE SAME IS LIKELY TO OCCUR UP THROUGH HTL/WEST BRANCH/GLADWIN...ETC. AFTER TALKING IT OVER WITH GRAND RAPIDS OFFICE DECIDED TO ISSUE A FREEZING RAIN ADVISORY VALID THROUGH EARLY AFTERNOON TO HANDLE THIS FIRST ROUND OF SHOWERS. NO OTHER CHANGES MADE FOR THE REST OF THE AFTERNOON AND THIS EVENING. NEXT ROUND OF SHOWERS AND POSSIBLE THUNDER LOOKING TO ARRIVE LATER IN THE AFTERNOON AND PARTICULARLY TONIGHT AS THE COLD FRONT PRESSES IN FROM THE WEST. BASICALLY...LOOKS WET WITH STRONG FORCING/IMPRESSIVE MOIST INFLOW UP INTO THE STATE - PWATS RUNNING 400 PERCENT OF NORMAL AS NOTED BY MIDNIGHT SHIFT. ADAM && .AVIATION...ISSUED AT 720 AM EDT. A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .APX WATCHES/WARNINGS/ADVISORIES...FREEZING RAIN ADVISORY... UNTIL 5 PM...MIZ029-030-034>036-041-042 && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 144 PM EDT WED MAR 21 2007 .AVIATION...AN INTERESTING SITUATION AS THE WARM FRONT IS STILL HUNG UP ALONG THE INDIANA/OHIO BORDER. BECAUSE OF THIS, THERE IS A SIZABLE SFC BASED INVERSION THAT WILL CONTINUE THROUGH 12Z THURSDAY WHEN THE COLD FRONT MOVES THROUGH. THE WARM FRONT IS CAUSING LOW LEVEL WIND SHEAR THAT THE KAPX RADAR IS PEGGING AROUND 35 KTS AROUND 1500 FT. THE MODELS SHOW THAT A LOW LEVEL JET MOVES THROUGH AHEAD OF THE COLD FRONT AND BRINGS IN THE POSSIBILITY OF 50+KTS OVERNIGHT AROUND 1500 TO 2000 FEET. OTHERWISE, THE THUNDERSTORMS LOOK TO BE TIMED MORE WITH THE COLD FRONT PASSING THROUGH THE REGION. SO HAVE THE THUNDERSTORMS IN THE HOURS JUST PRIOR TO FROPA. SFC TEMPERATURES ARE ABOVE FREEZING AT THE TAF SITES SO IT LOOKS LIKE AT THE SFC THE FREEZING RAIN IS NO LONGER AN ISSUE. && .UPDATE...ISSUED 1121 AM. OCCLUDED LOW PRESSURE SYSTEM MOVING INTO WESTERN ONTARIO THIS MORNING. ASSOCIATED OCCLUDED FRONT EXTENDS TO A TRIPLE POINT LOW OVER SOUTH DAKOTA...WARM FRONT STRETCHING SE INTO THE OHIO VALLEY. STRONG WARM/MOIST ADVECTION UNDERWAY ACROSS THE WESTERN GREAT LAKES ALONG AND AHEAD OF THE WARM FRONT. 12Z APX SOUNDING REVEALING ABOVE FREEZING WARM NOSE BETWEEN 940 AND 740 MB WITH A MAX TEMP OF +5C WITHIN THE LAYER...A +6C CHANGE IN THE LAST 12 HOURS. LOW LEVEL MOISTURE GRADIENT SITTING BETWEEN APX AND GRB PER 12Z SOUNDINGS AND INITIAL ROUND OF CONVECTIVE SHOWERS HAVE DEVELOPED ALONG THE MOISTURE AXIS (PER MOIST CONVERGENCE PROCESSES) AND NOW PASSING THROUGH NORTHERN LOWER MICHIGAN ATTM. ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOPING UPSTREAM IN THE IOWA/WISCONSIN/ILLINOIS AREA SPURRED ON BY BETTER CONDITIONAL INSTABILITY ALOFT SPREADING EASTWARD OUT OF THE PLAINS AND EXPECTED TO IMPACT THE REGION LATER IN THE AFTERNOON THROUGH TONIGHT. PER RADAR TRENDS...INITIAL ROUND OF SHOWERS LOOKING TO PASS THROUGH NORTHERN LOWER MICHIGAN THROUGH EARLY AFTERNOON WITH THE HEAVIEST QPF FALLING OVER THE SE QUARTER OF THE CWA. SFC TEMPS ACROSS THIS AREA STILL AT OR BELOW FREEZING PARTICULARLY OVER THE HIGHER TERRAIN. A BIT ON THE FENCE WITH THIS ONE...BUT SPOTTER REPORTS FROM GRAND RAPIDS CWA INDICATE SOME ROADWAY ICING OCCURRING IN COUNTIES JUST UPSTREAM AND THE SAME IS LIKELY TO OCCUR UP THROUGH HTL/WEST BRANCH/GLADWIN...ETC. AFTER TALKING IT OVER WITH GRAND RAPIDS OFFICE DECIDED TO ISSUE A FREEZING RAIN ADVISORY VALID THROUGH EARLY AFTERNOON TO HANDLE THIS FIRST ROUND OF SHOWERS. NO OTHER CHANGES MADE FOR THE REST OF THE AFTERNOON AND THIS EVENING. NEXT ROUND OF SHOWERS AND POSSIBLE THUNDER LOOKING TO ARRIVE LATER IN THE AFTERNOON AND PARTICULARLY TONIGHT AS THE COLD FRONT PRESSES IN FROM THE WEST. BASICALLY...LOOKS WET WITH STRONG FORCING/IMPRESSIVE MOIST INFLOW UP INTO THE STATE - PWATS RUNNING 400 PERCENT OF NORMAL AS NOTED BY MIDNIGHT SHIFT. ADAM && .AVIATION...ISSUED AT 720 AM EDT. A CNTRL PLAINS STORM SYS WILL MOVE TWD THE WRN LAKES RGN LATE THIS AFTN AND THIS EVENING. AN ASSOCIATED WARM FRNT WILL PUSH INTO SRN LWR MI THIS MORNING AND EARLY AFTN...SLOWLY PUSHING NORTH TO A LINE FROM TVC TO HTL TO MBS BY 00Z THU. CURRENTLY VFR CIGS AND VSBY ARE NOTED OVR NRN LOWER MICHIGAN. HOWEVER MSTR WILL CONT TO INCREASE OVR LOWER MI INTO THIS EVE...AS THE STORM SYSTEM MOVES CLOSER. CURRENT SFC OBS FROM ARND WI AND ILL SHOWS MVFR/IFR CIGS AND VSBY IN ADVANCE OF THE FRONT. IFR EXPECTED OVER NRN LOWER THIS EVENING AND OVERNIGHT AS THE COLD FRONT MOVES OVER LAKE MICHIGAN AND INTO THE WRN LAKES. WILL MENTION LLWS OVR NRN LWR TAFS INTO THIS AFTN. SFC WINDS WILL BE FROM THE SOUTHEAST AROUND 5 TO 15 MPH THIS MORNING...HOWEVER SOUNDING DATA SUGGESTS WINDS ARND 2K FT FROM THE SOUTHWEST ARND 35 KTS. SWR && .UPDATE...ISSUED 640 AM WED MAR 21...JUST SOME THOUGHTS ON FREEZING RAIN POTENTIAL. PER REPORTS FROM IWX...FT WAYNE AREA PICKED UP ABOUT 1/8 INCH OF ICE ON ELEVATED SURFACES (CARS/TREES). ROADS STAYED WET. SAME SORT OF STORY AT IWX PROPER. LATEST MODEL RUNS (06Z NAM INCLUDING BUFR DATA...09Z RUC) IN VERY GOOD AGREEMENT. BOTH ARE A BIT SLOWER WITH PRECIP ONSET FROM MBL TO HTL TO GLADWIN...TOWARD NOON AS OPPOSED TO 10AM. THIS WILL ALLOW FOR A BIT MORE DIURNAL HEATING THRU THE HIGH CLOUDS BEFORE PRECIP BEGINS (NOTE THAT HTL/MBL/BIG RAPIDS/MT PLEASANT ARE ALL STILL REPORTING NO CLOUDS BELOW 12K FEET...THICKER CLOUDS AS FAR NORTH AS I-96). BOTH MODELS ALSO SUBSTANTIALLY DIMINISH QPF AS PRECIP MARCHES NORTHWARD INTO THE COOL/DRY AIR. RUC KEEPS QPF LESS THAN A TENTH OF AN INCH...NAM .05 OR LESS. THIS IS A FAIR BIT DRIER THAN 00Z MODELS. THAT IS THE GOOD NEWS. BAD NEWS IS THAT NAM/RUC SOUNDINGS BOTH INDICATE THAT MARGINAL FZRA IS LIKELY WHEN PRECIP DOES REACH THE SOUTHERN ZONES. SURFACE TEMPS LOOK TO BE VERY CLOSE TO FREEZING... THUS PROBABLY LEADING TO AN IWX-TYPE SCENARIO (TREES ICY...ROADS NOT...THOUGH OUR COLDER GROUND TEMPS MAKE THAT FAR FROM CERTAIN). MAY UPDATE FORECAST BETWEEN 7 AND 8 AM TO TIGHTEN DOWN THE TIMING AND WORDING A BIT. AT THIS TIME STILL THINK THAT GOING WITHOUT A HEADLINE IS THE BEST COURSE (THOUGH I THINK I SAID THAT TWO MORNINGS AGO...AND THAT DEFINITELY DID NOT GO WELL). JZ && .PREV DISCUSSION ISSUED 340 AM WED MAR 21... HIGH PRESSURE EAST OF LAKE ONTARIO CONTINUES TO MOVE AWAY FROM THE REGION. CLOUD COVER AND SURFACE WINDS ARE INCREASING ON THIS EARLY SPRING MORNING...THOUGH TEMPS ARE RESPONDING VERY SLOWLY. SPOTTY DEEP CONVECTION WAS OCCURRING ALONG AND NORTH OF A WARM FRONT IN NORTHERN MN AND SW SUPERIOR. A MORE SUBSTANTIAL WARM FRONT WAS NEAR KC...ST LOUIS...AND LOUISVILLE. PRECIP WAS OCCURRING NORTH OF THE FRONT...IN NORTHERN IN/IL. SPOTTY DEEP CONVECTION WAS OCCURRING IN NORTHERN MO AND IOWA. AND A PACIFIC COLD FRONT WAS MOVING RAPIDLY EAST ACROSS THE DAKOTAS. IF IT SEEMS LIKE ALL THIS IS CONVERGING ON MI...YOU WOULD BE CORRECT. PRECIP TRENDS OVER THE NEXT 36 HOURS ARE THE CLEAR MAIN CHALLENGE. MODELS...NAM REMAINS SOMEWHAT FASTER BRINING THE COLD FRONT THRU EARLY THURSDAY. GIVEN THE POTENT FORCING SHORTWAVE BLASTING ACROSS SUPERIOR...AND 80KT 500MB WESTERLY JET ON IT/S SOUTH FLANK...THE FASTER SOLUTION IS PREFERRED. THIS ALSO LINES UP WITH MODEL TRENDS TOWARD A GENERALLY FASTER SOLUTION. TODAY...FIRST OFF...SURFACE FRONT AND MID LEVEL SHORTWAVE CONTRIBUTING TO CONVECTION OVER WESTERN SUPERIOR WILL BOTH HAVE SOME NORTHWARD COMPONENT TO THEIR MOTION. THIS WILL KEEP ASSOCIATED TSTORMS NORTH OF THE FORECAST AREA...THOUGH IT IS POSSIBLE THE GOOD PEOPLE OF WHITEFISH PT MAY BE ABLE TO SEE LIGHTNING FLASHES OUT OVER THE BIG LAKE THIS MORNING. ISOLATED SHOWERS ARE POSSIBLE IN EASTERN UPPER MI DURING THE PRE-DAWN HOURS. THE MORE SUBSTANTIAL PRECIP CONCERN WILL BE ARRIVING FROM THE SOUTH. THE NAM SHOWS THE SAME TRENDS AS YESTERDAY (WITH THE RUC IN DECENT AGREEMENT)...BRINGING SHOWERS INTO SOUTHERN AND CENTRAL LOWER MI TODAY...ASSOCIATED WITH THE LOW LEVEL JET AND MAXIMIZED THETA-E ADVECTION. ON THE OTHER HAND...THE GFS IS HANDLING ONGOING PRECIP POORLY. 850MB THETA-E RIDGE WILL ASCENT INTO SOUTHERN LOWER MI AT MIDDAY...WITH ALONG AND ON IT/S NORTH FLANK IN REGIME OF POSITIVE THETA-E ADVECTION. AIRMASS IS GENERALLY RATHER DRY AT THE MOMENT...BUT RAPID INCREASE IN SW LOW AND MID LEVEL FLOW WILL QUICKLY MOISTEN THINGS UP. RAIN WILL REACH OR APPROACH MBL AND GLADWIN BY 15Z...AND MOVE ENE ACROSS THE SE THIRD OF THE FORECAST AREA THRU LATE AFTERNOON. HIGHEST CHANCES FOR PRECIP WILL BE HERE. SURFACE WARM ADVECTION WILL BE INCREASING GREATLY THIS MORNING. HOWEVER...WE ARE RATHER NIPPY NOW...AND AM CONCERNED THAT A QUICK TOUCH OF ICING WILL OCCUR RIGHT AT ONSET. AIR TEMPS WILL CLIMB PAST FREEZING RIGHT ABOUT AT PRECIP ONSET IN THE SOUTHERN ZONES...BUT GROUND TEMPS WILL PROBABLY LAG BY JUST A BIT. WILL THUS MENTION A VERY BRIEF PERIOD (AT MIDDAY/PRECIP ONSET) OF MIXED RAIN/FREEZING RAIN FROM CAD EASTWARD. WILL NEED TO KEEP A VERY CLOSE EYE ON TEMP/RADAR TRENDS THIS MORNING. TO THE NORTH...AIRMASS SATURATES THIS AFTERNOON...BUT FORCING IS LESS THAN FURTHER SOUTH. 700-600MB Q-VECTOR CONVERGENCE WEAKENS AS IT HEADS NORTH...AND DOESN/T GET NORTH OF M-72 TIL ALMOST SUNDOWN. STILL...THE AIRMASS IS SOGGY ENOUGH...WITH GENERAL (THOUGH UNFOCUSED) ASCENT DUE TO WARM ADVECTION...TO WARRANT LIKELY POPS IN THE MID TO LATE AFTERNOON (EXCEPT EASTERN UPPER MI...TOO FAR NORTH FOR ANYTHING MORE THAN CHANCE). SURFACE TEMPS SHOULD RISE COMFORTABLY ABOVE FREEZING EVERYWHERE IN THE PM HOURS...AND AM NOT CONCERNED WITH FREEZING RAIN. THOUGH...AS SOUPY LOW LEVEL AIR MOVES IN OVER COLDER LAKES AND GROUND...SOME FOG IS A DISTINCT POSSIBILITY LATE IN THE DAY. TONIGHT...STRONG FORCING WILL ARRIVE OVERNIGHT AS THE COLD FRONT AND FORCING SHORTWAVE RACE IN FROM THE WEST. HOWEVER...NAM/GFS ARE COMING INTO REASONABLE AGREEMENT THAT EVEN THE EVENING HOURS WILL BE SOGGY. 850MB JET WILL CRANK UP TO 50KT BY LATE EVENING...CONTINUING TO ADVECT COPIOUS AMOUNTS OF MOISTURE INTO THE REGION (AT LEAST BY MARCH STANDARDS). PWATS WILL RISE TO 1.1-1.2 INCHES...SOME 400 PERCENT OF NORMAL. THOUGH THE MAIN SURGE OF PRECIP WILL BE ARRIVING OVERNIGHT FROM THE WEST...AT THIS TIME PLAN ON CARRYING CATEGORICAL POPS MOST OF THE NIGHT IN MOST OF THE FORECAST AREA (THE SE ZONES BEING THE EXCEPTION). ALSO WILL ADD FOG...AND LOCALLY HEAVY RAIN AS QPF AMOUNTS APPROACH AN INCH. SCT TSTORMS STILL ANTICIPATED... ESPECIALLY OVERNIGHT AS LAPSE RATES STEEPEN WITH FALLING HEIGHTS/ TEMPS ALOFT (700-500MB LAPSE RATES 6.5 TO 7 C/KM...CAPES 400-500J/KG WHEN LIFTING FROM 900MB). STORMS WILL BE ELEVATED...AND UNLIKELY TO BRING STRONG WINDS ALOFT DOWN TO THE SURFACE. FLOODING CONCERNS ARE SMALL BUT NON-ZERO...MUCH OF THE THAW IS DONE IN NORTHERN LOWER MI...BUT SOME PLACES RIVERS ARE STILL FAIRLY HIGH AND/OR ICY...AND THE COLD GROUND WILL NOT BE RECEPTIVE TO ABSORBING RAINFALL (AT LEAST IN SPOTS). IN EASTERN UPPER MI...MUCH MORE SNOW TO MELT...BUT SNOW MAY BE ABLE TO LARGELY ABSORB THE RAINFALL INSTEAD OF JUST MELTING ALL AT ONCE. NOT ENOUGH CONCERNS TO WARRANT A FLOOD WATCH...BUT WILL TALK ABOUT LOCAL HIGH PROBLEMS POSSIBLE IN OUTLOOK. THURSDAY...WITH A LITTLE FASTER COLD FRONTAL PASSAGE...WILL SPEED UP EXIT OF PRECIP THURSDAY MORNING. SHOWERS AND TSTORMS WILL BE CARRIED OUT OF THE REGION...WITH NO CHANCE OF RAIN BY AFTERNOON. AIRMASS BEHIND FRONT IS COOLISH BUT NOT COLD...THOUGH EASTERN UPPER MI WILL SEE A POCKET OF COLDER 850MB AIR (TO -10C) ARRIVE IN THE AFTERNOON. TEMPS WILL HOLD NEARLY STEADY FOR MOST OF THE DAY...EXCEPT FALLING OFF A BIT IN EASTERN UPPER MI...AND PERHAPS A DOWNSLOPE-ASSISTED SMALL DIURNAL RISE FROM APN SOUTHWARD. THURSDAY NIGHT/FRIDAY...ZONAL 500MB FLOW ESTABLISHED ACROSS THE REGION WILL KEEP THINGS RELATIVELY UNEVENTFUL. A COUPLE OF SHORTWAVES FLITTING BY NORTHERN LAKE SUPERIOR WILL PROVIDE SOME EXTRA CLOUD COVER TO EASTERN UPPER MI (PARTLY TO MOSTLY CLOUDY)...VS MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS TO THE SOUTH. WILL KEEP EASTERN UPPER MI DRY FOR NOW...THE LOW LEVELS STAY DRY AS THE MID LEVELS MOISTEN THU NIGHT...AND THE REVERSE TAKES PLACE ON FRIDAY. MIN TEMPS WILL BE MAINLY IN THE 20S...WITH MAX TEMPS 45 TO 55. ZOLTOWSKI FRIDAY NIGHT THRU SUNDAY...A WEAK WAVE IN THE 500 MB FLOW WILL SWING OVER ONTARIO AND UPPER MICHIGAN FRIDAY NIGHT/EARLY SAT...WITH A NARROW BAND OF 850/700MB MSTR PRESENT IN ADVANCE OF THE FEATURE. THE CURRENT FORECAST LOOKS GOOD...AS IT ALREADY HAS CHC PCPN OVER EAST UPPER AND THE STRAITS REGION FRIDAY/EARLY SATURDAY. THE MIX RA/SN LOOKS TO BE IN LINE...AS 850MB TEMPS ARE PROGGED TO BE ARND 0C. OTHERWISE...SFC HIGH PRES/RIDGING AND ANTI CYCLONIC FLOW WILL BE THE DOMINANT FEATURES OVER THE GREAT LAKES RGN THRU THE REST OF SAT AND SUNDAY. 500 MB HEIGHTS INCREASE SHARPLY OVER THE GREAT LAKES SATURDAY AND SUNDAY IN ADVANCE OF A STRENGTHENING / DEEPENING UPPER LVL TROF DEVELOPING OVER THE CENTRAL PLAINS. THEREFORE WILL CONTINUE WITH THE CURRENT DRY FCST THRU SUNDAY. WILL CONT THE MENTION OF AFTN HIGHS AROUND 50 SATURDAY AS 850 TEMPS NR +2C. SUNDAYS FCST HIGHS IN THE LOW TO MID 50S LOOK IN LINE...AS 850 MB TEMPS WARM TO +6C. SWR && .APX WATCHES/WARNINGS/ADVISORIES...FREEZING RAIN ADVISORY...UNTIL 2 PM...MIZ028>030-033>036-041-042. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 915 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY) LATEST SATELLITE IMAGERY SHOWS LINGERING UPPER RIDGE OVER THE REGION...WHICH IS CONTINUING TO CUT OFF LOW LEVEL GULF MOISTURE ACROSS THE REGION. REMOVED PATCHY MORNING FOG IN THE SOUTH AND PUT IN A LITTLE MORE CLOUD COVER FOR PARTLY TO MOSTLY SUNNY SKIES FROM THE HIGH CLOUDS SPILLING IN FROM THE WEST. THE REST OF FORECAST APPEARS TO BE ON TRACK WITH TEMPERATURES QUICKLY RISING TO THE 70S BY NOON BEFORE REACHING THE LOWER 80S THIS AFTERNOON./17/ .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI/HBG FOR SATURDAY MORNING. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA FOR SATURDAY MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT./17/ && .PREVIOUS DISCUSSION...252 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY THROUGH SATURDAY)...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH SATURDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL NOSE INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW OVER BAJA. THIS LOW IS PROGGED TO MOVE TO THE NORTHEAST OVER THE FOUR CORNERS REGION DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO SPREAD OVERHEAD FROM THE WEST BUT WL BE WELL ABOVE NORMAL EACH DAY...IN THE LOWER 80S THIS AFTERNOON AND SATURDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)...THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA INTO MONDAY...CONTINUING TO DEFLECT POTENTIAL SHORTWAVE ENERGY. BY LATE MONDAY AND TUESDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION...THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. WITH PASSAGE OF THE TROUGH THE MID LEVEL RIDGE IS FORECAST TO REBUILD OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER. THERE ARE STILL INDICATIONS IN THE MODELS THAT A MORE ACTIVE PATTERN WILL TAKE SHAPE OVER THE LOWER MS VALLEY REGION BY NEXT FRIDAY AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS AND FORCE A BREAKDOWN OF THE RIDGE. THE GFS/ ECMWF ARE CONSISTENT IN SHOWING THIS BREAK-DOWN...AND WILL KEEP THE CHANCE POPS OFFERED BY MEX MOS. /EC/ && .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI THIS MORNING AND AGAIN SATURDAY MORNING. IFR CONDITIONS ARE EXPECTED TO DEVELOP AROUND 11Z AT HBG AGAIN THIS MORNING AND SATURDAY MORNINGS. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA EACH MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 82 54 84 55 / 2 2 3 3 MERIDIAN 83 52 85 54 / 2 2 2 2 VICKSBURG 82 56 84 57 / 3 2 3 3 HATTIESBURG 82 54 84 54 / 3 2 2 5 NATCHEZ 81 56 83 58 / 3 2 3 4 GREENVILLE 81 57 83 57 / 7 2 3 3 GREENWOOD 83 56 85 57 / 6 2 3 3 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 915 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY) LATEST SATELLITE IMAGERY SHOWS LINGERING UPPER RIDGE OVER THE REGION...WHICH IS CONTINUING TO CUT OFF LOW LEVEL GULF MOISTURE ACROSS THE REGION. REMOVED PATCHY MORNING FOG IN THE SOUTH AND PUT IN A LITTLE MORE CLOUD COVER FOR PARTLY TO MOSTLY SUNNY SKIES FROM THE HIGH CLOUDS SPILLING IN FROM THE WEST. THE REST OF FORECAST APPEARS TO BE ON TRACK WITH TEMPERATURES QUICKLY RISING TO THE 70S BY NOON BEFORE REACHING THE LOWER 80S THIS AFTERNOON./17/ .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI FOR SATURDAY MORNING. IFR CONDITIONS ARE EXPECTED TO DEVELOP AROUND 11Z AT HBG FOR SATURDAY MORNING. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA FOR SATURDAY MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT./17/ && .PREVIOUS DISCUSSION...252 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY THROUGH SATURDAY)...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH SATURDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL NOSE INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW OVER BAJA. THIS LOW IS PROGGED TO MOVE TO THE NORTHEAST OVER THE FOUR CORNERS REGION DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO SPREAD OVERHEAD FROM THE WEST BUT WL BE WELL ABOVE NORMAL EACH DAY...IN THE LOWER 80S THIS AFTERNOON AND SATURDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)...THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA INTO MONDAY...CONTINUING TO DEFLECT POTENTIAL SHORTWAVE ENERGY. BY LATE MONDAY AND TUESDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION...THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. WITH PASSAGE OF THE TROUGH THE MID LEVEL RIDGE IS FORECAST TO REBUILD OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER. THERE ARE STILL INDICATIONS IN THE MODELS THAT A MORE ACTIVE PATTERN WILL TAKE SHAPE OVER THE LOWER MS VALLEY REGION BY NEXT FRIDAY AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS AND FORCE A BREAKDOWN OF THE RIDGE. THE GFS/ ECMWF ARE CONSISTENT IN SHOWING THIS BREAK-DOWN...AND WILL KEEP THE CHANCE POPS OFFERED BY MEX MOS. /EC/ && .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI THIS MORNING AND AGAIN SATURDAY MORNING. IFR CONDITIONS ARE EXPECTED TO DEVELOP AROUND 11Z AT HBG AGAIN THIS MORNING AND SATURDAY MORNINGS. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA EACH MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 82 54 84 55 / 2 2 3 3 MERIDIAN 83 52 85 54 / 2 2 2 2 VICKSBURG 82 56 84 57 / 3 2 3 3 HATTIESBURG 82 54 84 54 / 3 2 2 5 NATCHEZ 81 56 83 58 / 3 2 3 4 GREENVILLE 81 57 83 57 / 7 2 3 3 GREENWOOD 83 56 85 57 / 6 2 3 3 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 252 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY THROUGH SATURDAY)...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH SATURDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL NOSE INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW OVER BAJA. THIS LOW IS PROGGED TO MOVE TO THE NORTHEAST OVER THE FOUR CORNERS REGION DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO SPREAD OVERHEAD FROM THE WEST BUT WL BE WELL ABOVE NORMAL EACH DAY...IN THE LOWER 80S THIS AFTERNOON AND SATURDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)...THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA INTO MONDAY...CONTINUING TO DEFLECT POTENTIAL SHORTWAVE ENERGY. BY LATE MONDAY AND TUESDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION...THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. WITH PASSAGE OF THE TROUGH THE MID LEVEL RIDGE IS FORECAST TO REBUILD OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER. THERE ARE STILL INDICATIONS IN THE MODELS THAT A MORE ACTIVE PATTERN WILL TAKE SHAPE OVER THE LOWER MS VALLEY REGION BY NEXT FRIDAY AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS AND FORCE A BREAKDOWN OF THE RIDGE. THE GFS/ ECMWF ARE CONSISTENT IN SHOWING THIS BREAK-DOWN...AND WILL KEEP THE CHANCE POPS OFFERED BY MEX MOS. /EC/ && .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI THIS MORNING AND AGAIN SATURDAY MORNING. IFR CONDITIONS ARE EXPECTED TO DEVELOP AROUND 11Z AT HBG AGAIN THIS MORNING AND SATURDAY MORNINGS. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA EACH MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 82 54 84 55 / 2 2 3 3 MERIDIAN 83 52 85 54 / 2 2 2 2 VICKSBURG 82 56 84 57 / 3 2 3 3 HATTIESBURG 82 54 84 54 / 3 2 2 5 NATCHEZ 81 56 83 58 / 3 2 3 4 GREENVILLE 81 57 83 57 / 7 2 3 3 GREENWOOD 83 56 85 57 / 6 2 3 3 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 935 AM CDT THU MAR 22 2007 .SHORT TERM...LATEST SATELLITE IMAGERY SHOWS THE REGION UNDER AN UPPER RIDGE...WHICH IS CONTINUING OUR LONG ROUND OF DRY WEATHER. SHOULD GET SOME SCATTERED CLOUDS MOSTLY IN THE FORM OF HIGH LEVEL CLOUDS FOR THIS AFTERNOON. THE FOG HAS LIFTED OVER OUR THE SOUTHEAST ZONES...SO HAVE ALLOWED THE DENSE FOG ADVISORY TO EXPIRE. CURRENT HIGHS IN THE LOWER 80S SEEMS TO BE ON TRACK. SO WILL MAKE NO OTHER CHANGES TO THE ZONES./17/ .AVIATION...PATCHES OF LIFR CIGS/VSBY WILL BE POSSIBLE IN AREAS ALONG AND S OF HIGHWAY 84 FOR FRIDAY MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME AREAWIDE BY 15Z FRIDAY./17/ .PREVIOUS DISCUSSION... TODAY THROUGH FRIDAY...GRADIENT WINDS HAVE CONTINUED OVER MUCH OF CWA THIS MORNING WITH THE EXCEPTION OF SOUTHEAST MISSISSIPPI LAST HOUR. PINE BELT AIRPORT WAS REPORTING VISIBILITY RESTRICTIONS ALREADY. WL CONTINUE TO MONITOR OUR SOUTHEAST ZONES FOR AN ADVISORY AGAIN THIS MORNING...BUT CURRENTLY EXPECTING ANY DENSE FOG DEVELOPMENT TO REMAIN PATCHY. ELSE...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH FRIDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL BUILD INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW DROPPING SOUTH OFF THE SOUTHERN CALIFORNIA COAST. THIS LOW IS PROGGED TO MOVE OVER BAJA DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. SOME MID AND HIGH LEVEL CLOUDS WILL SPREAD OVERHEAD FROM THE WEST BUT WL STILL REACH WELL ABOVE NORMAL...AROUND 80 DEGREES THIS AFTERNOON AND FRIDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ FRIDAY NIGHT THROUGH NEXT WEEK... THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA THIS WEEKEND...TENDING TO DEFLECT ANY POTENTIAL SHORTWAVE TROUGHS. WITH THAT IN MIND...THE GFS SEEMS A LITTLE TOO QUICK IN INCREASING RAIN CHANCES SUNDAY AND SUNDAY NIGHT AND WILL KEEP THE FORECAST DRY. BY MONDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION... THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. THE MID LEVEL RIDGE REBUILDS OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER FOR THE FORECAST AREA. THERE ARE INDICATIONS THAT A MORE ACTIVE PATTERN COULD TAKE SHAPE OVER THE LOWER MS VALLEY REGION NEXT WEEKEND AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS. THE GFS/UKMET/ECMWF ARE ALL IN AGREEMENT ON THIS SCENARIO...BUT PERSISTENCE CERTAINLY ARGUES AGAINST IT. /EC/ .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 230 AM CDT THU MAR 22 2007 .DISCUSSION... TODAY THROUGH FRIDAY...GRADIENT WINDS HAVE CONTINUED OVER MUCH OF CWA THIS MORNING WITH THE EXCEPTION OF SOUTHEAST MISSISSIPPI LAST HOUR. PINE BELT AIRPORT WAS REPORTING VISIBILITY RESTRICTIONS ALREADY. WL CONTINUE TO MONITOR OUR SOUTHEAST ZONES FOR AN ADVISORY AGAIN THIS MORNING...BUT CURRENTLY EXPECTING ANY DENSE FOG DEVELOPMENT TO REMAIN PATCHY. ELSE...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH FRIDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL BUILD INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW DROPPING SOUTH OFF THE SOUTHERN CALIFORNIA COAST. THIS LOW IS PROGGED TO MOVE OVER BAJA DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. SOME MID AND HIGH LEVEL CLOUDS WILL SPREAD OVERHEAD FROM THE WEST BUT WL STILL REACH WELL ABOVE NORMAL...AROUND 80 DEGREES THIS AFTERNOON AND FRIDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ FRIDAY NIGHT THROUGH NEXT WEEK... THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA THIS WEEKEND...TENDING TO DEFLECT ANY POTENTIAL SHORTWAVE TROUGHS. WITH THAT IN MIND...THE GFS SEEMS A LITTLE TOO QUICK IN INCREASING RAIN CHANCES SUNDAY AND SUNDAY NIGHT AND WILL KEEP THE FORECAST DRY. BY MONDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION... THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. THE MID LEVEL RIDGE REBUILDS OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER FOR THE FORECAST AREA. THERE ARE INDICATIONS THAT A MORE ACTIVE PATTERN COULD TAKE SHAPE OVER THE LOWER MS VALLEY REGION NEXT WEEKEND AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS. THE GFS/UKMET/ECMWF ARE ALL IN AGREEMENT ON THIS SCENARIO...BUT PERSISTENCE CERTAINLY ARGUES AGAINST IT. /EC/ && .AVIATION...PATCHES OF LIFR CIG/VSBY WILL BE POSSIBLE IN AREAS ALONG AND S OF HIGHWAY 84 THIS MORNING AND AGAIN FRIDAY MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME AREAWIDE BY 15Z EACH MORNING. /22/ && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1055 AM CDT FRI MAR 23 2007 .UPDATE... FORECAST UPDATED TO ACCOUNT FOR THE LATEST RADAR TRENDS. AXIS OF SHRA/TSRA HAS DEVELOPED ALONG A MID/UPPER LEVEL SHEAR AXIS EXTENDING FROM NE MO THROUGH SE KS AND INTO NE TX. DECENT MOISTURE TRANSPORT IS NOTED IN THE LOW LEVELS OF THE ATMOSPHERE...WITH THETA-E RIDGING TO THE TUNE OF 328K NOSING INTO WEST CENTRAL MISSOURI. THE MOST CONCENTRATED AREAS OF SHRA/TSRA CURRENTLY RESIDES OVER JASPER COUNTY MO AND CHEROKEE COUNTY MO. ADDITIONAL...MORE SCATTERED ACTIVITY EXTENDS FARTHER EAST ON THE NE PERIPHERY OF THE BEST LOW LEVEL MOISTURE TRANSPORT VECTORS (AS VIEWED THROUGH THE LATEST RUC INITIALIZATIONS). WITH PWS FROM THE MORNING KSGF SOUNDING AROUND 1.15 INCHES AND KIS IN EXCESS OF 30...THIS ACTIVITY WILL BE EFFICIENT IN RAINFALL PRODUCTION. METARS ACROSS SE KS CORRELATE WELL TO 1-HR RAINFALL RATES. WITH THE RADAR CURRENTLY INDICATING HOURLY RAINFALL AMOUNTS BETWEEN ONE AND TWO INCHES...A FLASH FLOOD THREAT EXISTS. THE PRIMARY CONCERN REMAINS EXTREME SE KS AND WESTERN MO WHERE FLASH FLOOD GUIDANCE VALUES REMAIN LOW FROM RECENT RAINS. INDICATIONS ARE THAT WHILE THIS AREA OF RAINFALL WILL REMAIN ELONGATED AND RATHER NARROW...THE SLOW MOVEMENT OF THE SHEAR AXIS WILL PROMOTE TRAINING CONVECTION IN AN AREA WITH LOWER TOLERANCE FOR HEAVY RAINFALL AMOUNTS. ALL PRODUCTS HAVE BEEN UPDATED AND SENT. GAGAN && .PREVIOUS DISCUSSION... //303 AM CDT FRI MAR 23 2007// THE UNSEASONABLY WARM AND UNSETTLED PATTERN WILL PERSIST THROUGH MUCH OF THE SEVEN DAY FORECAST PERIOD. UNUSUAL FOR THE TIME OF YEAR...NO COLD FRONTS OR MAJOR WEATHER SYSTEMS ARE EXPECTED TO PASS OVERHEAD. HOWEVER...DUE TO AN EXTENDED PERIOD OF GULF INFLUX...SCATTERED CLUSTERS OF SHOWERS AND THUNDERSTORMS ARE IN THE OFFING FOR THE NEXT SEVERAL DAYS. THEREFORE...THE PRIMARY FORECAST CONCERN IN THIS MORNINGS ANALYSIS WAS PRECIP CHANCES IN BOTH THE SHORT AND LONG TERM TIME FRAMES. ONE ITEM TO NOTE...BECAUSE OF EAST TO NORTHEAST FLOW OVER MUCH OF THE GULF OF MEXICO...A RATHER HOMOGENEOUS AIRMASS WILL CONTINUE FROM THE GULF INTO MID AMERICA. DRY ADVECTION FROM THE ATLANTIC REGIONS CONTINUE TO LIMIT DEEP RICH MOISTURE FROM MATERIALIZING WITHIN THE WESTERN GULF SOURCE REGION. THEREFORE...DESPITE THE LONG PERIOD OF SOUTHERLY FLOW...INSTABILITY WILL REMAIN UNUSUALLY LIMITED FOR STRONG TO SEVERE CONVECTION THE NEXT FEW DAYS. SHORT TERM (TODAY - SUNDAY NIGHT)... A SYNOPTIC SCALE CYCLONE CENTERED OVER THE BAJA OF CALIFORNIA CONTINUES TO INFLUENCE THE OVERALL PATTERN OVER THE SOUTHERN PLAINS AND MISSOURI OZARKS REGION. A BELT OF SUBTROPICAL MOISTURE EXTENDS AROUND THE EASTERN FLANK OF THE CYCLONE...AND IS CORRELATED WITH LARGE SCALE LIFT MAINLY IN THE FORM OF JET STREAM LEVEL DIFFLUENCE. A FEW CLUSTERS OF CONVECTION WITHIN THE PACIFIC MOISTURE PLUME APPEAR TO BE CORRELATED WITH ENHANCED AREAS OF UPPER LEVEL DIFFLUENCE...WHICH IS VERIFIED BY THE SOUTHERN PLAINS PROFILER NETWORK WHEN ANALYZING 250 MB WIND VECTOR MEASUREMENTS. ONE OF THESE CONVECTIVE CLUSTERS IS CURRENTLY IMPACTING EXTREME SOUTHEAST KANSAS AND SOUTHWEST MISSOURI. DUE TO LIMITED INSTABILITY...THE PRIMARY HAZARDS WITH THIS CLUSTER APPEARS TO BE MODERATE TO HEAVY RAIN...ALONG WITH A FEW CLOUD TO GROUND LIGHTNING STRIKES. TIMING OF THIS CONVECTIVE CLUSTER AND HOW IT EVOLVES WITH RESPECT TO AREAL COVERAGE WAS THE INITIAL FORECAST CONCERN FOR TODAYS PERIOD. EXTRAPOLATION WITH THE CLUSTERS CURRENT MOVEMENT SUGGESTS THAT AFTER 12Z...THE PRECIPITATION SHIELD WILL BE OVER MUCH OF SOUTH CENTRAL AND CENTRAL MISSOURI. RAIN WILL LIKELY END IN THE SPRINGFIELD METRO AREA SOMETIME BETWEEN 6 - 8AM. THEREFORE WILL ADJUST MORNING POPS TO REPRESENT THIS EXTRAPOLATION...WITH LIKELY TO CATEGORICAL POPS OVER THE EASTERN HALF OF THE CWA...THEN TAPERING THE GRID TO SLIGHT CHANCES OUT WEST. IT`S LIKELY THAT THE CLUSTER WILL LOSE SOME OF IT`S LOW LEVEL FORCING WITH NOCTURNAL VEERING OF LOW LEVEL WINDS. BOTH THE WRF AND THE GFS INDICATE A SECOND CLUSTER OF CONVECTION TO IMPACT THE OZARKS THIS AFTERNOON. AGAIN...THE ONLY KINEMATIC MECHANISM TO CAUSE THIS APPEARS TO BE AN AREA OF ENHANCED UPPER DIFFLUENCE CURRENTLY BECOMING MORE ORGANIZED NEAR ABILENE TEXAS. HOW THIS FORECASTED BAND OF FORCING WILL IMPACT THE OZARKS REMAINS VERY QUESTIONABLE. QPF FIELDS FROM THE WRF AND GFS ARE VERY INCONSISTENT AND NOT IMPRESSIVE AT ALL. HOWEVER MOS GUIDANCE SUGGEST CATEGORICAL POPS IN ALL LOCATIONS. WILL ADJUST THE AFTERNOON POP GRID TO 50 POPS DUE TO THE UNCERTAINTY ON HOW THIS EVOLVES. ONE ELEMENT THAT WE DO KNOW FOR SURE IS THAT CONSIDERABLE CLOUD COVER WILL EXIST THROUGH THE ENTIRE DAY...WHICH WILL HAVE SOME IMPACTS ON TEMPERATURES. WITH EARLY MORNING TEMPERATURES STARTING OUT IN THE LOW TO MID 60S...DESPITE CLOUD COVER AND PRECIP READINGS SHOULD WARM INTO THE 70S IN MOST LOCATIONS. HEADING INTO THE WEEKEND...THE BAJA LOW WILL FILL WHILE THE MAIN CIRCULATION SHIFTS INTO THE HIGH PLAINS. MASS AND MOISTURE FIELDS FROM THE GFS INDICATE THAT THE AXIS OF SUBTROPICAL MOISTURE SHIFTS EAST OF THE CWA...HOWEVER...LOW LEVEL JET AND WARM CONVEYOR BELT PROCESSES OCCUR BY SATURDAY MORNING. THIS WILL YIELD MORE AREAS OF CONVECTIVE CLUSTERS SOMEWHERE ALONG THE SOUTHERN/CENTRAL PLAINS CORRIDOR. RESIDUAL CLUSTERS WILL LIKELY SHIFT EASTWARD DURING THE DAY ON SATURDAY...POSSIBLY IMPACTING THE CWA. WILL KEEP ONGOING THUNDERSTORM CHANCES GOING IN THE GRIDS DUE TO SIGNALS FROM BOTH THE GFS AND WRF FOR INCREASED INSTABILITY WITHIN THIS PERIOD. NOT MUCH CHANGE IN THE LARGE SCALE PATTERN CAN BE ANALYZED WITHIN MODEL DATA. THEREFORE SINCE WE WILL REMAIN UNDER THIS EXTENDED WARM/MOISTURE ADVECTION REGIME...WILL KEEP THUNDERSTORM CHANCES GOING THROUGH SUNDAY NIGHT. LONG TERM (MONDAY - THURSDAY)... AN UPPER LEVEL WEAKNESS...BASICALLY THE RESIDUAL TROUGHING FROM THE ONGOING BAJA CYCLONE IS SUGGESTED TO GRADUALLY PASS THROUGH THE AREA MONDAY OR TUESDAY. NOT MUCH OF A RESPONSE OCCURS AT THE SURFACE AS THE OZARKS REMAINS UNDER SOUTHERN FLOW. COOLING ALOFT MAY PROMOTE INCREASED INSTABILITY...ESPECIALLY TUESDAY AFTERNOON. WILL KEEP ONGOING TSTORM CHANCES ON TUESDAY LOOK GOOD AND MADE LITTLE CHANGE. MEDIUM RANGE MODELS INDICATE THAT LONG WAVE TROUGHING WILL REDEVELOP ACROSS THE WESTERN THIRD OF THE CONUS. THIS WILL REINFORCE THE UNSETTLED PATTERN AND OFFER A CONTINUATION OF UNSEASONABLY WARM TEMPERATURES. I MADE A FEW ADJUSTMENTS TO TEMPERATURES BY WARMING THESE GRIDS BY SEVERAL DEGREES IN THE EXTENDED. ECMWF HAS BEEN PERFORMING THE BEST OVER THE PAST FEW WEEKS...WHICH SHOWS ENERGY APPROACHING THE NATIONS MID SECTION BY THURSDAY. THE GFS IS NOT MUCH DIFFERENT WITH A SIMILAR SOLUTION. THEREFORE NO ADJUSTMENTS TO THESE ONGOING THUNDERSTORM CHANCES WERE NEEDED. CRAMER && .AVIATION... TAF SITES WERE AMENDED EARLIER TO GAUGE RAINFALL/TS TIMING. IT APPEARS THAT CIGS/VIS WILL WAVER FROM VFR TO MVFR WITH THE ON AGAIN...OFF AGAIN HEAVIER CONVECTIVE ELEMENTS. RAINFALL WILL PERSIST AT JLN INTO THE EARLY AFTERNOON. AT SGF...CONFIDENCE IS A LITTLE LOWER IN TIMING DUE TO THE SLOW EASTWARD DRIFT OF CONVECTION...AN ESTIMATED TIMING IS PROVIDED IN THE LATEST TAF TARGETING THE EARLY TO MID AFTERNOON HOURS. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO SGF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 800 PM CDT WED MAR 21 2007 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... COLD FRONT HAS MOVED INTO SOUTHEASTERN NEBRASKA AND NORTH CENTRAL KANSAS WITH A LINE OF THUNDERSTORMS DEVELOPING ALONG THE FRONT FROM NEAR CONCORDIA NORTHEAST TO SOUTH OF OMAHA. REPORTS FROM OAX INDICATED NUMEROUS THREE QUARTER TO ONE AND ONE QUARTER HAIL REPORTS WITH THIS LINE. MLCAPES AROUND 1500-2000 J/KG...STEEP MID LEVEL LAPSE RATES AND SFC-6KM SHEAR FROM 30-40 KNOTS WILL CONTINUE TO SUPPORT THE THREAT OF HAIL AS THE THUNDERSTORMS MOVE EAST INTO EXTREME NORTHWEST MISSOURI. THE LINE OF THUNDERSTORMS WILL CONTINUE TO MOVE SOUTH AND EAST THROUGH THE NIGHT WITH THE SEVERE WEATHER THREAT GRADUALLY DIMINISHING. LATEST RUC AND NAM SUGGEST THAT THE CAP OVER THE CWA WILL GRADUALLY ERODE...BUT WITH THE LACK OF INSOLATION...SBCAPE AND MUCAPE DROP TO 1000-1250 J/KG BETWEEN 09-12Z. SHEAR WILL REMAIN MARGINAL THROUGH THE NIGHT. THE LINE OF CONVECTION IS EXPECTED TO REACH A KANSAS CITY TO PRINCETON LINE BY 08Z. BY 12Z...ONLY SMALL HAIL IS EXPECTED. DB && .PREVIOUS DISCUSSION... 331 PM... VERY CHALLENGING FORECAST THROUGH THE EARLY PERIODS AS LARGE SCALE PATTERN CHANGE HAS PLACED THE LOWER MISSOURI VALLEY REGION IN A FAVORED AREA FOR REPEATED PRECIPITATION EVENTS. 19Z SURFACE ANALYSIS DEPICTS A SEASONABLY MOIST WARM SECTOR AIRMASS OVER THE CWA THIS AFTERNOON...CHARACTERIZED BY DEWPOINTS APPROACHING 60 DEGREES. RUC SOUNDINGS SHOW THAT AN ELEVATED MIXED LAYER WITH STEEP MID-LEVEL LAPSE RATES HAS OVERSPREAD THE REGION...LEAVING THE AREA CAPPED ABOVE AN EXTENSIVE STRATUS CANOPY. PACIFIC COLD FRONT/DRYLINE STRETCHED FROM NORFOLK TO KEARNEY NEBRASKA...AND PER VISIBLE SATELLITE IMAGERY HAS BEEN PRECEDED BY AN INTERESTING GRAVITY WAVE. SHORT MODEL PROGS COLLABORATE WELL WITH OBSERVATIONAL DATA...SHOWING THAT CONVECTION WILL LIKELY DEVELOP OVER SE NEBRASKA IN THE NEXT SEVERAL HOURS WHERE BETTER SURFACE CONVERGENCE IS FOCUSED ALONG THE ADVANCING FRONT AND JUST EAST OF THE ANALYZED SURFACE LOW. ATTENDANT SEVERE THREAT APPEARS TO BE PRIMARILY IN THE FORM OF DAMAGING LINE SEGMENTS WITH ATTENDANT LARGE HAIL AS STEEP MID LEVEL LAPSE RATES COUPLE WITH INCREASING UNIDIRECTIONAL SHEAR AFTER DARK. CERTAINLY STORMS MOVING TOWARD THE NORTHEAST WOULD HAVE THE GREATER THREAT FOR SEVERE. THE QUESTION REMAINS AS TO HOW LONG THE THREAT WILL PERSIST AFTER DARK...AND CURRENT THINKING IS THAT IT MAY TAKE SOME TIME FOR CONVECTION TO WIND DOWN AS LOW LEVEL INSTABILITY IS MAINTAINED BY A WELL MIXED BOUNDARY LAYER AND EXTENSIVE CLOUD COVER. INCREASED LIKELIHOOD OF SEVERE WEATHER REMAINS PRIMARY FOCUSED IN AREAS NORTH AND WEST OF A KANSAS CITY TO TRENTON LINE. SURFACE FRONT WILL BEGIN TO STALL SOMEWHERE ALONG EAX/SGF CWA BORDER TOMORROW MORNING...AND WAFFLE OVER THE NEXT SEVERAL DAYS AS A SERIES OF MID LEVEL DISTURBANCES ARE EJECTED FROM A DEEP UPPER LOW ENTRENCHED IN THE BAJA. VERY UNUSUAL FLOW PATTERN FOR THIS TYPE OF YEAR...BUT THE QUALITY AND DEPTH OF MOISTURE THAT PERSISTS THROUGH THE WEEKEND CERTAINLY RAISES A RED FLAG THAT CUMULATIVE RAINFALL TOTALS COULD LEAD TO FLOODING BY THE WEEKEND. EVEN MORE CHALLENGING WILL BE THE TEMPERATURES AS THE QUASI-STATIONARY BOUNDARY COULD LEAD TO LARGE ERRORS DEPENDING ON ITS DAY TO DAY PLACEMENT AND PROPAGATION. WHERE PERIODIC SUNSHINE IS ABLE TO MANIFEST BETWEEN THESE SYSTEMS...RAPID WARMING INTO THE UPPER 60S-MID 70S COULD OCCUR GIVEN BALMY MID LEVEL TEMPERATURES BENEATH WEAK 500MB RIDGING AND SOUTHWEST UPPER FLOW. EQUALLY POSSIBLE ARE HIGHS IN THE 50S WHERE MCS INDUCED PRECIPITATION/CLOUD DEBRIS KEEP READINGS NEARLY WET BULBED. BOOKBINDER VERY LITTLE CHANGE TO PREVIOUS THINKING REGARDING THE PROGRESS OF THE CLOSED BAJA LOW INTO THE CNTRL CONUS THIS WEEKEND. ECMWF STILL REMAINS THE MODEL OF CHOICE...ALTHOUGH THE OPERATIONAL GFS AND GFS ENSEMBLES HAVE STEADILY BEEN TRENDING TOWARDS THIS SOLUTION THE PAST SEVERAL RUNS. BEFORE THE MAIN BRUNT OF MIDLEVEL ENERGY EJECTS TOWARDS THE REGION LATE SUNDAY...NUMEROUS WEAK SHORTWAVES WILL RIDE OVER THE RIDGE AXIS WHOSE WRN PERIPHERY SHOULD ALIGN ALONG THE LOWER MISSOURI RIVER VALLEY. EACH PASSING SHORTWAVE WILL INVIGORATE LIFT ASSOCIATED WITH WAA ABOVE THE BOUNDARY LAYER...AND LEAD TO SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS. HAVE TRIMMED POPS SLIGHTLY FOR THE SAT NIGHT TIME PERIOD AS SFC AND LOW LEVEL FRONT APPEARS AS IF IT WILL LIFT NORTH OF MISSOURI KEEPING FOCUSING MECHANISM FURTHER NORTH OF THE AREA. SOME CONCERN THAT PRE-EXISTING CONVECTION GENERATED OVER THE HIGH PLAINS WILL DRIFT INTO THE AREA ASSISTED BY A STRENGTHENING NOCTURNAL LLJ...SO HAVE CONTINUED A 30-40 PERCENT POP RANGE. MODELS CONTINUE TO ADVERTISE THE POSSIBILITY OF A POTENT WEATHER SCENARIO FOR SUNDAY. AS WITH PREVIOUS MODEL RUNS...ECMWF LIFTS THE UPPER WAVE A LITTLE FURTHER WEST OF THE AREA SHEARED MORE SO OVER THE RIDGE AXIS. REGARDLESS...AS THE WAVE EJECTS INTO THE CNTRL PLAINS...INCREASING H5/H7 LAPSE RATES IN EXCESS OF 6C/KM WILL ADVECT INTO THE AREA OVERTOP OF INCREASING MODIFIED GULF MOISTURE LEADING TO HEIGHTENED INSTABILITY WITH MUCAPES FORECAST AOA 1000 J/KG. AT THE SAME TIME...STRENGTHENING WINDS ALOFT WILL LEAD TO 0-6KM BULK SHEAR VECTORS AOA 50KT WITH THE REGION SITUATED UNDER THE FAVORABLE LEFT FRONT EXIT REGION OF A 90+ KT UPPER JET. OTHER THAN THE UPPER WAVE AND LOW LEVEL FOCUSING MECHANISM PLACEMENT...MAIN UNCERTAINTY APPEARS TO BE TIED TO ANY MORNING CONVECTION CONTAMINATING THE MODIFIED AIRMASS PROHIBITING FULL AFTERNOON DESTABILIZATION. AFTER THE UPPER WAVE MOVES NORTHEAST OF THE AREA INTO THE GREAT LAKES...A SFC FRONT WILL SAG THROUGH THE AREA...HOWEVER ONCE AGAIN STALL JUST SOUTH OF THE FORECAST AREA AS ANOTHER LARGE CHUNK OF ENERGY ESTABLISHES A LONGWAVE TROUGH OVER THE WRN CONUS. PREFER A SOLUTION SLOWER THAN THE OPERATIONAL GFS WHICH PUSHES THIS LONGWAVE FEATURE EAST INTO THE INTERMOUNTAIN REGION BY NEXT WEDNESDAY. FOLLOWED CLOSER TO THE GFS ENSEMBLE MEAN IN THIS RESPECT WHICH KEEPS THE AREA MAINLY DRY...ALBEIT QUITE WARM FOR THE END OF THE FORECAST PERIOD. 21 && .AVIATION... VFR CEILINGS ARE EXPECTED THIS EVENING WITH THE LINE OF CONVECTION REACHING STJ AROUND 07Z. THE CONVECTION WILL LAST LESS THAN 2 HOURS. AN ISOLATED STORM MAY BE MARGINALLY SEVERE WITH A HAIL THREAT. THE CEILINGS AND VISIBILITIES ARE EXPECTED TO BE MVFR...POSSIBLY VERY BRIEFLY IFR. THE THUNDERSTORMS WILL MOVE SOUTHEAST INTO THE KANSAS CITY AREA BETWEEN 08Z AND 10Z. ONCE THE THUNDERSTORMS MOVE SOUTHEAST OF THE AIRPORTS AND THE COLD FRONT MOVES THROUGH...VFR CEILINGS ARE EXPECTED AFTER 10Z AT STJ AND AFTER 12Z AT MKC AND MCI. ANOTHER ROUND OF THUNDERSTORMS IS POSSIBLE DURING THE AFTERNOON HOURS ON THURSDAY. DB && EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 1040 AM MST FRI MAR 23 2007 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM TO OUR SOUTH WILL MOVE SLOWLY EAST ACROSS NORTHERN MEXICO TODAY. EXPECT A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT...WITH HEAVIEST PRECIPITATION LIKELY FROM PHOENIX EASTWARD. THE CHANCE FOR SHOWERS WILL LINGER INTO SATURDAY OVER SOUTH-CENTRAL ARIZONA. HOWEVER...HIGHER PRESSURE FROM THE PACIFIC WILL MOVE CLOSER TO ARIZONA AS THE WEEKEND PROGRESSES... BRINGING A SLOW DRYING TREND. EXPECT A WARMING TREND TO COMMENCE OUT WEST SATURDAY...AND OVER ALL OF THE FORECAST AREA BY SUNDAY...WITH ABOVE NORMAL DAYTIME HIGHS SUNDAY THROUGH TUESDAY. ANOTHER STRONG WEATHER DISTURBANCE AND ASSOCIATED COLD FRONT WILL PRODUCE WINDY CONDITIONS NEXT TUESDAY...AND USHER IN COOLER TEMPERATURES NEXT WEDNESDAY. && .SHORT TERM... TODAY THROUGH SUNDAY... UPPER LOW OVER NORTHERN GULF OF CALIFORNIA AS OF 16Z...AND WAS MOVING SLOWLY TOWARD THE EAST. FLOW ALOFT HAS BACKED OVERNIGHT...AND IS NOW FROM THE SOUTHEAST ACROSS SOUTH-CENTRAL AZ. UPPER LOW IS PROGGED TO MOVE SLOWLY TOWARD THE NORTH AND EAST TODAY...BE OVER FAR SOUTHEAST AZ BY MIDNIGHT...THEN ACCELERATE AS IT MOVES NORTHEAST AND AWAY FROM OUR FORECAST AREA ON SATURDAY. HOWEVER...WEAK RESIDUAL TROUGHING REMAINS OVER OUR REGION ALL DAY SATURDAY. AS OF 10 AM...SHWRS AND ISOLATED TRW WERE OCCURRING FROM EASTERN MARICOPA COUNTY ACROSS NORTHEAST PINAL COUNTY INTO SOUTHERN GILA COUNTY. SOME TEMPORARY CLEARING WAS NOTED TO THE REAR OF THIS BAND OF SHOWERS AND STORMS...MAINLY OVER SOUTHEAST PINAL COUNTY AND MUCH OF PIMA COUNTY. COMBINATION OF TEMPORARY CLEARING TO OUR SOUTH... COOLING MID LEVEL TEMPS (500 MB TEMP DOWN TO -22C OVER AND SOUTH OF PHOENIX ACCORDING TO THE RUC)...AND CURRENT DEVELOPMENT OF CUMULUS CLOUD STREETS OVER EASTERN PIMA COUNTY BODES WELL FOR THUNDERSTORMS TO REDEVELOP TO THE SOUTH AND EAST OF OUR CWA TODAY...WITH STORMS PROPAGATING OVER PORTIONS OF SOUTH-CENTRAL AZ FROM MID-LATE AFTERNOON TODAY INTO TONIGHT. UPPER FORCING...IN TERMS OF OMEGA AND DIVERGENCE...IS NOT IMPRESSIVE LIKE IT WAS YESTERDAY AFTERNOON /EVENING...WHICH SUGGESTS AREAL AVERAGE PRECIP OVER S-CNTRL AZ WILL BE LOWER TODAY/TONIGHT. HOWEVER...FAVORABLE THERMODYNAMICS (MIXED-LAYER LI -2 TO -4C) AND TRACK OF UPPER LOW SUPPORT IDEA THAT PORTIONS OF SOUTH-CENTRAL AZ COULD PICK UP DECENT ADDITIONAL RAINFALL...THOUGH THE AMOUNTS WILL VARY WIDELY FROM LOCATION TO LOCATION (UNLIKE YESTERDAY...WHEN MOST OF S-CNTRL AZ PICKED UP ONE HALF TO SLIGHTLY OVER 1 INCH OF RAIN). MEANWHILE...WRAPAROUND CLOUD BAND AND LIGHT SHOWERS EXISTED OVER MUCH OF FAR SOUTHEAST CALIFORNIA AND FAR WESTERN AZ THIS MORNING...WHERE FLOW ALOFT IS FROM THE NORTHEAST. CLOUD/SHWR PLUME EXTENDS WELL NORTH AND EAST OF OUR CWA...SO AGREE WITH LATEST GFS THAT THIS PORTION OF THE CWA WILL EXPERIENCE PERSISTENT CLOUD COVER AND MAINLY LIGHT RAIN SHOWERS TODAY...THOUGH AN ISOLATED THUNDERSTORM IS POSSIBLE. I HAVE TRIMMED SEVERAL DEGREES OFF FORECAST MAX TEMPS FOR THIS AREA FOR TODAY GIVEN PREVAILING WX CONDITIONS. ONE OTHER ITEM...GIVEN THE VERY HIGH BOUNDARY LAYER MOISTURE LEVELS...AND POSSIBILITY OF SOME BREAKS IN THE OVERCAST TONIGHT INTO SATURDAY AM...CANNOT RULE OUT SOME PATCHY FOG. HAVE NOT INCLUDED THAT ON WX GRIDS THIS AM DUE TO EXPECTED LOCALIZED NATURE OF THE FOG...BUT IT IS SOMETHING THAT WILL NEED TO BE MONITORED. FROM PREVIOUS DISCUSSION...AS THE LOW ZIPS NEWD INTO COLORADO BY SATURDAY AFTN...THERE WILL BE A DECREASING CLOUDS AND POPS FROM THE WEST...WITH WRAP AROUND MOISTURE GRADUALLY THINNING OVER SOUTH-CENTRAL AZ...BUT THERE WILL STILL BE A GOOD CHANCE FOR SHOWERS AND A POSSIBLE THUNDERSTORM IN ZONE 24. HIGH TEMPS WILL MODERATE SLIGHTLY OVER THE CENTRAL DESERTS SAT AND RISE SEVERAL DEGREES OVER SERN CA AND THE WESTERN DESERTS AS SUNSHINE INCREASES. HIGHER PRESSURE WILL BUILD IN FROM THE WEST SUNDAY FOR DRY AND SOMEWHAT WARMER CONDITIONS. && .LONG TERM... SUNDAY THROUGH THURSDAY... DRY PATTERN. STRONG SHORT WAVE WILL TRAVERSE THE FORECAST AREA TUESDAY-WEDNESDAY. THIS WILL ALSO RESULT IN A SIGNIFICANT WIND EVENT...WITH RATHER TIGHT LOW LEVEL WINDS (AT 700MB GFS SHOWS 40-50KTS BY MID DAY TUESDAY)...AND A VERY WINDY SCENARIO COULD LEAD TO FIRE WEATHER CONCERNS...ESPECIALLY OVER FAR SE CAL AS SYSTEM ADVECTS DRY AIR OVER THE REGION. SEE FIRE WX DISCUSSION BELOW FOR DETAILS. AFTER A DECENT WARMUP SUNDAY-TUESDAY NOTICEABLY COOLER WEATHER IS LIKELY ON WEDNESDAY...WITH SOME MODERATION IN TEMPS AFTER THAT TIME. && AVIATION... SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH AND NORTHWEST THROUGH THE AFTERNOON. SMALL HAIL AND GUSTY WINDS ARE POSSIBLE WITH THE STRONGER STORMS AS PRECIPITATION BANDS CONTINUE TO ROTATE THROUGH SOUTHERN AZ AND SE CA AROUND THE UPPER BAJA LOW. CIGS AS LOW AS 3000 FEET AND VSBYS DOWN TO 3-4 SM MAY PERIODICALLY OCCUR THROUGHOUT THE DAY...ESPECIALLY IN AND NEAR STRONG THUNDERSTORMS. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EARLY NEXT WEEK (TUESDAY-WEDNESDAY)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE...ESPECIALLY OVER FAR SE CALIFORNIA AND WRN AZ WHERE LESS PRECIPITATION OCCURRED WITH CURRENT STORM SYSTEM. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX /DG/11/10/MEYERS/ROGERS az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 945 AM MST THU MAR 22 2007 .SYNOPSIS... A STRONG PACIFIC LOW PRESSURE SYSTEM WAS LOCATED JUST OFF THE NORTHERN BAJA CALIFORNIA COAST THIS MORNING. IT WILL MOVE VERY SLOWLY EAST ACROSS NORTHERN MEXICO FRIDAY INTO SATURDAY. THIS STORM SYSTEM WILL BRING INCREASING CLOUDINESS...COOLER DAYTIME HIGHS...AND PERIODS OF SHOWERS AND THUNDERSTORMS TODAY THROUGH SATURDAY...WITH THE BEST CHANCE FOR PRECIPITATION OVER SOUTH-CENTRAL ARIZONA. HIGHER PRESSURE ALOFT FROM THE PACIFIC WILL BRING DRY WEATHER WITH SOME RECOVERY OF TEMPERATURES SUNDAY AND MONDAY. ANOTHER RATHER STRONG WEATHER DISTURBANCE WILL PRODUCE BREEZY TO WINDY CONDITIONS ALONG WITH SOME COOLING NEXT TUESDAY AND WEDNESDAY. && .SHORT TERM... TODAY THROUGH SATURDAY... 12Z POSITION OF CLOSED LOW WAS NEAR 30N/117W WITH SEVERAL VORTICITY CENTERS ROTATING AROUND ITS PERIMETER. NAM/GFS SOLUTIONS APPEARED TO BE SOMEWHAT SOUTH OF LATEST RUC...WITH ALL MODELS INDICATING THE STRONGEST VORT CENTER SOUTH OF THE LOW. THE 500MB WIND SPEEDS WERE ALSO STRONGEST AROUND THE SOUTHERN QUADRANTS OF THE LOW...50-70KTS. AFTER SUNRISE THE CONVECTION PICKED UP IN OUR CWA...AND CONTINUED TO DRIFT INTO YAVAPAI COUNTY. BY FAR THE HEAVIEST PRECIP WAS THROUGH SOUTHERN GILA COUNTY WHERE SPOTTERS/RAWS DATA REPORTED .30 TO .45 INCH UP TO 6 AM. SIGNIFICANT DIFFLUENCE WAS ALSO INDICATED ACROSS EASTERN AZ EARLIER TODAY. UPDATES ISSUED BY 8 AM TO COVER 88D TRENDS. WILL CONTINUE TO EXPECT STRONGEST LIFT AND LOWEST STABILITY INDICES AFTER 18Z FRIDAY...AND THAT FITS NICELY WITH OUR CURRENT FCSTS. ALTHOUGH LATEST NAM GIVES PHX A 24 HR PRECIP AMOUNT OF .38 INCH WE WILL STILL EXPECT GENERALLY LIGHTER AMOUNTS ACROSS ZONE 23. HOWEVER WE COULD SEE MUCH MORE...ACROSS ZONE 24...PER HPC OUTPUT. OUR WESTERN ZONES WILL STAY MUCH DIRER...WITH SOME PATCHY BLWG DUST TODAY. IN FACT ONE SHARP-EYED SPOTTER CALLED IN A REPORT OF BLOWING DUST NEAR A FARM FIELD WEST OF TONOPAH. MODEL TRENDS CONTINUE TO BE VERY CONSISTENT IN KEEPING THE CLOSED LOW OVER NRN MEX INTO FRIDAY NIGHT. BY 12Z SAT LATEST GFS CALLS FOR THE CENTER OF CIRCULATION TO LIFT OUT TO NEAR ABQ...WITH CSDRBL RH THROUGH A DEEP LAYER EVEN WEST OF PHX. UPPER RIDGE AND WARMER TEMPS WILL ALSO SPREAD ACROSS ENTIRE CWA FOR FRIDAY AND SATURDAY. && .LONG TERM... SATURDAY NIGHT THROUGH WEDNESDAY... WITH SLOWER EXIT OF THE SYSTEM AND POTENTIAL FOR MORE MOISTURE... ADDED SOME SLIGHT CHANCE POPS IN EASTERN PORTIONS OF THE FORECAST AREA SATURDAY NIGHT. THIS IS FOLLOWED BY RIDGE BUILDING FOR A QUICK WARMUP. IN THE LATTER PART OF THE EXTENDED...GFS AND ECWMF ARE SHOWING ANOTHER SYSTEM AFFECTING US. HOWEVER...IT LOOKS TO BE OF A DIFFERENT CHARACTER...MUCH LESS APT TO SLOW DOWN AND JOG SOUTHWARD. HOWEVER...THERE ARE SOME DIFFERENCES. THE GFS ENSEMBLE MEAN HAS A SIMILAR TRACK TO THE 12Z OPERATIONAL GFS...TAKING THE BULK OF THE SYSTEM JUST NORTH OF OUR AREA...BUT SHOWS LOWER HEIGHTS. THE ECMWF IS EVEN COOLER LOOKING THAN THE ENSEMBLE MEAN...AND A BIT SLOWER. THUS...UNDERCUT GFS-BASED TEMPERATURE GUIDANCE. TRAJECTORY OF THIS NEXT SYSTEM DOES NOT FAVOR MUCH IN THE WAY OF POPS...SO HELD OFF ON INTRODUCING ANY. IF ECMWF SOLUTION WINDS UP BEING CORRECT...THEN WE MIGHT NEED TO ADD SOME SLIGHT CHANCE POPS AT SOME POINT. ALSO...IF ECMWF SOLUTION PANS OUT...MIGHT NEED EVEN COOLER TEMPS. && .AVIATION... GENERALLY LGT SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH TODAY. WINDS IN THE 6 TO 12 THSD LAYER PROGGED TO REMAIN 180/22 THIS AFTERNOON...WITH MUCH STRONGER SPEEDS ALOFT. SOME GUSTY WINDS TO 35KTS OR SO STILL POSSIBLE IN THE KPHX AREA LATE THIS AFTERNOON AND INTO TONIGHT. WITH ADDITIONAL MOISTURE THROUGH A DEEP LAYER...WE COULD EASILY SEE LOWER CIGS LESS THAN 6-7 THSD FT. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EXPECT PERIODS OF WETTING RAINFALL OVER MUCH OF THE FORECAST AREA THURSDAY THROUGH SATURDAY...MAINLY OVER THE EASTERN ZONES...WITH THE HEAVIEST PRECIPITATION LIKELY OVER SOUTHERN GILA COUNTY AND THE RIM FRI AFTERNOON INTO SAT MORNING. DRY CONDITIONS RETURN TO THE WESTERN PORTION OF THE REGION BY SATURDAY AND THE REMAINDER OF THE FORECAST AREA BY SUNDAY. EARLY NEXT WEEK (MON NIGHT THROUGH TUE)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX 10 az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 1253 AM CDT FRI MAR 23 2007 .AVIATION... HIGH PRESSURE CONTINUES OVER THE SOUTHEAST UNITED STATES. THUNDERSTORMS ARE ONGOING IN OKLAHOMA WITH A SLOW EASTWARD PROGRESSION. EXPECT THUNDERSTORMS TO ONLY AFFECT NORTH ARKANSAS TOWARDS 12Z AND INTERMITTENTLY THROUGH 18Z. MVFR CONDITIONS ARE EXPECTED IN THE NORTH AND VFR ELSEWHERE. CEILINGS IN THE NORTH WILL DROP TO 2500 FT WITH VISIBILITIES DOWN TO 5SM. THE UPPER LEVEL DISTURBANCE TRIGGERING THE THUNDERSTORMS WILL MOVE NORTH OF THE AREA AROUND 18Z. DRY WEATHER IS THEN EXPECTED INTO SATURDAY. && .PREV DISCUSSION... /ISSUED 905 PM CDT THU MAR 22 2007/ UPDATE... SHORTWAVE EJECTING OUT OF THE SOUTHWEST CONUS UPPER LOW CONTINUES TO RIDE A STALLED OUT BOUNDARY WHICH IS POSITIONED ALONG THE NORTHERN EDGE OF MID LEVEL RIDGE BUILDING INTO THE REGION FROM GULF. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE TEXAS PANHANDLE IN RESPONSE IN AN AREA OF STRONG LIFT. NEW RUC13 AND NAM 12 KEEP AREA OF PRECIPITATION ACROSS FAR NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI OVERNIGHT. NAM12 AND WRF10 DO MOVE SOME PRECIPITATION ACROSS THE NORTHWEST PART OF THE LZK CWA AFTER 12Z BUT CONFIDENCE IS LOW THIS WILL DEVELOP AS OTHER SHORT RANGE MODELS INDICATE RIDGE BUILDING IN THE MID LEVELS THAT WILL KEEP PRECIPITATION OUT OF THE CWA. CURRENT DISTRIBUTION OF SMALL POPS OVER THE NORTHWEST PART OF THE CWA TONIGHT THROUGH PARTS OF FRIDAY LOOKS REASONABLE AND WILL BE LEFT IN PLACE. ONLY CHANGES TO ONGOING FORECAST WERE TO TWEAK SKY...DEW POINT AND RH GRIDS TO REFLECT CURRENT TRENDS. OVERNIGHT LOWS RAISED A TAD AS WELL. UPDATES OUT SHORTLY. PREV DISCUSSION... /ISSUED 629 PM CDT THU MAR 22 2007/ AVIATION... CLOUDS WILL CONTINUE TO MOVE IN FROM THE WEST WITH CEILINGS NEAR 7 THSD OR HIGHER. AREAS OF CEILINGS NEAR 35 HND WILL MOVE IN ARND 06Z. SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE NORTH AND WEST AFTER 08Z.(38) PREV DISCUSSION... /ISSUED 235 PM CDT THU MAR 22 2007/ SHORT TERM...TONIGHT THROUGH SUNDAY BLOCKING PATTERN STILL THE MAIN STORY IN THE SHORT TERM...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE GULF COAST. FRONT TO NORTH WILL TRY TO PUSH INTO ARKANSAS LATER TONIGHT/FRIDAY...BUT WILL STALL DUE TO THE HIGH AND SOUTHWEST WINDS ALOFT. EVEN SO...PUT SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS MAINLY IN AREAS NEAR THE ARKANSAS AND MISSOURI BORDER. FRONT WILL LIFT TO THE NORTH FRIDAY NIGHT/SATURDAY...WITH DRY AND WARM WEATHER TO START THE WEEKEND. LATE IN THE WEEKEND AND EARLY NEXT WEEK...LARGE STORM SYSTEM IN THE SOUTHWEST UNITED STATES WILL FINALLY ARRIVE...WITH HIGH PRESSURE SHIFTING SLOWLY TO THE EAST. BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST LATE SUNDAY INTO THE LONG TERM. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE PERIOD. (46) LONG TERM...SUNDAY NIGHT THROUGH THURSDAY REMNANTS OF A WEAKENING UPPER LOW WILL BE CROSSING ARKANSAS AS A SHORT WAVE. IT WILL BE JUST EAST OF THE STATE BY MIDDAY TUESDAY SINCE A LONG WAVE TROF WILL BE TRAVERSING THE INTERMOUNTAIN WEST ON TUESDAY. BY WEDNESDAY AFTERNOON IT WILL BE OVER THE NORTHERN PLAINS AND WEAKENING. THE SURFACE PATTERN WILL KEEP A SOUTHEAST OR SOUTH COMPONENT TO OUR WINDS THAT WILL PUMP MOISTURE NORTHWARD INTO THE PATH OF THE UPPER SYSTEM. WARMTH AND INSTABILITY WILL CAUSE SCATTERED CONVECTION TO DEVELOP SUNDAY NIGHT OVER NORTHWESTER SECTIONS. THEN...IT WILL KEEP ON MOVING EAST DURING THE DAY MONDAY. CONVECTION WILL BE OVER THE EASTERN HALF OF THE FORECAST AREA MONDAY NIGHT AND MOSTLY OUT OF THE STATE TUESDAY AFTERNOON AS THE SHORT WAVE DRIVING IT GOES ON BY ALOFT. WILL KEEP THE FORECAST DRY FROM TUESDAY NIGHT ON THROUGH THE END OF THE LONG TERM. THE UPPER SUPPORT FOR THE NEXT SYSTEM WILL BE SO FAR NORTH THAT DECIDED TO WAIT UNTIL THIS TREND GETS PICKED UP IN OTHER RUNS. NO CHALLENGE TO THE ABOVE NORMAL TRENDS WILL BE MADE DURING THIS PERIOD. (32) && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 56 76 58 76 / 20 10 10 20 CAMDEN AR 58 79 61 78 / 10 10 10 20 HARRISON AR 55 75 58 73 / 20 10 10 40 HOT SPRINGS AR 58 78 59 76 / 10 10 10 40 LITTLE ROCK AR 58 78 60 77 / 10 10 10 20 MONTICELLO AR 58 80 60 80 / 10 10 10 20 MOUNT IDA AR 57 78 59 75 / 10 10 10 40 MOUNTAIN HOME AR 54 75 56 75 / 20 10 10 40 NEWPORT AR 57 76 58 77 / 20 10 10 20 PINE BLUFF AR 59 79 61 78 / 10 10 10 20 RUSSELLVILLE AR 56 77 59 75 / 10 10 10 40 SEARCY AR 58 77 59 77 / 10 10 10 20 STUTTGART AR 59 78 60 78 / 10 10 10 20 && .LZK WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION...51 ar AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 905 PM CDT THU MAR 22 2007 .UPDATE... SHORTWAVE EJECTING OUT OF THE SOUTHWEST CONUS UPPER LOW CONTINUES TO RIDE A STALLED OUT BOUNDARY WHICH IS POSITIONED ALONG THE NORTHERN EDGE OF MID LEVEL RIDGE BUILDING INTO THE REGION FROM GULF. SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE TEXAS PANHANDLE IN RESPONSE IN AN AREA OF STRONG LIFT. NEW RUC13 AND NAM 12 KEEP AREA OF PRECIPITATION ACROSS FAR NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI OVERNIGHT. NAM12 AND WRF10 DO MOVE SOME PRECIPITATION ACROSS THE NORTHWEST PART OF THE LZK CWA AFTER 12Z BUT CONFIDENCE IS LOW THIS WILL DEVELOP AS OTHER SHORT RANGE MODELS INDICATE RIDGE BUILDING IN THE MID LEVELS THAT WILL KEEP PRECIPITATION OUT OF THE CWA. CURRENT DISTRIBUTION OF SMALL POPS OVER THE NORTHWEST PART OF THE CWA TONIGHT THROUGH PARTS OF FRIDAY LOOKS REASONABLE AND WILL BE LEFT IN PLACE. ONLY CHANGES TO ONGOING FORECAST WERE TO TWEAK SKY...DEW POINT AND RH GRIDS TO REFLECT CURRENT TRENDS. OVERNIGHT LOWS RAISED A TAD AS WELL. UPDATES OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 629 PM CDT THU MAR 22 2007/ AVIATION... CLOUDS WILL CONTINUE TO MOVE IN FROM THE WEST WITH CEILINGS NEAR 7 THSD OR HIGHER. AREAS OF CEILINGS NEAR 35 HND WILL MOVE IN ARND 06Z. SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE NORTH AND WEST AFTER 08Z.(38) PREV DISCUSSION... /ISSUED 235 PM CDT THU MAR 22 2007/ SHORT TERM...TONIGHT THROUGH SUNDAY BLOCKING PATTERN STILL THE MAIN STORY IN THE SHORT TERM...WITH HIGH PRESSURE BUILDING OVER THE REGION FROM THE GULF COAST. FRONT TO NORTH WILL TRY TO PUSH INTO ARKANSAS LATER TONIGHT/FRIDAY...BUT WILL STALL DUE TO THE HIGH AND SOUTHWEST WINDS ALOFT. EVEN SO...PUT SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS MAINLY IN AREAS NEAR THE ARKANSAS AND MISSOURI BORDER. FRONT WILL LIFT TO THE NORTH FRIDAY NIGHT/SATURDAY...WITH DRY AND WARM WEATHER TO START THE WEEKEND. LATE IN THE WEEKEND AND EARLY NEXT WEEK...LARGE STORM SYSTEM IN THE SOUTHWEST UNITED STATES WILL FINALLY ARRIVE...WITH HIGH PRESSURE SHIFTING SLOWLY TO THE EAST. BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST LATE SUNDAY INTO THE LONG TERM. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE PERIOD. (46) LONG TERM...SUNDAY NIGHT THROUGH THURSDAY REMNANTS OF A WEAKENING UPPER LOW WILL BE CROSSING ARKANSAS AS A SHORT WAVE. IT WILL BE JUST EAST OF THE STATE BY MIDDAY TUESDAY SINCE A LONG WAVE TROF WILL BE TRAVERSING THE INTERMOUNTAIN WEST ON TUESDAY. BY WEDNESDAY AFTERNOON IT WILL BE OVER THE NORTHERN PLAINS AND WEAKENING. THE SURFACE PATTERN WILL KEEP A SOUTHEAST OR SOUTH COMPONENT TO OUR WINDS THAT WILL PUMP MOISTURE NORTHWARD INTO THE PATH OF THE UPPER SYSTEM. WARMTH AND INSTABILITY WILL CAUSE SCATTERED CONVECTION TO DEVELOP SUNDAY NIGHT OVER NORTHWESTER SECTIONS. THEN...IT WILL KEEP ON MOVING EAST DURING THE DAY MONDAY. CONVECTION WILL BE OVER THE EASTERN HALF OF THE FORECAST AREA MONDAY NIGHT AND MOSTLY OUT OF THE STATE TUESDAY AFTERNOON AS THE SHORT WAVE DRIVING IT GOES ON BY ALOFT. WILL KEEP THE FORECAST DRY FROM TUESDAY NIGHT ON THROUGH THE END OF THE LONG TERM. THE UPPER SUPPORT FOR THE NEXT SYSTEM WILL BE SO FAR NORTH THAT DECIDED TO WAIT UNTIL THIS TREND GETS PICKED UP IN OTHER RUNS. NO CHALLENGE TO THE ABOVE NORMAL TRENDS WILL BE MADE DURING THIS PERIOD. (32) && .PRELIMINARY POINT TEMPS/POPS... BATESVILLE AR 59 76 56 76 / 10 20 20 10 CAMDEN AR 60 80 58 79 / 10 10 10 10 HARRISON AR 59 75 55 75 / 30 30 20 10 HOT SPRINGS AR 60 78 58 78 / 10 10 10 10 LITTLE ROCK AR 60 78 58 78 / 10 10 10 10 MONTICELLO AR 59 80 58 80 / 10 10 10 10 MOUNT IDA AR 58 78 57 78 / 10 10 10 10 MOUNTAIN HOME AR 59 75 54 75 / 30 30 20 10 NEWPORT AR 59 77 57 76 / 10 20 20 10 PINE BLUFF AR 60 79 59 79 / 10 10 10 10 RUSSELLVILLE AR 59 77 56 77 / 20 20 10 10 SEARCY AR 60 78 58 77 / 10 10 10 10 STUTTGART AR 60 79 59 78 / 10 10 10 10 && .LZK WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...56 / LONG TERM...38 ar AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 1040 AM MST FRI MAR 23 2007 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM TO OUR SOUTH WILL MOVE SLOWLY EAST ACROSS NORTHERN MEXICO TODAY. EXPECT A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS TODAY AND TONIGHT...WITH HEAVIEST PRECIPITATION LIKELY FROM PHOENIX EASTWARD. THE CHANCE FOR SHOWERS WILL LINGER INTO SATURDAY OVER SOUTH-CENTRAL ARIZONA. HOWEVER...HIGHER PRESSURE FROM THE PACIFIC WILL MOVE CLOSER TO ARIZONA AS THE WEEKEND PROGRESSES... BRINGING A SLOW DRYING TREND. EXPECT A WARMING TREND TO COMMENCE OUT WEST SATURDAY...AND OVER ALL OF THE FORECAST AREA BY SUNDAY...WITH ABOVE NORMAL DAYTIME HIGHS SUNDAY THROUGH TUESDAY. ANOTHER STRONG WEATHER DISTURBANCE AND ASSOCIATED COLD FRONT WILL PRODUCE WINDY CONDITIONS NEXT TUESDAY...AND USHER IN COOLER TEMPERATURES NEXT WEDNESDAY. && .SHORT TERM... TODAY THROUGH SUNDAY... UPPER LOW OVER NORTHERN GULF OF CALIFORNIA AS OF 16Z...AND WAS MOVING SLOWLY TOWARD THE EAST. FLOW ALOFT HAS BACKED OVERNIGHT...AND IS NOW FROM THE SOUTHEAST ACROSS SOUTH-CENTRAL AZ. UPPER LOW IS PROGGED TO MOVE SLOWLY TOWARD THE NORTH AND EAST TODAY...BE OVER FAR SOUTHEAST AZ BY MIDNIGHT...THEN ACCELERATE AS IT MOVES NORTHEAST AND AWAY FROM OUR FORECAST AREA ON SATURDAY. HOWEVER...WEAK RESIDUAL TROUGHING REMAINS OVER OUR REGION ALL DAY SATURDAY. AS OF 10 AM...SHWRS AND ISOLATED TRW WERE OCCURRING FROM EASTERN MARICOPA COUNTY ACROSS NORTHEAST PINAL COUNTY INTO SOUTHERN GILA COUNTY. SOME TEMPORARY CLEARING WAS NOTED TO THE REAR OF THIS BAND OF SHOWERS AND STORMS...MAINLY OVER SOUTHEAST PINAL COUNTY AND MUCH OF PIMA COUNTY. COMBINATION OF TEMPORARY CLEARING TO OUR SOUTH... COOLING MID LEVEL TEMPS (500 MB TEMP DOWN TO -22C OVER AND SOUTH OF PHOENIX ACCORDING TO THE RUC)...AND CURRENT DEVELOPMENT OF CUMULUS CLOUD STREETS OVER EASTERN PIMA COUNTY BODES WELL FOR THUNDERSTORMS TO REDEVELOP TO THE SOUTH AND EAST OF OUR CWA TODAY...WITH STORMS PROPAGATING OVER PORTIONS OF SOUTH-CENTRAL AZ FROM MID-LATE AFTERNOON TODAY INTO TONIGHT. UPPER FORCING...IN TERMS OF OMEGA AND DIVERGENCE...IS NOT IMPRESSIVE LIKE IT WAS YESTERDAY AFTERNOON /EVENING...WHICH SUGGESTS AREAL AVERAGE PRECIP OVER S-CNTRL AZ WILL BE LOWER TODAY/TONIGHT. HOWEVER...FAVORABLE THERMODYNAMICS (MIXED-LAYER LI -2 TO -4C) AND TRACK OF UPPER LOW SUPPORT IDEA THAT PORTIONS OF SOUTH-CENTRAL AZ COULD PICK UP DECENT ADDITIONAL RAINFALL...THOUGH THE AMOUNTS WILL VARY WIDELY FROM LOCATION TO LOCATION (UNLIKE YESTERDAY...WHEN MOST OF S-CNTRL AZ PICKED UP ONE HALF TO SLIGHTLY OVER 1 INCH OF RAIN). MEANWHILE...WRAPAROUND CLOUD BAND AND LIGHT SHOWERS EXISTED OVER MUCH OF FAR SOUTHEAST CALIFORNIA AND FAR WESTERN AZ THIS MORNING...WHERE FLOW ALOFT IS FROM THE NORTHEAST. CLOUD/SHWR PLUME EXTENDS WELL NORTH AND EAST OF OUR CWA...SO AGREE WITH LATEST GFS THAT THIS PORTION OF THE CWA WILL EXPERIENCE PERSISTENT CLOUD COVER AND MAINLY LIGHT RAIN SHOWERS TODAY...THOUGH AN ISOLATED THUNDERSTORM IS POSSIBLE. I HAVE TRIMMED SEVERAL DEGREES OFF FORECAST MAX TEMPS FOR THIS AREA FOR TODAY GIVEN PREVAILING WX CONDITIONS. ONE OTHER ITEM...GIVEN THE VERY HIGH BOUNDARY LAYER MOISTURE LEVELS...AND POSSIBILITY OF SOME BREAKS IN THE OVERCAST TONIGHT INTO SATURDAY AM...CANNOT RULE OUT SOME PATCHY FOG. HAVE NOT INCLUDED THAT ON WX GRIDS THIS AM DUE TO EXPECTED LOCALIZED NATURE OF THE FOG...BUT IT IS SOMETHING THAT WILL NEED TO BE MONITORED. FROM PREVIOUS DISCUSSION...AS THE LOW ZIPS NEWD INTO COLORADO BY SATURDAY AFTN...THERE WILL BE A DECREASING CLOUDS AND POPS FROM THE WEST...WITH WRAP AROUND MOISTURE GRADUALLY THINNING OVER SOUTH-CENTRAL AZ...BUT THERE WILL STILL BE A GOOD CHANCE FOR SHOWERS AND A POSSIBLE THUNDERSTORM IN ZONE 24. HIGH TEMPS WILL MODERATE SLIGHTLY OVER THE CENTRAL DESERTS SAT AND RISE SEVERAL DEGREES OVER SERN CA AND THE WESTERN DESERTS AS SUNSHINE INCREASES. HIGHER PRESSURE WILL BUILD IN FROM THE WEST SUNDAY FOR DRY AND SOMEWHAT WARMER CONDITIONS. && .LONG TERM... SUNDAY THROUGH THURSDAY... DRY PATTERN. STRONG SHORT WAVE WILL TRAVERSE THE FORECAST AREA TUESDAY-WEDNESDAY. THIS WILL ALSO RESULT IN A SIGNIFICANT WIND EVENT...WITH RATHER TIGHT LOW LEVEL WINDS (AT 700MB GFS SHOWS 40-50KTS BY MID DAY TUESDAY)...AND A VERY WINDY SCENARIO COULD LEAD TO FIRE WEATHER CONCERNS...ESPECIALLY OVER FAR SE CAL AS SYSTEM ADVECTS DRY AIR OVER THE REGION. SEE FIRE WX DISCUSSION BELOW FOR DETAILS. AFTER A DECENT WARMUP SUNDAY-TUESDAY NOTICEABLY COOLER WEATHER IS LIKELY ON WEDNESDAY...WITH SOME MODERATION IN TEMPS AFTER THAT TIME. && AVIATION... SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH AND NORTHWEST THROUGH THE AFTERNOON. SMALL HAIL AND GUSTY WINDS ARE POSSIBLE WITH THE STRONGER STORMS AS PRECIPITATION BANDS CONTINUE TO ROTATE THROUGH SOUTHERN AZ AND SE CA AROUND THE UPPER BAJA LOW. CIGS AS LOW AS 3000 FEET AND VSBYS DOWN TO 3-4 SM MAY PERIODICALLY OCCUR THROUGHOUT THE DAY...ESPECIALLY IN AND NEAR STRONG THUNDERSTORMS. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EARLY NEXT WEEK (TUESDAY-WEDNESDAY)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE...ESPECIALLY OVER FAR SE CALIFORNIA AND WRN AZ WHERE LESS PRECIPITATION OCCURRED WITH CURRENT STORM SYSTEM. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX /DG/11/10/MEYERS/ROGERS ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 845 PM PDT THU MAR 22 2007 .UPDATE...A FEW PATCHES OF HIGH CLOUDS MOVING THRU...OTHERWISE SKIES ARE CLEAR. MID LEVEL CLOUDS WRAPPING AROUND THE NRN BAJA LOW ARE JUST EAST OF KERN CO. SOME OF THESE MID CLOUDS COULD MOVE ACROSS THE KERN DESERT FROM TIME TO TIME OVERNITE SO PTCLDY THERE LOOKS GOOD. TEMPS THIS EVE RUNNING 6-8 DEGS HIGHER THAN YESTERDAY AT THIS TIME...SO CONTINUED GOOD WARMING EXPECTED TOMORROW. CURRENT FCST ON TRACK AND NO UPDATE NEEDED THIS EVE. && .DISCUSSION...AS THE CLOSED UPPER LOW DRIFTS FURTHER OVER THE DESERT SOUTHWEST...THE WEATHER OVER CENTRAL CALIFORNIA CONTINUES TO SETTLE DOWN. WITH THE SUNSHINE...TEMPERATURES SAW ANOTHER WARMING TREND AS MANY VALLEY LOCATIONS WERE RUNNING 5 TO 10 DEG-F ABOVE THAT OF WEDNESDAY AFTERNOON. WITH THE OFFSHORE FLOW ALOFT SUPPORTING TODAY/S WARMING TEMP/S...WILL HAVE NO PROBLEM REACHING THE 70S. WHILE WRAP AROUND MOISTURE IS BEING OBSERVED OVER THE DESERT SOUTHWEST...ASSOCIATED WITH THE CLOSED UPPER LOW...AND TRACKING NORTHEAST. WHILE SOME CLOUDS SHOULD ADVANCE INTO THE DISTRICT LATE THIS AFTERNOON...RUC ANALYSIS AND VISIBLE SATELLITE IMAGERY IS SHOWING ONLY MINIMAL AMOUNTS REACHING THE AREA. THEREFORE...WILL MAINTAIN MOSTLY CLEAR CONDITIONS WITH NO POSSIBLE WEATHER. YET...THE KERN COUNTY DESERTS MAY BE CLOSER TO THE STORM THEN THE REST OF THE DISTRICT. THEREFORE...WILL MAINTAIN THE SLIGHT CHANCE POPS OVER THE DESERTS (TOKEN) JUST IN CASE THE MOISTURE IS ABLE TO MAKE IT THIS FAR NORTH. IN ADDITION...BECAUSE OF THE SLOW DRIFT OF THE UPPER LOW...STRONG WINDS WILL CONTINUE TO BE OBSERVED OVER THE DESERT AND HIGHER ELEVATIONS OF THE DISTRICT THROUGH THIS EVENING. AS THE UPPER LOW SLOWLY TRACKS EAST OVER THE NEXT SEVERAL DAYS...WILL SEE THE UPPER LEVEL RIDGE DOMINATE THE WEST THROUGH THE WEEKEND. DRY WEATHER WILL PREVAIL WITH A WARMING TREND IN TEMPERATURES THROUGH ABOUT SUNDAY. AROUND SUNDAY...SHORT RANGE MODELS BEGIN LOWERING HEIGHTS AND SWITCH TO A MORE ZONAL FLOW PATTERN BEFORE ALLOWING ANOTHER TROF TO APPROACH THE WEST COAST. LATEST TIMING STILL HAS THE NEXT TROF OVER THE WEST COAST AROUND LATE MONDAY INTO EARLY TUESDAY. ENSEMBLES SHOWING LITTLE PHASE UNCERTAINTY BUT IS SHOWING GOOD SPREAD ON THE AMPLITUDE AROUND 12Z TUESDAY. THEREFORE...WILL KEEP THE BETTER CHANCES OF MEASURABLE PRECIP NORTH OF KERN COUNTY DURING THE EVENT. IN ADDITION...DURING TROF PASSAGE...MEDIUM RANGE MODELS SHOW 500MB TEMP/S DROPPING TO AROUND MINUS 24-28 DEG-C. BEING THAT THIS MAY BE A COLD SYSTEM...WILL MAINTAIN LOW SNOW LEVELS DURING THE STORM. FURTHERMORE...WITH SUCH COLD AIR ALOFT OVER THE REGION AT THIS TIME OF THE YEAR...CONDITIONS MAY BECOME VERY UNSTABLE DURING THE STORM EVENT. LINGERING SHOWERS OVER THE MOUNTAIN TOWARD TUESDAY WILL GIVE WAY TO CLEARING BY WEDNESDAY AND THURSDAY. && .AVIATION...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 06Z SATURDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES... NONE && .HNX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ BINGHAM/MOLINA/MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 232 PM PDT THU MAR 22 2007 .DISCUSSION...AS THE CLOSED UPPER LOW DRIFTS FURTHER OVER THE DESERT SOUTHWEST...THE WEATHER OVER CENTRAL CALIFORNIA CONTINUES TO SETTLE DOWN. WITH THE SUNSHINE...TEMPERATURES SAW ANOTHER WARMING TREND AS MANY VALLEY LOCATIONS WERE RUNNING 5 TO 10 DEG-F ABOVE THAT OF WEDNESDAY AFTERNOON. WITH THE OFFSHORE FLOW ALOFT SUPPORTING TODAY/S WARMING TEMP/S...WILL HAVE NO PROBLEM REACHING THE 70S. WHILE WRAP AROUND MOISTURE IS BEING OBSERVED OVER THE DESERT SOUTHWEST...ASSOCIATED WITH THE CLOSED UPPER LOW...AND TRACKING NORTHEAST. WHILE SOME CLOUDS SHOULD ADVANCE INTO THE DISTRICT LATE THIS AFTERNOON...RUC ANALYSIS AND VISIBLE SATELLITE IMAGERY IS SHOWING ONLY MINIMAL AMOUNTS REACHING THE AREA. THEREFORE...WILL MAINTAIN MOSTLY CLEAR CONDITIONS WITH NO POSSIBLE WEATHER. YET...THE KERN COUNTY DESERTS MAY BE CLOSER TO THE STORM THEN THE REST OF THE DISTRICT. THEREFORE...WILL MAINTAIN THE SLIGHT CHANCE POPS OVER THE DESERTS (TOKEN) JUST IN CASE THE MOISTURE IS ABLE TO MAKE IT THIS FAR NORTH. IN ADDITION...BECAUSE OF THE SLOW DRIFT OF THE UPPER LOW...STRONG WINDS WILL CONTINUE TO BE OBSERVED OVER THE DESERT AND HIGHER ELEVATIONS OF THE DISTRICT THROUGH THIS EVENING. AS THE UPPER LOW SLOWLY TRACKS EAST OVER THE NEXT SEVERAL DAYS...WILL SEE THE UPPER LEVEL RIDGE DOMINATE THE WEST THROUGH THE WEEKEND. DRY WEATHER WILL PREVAIL WITH A WARMING TREND IN TEMPERATURES THROUGH ABOUT SUNDAY. AROUND SUNDAY...SHORT RANGE MODELS BEGIN LOWERING HEIGHTS AND SWITCH TO A MORE ZONAL FLOW PATTERN BEFORE ALLOWING ANOTHER TROF TO APPROACH THE WEST COAST. LATEST TIMING STILL HAS THE NEXT TROF OVER THE WEST COAST AROUND LATE MONDAY INTO EARLY TUESDAY. ENSEMBLES SHOWING LITTLE PHASE UNCERTAINTY BUT IS SHOWING GOOD SPREAD ON THE AMPLITUDE AROUND 12Z TUESDAY. THEREFORE...WILL KEEP THE BETTER CHANCES OF MEASURABLE PRECIP NORTH OF KERN COUNTY DURING THE EVENT. IN ADDITION...DURING TROF PASSAGE...MEDIUM RANGE MODELS SHOW 500MB TEMP/S DROPPING TO AROUND MINUS 24-28 DEG-C. BEING THAT THIS MAY BE A COLD SYSTEM...WILL MAINTAIN LOW SNOW LEVELS DURING THE STORM. FURTHERMORE...WITH SUCH COLD AIR ALOFT OVER THE REGION AT THIS TIME OF THE YEAR...CONDITIONS MAY BECOME VERY UNSTABLE DURING THE STORM EVENT. LINGERING SHOWERS OVER THE MOUNTAIN TOWARD TUESDAY WILL GIVE WAY TO CLEARING BY WEDNESDAY AND THURSDAY. && .AVIATION...GUSTY OFFSHORE WINDS WILL CONTINUE OVER KERN COUNTY DESERTS THROUGH EARLY EVENING THURSDAY...DIMINISHING THEREAFTER. OTHERWISE...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 00Z SATURDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES...NONE. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC:MOLINA AVIATION:MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 945 AM MST THU MAR 22 2007 .SYNOPSIS... A STRONG PACIFIC LOW PRESSURE SYSTEM WAS LOCATED JUST OFF THE NORTHERN BAJA CALIFORNIA COAST THIS MORNING. IT WILL MOVE VERY SLOWLY EAST ACROSS NORTHERN MEXICO FRIDAY INTO SATURDAY. THIS STORM SYSTEM WILL BRING INCREASING CLOUDINESS...COOLER DAYTIME HIGHS...AND PERIODS OF SHOWERS AND THUNDERSTORMS TODAY THROUGH SATURDAY...WITH THE BEST CHANCE FOR PRECIPITATION OVER SOUTH-CENTRAL ARIZONA. HIGHER PRESSURE ALOFT FROM THE PACIFIC WILL BRING DRY WEATHER WITH SOME RECOVERY OF TEMPERATURES SUNDAY AND MONDAY. ANOTHER RATHER STRONG WEATHER DISTURBANCE WILL PRODUCE BREEZY TO WINDY CONDITIONS ALONG WITH SOME COOLING NEXT TUESDAY AND WEDNESDAY. && .SHORT TERM... TODAY THROUGH SATURDAY... 12Z POSITION OF CLOSED LOW WAS NEAR 30N/117W WITH SEVERAL VORTICITY CENTERS ROTATING AROUND ITS PERIMETER. NAM/GFS SOLUTIONS APPEARED TO BE SOMEWHAT SOUTH OF LATEST RUC...WITH ALL MODELS INDICATING THE STRONGEST VORT CENTER SOUTH OF THE LOW. THE 500MB WIND SPEEDS WERE ALSO STRONGEST AROUND THE SOUTHERN QUADRANTS OF THE LOW...50-70KTS. AFTER SUNRISE THE CONVECTION PICKED UP IN OUR CWA...AND CONTINUED TO DRIFT INTO YAVAPAI COUNTY. BY FAR THE HEAVIEST PRECIP WAS THROUGH SOUTHERN GILA COUNTY WHERE SPOTTERS/RAWS DATA REPORTED .30 TO .45 INCH UP TO 6 AM. SIGNIFICANT DIFFLUENCE WAS ALSO INDICATED ACROSS EASTERN AZ EARLIER TODAY. UPDATES ISSUED BY 8 AM TO COVER 88D TRENDS. WILL CONTINUE TO EXPECT STRONGEST LIFT AND LOWEST STABILITY INDICES AFTER 18Z FRIDAY...AND THAT FITS NICELY WITH OUR CURRENT FCSTS. ALTHOUGH LATEST NAM GIVES PHX A 24 HR PRECIP AMOUNT OF .38 INCH WE WILL STILL EXPECT GENERALLY LIGHTER AMOUNTS ACROSS ZONE 23. HOWEVER WE COULD SEE MUCH MORE...ACROSS ZONE 24...PER HPC OUTPUT. OUR WESTERN ZONES WILL STAY MUCH DIRER...WITH SOME PATCHY BLWG DUST TODAY. IN FACT ONE SHARP-EYED SPOTTER CALLED IN A REPORT OF BLOWING DUST NEAR A FARM FIELD WEST OF TONOPAH. MODEL TRENDS CONTINUE TO BE VERY CONSISTENT IN KEEPING THE CLOSED LOW OVER NRN MEX INTO FRIDAY NIGHT. BY 12Z SAT LATEST GFS CALLS FOR THE CENTER OF CIRCULATION TO LIFT OUT TO NEAR ABQ...WITH CSDRBL RH THROUGH A DEEP LAYER EVEN WEST OF PHX. UPPER RIDGE AND WARMER TEMPS WILL ALSO SPREAD ACROSS ENTIRE CWA FOR FRIDAY AND SATURDAY. && .LONG TERM... SATURDAY NIGHT THROUGH WEDNESDAY... WITH SLOWER EXIT OF THE SYSTEM AND POTENTIAL FOR MORE MOISTURE... ADDED SOME SLIGHT CHANCE POPS IN EASTERN PORTIONS OF THE FORECAST AREA SATURDAY NIGHT. THIS IS FOLLOWED BY RIDGE BUILDING FOR A QUICK WARMUP. IN THE LATTER PART OF THE EXTENDED...GFS AND ECWMF ARE SHOWING ANOTHER SYSTEM AFFECTING US. HOWEVER...IT LOOKS TO BE OF A DIFFERENT CHARACTER...MUCH LESS APT TO SLOW DOWN AND JOG SOUTHWARD. HOWEVER...THERE ARE SOME DIFFERENCES. THE GFS ENSEMBLE MEAN HAS A SIMILAR TRACK TO THE 12Z OPERATIONAL GFS...TAKING THE BULK OF THE SYSTEM JUST NORTH OF OUR AREA...BUT SHOWS LOWER HEIGHTS. THE ECMWF IS EVEN COOLER LOOKING THAN THE ENSEMBLE MEAN...AND A BIT SLOWER. THUS...UNDERCUT GFS-BASED TEMPERATURE GUIDANCE. TRAJECTORY OF THIS NEXT SYSTEM DOES NOT FAVOR MUCH IN THE WAY OF POPS...SO HELD OFF ON INTRODUCING ANY. IF ECMWF SOLUTION WINDS UP BEING CORRECT...THEN WE MIGHT NEED TO ADD SOME SLIGHT CHANCE POPS AT SOME POINT. ALSO...IF ECMWF SOLUTION PANS OUT...MIGHT NEED EVEN COOLER TEMPS. && .AVIATION... GENERALLY LGT SHOWERS WITH EMBEDDED -TSRA WILL CONTINUE TO DRIFT TOWARD THE NORTH TODAY. WINDS IN THE 6 TO 12 THSD LAYER PROGGED TO REMAIN 180/22 THIS AFTERNOON...WITH MUCH STRONGER SPEEDS ALOFT. SOME GUSTY WINDS TO 35KTS OR SO STILL POSSIBLE IN THE KPHX AREA LATE THIS AFTERNOON AND INTO TONIGHT. WITH ADDITIONAL MOISTURE THROUGH A DEEP LAYER...WE COULD EASILY SEE LOWER CIGS LESS THAN 6-7 THSD FT. SEE TAFS PHXTAFPHX...PHXTAFIWA...PHXTAFYUM...LAXTAFBLH AND LAXTAFIPL FOR MORE DETAILED INFORMATION. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... EXPECT PERIODS OF WETTING RAINFALL OVER MUCH OF THE FORECAST AREA THURSDAY THROUGH SATURDAY...MAINLY OVER THE EASTERN ZONES...WITH THE HEAVIEST PRECIPITATION LIKELY OVER SOUTHERN GILA COUNTY AND THE RIM FRI AFTERNOON INTO SAT MORNING. DRY CONDITIONS RETURN TO THE WESTERN PORTION OF THE REGION BY SATURDAY AND THE REMAINDER OF THE FORECAST AREA BY SUNDAY. EARLY NEXT WEEK (MON NIGHT THROUGH TUE)...AN INTENSE LOW PRESSURE SYSTEM WILL SWING THROUGH THE GREAT BASIN AND NORTHERN AZ GENERATING STRONG GUSTY WEST WINDS REGION-WIDE. WINDY CONDITIONS WILL BE LIKELY...AND IF HUMIDITIES AND FUEL MOISTURES REMAIN LOW...A CRITICAL FIRE WEATHER DAY WILL BE POSSIBLE. ALL INTERESTED AGENCIES ARE ENCOURAGED TO MONITOR THE LATEST FIRE WEATHER FORECASTS AND DISCUSSIONS. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX 10 ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 916 AM PDT THU MAR 22 2007 .DISCUSSION...CLOSED UPPER LOW CONTINUES TO SWINGS EASTWARD THIS MORNING AROUND BAJA CALIFORNIA...WITH CHANNELED FLOW OVER THE DISTRICT. AT THE 250MB LEVEL...RUC ANALYSIS HAS A +100KT JET MAX EXITING THE AREA WITH A GOOD DOWNWARD TRANSFER OF WINDS THIS MORNING. WHILE WINDS OVER THE MOUNTAINS AND DESERTS WERE DIMINISHING THIS MID MORNING...WINDS EARLIER WERE ABLE TO REACH 30 TO 40 MPH. AS THE JET MOVES FURTHER AWAY...WILL SEE MOUNTAIN WINDS DECREASE FURTHER AS A SHORT WAVE RIDGE SHIFTS INTO CALIFORNIA. FURTHERMORE...THE FLOW THIS MORNING HAS BEEN OFF-SHORE WHICH WILL SUPPORT THE EXPECTED WARM UP THIS AFTERNOON. OTHERWISE...AS THE CLOSED UPPER LOW MOVES FURTHER OUT...WILL SEE GENERAL CLEARING THROUGH THE END OF THE WEEK AND INTO THE WEEKEND WITH A CONTINUAL WARMING OF TEMPERATURES. NO UPDATES NEEDED. && .AVIATION...LOCAL MVFR CEILINGS AND VISIBILITIES WILL PERSIST ALONG THE EAST SIDE AND SOUTH END OF THE SAN JOAQUIN VALLEY AS WELL AS THE NORTH FACING SLOPES OF THE TEHACHAPI MOUNTAINS UNTIL 17Z. LOCALLY STRONG WINDS WILL ALSO BUFFET THE HIGHER ELEVATIONS OF THE SIERRA NEVADA AND THE INDIAN WELLS VALLEY THIS MORNING. OTHERWISE...VFR CONDITIONS WILL PREVAIL OVER THE CENTRAL CALIFORNIA INTERIOR THROUGH 12Z FRIDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL AND TWEB ROUTES 421 AND 423. && .AIR QUALITY ISSUES...NONE. && .HNX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC:MOLINA AVIATION:MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 437 AM MDT FRI MAR 23 2007 .SHORT TERM... (TODAY AND TONIGHT) ...ISOLD-SCT SHOWERS AND A FEW THUNDERSTORMS POSSIBLE TODAY... CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES HAD A MATURING CLOSED LOW OVER THE CA BAJA WITH AN EXPANDED SYNOPTIC SCALE PRECIPITATION SHIELD IN THE NORTH-EAST QUADRANTS ACROSS AZ/WRN NM. SOME OF THE MIDDLE/HIGH LEVEL CLOUD SHIELD WAS MOVING INTO EXTREME SWRN CO. THERE WAS A ROGUE SMALL CLUSTER OF SHRA/TSRA OVER E CNTRL NM MOVING NWD...BUT IT CONTINUES TO DISSIPATE AS TO MOVES AWAY FROM ITS LOW LEVEL FORCING AND NO UPPER AIR SUPPORT. ISENTROPIC ASCENT DRIVEN ISOLD-SCT TSRA WAS ACROSS SRN NM JUST NORTH OF THE SURFACE WARM FRONT. THIS NEW MINI-MESOSCALE CONVECTIVE SYSTEM MAY FALL APART ONCE IT GETS INTO NERN NM EARLY THIS MORNING. BASICALLY...JUST SOME HIGH CLOUDS MOVING INTO OUR WRN CWFA/CONTDVD AND IN EXTREME SERN CO. TEMPERATURES ARE RELATIVELY MILD WITH 40S/LOWER 50S ACROSS SERN CO AND 20S/30S IN THE MOUNTAINS/ HIGH VALLEYS. TODAY...WE WILL BE WAITING FOR THE OLD CLOSED LOW TO EJECT LATER TONIGHT...SO NOT ANTICIPATING MUCH "SIGNIFICANT" WEATHER UNTIL LATER TONIGHT. THERE WILL BE ENOUGH MIDLEVEL MOISTURE AND INSTABILITY LATER THIS AFTERNOON TO TRIGGER SOME SHRA/TSRA OVER THE MOUNTAINS. ACROSS SERN CO...PRECIP MIGHT HAVE A TOUGH TIME REACHING THE GROUND...INITIALLY...GIVEN INVERTED-V THERMAL STRUCTURE SUPPORTING VIRGA AND LOCALLY GUSTY WINDS. SOME OF THE PRECIPITATION SHAFTS...IF THEY FORM...MAY MAKE IT TO THE GROUND BY MIDDLE TO LATE AFTERNOON ACROSS SERN CO. ANY SNOW POTENTIAL WOULD BE AT OR ABOVE 10K FT MSL LATER TODAY. CURRENT TEMPERATURES LOOK FAIRLY DOABLE AND BLENDED WITH LATEST MOS GUIDANCE. TONIGHT...06Z/23 WRF IS INTERESTING COMPARED TO THE 00Z/23 RUN. THE 00Z/23 RUN HAD THE TYPICAL DIURNAL CONVECTIVE PRECIPITATION DISSIPATING AFTER SUNSET WHILE WE WAIT FOR THE LOW AND ANY POTENTIAL SYNOPTIC SCALE ASCENT PRECIPITATION TO GENERATE TOWARDS SAT AM. WELL...NOW IT "BLOWS" UP SOME PRECIPITATION OVER THE SANGRE DE CRISTO MOUNTAINS AFTER MIDNIGHT...WHILE THE 00Z/23 DID NOT "BLOW UP" PRECIPITATION IN THIS AREA. ONE CONSISTENT PRECIPITATION ZONE DEVELOPING MAY BE ACROSS ERN NM/WRN TX/WRN OK INTO EXTREME SERN CO LATE TONIGHT. AS THE OLD CLOSED LOW LIFTS N-NEWD OUT OF AZ/WRN NM...RELATIVELY DEEP SLY FLOW BEGINS TO TRANSPORT MOISTURE PER H7 MOISTURE TRANSPORT VECTORS/MAG. THIS WILL HELP DESTABILIZE THE AIR MASS TO GENERATE NOCTURNAL THUNDERSTORMS ACROSS JUST S OF EXTREME SERN CO AND POSSIBLY MOVING INTO SERN CO AFTER MIDNIGHT. WRF SUGGESTING A LINEAR MESOSCALE CONVECTION SYSTEM JUST AHEAD OF THE CLOSED LOW IN THE AFOREMENTIONED AREA. MIGHT SEE SOME MODERATE TO HEAVY RAIN ACROSS EXTREME SERN CO AND SWD GIVEN GEORGE/S K-INDICES OF 35-40C AND H7-H5 SPECIFIC HUMIDITY AROUND 5 G/KG AND MORE IMPORTANTLY ANY PRECIPITATION TRAINING GIVEN A DEEP SLY FLOW. THE GREATER THREAT FOR MODERATE TO HEAVY RAIN WOULD BE S-SE OF EXTREME SERN CO...BUT IT MIGHT MOVE INTO BACA COUNTY IF CELLS CAN HOLD TOGETHER. INCREASED POPS ACROSS EXTREME SERN CO TO LIKELY FOR LATER TONIGHT. ANY SNOW POTENTIAL WOULD BE AT OR ABOVE 9K FT MSL. METZE .LONG TERM... (SATURDAY THROUGH THURSDAY) MODELS FINALLY COMING INTO BETTER CONSENSUS LIFTING CLOSED LOW FROM CENTRAL NM AND THE 4 CORNERS REGION THROUGH CENTRAL CO...AND INTO NE CO/SW NE BY 00Z SUNDAY. THIS BRINGS FCST AREA UNDER FAIRLY STRONG QG FORCING BY SAT MORNING...SPREADING NORTHWARD QUICKLY DURING THE LATE MORNING/EARLY AFTN. ATMOS BECOMES CONVECTIVELY UNSTABLE AS COLD CORE ALOFT MOVES OVER THE REGION BY AFTN...SO SHOULD SEE SOME EMBEDDED THUNDERSTORMS AS WELL. LOW LEVELS STILL LOOK FAIRLY WARM WITH THIS SYSTEM...WITH SNOW LEVELS STARTING AROUND 9KFT...DROPPING TO 8KFT BY LATE AFTN. BEST LIFT ACCORDING TO 00Z RUNS WILL AFFECT CEN CO UNDER DEFORMATION BAND AND MID LEVEL TROWAL. HOWEVER...WITH CONVECTIVE INSTABILITY...COULD SEE BOUTS OF HEAVY SNOW ACROSS JUST ABOUT ANY OF THE MTS. FOR THE SOUTHEAST PLAINS/ADJACENT INTERSTATE 25 CORRIDOR...SHOULD SEE SNOW SHOWERS RAMPING UP IN THE MID TO LATE MORNING AS H7 WINDS BRIEFLY BECOME EASTERLY AS H7 CLOSED LOW LIFTS NORTHWARD. FAR EASTERN PLAINS QUICKLY BECOME DRY SLOTTED BY MID/LATE MORNING THOUGH AS 90 KT UPPER JET CORE LIFTS NORTH INTO SE CO...SO COULD SEE A LULL IN THE SHOWERS LATE SAT MORNING...BEFORE THEY REDEVELOP ALONG THE FRONT DURING THE AFTN. NAM/GFS HAVE THE FRONT POSITIONED ALONG THE PALMER DIVIDE BY MID AFTN...WITH AROUND 800 J/KG OF CAPE ALONG/NORTH OF THE BOUNDARY. SOUTH OF A LINE FROM PUEBLO TO EADS...WESTERLY DOWNSLOPE FLOW QUICKLY MIXES OUT LOW LEVEL MOISTURE...WHICH SHOULD LIMIT AFTERNOON SHOWERS/THUNDERSTORMS POTENTIAL. WILL STILL HAVE TO MONITOR POTENTIAL FOR STRONG STORMS...MAINLY ACROSS KIOWA COUNTY...HOWEVER LATEST RUNS APPEAR TO KEEP BEST SVR POTENTIAL JUST TO THE EAST AND NORTHEAST. OF COURSE BIGGEST CHALLENGE WILL BE SNOW AMOUNTS ACROSS THE MOUNTAINS. NAM PAINTS A GENEROUS 4-8 INCHES OF SNOW FOR SAT ACROSS ALL BUT THE SRN SANGRES (IN PROXIMITY OF DRY SLOT)...WITH AN ADDITIONAL 3 INCHES OF SNOWFALL ACROSS THE CENTRAL MTS SAT NIGHT. GFS ON THE OTHER HAND HAS UP TO A FOOT OF SNOWFALL ACROSS THE CEN/SW MTS UNDER DEFORMATION BAND ON SAT...WITH UP TO AN ADDITIONAL 3 INCHES POSSIBLE ACROSS THE CENTRAL MTS SAT NIGHT. GFS MAY BE A LITTLE OVERDONE GIVEN CONVECTIVE NATURE...BUT WOULDNT BE SURPRISED TO SEE AROUND 4-8 INCHES OF SNOW FOR THE HIGHER MTN AREAS...WITH LOCALLY HEAVIER AMOUNTS POSSIBLE GIVEN CONVECTIVE POTENTIAL. ALL IN ALL...STILL LOOKS LIKE A POTENTIAL ADVISORY EVENT. DEPENDING ON WESTWARD EXTENT OF DRY SLOT...PIKES PEAK AND THE WET MTS COULD ALSO SEE LOW END ADVISORY NUMBERS...THOUGH BREVITY OF UPSLOPE MAY KEEP THEM JUST SHY. STILL SOME UNCERTAINTIES WITH THE POSITION OF DRY AIR WRAPPING AROUND UPPER LOW...WHICH COULD MAKE/BREAK THE SNOW AMOUNT FCST. SO WILL NOT HOIST ANY HIGHLIGHTS JUST YET. WILL LET DAY SHIFT GET A LOOK AT ANOTHER SET OF RUNS. SYSTEM PULLS EAST OF THE AREA BY SUN WITH SNOW SHOWERS QUICKLY WINDING DOWN. TEMPS REBOUND NICELY FOR THE EARLY PART OF NEXT WEEK...THEN GFS BRINGS ANOTHER CLOSED LOW ACROSS NRN CO/WY TUES NIGHT. THIS WILL BRING WARM AND WINDY CONDITIONS TO THE AREA ON TUES AHEAD OF THE SYSTEM...THEN INCREASING CHANCES FOR PRECIPITATION FOR THE MTS ALONG/WEST OF THE CONTINENTAL DIVIDE FOR TUES NIGHT/EARLY WED. THIS COULD POSE PROBLEMS FOR FIRE WEATHER CONCERNS GIVEN THE STRONG WINDS/LOW RH POTENTIAL ON FOR MID WEEK. NO CHANGES MADE TO GRIDS BEYOND TUES. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/31 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 328 AM EDT FRI MAR 23 2007 .SYNOPSIS...SFC HIGH PRES RIDGE JUST OUR N WITH PREVAILING LOW LEVEL NE TO E FLOW OVER THE FORECAST AREA. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW THE MID-UPPER RIDGE FROM CENTRAL GOMEX NEWD INTO THE SE STATES. MOIST BOUNDARY LAYER...CLEAR SKIES AND CALM WINDS OVER SE GA SUPPORTING FOG DEVELOPMENT WITH ALMA OCCASIONAL REPORTING VIS BELOW 1SM. EXPECT MORE FOG DEVELOPMENT OVER ENTIRE CWA NEXT FEW HOURS WITH THE DENSE FOG MAINLY CONFINED IN INTERIOR SE GA. && .SHORT TERM...HIGH PRES SFC AND ALOFT WILL DOMINATE THE REGION WITH A 1026 MB SFC HIGH PINCHING OFF OVER SRN AL AND GA SAT-SUN. STRONG RIDGING ALOFT WILL ENSURE A DEFINITE WARMING TREND FOR MOST AREAS TODAY THROUGH SUNDAY. TODAY...PATCHY DENSE FOG EXPECTED THROUGH EARLY MORNING OVER SE GA WITH PATCHY FOG MOST OTHER AREAS. FOR MAX TEMPS PREFERRED A BLEND BUT MOSTLY LIKED THE MAV GUIDANCE AS MET VERIFYING A BIT TOO COOL. MID 80S ARE POSSIBLE INLAND SECTIONS. WEAKER PRES GRADIENT WILL PROVIDE MOSTLY ELY 10-15 MPH WINDS BUT STILL SOME GUSTINESS IN AFTERNOON BUT LOWER THAN PREVIOUS DAYS. TONIGHT...STRONGER HIGH PRES ALOFT WITH WEAKER BOUNDARY LAYER WINDS SPELLS FOR ANOTHER ROUND OF AREAS OF FOG AFTER MIDNIGHT LESS THAN 1SM AT TIMES BUT OTHERWISE MOSTLY CLEAR SKIES. LOWS MOSTLY IN THE MID 50S. SAT...MORNING FOG DISSIPATES GIVING WAY TO PARTLY TO MOSTLY SUNNY SKIES AND WARM TEMPS WITH MID 80S INLAND...UPPER 70S NEAR THE COAST. SAT NIGHT...MOSTLY CLEAR SKIES AND PATCHY TO AREAS OF FOG EXPECTED. LOWS CONTINUE TO BE MOSTLY MID 50S. SUNDAY...SFC HIGH PRES CONTINUES WITH WARM TEMPS FROM MID 80S TO UPPER 70S AGAIN. WILL BE SEEING A BACK-DOOR COLD FRONT SLIDE DOWN THE E COAST THROUGH CAROLINAS LATE IN THE DAY. .LONG TERM...SUN NIGHT-THU. MODEL GUIDANCE FASTER THAN YESTERDAY`S RUN SHOWING BACK-DOOR FRONT MOVING INTO THE FORECAST AREA. NAM AND GFS SHOWING FRONT MOVING INTO SE GA BETWEEN 06Z-12Z MON WITH POSSIBLE LIGHT SHOWERS ACCOMPANYING THE FRONT. FRONT PUSHES THROUGH ALL THE CWA WITH TEMPS A BIT COOLER ON NE FLOW THANKS TO 1033 MB HIGH OFF THE MID ATLC. PRES GRADIENT WILL HAVE INCREASED MON WITH BREEZY CONDS DEVELOPING OVER ERN ZONES. HAVE MOVED UP POPS TO MON AT 20% FOR PORTIONS OF SE GA AND NE FL AS ASSOCD MOISTURE WITH FRONT PUSHES THROUGH. SFC HIGH PRES RIDGE BUILDS SWD TUE-THU WITH NO MENTION OF POPS WITH SLIGHTLY WARMER TEMPS ANTICIPATED. && .AVIATION...WILL SEE TEMPO MVFR AT ALL TAF SITES BETWEEN 09Z AND 12Z DUE MAINLY TO VSBY. OTHERWISE VFR. EAST WINDS INCREASE BY EARLY THIS AFTERNOON WITH GUSTS TO NEAR 20 KNOTS AFTER 16Z. && .MARINE...WITH RIDGE BUILDING IN...WINDS AND EASTERLY SWELLS WILL SUBSIDE TODAY AND THROUGH THE WEEKEND. WILL KEEP THE ADVISORY FOR SEAS GOING THROUGH SATURDAY AND DROP ON SUNDAY. A STRONG BACK DOOR FRONT MOVES DOWN THE COAST MONDAY AND WILL PROBABLY SEE SCA CONDITIONS RETURN AGAIN. && .FIRE WX...BRIEF DURATIONS OF RH`S AOB 35% POSSIBLE TODAY AND SAT AFTN ACROSS THE SUWANNEE RIVER VALLEY IN NE FL. OTHERWISE NO MAJOR CONCERNS THROUGH THE WEEKEND. WINDS ARE EXPECTED TO INCREASE TO 15 MPH INLAND AND 15 TO 20 MPH ALONG THE COAST MONDAY WHEN A BACK DOOR FRONT SWEEPS THROUGH THE AREA. && .PRELIMINARY POINT TEMPS/POPS... AMG 83 54 85 53 / 10 10 10 10 SSI 74 58 76 57 / 0 0 0 10 JAX 79 55 81 55 / 10 10 10 10 SGJ 74 59 75 60 / 10 10 0 10 GNV 83 53 83 55 / 10 10 0 10 OCF 83 55 83 55 / 10 10 0 10 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 3 PM EDT SATURDAY FOR ALTAMAHA SOUND GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE-FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE-ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 PM EDT THIS EVENING FOR FERNANDINA BEACH TO ST AUGUSTINE FL OUT 20 NM- ST AUGUSTINE TO FLAGLER BEACH FL OUT 20 NM. && $$ SHASHY/PETERSON fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 940 PM EDT WED MAR 21 2007 .SHORT TERM UPDATE /TONIGHT/... PER RADAR/SATELLITE TRENDS...DEPICTING CLOUDS/SHOWERS PUSHING TOWARD SHORE ON THE SOUTHERN PERIPHERY OF HIGH PRES CENTERED EAST OF NEW ENGLAND...EXPANDED ISOLATED SHOWERS INTO GA COUNTIES OVERNIGHT. 18Z NAM12/WRF AND 0Z RUC40 SUGGEST THAT PRECIP WILL STRUGGLE TO PUSH ONSHORE OVERNIGHT...SO WILL NOT RAISE POPS. HOWEVER...WILL CONTINUE TO MONITOR TRENDS AND MAY YET RAISE POPS IF NEEDED...ESP ACROSS SC COUNTIES. OTHERWISE...DEWPOINTS IN THE 50S AND BREAKS IN THE CLOUD COVER SUPPORT THE ONGOING FORECAST OF PATCHY FOG. && .MARINE... RECENT REPORTS FROM AREA BUOYS AND FROM THE CHARLESTON AND SAVANNAH PILOT BOATS SUGGEST THAT SEAS ARE BUILDING AHEAD OF SCHEDULE...AND CURRENT TRENDS SUGGEST THAT 6 FT SEAS WILL PROBABLY SLIP INTO NEARSHORE WATERS OVERNIGHT. THUS...MOVED UP START TIME OF ONGOING SCAS FOR SC/GA NEARSHORE WATERS FROM NOON THU TO 2 AM THU. && .AVIATION /02Z-24Z/...VFR CONDITIONS WILL PREVAIL UNTIL AFTER 8Z...WHEN AT LEAST MVFR VISIBILITY SHOULD DEVELOP AT KCHS...WHILE OCCASIONAL IFR CIGS/VSBYS SHOULD DEVELOP AT KSAV AROUND DAYBREAK. THEN...AFTER 12Z...VFR CONDITIONS SHOULD PREVAIL FOR THE REMAINDER OF THE FORECAST PERIOD. MEANWHILE...TAFS INDICATE SHOWERS IN THE VICINITY UNTIL 9Z...WILL AMEND AS NEEDED FOR TIMING OF INDIVIDUAL SHOWERS. && .RIP CURRENTS... PERSISTENT ONSHORE FLOW AND DEVELOPING LONG PERIOD EASTERLY SWELL WILL RESULT IN A MODERATE RISK OF RIP CURRENTS THURSDAY. THE INCREASED THREAT OF RIP CURRENTS MAY CONTINUE UNTIL THE SWELL SUBSIDES SATURDAY. && .COASTAL FLOODING/HIGH SURF... GIVEN PERSISTENT ONSHORE FLOW...BUILDING E SWELL AND ASTRONOMICAL COMPONENT OF TIDES...STILL CLOSE TO THE MARCH 19 NEW MOON...WILL CONTINUE TO CLOSELY MONITOR WATER LEVELS AROUND THE TIMES OF HIGH TIDE TONIGHT AND AGAIN THURSDAY NIGHT. ALSO...WILL NEED TO ASSESS NEED FOR A HIGH SURF ADVISORY THU...AS WAVES IN SURF ZONE COULD BE CLOSE TO 5 FT. THIS COULD ALSO CONTRIBUTE TO MINOR BEACH EROSION AT HIGH TIDE...ESPECIALLY THU AND THU NIGHT. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM THURSDAY TO 6 AM EDT FRIDAY FOR AMZ350-352-354. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT SUNDAY FOR AMZ374. && $$ SPR ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 130 PM CDT THU MAR 22 2007 .DISCUSSION FOR ZONES/GRIDS... 11AM...SKIES ARE CLEARING OVER MUCH OF FCST AREA AT LATE MRNG AS WINDS TURN NW AND TEMPS STEADY OUT. COLD ADVECTION ON NW WINDS WILL HOLD TEMPS WITHIN FEW DEG OF CURRENT LEVELS THROUGH THE AFTERNOON. HIGH PERS OVER NW IOWA SHOULD DRIFT ACROSS TONIGHT FOR SOMEHWAT COOLER TEMPS. RETURN MOISTURE AND CLOUDS ETC LKLY TO BEGIN LATER TONIGHT AND CONTINUE FRIDAY. CHARACTER OF THAT RETURN REMAINS TO BE SEEN AND WILL TRIM/DELAY RETURN A LITTLE IN UPDATED GRIDS. FAIRLY MARKED DIFFERENCES IN GFS AND NAM IN GROWING AMPLITUDE OF EJECTING WESTERN TROUGH NEXT 48HRS IS ONE SOURCE OF UNCERTAINTY. KL PREVIOUS DISCUSSION 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... THE COLD FRONT HAS MOVED SOUTH OF THE TAF FORECAST AREA OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA. THE WIND PROFILER DATA SHOWS A WEST WIND IN ILLINOIS AT 700 MB AND AT 850 MB. WITH THIS WIND PATTERN ALOFT THE FRONT WILL PROBABLY STALL OVER CENTRAL ILLINOIS. A HIGH WILL MOVE ACROSS THE NORTH CENTRAL PART OF THE STATE THIS EVENING. THE WIND WILL BECOME SOUTHERLY AND THE FRONT WILL MOVE NORTH INTO NORTH CENTRAL ILLINOIS AND NORTHWEST INDIANA LATE TONIGHT. WE WILL ADD THUNDERSTORMS TOWARD FROM 11 TO 12 UTC. THIS IS THE TIME OF MAXIMUM CONVERGENCE AS THE FRONT MOVES THROUGH. WE WILL HAVE LIGHT RAIN THROUGH THE MORNING ACROSS THE FORECAST AREA. WE EXPECT A SOUTHEAST WIND AFTER MIDNIGHT TONIGHT. WE USED THE NAM AND A LOCALLY RUN WRF MODEL. && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1100 AM CDT THU MAR 22 2007 .DISCUSSION FOR ZONES/GRIDS... 11AM...SKIES ARE CLEARING OVER MUCH OF FCST AREA AT LATE MRNG AS WINDS TURN NW AND TEMPS STEADY OUT. COLD ADVECTION ON NW WINDS WILL HOLD TEMPS WITHIN FEW DEG OF CURRENT LEVELS THROUGH THE AFTERNOON. HIGH PERS OVER NW IOWA SHOULD DRIFT ACROSS TONIGHT FOR SOMEHWAT COOLER TEMPS. RETURN MOISTURE AND CLOUDS ETC LKLY TO BEGIN LATER TONIGHT AND CONTINUE FRIDAY. CHARACTER OF THAT RETURN REMAINS TO BE SEEN AND WILL TRIM/DELAY RETURN A LITTLE IN UPDATED GRIDS. FAIRLY MARKED DIFFERENCES IN GFS AND NAM IN GROWING AMPLITUDE OF EJECTING WESTERN TROUGH NEXT 48HRS IS ONE SOURCE OF UNCERTAINTY. KL PREVIOUS DISCUSSION 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 650 AM CDT MID LVL S/WV TROF CONTINUES TO PLOW INTO WRN GRTLKS REGION THIS MORNING...COLD FRONT PUSHING THRU FCST AREA AT 12Z. BAND OF ELEVATED CONVECTION ASSOCIATED WITH 55 KT LLJ NOW PUSHING OFF TO THE EAST OF FCST AREA AS 950-850 HPA FLOW BECOMING A BIT MORE WESTERLY WITH APPROACH OF TROF...THOUGH A FEW ISOLATED CELLS STILL DVLPG GENERALLY ALONG/SOUTH OF A KVYS...KLOT...KGYY LINE ASSOCIATED WITH ELEVATED INSTABILITY PLUME/LLJ AXIS. EXPECT THESE TO REMAIN SOUTH OF TERMINALS WITH EXCEPTION OF KGYY FIRST COUPLE OF HOURS OF TAF PERIOD EARLY THIS MORNING. OTHERWISE...COLD FROPA HAS OCCURRED AT KRFD AND WILL BE INTO CHI AREA TERMINALS NEXT 1-2 HRS. PATCHY MVFR CIGS IN 1500-2000 FT RANGE IMMEDIATELY BEHIND FRONT...THOUGH STRONG LLVL DRY ADVECTION DVLPG POST FRONTAL SHOULD CLR THIS OUT BY LATE MORNING. STRONG ISALLOBARIC GRADIENT WITH PRESSURE RISES BEHIND FRONT...SO WITH WSFT TO NW XPCT TO CONTINUE TO SEE GUSTS INTO THE LOW/MID 20 KT RANGE THIS MORNING. SFC HIGH PRESSURE BUILDS IN RAPIDLY THIS AFTN/THIS EVE ALLOWING WINDS TO DECREASE QUICKLY...GOING VRBL THIS EVE. WILL LIKELY SEE A BIT OF A LAKE BREEZE TOWARD EVE ALONG IL/IND LAKE MICH SHORE AS GRADIENT RELAXES. NEXT S/WV PROPAGATES ACROSS UPPER MIDWEST TONIGHT...WITH ANOTHER ROUND OF WAA/UPGLIDE DVLPG ACROSS BAROCLINIC FRONTAL ZONE TO SOUTH OF FCST AREA OVRNGT. 06Z NAM/GFS RUNS BOTH FOCUS PCPN SOUTH OF TERMINALS WITH VFR CIG DVLPG. COULD SEE PCPN FARTHER NORTH INTO TERMINAL SITES AFTER 06Z TONIGHT...THOUGH CONFIDENCE THAT FAR NORTH IS LOW ATTM. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 650 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSIPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXIMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITIONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 650 AM CDT MID LVL S/WV TROF CONTINUES TO PLOW INTO WRN GRTLKS REGION THIS MORNING...COLD FRONT PUSHING THRU FCST AREA AT 12Z. BAND OF ELEVATED CONVECTION ASSOCIATED WITH 55 KT LLJ NOW PUSHING OFF TO THE EAST OF FCST AREA AS 950-850 HPA FLOW BECOMING A BIT MORE WESTERLY WITH APPROACH OF TROF...THOUGH A FEW ISOLATED CELLS STILL DVLPG GENERALLY ALONG/SOUTH OF A KVYS...KLOT...KGYY LINE ASSOCIATED WITH ELEVATED INSTABILITY PLUME/LLJ AXIS. EXPECT THESE TO REMAIN SOUTH OF TERMINALS WITH EXCEPTION OF KGYY FIRST COUPLE OF HOURS OF TAF PERIOD EARLY THIS MORNING. OTHERWISE...COLD FROPA HAS OCCURRED AT KRFD AND WILL BE INTO CHI AREA TERMINALS NEXT 1-2 HRS. PATCHY MVFR CIGS IN 1500-2000 FT RANGE IMMEDIATELY BEHIND FRONT...THOUGH STRONG LLVL DRY ADVECTION DVLPG POST FRONTAL SHOULD CLR THIS OUT BY LATE MORNING. STRONG ISALLOBARIC GRADIENT WITH PRESSURE RISES BEHIND FRONT...SO WITH WSFT TO NW XPCT TO CONTINUE TO SEE GUSTS INTO THE LOW/MID 20 KT RANGE THIS MORNING. SFC HIGH PRESSURE BUILDS IN RAPIDLY THIS AFTN/THIS EVE ALLOWING WINDS TO DECREASE QUICKLY...GOING VRBL THIS EVE. WILL LIKELY SEE A BIT OF A LAKE BREEZE TOWARD EVE ALONG IL/IND LAKE MICH SHORE AS GRADIENT RELAXES. NEXT S/WV PROPAGATES ACROSS UPPER MIDWEST TONIGHT...WITH ANOTHER ROUND OF WAA/UPGLIDE DVLPG ACROSS BAROCLINIC FRONTAL ZONE TO SOUTH OF FCST AREA OVRNGT. 06Z NAM/GFS RUNS BOTH FOCUS PCPN SOUTH OF TERMINALS WITH VFR CIG DVLPG. COULD SEE PCPN FARTHER NORTH INTO TERMINAL SITES AFTER 06Z TONIGHT...THOUGH CONFIDENCE THAT FAR NORTH IS LOW ATTM. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 330 AM CDT THU MAR 22 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 330 AM CDT MAIN FORECAST CONCERN WILL BE ON CONVECTION MAINLY THIS MORNING...AND THEN CONTINUED CHANCES OF SHOWERS/THUNDERSTORMS FROM LATER TONIGHT THROUGH THE WEEKEND AND THE POTENTIAL FOR HEAVY RAINFALL AND CONTINUED FLOOD POTENTIAL. APOLOGIES FOR AN ABBREVIATED DISCUSSION DUE TO INCREASING CONVECTION ACROSS THE AREA THIS MORNING. SURFACE COLD FRONT IS NOW APPROACHING THE MISSISSPPI RIVER WITH SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATING BETWEEN 500-1000 J/KG OF ELEVATED INSTABILITY IN CLOSE PROXMITY TO THE SFC FRONT WHERE LOW LEVEL DEW POINT POOLING IS OCCURRING. EXPECTING INCREASE COVERAGE OF SHOWERS AND THUNDERSTORMS THIS MORNING WITH APPROACH OF THIS INSTABILITY AXIS AND ALSO INCREASING UPPER SUPPORT TOWARD 12Z AS NORTHERN STREAM VORT MAX PUSHES INTO THE NORTHERN GREAT LAKES AND AS UPPER JET STREAK CUTS THROUGH THE BASE OF THIS TROUGH INTO THE MID MISSISSIPPI RIVER VALLEY. FRONT WILL RAPIDLY MOVE ACROSS THE CWA TODAY...AND BY LATE MORNING ANY REMAINING SHOWERS/THUNDERSTORMS SHOULD BE CONFINED TO FAR SOUTHEASTERN SECTIONS OF THE CWA. GIVEN INSTABILITY AND INCREASING SHEAR NEAR THE FRONTAL BOUNDARY...WILL HAVE TO MONITOR FOR WIND/HAIL THREAT FOR FIRST FEW HOURS THIS MORNING. FAST MOVING NATURE OF STORMS SHOULD KEEP RAINFALL TOTALS UNDER CONTROL BUT COMBINATION OF ADDITIONAL RAINFALL AND RAIN OF PREVIOUS AFTERNOON MAY LEAD TO SOME MINOR FLOODING PROBLEMS THIS MORNING. HAVE MADE SOME REVISIONS TO THE FORECAST TONIGHT INTO FRIDAY...WITH LATEST MODEL RUNS COMING INTO BETTER AGREEMENT IN A MORE NORTHERLY POSITION OF SFC FRONTAL BOUNDARY AND BETTER CHANCES OF PERIODIC EPISODES OF SHOWERS/THUNDERSTORMS...ESPECIALLY SOUTH OF INTERSTATE 80 WHERE ISENTROPIC LIFT WILL BE MORE PRONOUNCED. ALREADY HIGH RIVER LEVELS WILL HAVE TO BE MONITOR FOR ADDITONAL FLOODING GIVEN. WILL REINTRODUCE LIKELY POPS FOR TSRA ACROSS SOUTHERN AREAS LATE TONIGHT...AND LIKELY SHOWERS AS FAR NORTH AS INTERSTATE 88...TAPERING TO CHANCE POPS FAR NORTH. ALSO INCREASED POPS FOR FRIDAY WITH BOUNDARY STILL IN THE AREA. LITTLE CHANGES MADE TO THE REMAINDER OF THE FORECAST. MARSILI && .AVIATION... 1254 AM CDT VIGOROUS S/WV TROF PROPAGATING ACROSS NRN PLAINS AND UPPER MIDWEST EARLY THIS MORNING...WITH ASSOCIATED SFC TROF/COLD FRONT FROM NRN WI TO ERN IA AT 05Z. REGIONAL PROFILER DATA...AND 0445Z ACARS SOUNDING OUT OF KRFD INDICATE 55 KT SOUTHWESTERLY LLJ IN 930-850 HPA LAYER AHEAD OF LOW LEVEL TROF/FRONT. SOUNDING ALSO INDICATES STEEP LAPSE RATES IN THIS LAYER...THOUGH A BIT OF A CAP NOTED AROUND 670 MB. ISOLATED WEAK ELEVATED CONVECTIVE CELLS HAVE BEEN TRYING TO INITIATE IN THIS REGION OF MOIST/WAA ACROSS FAR NRN IL...THOUGH APPEARS THEY ARE FIGHTING CAP. NAM FCST SOUNDINGS DEPICT COOLING OF MID/UPR LVLS WITH APPROACH OF S/WV EARLY THIS MORNING HOWEVER...WITH ELEVATED CAPE INCREASING TO 550-650 J/KG FOR PARCELS BASED 875-900 HPA. THIS ALONG WITH INCREASING LLVL CONVERGENCE AHEAD OF FRONT SHOULD BE SUFFICIENT TO RESULT IN SCATTERED TRW AS BOUNDARY ADVANCES ACROSS FCST IL. CURRENT REGIONAL RADAR TRENDS INDICATE STRONG CONVECTION IN SWRN WI AND SRN IA...WITH SOME INCREASE IN CELL DEVELOPMENT ACROSS ERN IA. GIVEN STRONG FAIRLY UNIDIRECTIONAL WIND FIELD MAY SEE SOME GUSTS IN 40 KT RANGE WITH TSTMS...AND PERHAPS SOME SMALL HAIL GIVEN MARGINAL CAPE PROFILES. THUS WILL MAINTAIN TS IN TERMINALS THIS MORNING...MAINLY DURG 09-13Z PERIOD FROM WEST TO EAST AS FRONT MOVES THRU. MAY SEE BRIEF PERIOD OF MVFR CIGS IN FRONTAL ZONE...THOUGH STRONG LLVL DRYING BEHIND FRONT SHOULD DECREASE CLOUDS FAIRLY RAPIDLY WITH VFR CONDITIONS PREVAILING WITHIN A FEW HOURS OF SUNRISE. STRONG SW LLVL WIND FIELD IN TIGHT PRES GRADIENT AHEAD OF COLD FRONT RESULTING IN GUSTY 20-30 KT WINDS ATTM. WILL SEE GRADIENT DECREASE JUST A BIT WITHIN TROF AXIS TOWARD SUNRISE...THEN WSHFT TO NWLY DIRECTION. SOME GUSTINESS AS SFC PRES RISE BUILDS IN EARLY MORNING...THEN DECREASING WINDS THIS AFTN AS WEAK SFC HIGH BUILDS IN. DVLPMNT OF NE WINDS OFF LAKE A GOOD PROBABILITY VERY LATE AFTN/EARLY EVE AS GRADIENT WINDS DECREASE. NEXT S/WV AND ELEVATED PCPN THREAT BEYOND 06Z TONIGHT...MORE ON THAT WITH NEXT FCST ISSUANCE. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...SMALL CRAFT ADVISORY ILLINOIS NEARSHORE THROUGH 18Z THURS. SMALL CRAFT ADVISORY INDIANA NEARSHORE 18Z WED-18Z THURS. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 745 PM EDT WED MAR 21 2007 .DISCUSSION FOR 00Z TAFS...WARM SECTOR AIR OVER TAF ROUTES WITH SCT AC AND CI OVR INDIANA WHILE CONVECTION OCCURRING NEAR WRM FNT ACRS SRN GRTLKS. PATCHY MID CLOUD EMBEDDED IN SW FLOW AHEAD OF CDFNT MEANS VFR TO CONTINUE TIL DAYBREAK WHILE GUSTY WINDS AT SUNSET TODAY BECOME STEADY OVRNGT. MODELS TIMING OF CDFNT THU FAIRLY SIMILAR AND APPEARS BEST LIFT WILL OCCUR JUST PRIOR TO AND DURING FROPA SO HAVE KEPT PCPN OUT OF FCST TIL THEN. EXPECT PERIOD OF MVFR VSBY WITH SHRA AND CB DURING CDFNT PASSAGE AND TREND TO MVFR CIGS OVC020 IN COLD AIR BEHIND FNT. INCREASED STABILITY SHOULD LEAD TO END OF TSHRA SHORTLY AFT FROPA. && .PREV DISCUSSION...SURFACE FRONT CURRENTLY LOCATED OVER NORTHERN PLAIN/UPPER MIDWEST WILL MOVE SOUTH INTO THE AREA THURSDAY. HAVE ADJUSTED PRECIP TIMING ACCORDINGLY. HAVE KEPT A CHANCE IN MOST AREAS DURING THE OVERNIGHT HOURS TO ACCOUNT FOR ANY PRE-FRONTAL ELEVATED CONVECTION THAT MAY FIRE AS S/W OVER S. MO AND N. AR MOVES INTO AREA ALONG WITH INCREASING ISENTROPIC LIFT FROM THE LLJ. THE MID LEVEL FORCING ASSOCIATED WITH THE ACCOMPANYING S/W IS FCST TO MOVE ACRS THE UPPER MIDWEST AND LAKES REGION SHOULD REMAIN DISPLACED AWAY FROM CENTRAL INDIANA. THIS WILL TEND TO LIMIT DESTABILIZATION OVERTOP MOIST TONGUE ADVECTING INTO THE REGION TONIGHT AND EARLY TOMORROW. MODEL CONSENSUS FCST SOUNDINGS INDICATING MODEST LOW LEVEL FLOW DURING THE AFTERNOON HOURS TOMORROW BUT SEVERE POTENTIAL WILL BE LIMITED MAINLY BY VERY WEAK INSTABILITY. FRONTOGENESIS MOVES INTO AREA BY THURS MORNING AND REMAINS QUASI STATIONARY OVER THE OH VALLEY THRU SATURDAY ACCORDING TO NAM/GFS. ADDITIONAL EMBEDDED SHORTWAVES IN MEAN FLOW WILL HELP TO TRIGGER OCCASL CONVECTIVE SHOWERS/TSTMS IN CONJUNCTION WITH FRONTAL LIFTING IN REGION. PWATS VALUES WILL BE ON THE ORDER OF 1.2 TO 1.5 INCHES OVERNIGHT AND THURSDAY AS LLJ MOVES INTO THE AREA AND ACTS AS MSTR TRANSPORT MECHANISM...THEREFORE POTENTIAL EXISTS FOR HEAVY RAIN AMOUNTS. HPC GUIDANCE CURRENTLY HAS ROUGHLY 1.5 INCHES ACCUMULATING OVER THE ENTIRE FCST AREA...WITH POTENTIAL FOR UP TO 3 INCH AMOUNTS IN ISOLATED AREAS IN THE NEXT 48-60 HRS. AT THIS TIME...1 TO 2 INCH AMTS APPEAR TO BE THE MORE PROBABLE SCENARIO. WILL ISSUE AN ESF TO INCREASE AWARENESS ABOUT THE WATER THREAT BUT WILL HOLD OFF ON ANYTHING ELSE WHEN/IF FOCUS FOR LIFT BECAUSE MORE APPARENT. HAVE ADJUSTED TEMPS SLIGHTLY TO ALIGN THEM IN A NORTH-SOUTH GRADIENT AS THE MODEL CONSENSUS INDICATES AN EAST-WEST FRONTAL POSITION OVER THE TONIGHT THRU FRIDAY NIGHT PERIOD. LONG TERM...AFT 12Z ON MARCH 24...CONSENSUS IS WARM AND OFTEN WET WITH STRONG SW FLOW AND FRONT WEAVING BACK AND FORTH ACROSS AREA. HOWEVER JUST HOW THE FRONT AND SHORT WAVES MOVING THROUGH AREA INTERACT COULD MAKE A BIG DIFFERENCE IN JUST HOW WARM AND HOW WET WE GET. FOR NOW WILL STICK CLOSE TO NCEP GUIDANCE BECAUSE DONT HAVE A BETTER IDEA...BUT THIS IS NOT A HIGH CONFIDENCE FCST. && .AVIATION...DISCUSSION FOR 18Z TAFS COULD SEE A FEW POP UP RW`S OR POSSIBLY TRW`S THIS AFT AS TAF SITES ARE NOW IN THE WARM SECTOR WITH LAPS DATA AND MODIFIED SOUNDINGS REVEALING SLGT INSTABILITY AND RUC40 SHOWING S/W MOVING E ACRS SRN IL WHICH WL MOV ACRS THE FA THIS AFTERNOON. SHOULD SEE ANOTHER CHC DURING THE EVE AS S/W ACRS NERN OK...PER H20 VAPOR IMAGERY AND MODELS...APPROACHES. BEST CHC SHOULD BE AFTER 12Z...HOWEVER...AS CD FNT APPROACHES FM THE NW...AND MODEL TIME SECS SHOW MOIST DEEPENING AND DECENT UVM AHEAD OF ANOTHER S/W. DIURNAL CU EXPECTED TO DEVELOP THIS AFTERNOON AND SHOULD BE JUST INTO THE VFR CAT. SHOULD START TO SEE THE CLDS LOWER INTO THE MVFR RANGE AROUND DAYBREAK AS THE CD FNT APPROACHES. FINALLY...EXPECT WIND GUSTS TO 25 KTS THIS AFTERNOON AS SOUNDINGS FAVOR PLNTY OF MIXING. EXPECT THE MIXING TO PUT AN END TO THE HAZE. WINDS WL STAY UP PLNTY ENOUGH TNGT TO AVOID FOG. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...SMITH/JK AVIATION...TUCEK in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 924 AM MDT FRI MAR 23 2007 .UPDATE...ZONES HAVE BEEN UPDATED TO EXTEND THE DENSE FOG ADVISORY FOR THE KANSAS AND SOUTHWEST NEBRASKA COUNTIES UNTIL 11 AM MDT/ NOON CDT. LATEST RUC SOUNDINGS SHOW INVERSION TO TAKE A LITTLE LONGER TO BREAK WITH GOOD AMOUNT OF LOW LEVEL MOISTURE. SURFACE OBSERVATIONS STILL AT A QUARTER OF A MILE REPORTED AT SOME LOCATIONS INCLUDING GOODLAND...COLBY AND MCCOOK. EXPECT FOG TO LIFT BY LATER IN THE MORNING. REST OF FORECAST STILL ON TRACK. WILL BE WATCHING HIGH TEMPERATURES TODAY CLOSELY WHICH MAY BE DEPENDENT ON AMOUNT OF CLOUDINESS THROUGHOUT THE DAY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...DENSE FOG ADVISORY UNTIL 11 AM MDT /NOON CDT/ THIS MORNING FOR KSZ001>004-013>016-027>029-041-042. NE...DENSE FOG ADVISORY UNTIL 11 AM MDT /NOON CDT/ THIS MORNING FOR NEZ079>081. CO...NONE. && $$ LAMMERS ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1038 AM CDT THU MAR 22 2007 .UPDATE... SURFACE FRONT HAD BECOME QUASI-STATIONARY GENERALLY JUST SOUTH OF HIGHWAY 50 AT MID-MORNING...WITH THE LATEST NAM AND RUC SUGGESTING A SLIGHT NORTHWARD MOVE INTO THE AFTERNOON. THIS IS SLIGHTLY NORTH OF EARLY MORNING GRID PACKAGE...SO HAVE REFLECTED THE CHANGES IN THE LATEST GRID/FORECAST UPDATE. AS FOR CONVECTIVE CHANCES FOR THIS AFTERNOON...A LOT WILL DEPEND ON DIURNAL HEATING (IE. CLOUD TRENDS) ALONG AND SOUTH OF SURFACE FRONTAL BOUNDARY. DESPITE SOME HOLES INTO MIDDAY...HIGHER LEVEL CLOUDS LOOK TO ENCROACH SOUTH CENTRAL KANSAS DURING THE EARLY AFTERNOON. CONVERGENCE ALONG THE BOUNDARY LOOKS SUFFICIENT TO FOCUS CONVECTION WITH POTENTIAL ML CAPES OF AROUND 1800 J/KG LATER THIS AFTERNOON. SO LITTLE CHANGE TO THE GOING POP FORECAST AND FLOOD WATCH HEADLINE. BETTER CHANCES FOR ELEVATED CONVECTION APPEAR TO BE IN THE OFFING LATE THIS EVENING OR OVERNIGHT...ALONG AND NORTH OF SURFACE FRONT. KED && .PREV DISCUSSION... /ISSUED 328 AM CDT THU MAR 22 2007/ DISCUSSION... FORECAST CONCERNS TODAY ARE TSRA CHANCES FOR TODAY THROUGH THE WEEKEND AND ALSO TEMPS. TODAY: WAVY FRONTAL BOUNDARY MAKING SLOW PROGRESS INTO THE SOUTHERN KS AT THIS TIME. SOME WIDELY SCATTERED TSRA FINALLY HAVE DEVELOPED ALONG THE BOUNDARY AS LOW LEVEL JET INCREASES OVER THE TOP OF THE FRONT HELPING TO GET ELEVATED STORMS GOING. QUESTION TODAY IS HOW FAR SOUTH /IF AT ALL/ THIS FRONT WILL MAKE IT BEFORE STALLING OUT LATER THIS MORNING. SOME PRESSURE RISES STILL NOTED BEHIND THE BOUNDARY SO PREFER THE NAM-WRF FOR FRONTAL PLACEMENT GENERALLY ALONG AN EMP-HUT LINE BEFORE IT STALL. WHERE THE BOUNDARY WILL ULTIMATELY STALL OUT IS THE BIG PROBLEM TODAY AS THIS BOUNDARY WILL PROVIDE THE FOCUS FOR CONVECTION AND POSSIBLE TRAINING ECHOES. EXPECT SOME CONVECTION TO BE ONGOING EARLY IN THE PERIOD...BUT MAIN TSRA CHANCE WILL BE THIS AFTERNOON AS A MID LEVEL IMPULSE IN THE SOUTHWEST FLOW AND INCREASING ISENTROPIC LIFT IN THE 305K LAYER WILL STEEPEN LAPSE RATES ENOUGH FOR A MORE WIDESPREAD CONVECTION CHANCE. INSTABILITY IS MODEST WITH MUCAPE VALUES THIS AFTERNOON ONLY AROUND 1000 J/KG...BUT 0-6KM SHEAR VALUES STILL SUGGEST A POSSIBLE LARGE HAIL THREAT FOR AREAS WHERE SURFACE HEATING CAN BE MAXIMIZED. WITH SOME SURFACE BASED CONVECTION POSSIBLE SOUTH OF THE BOUNDARY OVER AREAS WITH SATURATED GROUNDS...WILL LEAVE THE FLOOD WATCH GOING FOR SOUTH CENTRAL AND SOUTHEAST KS BUT DAY SHIFT WILL PROBABLY HAVE TO BETTER DEFINE THIS ONCE BOUNDARY DECIDES TO STOP ITS SOUTHERN PROGRESS. WILL RAISE MAX TEMPS IN SOUTHERN KS AS BOUNDARY JUST TO THE NORTH OF THIS AREA WILL ALLOW TEMPS TO CLIMB INTO THE LOWER 70S. TONIGHT: BOUNDARY DRIFTS TO THE NORTH SOME AS THE NIGHT PROGRESSES...WITH SOME ISENTROPIC LIFT STILL LOCATED SOUTH OF THE BOUNDARY. SO EXPECT SOME CONVECTION IN SOUTHEAST KS EARLY BUT PROBABLY DIMINISHING OVERNIGHT. THIS LIFT WILL PROBABLY LEAD TO SOME TRANING STORMS IN AND NEAR THE BOUNDARY...SO FLOODING THREAT WILL DEFINATELY HAVE TO BE WATCHED. FRI-FRI NIGHT: NOT ALOT OF CONFIDENCE IN FRONTAL PLACEMENT AND POSSIBLE CONVECTION FOR FRI. MODELS ALSO DIFFER ON MID LEVEL IMPULSES EXPECTED TO MOVE ACROSS THE AREA IN THE SOUTHWEST FLOW. WITH THE BOUNDARY STILL EXPECTED TO BE IN THE AREA WILL LEAVE CHANCE POPS IN MOST LOCATIONS AS ANY WEAK IMPULSE COULD LEAD TO DEVELOPMENT...BUT DO NOT EXPECT TSRA CHANCE TO BE WIDESPREAD. BETTER DEVELOPMENT LOOKS TO BE FRI NIGHT AS ISENTROPIC LIFT AGAIN INCREASES ACROSS THE AREA. WILL STILL ONLY GO CHANCE POPS FOR NOW AS PLACEMENT OF THE BOUNDARY IN LATER RUNS WILL BETTER DEFINE HIGHEST POP AREAS. SAT-SUN: CONFIDENCE REMAINS LOW DURING THIS TIME FRAME AS BOUNDARY REMAINS SOMEWHAT STATIONARY ON SAT FOR BEGINNING TO LIFT TO THE NORTH AGAIN AS A WARM FRONT ON SUN AND MAIN SHORTWAVE REMAINS SOUTHWEST OF THE AREA UNTIL SUN EVENING. WITH LOTS OF LOW LEVEL MOISTURE AROUND HEAVY RAINFALL THREAT WILL ALSO CONTINUE. WILL HAVE TO KEEP AN EYE ON SEVERE THREAT ON SAT AS SHEAR VALUES LOOK FAVORABLE BUT INSTABILITY LOOKS MODEST. MONDAY-WEDNESDAY: PRECIP CHANCES LOOK TO COME TO AN END ON MONDAY AS MED RANGE MODELS FINALLY MOVE THE MAIN SHORTWAVE ACROSS THE AREA. LOOKS LIKE TUESDAY WILL BE A DAY TO DRY OUT WITH WEAK RIDGING IN THE MID LAYERS. A RATHER RIGOROUS SHORTWAVE MOVES INTO THE PLAINS ON WED FOR ANOTHER POSSIBLE ROUND OF CONVECTION. KETCHAM && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 74 59 72 58 / 50 60 40 40 HUTCHINSON 70 58 72 57 / 40 50 40 40 NEWTON 71 58 71 57 / 50 60 40 40 ELDORADO 73 59 72 58 / 60 60 40 40 WINFIELD-KWLD 73 60 73 59 / 60 60 40 40 RUSSELL 61 51 71 53 / 20 30 40 40 GREAT BEND 64 53 71 55 / 30 40 40 40 SALINA 63 52 69 54 / 30 50 40 40 MCPHERSON 67 56 71 56 / 40 50 40 40 COFFEYVILLE 76 61 73 59 / 60 60 40 30 CHANUTE 74 60 72 59 / 60 60 40 30 IOLA 73 59 72 58 / 60 60 40 30 PARSONS-KPPF 74 61 73 59 / 60 60 40 30 && .ICT WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH FRIDAY MORNING FOR KSZ069>072-083-092>096- 098>100. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 440 AM CDT THU MAR 22 2007 .DISCUSSION... THE UNSETTLED PATTERN CONTINUES. INTERESTING SET UP TODAY WITH SFC BNDRY TO THE SOUTH AND GOOD OVER-RUNNING PATTERN DEVELOPING. LATEST RUC SOUNDINGS SHOW GOOD ELEVATED LIFT DEVELOPING NORTH OF THE SFC BNDRY BY MIDDAY ALONG OR JUST SOUTH OF INTERSTATE 70. OPTIMUM ELEVATED LIFT WITH FAIRLY GOOD CHANCE FOR THUNDERSTORMS MOVES SLOWLY NORTH THROUGH THE AFTERNOON AND OVERNIGHT...REACHING THE NORTHERN BORDER AFTER MIDNIGHT. PATTERN SUPPORTIVE OF LOCALLY HEAVY RAINS WITH TRAINING OVER SAME AREAS. NO FLOOD WATCH ISSUED YET...BUT BEARS WATCHING IN 12Z RUN. PRECIPITABLE WATER VALUES EXCEEDINGLY HIGH FOR THIS TIME OF YEAR...RUNNING NEARLY 250% OF NORMAL! THIS HIGH WATER CONTENT CONTINUES INTO THE WEEKEND AND DOES NOT REALLY GET MODIFIED TO ANY GREAT EXTENT UNTIL UPPER SYSTEM FINALLY LIFTS THROUGH FROM THE SOUTHWEST STATES EARLY NEXT WEEK. UNTIL THEN, PERIODIC CHANCES FOR CONVECTION...SOME OF WHICH MAY BE STRONG TO SEVERE. SETUP FOR SEVERE TODAY IS MAXIMIZED ALONG AND NORTH OF THE WARMFRONT. CONSIDERABLE HIGH CLOUDINESS WILL LIMIT SOLAR INSOLATION TO FRONTAL AREA OTHERWISE TEMPERATURES WOULD BE WARMER AND THE THREAT FOR SEVERE HAIL WOULD BE EVEN GREATER. SHEAR SEEMS TO BE SUFFICIENT FOR LARGE HAIL LATER TODAY AS WELL. TEMPERATURES IN TURN A REAL CHALLENGE WITH CLOUDS HANGING TOUGH TO THE NORTH OF THE FRONT. HAVE FOLLOWED NAM CLOSELY WITH IT`S SFC TEMPERATURE FCST. THUS COULD RANGE FROM THE UPPER 40S NORTH TO THE LOWER 70S SOUTH. BY FRIDAY THE FRONT SHOULD RESIDE ALONG THE NORTHERN BORDER WAITING FOR AN UPPER WAVE TO EJECT OUT OF MEAN WESTERN TROF POSITION. THIS COULD TRIGGER ANOTHER ROUND OF CONVECTION FRIDAY NIGHT. BETTER CHANCE APPEARS SATURDAY NIGHT INTO SUNDAY NIGHT AS UPPER SYSTEM LIFTS NORTHEAST INTO THE PLAINS. LATER PERIODS OF THE FORECAST NOT CHANGED MUCH AS IS IMPOSSIBLE TO ADD MUCH DETAIL OR FIND REASONS TO MAKE CHANGES IN SUCH AN UNSETTLED PATTERN. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 358 AM CDT THU MAR 22 2007 .DISCUSSION... DAYS 1-2... A NORTHERN STREAM SHORTWAVE TROUGH PASSED ACROSS THE NORTHERN PLAINS AND INTO THE GREAT LAKES OVERNIGHT. THIS HELPED PUSH A COLD FRONT THROUGH MOST OF SW KS. THE FRONT AS OF 3 AM STRETCHED FROM NORTH OF HUGOTON TO HUTCHINSON. SFC TEMPS WERE VERY BALMY SOUTH OF THE FRONT(71 AT BUFFALO,OK AND 65 AT LIBERAL). THE SFC DRYLINE WAS CURRENTLY MOVING NW THROUGH WEST TEXAS. AN UPPER LOW WAS SITUATED JUST OFF THE SOUTHERN CA COAST. 500MB TEMPS HAVE TURNED OUT TO BE WARMER THAN THE MODELS WERE FORECASTING A FEW DAYS AGO. IN FACT THE NAM HAS 500MB TEMPS AROUND -13C THIS AFTERNOON. SURFACE DEWPOINTS HAVE CLIMBED INTO THE UPPER 50S AND LOWER 60SF ACROSS OK/SOUTHERN KS. A LARGE AREA OF MID TO HIGH LEVEL CLOUD WAS MOVING NE INTO NM AND WEST TX. IN THE ABSENCE OF STRONG SYNOPTIC SCALE DYNAMICS TODAY...THE LOCATION OF SFC BOUNDARIES WILL DETERMINE THE PLACEMENT OF SHOWER/THUNDERSTORM INITIATION. THE NAM/GFS AND SOME OF THE RUC MEMBERS SURGE THE FRONT BACK TO THE NORTH TODAY TO A GCK TO HAYS LINE. I HAVE CHOSEN TO GO WITH THE RUC13 SOLUTION FOR TODAY. THIS MODEL KEEPS THE FRONT NEARLY STATIONARY ALL DAY. WITH BROKEN MID TO HIGH CLOUDS AND LOW LEVEL UPSLOPE FLOW... TEMPS WILL STAY IN THE 60S NORTH OF THE FRONT. BUT LOCATIONS ALONG THE OK STATE LINE COULD REACH THE UPPER 70S. I EXPECT THE SFC DRYLINE TO STRETCH FROM DALHART TO CARLSBAD,NM BY THIS AFTERNOON. THE DRYLINE WILL INTERSECT THE FRONT CLOSE TO DALHART. FAIRLY WEAK CAPPING...SOME ELEVATED HEATING ON THE HIGH PLAINS... AND CONVERGENCE ALONG THE DRYLINE AND NEAR THE FRONT/DRYLINE INTERSECTION WILL ALLOW STORMS TO DEVELOP BY 21Z. LOCAL POOLING OF MOISTURE MAY ALLOW FOR SFC BASED CAPES AS HIGH AS 1000-1500 J/KG FROM P28 TO ENGLEWOOD. AS STORMS MOVE INTO THIS AREA...A FEW OF THEM COULD BECOME SEVERE. VERTICAL SHEAR PROFILES WILL BE FAVORABLE FOR SEVERE STORMS. BUT THE MAIN LIMITING FACTOR FOR SEVERE STORMS WILL BE THE MARGINAL INSTABILITY. BUT AS WE HAVE SEEN IN THE RECENT PAST...STRONG VERTICAL WIND SHEAR AND CAPES AROUND 1000 J/KG CAN BE ENOUGH FOR SEVERE STORMS. ANY STORMS THAT DEVELOP THIS AFTERNOON WILL PROBABLY LINGER INTO TONIGHT. BUT THE STORM ACTIVITY WILL SHIFT OFF TO THE NE BY FRIDAY BEFORE THE MAIN UPPER LOW EJECTS INTO THE PLAINS ON SATURDAY. SOME POPS WERE MAINTAINED FOR FRIDAY FOR CONSISTENCY SAKE AND SINCE THERE IS SOME UNCERTAINTY. DAYS 3-7... NOT GOING TO CHANGE MUCH IN THE GOING EXTENDED. BOTH THE UKMET AND GFS BRING AN ORGANIZED SYSTEM UP FROM SOUTHERN BAHA CALIFORNIA TO WESTERN KANSAS FROM FRIDAY INTO SUNDAY. THE BEST CHANCES FOR PRECIPITATION LOOK TO BE ON SATURDAY AFTERNOON...WHERE WE HAVE 40 POPS GOING NOW. THESE POPS MAY HAVE TO BE RAISED IF THE TRACK OF THE UPPER SYSTEM BEARS OUT. TEMPERATURES LOOKED REASONABLE AND IN LINE WITH SURROUNDING WFO GRIDS. TUESDAY LOOKS TO BE WARM...PERHAPS WITH 80S SOMEWHERE IN OUR CWA. LEFT TUES MAX T`S ALONE FOR NOW...AS OUR SW HAS MID 70S GOING. && .AVIATION... AS LOW LEVEL MOISTURE CONTINUES TO CONVERGE ALONG AND SOUTH OF A FRONTAL BOUNDARY LYING ACROSS SOUTHERN KANSAS...STRATUS WILL LIKELY FORM AT DDC AND GCK IN THE 012 TO 015 FEET RANGE BY 11Z THIS MORNING. DO NOT EXPECT THE STRATUS TO LINGER MUCH BEYOND 15-16Z. ALSO...FOG WITH VSBYS IN THE 4-5SM RANGE WILL FORM AT DDC...GCK AND HYS AND LAST THROUGH 15Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 53 71 56 / 20 30 20 20 GCK 64 45 72 53 / 20 20 20 20 EHA 71 47 71 53 / 20 20 20 20 LBL 73 51 71 56 / 20 30 20 20 HYS 61 48 72 55 / 20 20 20 20 P28 76 59 70 61 / 30 30 30 20 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN24/12 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 200 AM MDT THU MAR 22 2007 .DISCUSSION... PRIMARY UPPER FEATURE FOR THE SHORT TERM PERIOD WILL BE CUT OFF LOW OVER THE DESERT SOUTHWEST. FORECAST AREA TO REMAIN UNDER THE SOUTHWEST FLOW AHEAD OF THE MAIN LOW FOR THE NEXT SEVERAL DAYS. THE UPPER LOW WILL THEN BEGIN TO LIFT NORTH/NORTHEAST OVER THE WEEKEND. UNFORTUNATELY MODELS IN POOR AGREEMENT ON FINER DETAILS. EVEN AS EARLY AS TODAY...NAM BRINGING A FAIRLY WELL DEFINED VORT MAX OVER THE AREA/WHEREAS GFS SHOWS LITTLE IF ANYTHING. WATER VAPOR IMAGERY INCONCLUSIVE...SINCE JUST SEE A BROAD SOUTHWEST FLOW WITH DEEP TROPICAL PLUME AHEAD OF THE MAIN LOW. WITH LITTLE TO GO ON WILL PLAY THE PERCENTAGES AND HAVE SOME SLIGHT/LOW CHANCE POPS THIS AFTERNOON AND EVENING ACROSS SOUTHEAST COUNTIES. SOMEWHAT RELIABLE RUC CEILING FORECAST SHOWS 2KFT BROKEN DECK OVERSPREADING THE CWA FROM THE SOUTH THIS AFTERNOON...WILL FAVOR COOLER GUIDANCE FOR HIGHS AS A RESULT. FRIDAY WILL BE A VIRTUAL REPEAT...THOUGH MODELS SWITCH PLACES WITH GFS WET AND NAM DRY. IT DOES APPEAR THE AREA WILL COME UNDER FAVORABLE RIGHT ENTRANCE REGION OF JET WHICH DEVELOPS FRIDAY NIGHT/SATURDAY MORNING OVER THE MIDWEST. SURFACE FRONT WILL ALSO BE SURGING NORTH INTO THE AREA. NONETHELESS...ISC CONSTRAINTS WILL DICTATE LOW CHANCE POPS. THEN WILL HAVE TO DEAL WITH THE MAIN LOW OVER THE WEEKEND. MODELS ALL OVER THE PLACE...WHICH LENDS LITTLE TO NO CONFIDENCE TO THE PRECIPITATION CHANCES. GFS ENSEMBLE AVERAGES GIVE SOLID CHANCE POPS THROUGH SATURDAY...GRADUALLY DIMINISHING SATURDAY NIGHT AND SUNDAY TO SLIGHT CHANCES. THE ENSEMBLE APPROACH SEEMS REASONABLE GIVEN THE UNCERTAINTIES. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JDK ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 100 AM EDT FRI MAR 23 2007 AVIATION (06Z TAFS)... NO AVIATION CONCERNS THROUGH THE MORNING HOURS FRIDAY EXCEPT FOR SOME HIGH CLOUDINESS EXPECTED AT SDF AND LEX. THESE HIGH CLOUDS ARE CONVECTIVE DEBRIS CLOUDS DOWNSTREAM FROM WIDESPREAD CONVECTION ACROSS CENTRAL INDIANA AND ILLINOIS. SKIES WILL REMAIN CLEAR AT BWG OVERNIGHT. FOG FORMATION WILL NOT BE A FACTOR AS DECENT SOUTHERLY WINDS AT 1500FT (25KT) WILL KEEP THE BOUNDARY LAYER SOMEWHAT MIXED. ALSO NOTED THAT A 10-15 DEGREE DEWPOINT DEPRESSIONS ARE PRESENT EVEN NOW WITH THE LATEST SURFACE OBS. SKIES WILL BECOME INCREASINGLY CLOUDY LATE THIS AFTERNOON. SCATTERED SHOWER MAY DEVELOP AFTER 18Z ACROSS LEX AND SDF. CEILINGS WILL STAY VFR TOMORROW AFTERNOON EXCEPT UNDERNEATH ANY LOCAL SHOWERS. JSD && .PREV DISCUSSION... /ISSUED 729 PM EDT THU MAR 22 2007/ EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIFY CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 902 PM CDT THU MAR 22 2007 .UPDATE... FORECAST UPDATED MAINLY TO REMOVE EVENING WORDING. ADDED A SLIGHT CHANCE POP FOR SW INDIANA OVERNIGHT DUE TO THE CLOSE PROXIMITY OF THE SURFACE BOUNDARY. GRADUAL INCREASE IN CONVECTION NOTED OVER CENTRAL IL/CENTRAL MO/EASTERN KS OVER THE PAST COUPLE OF HOURS. THIS CONVECTION IS ALONG THE FRONT...WHICH THE MODELS KEEP QUASI STATIONARY FOR THE NEXT FEW DAYS. THIS CONVECTION MAY PROPAGATE SOUTHEAST AWAY FROM THE BOUNDARY INTO SRN ILLINOIS AND SE MISSOURI OVERNIGHT. RUC MODEL CORFIDI VECTORS INDICATE A SE MOVEMENT TO ANY ORGANIZED MCS THAT DEVELOPS. && .PREVIOUS DISCUSSION... MAIN CONCERNS FOR THIS FORECAST CONTINUE TO BE POPS THROUGH THE ENTIRE PERIOD...AS TEMPERATURES WILL REMAIN MILD THROUGHOUT. ELEVATED CONVECTION HAS SHRUNK DOWN TO A NARROW BAND OF SHOWERS RIGHT THROUGH THE MID-SECTION OF THE AREA...AND IT APPEARS TO BE WEAKENING AND FINALLY PUSHING OFF TO THE EAST. WITH THE AIRMASS THOROUGHLY WORKED OVER...AND THE SURFACE BOUNDARY WELL NORTH OF THE AREA...SEE LITTLE REASON TO HAVE MUCH POP IN THE AREA THIS EVENING. WILL HOWEVER...INCLUDE A SMALL CHANCE IN THE NORTHEAST IN AN ATTEMPT TO FIT IN TO SOME DEGREE WITH NEIGHBORS. OVERNIGHT...THE GFS IS A BIT FASTER BRINGING ANOTHER ROUND OF ELEVATED CONVECTION EASTWARD INTO THE REGION...AS ANOTHER MID-LEVEL DISTURBANCE BRINGS AN AREA OF LOW-LEVEL THETA-E ADVECTION INTO THE REGION. IF THE NAM IS RIGHT...THE CONVECTION WILL STAY TO OUR WEST THROUGH 12Z...BUT THE GFS BRINGS INTO OUR WEST JUST BEFORE 12Z. WILL MENTION A CHANCE OVERNIGHT IN THE WEST...AND THEN RAMP UP TO 50-60 POPS SOUTH TO NORTH ON FRIDAY. THIS SIGNAL HAS BEEN THERE FOR A COUPLE OF DAYS...HOWEVER...IF IT IS AS FOCUSED AS TODAYS CONVECTION HAS BEEN...SOME AREAS MAY NOT GET WET. THEREFORE WILL NOT GO HIGHER THAN 60S FOR NOW. THOSE 60S WILL BE IN THE NORTH WHERE THE MODELS ARE IN BETTER AGREEMENT WITH THE QPF. THE NAM IS NOT SURE ABOUT OUR SOUTHERN ZONES GETTING WET. MAY SEE SOME LINGERING CONVECTION FRIDAY NIGHT MAINLY NORTHEAST...SO WILL LEAVE A 20-30 POP ACROSS MUCH OF THE AREA. ON SATURDAY...THE FRONT RE-LOCATES WELL NORTH OF THE AREA...AND WILL KEEP THE FOCUS FOR CONVECTION TO OUR NORTH AS WELL. THE 12Z NAM TRIES TO REGENERATE CONVECTION ALL OVER THE AREA ON SATURDAY...BUT IT IS THE LONE MODEL THAT DOES NOT BUILD A MID/UPPER-LEVEL RIDGE THROUGH THE AREA. WILL THEREFORE IGNORE ITS SOLUTION FOR NOW. THE WEEKEND SHOULD BE QUITE GLORIOUS WITH TEMPS PUSHING 80 EACH AFTERNOON AND LOWS IN THE 50S. IN THE MEDIUM RANGE...EVEN THE ECMWF IS NOW TRYING TO DRAG SOME REMNANT OF THE SW U.S. CUT OFF LOW ACROSS THE AREA SOMETIME MONDAY OR TUESDAY. WILL THROW IN 20-30 POPS FOR THIS PERIOD WITH THE BEST CHANCES MONDAY NIGHT INTO TUESDAY. TUESDAY NIGHT AND WEDNESDAY LOOK DRY...BUT A MORE SIGNIFICANT SYSTEM MAY BEGIN TO EFFECT THE AREA ON THURSDAY OR FRIDAY. TEMPERATURES WILL CONTINUE TO BE WELL ABOVE NORMAL THROUGH THE ENTIRE 7 DAY PERIOD...WITH HIGHS IN THE 70S OR LOWER 80S AND LOWS IN THE 50S OR LOWER 60S. THE EXCEPTION WILL BE TOMORROW WHERE THE CONVECTION MAY HOLD TEMPS IN THE 60S. HOWEVER...IT IS NOT CERTAIN WHERE THE PRECIPITATION WILL BE FOCUSED ACROSS THE AREA TOMORROW. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ UPDATE...MY PREVIOUS...DRS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 953 PM EDT THU MAR 22 2007 .UPDATE... SMALL UPDATE TO SLIGHTLY LOWER OVERNIGHT LOWS A DEGREE OR TWO ACROSS PORTIONS OR THE NORTHERN AREA AROUND SDF AND LEX...NOT SO MUCH ACROSS THE SOUTHERN HALF OF THE AREA. -SCHOTT && .PREV DISCUSSION... /ISSUED 729 PM EDT THU MAR 22 2007/ EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT AVIATION DISCUSSION (00Z TAFS)... GRADUAL CLEARING APPEARS TO BE DEVELOPING IN THE LATEST VIS SAT LOOP...NOTHING OF ANY SIGNIFICANCE LOOKS TO EFFECT AVIATION CONCERNS THROUGH DAYBREAK FRIDAY. MODEST LOW LEVEL JET DEVELOPS TONIGHT BUT DOESN`T REACH THE 20 KNOTS GREATER THAN SFC WINDS TO MENTION IN THE TAFS...BUT 20 TO 25 KTS AROUND 1500 TO 2000 FEET LOOKS LIKELY OVERNIGHT. VFR CONDITIONS AT ALL THREE TAFS SITES LOOKS AS A GOOD BET THROUGH THE PERIOD...SOME SCATTERED SHOWER AND THUNDERSTORM ACTIVITY LOOKS TO PUSH SOUTH INTO THE NORTHERN TAF SITES OF SDF AND LEX AFTER 14 TO 18Z...WITH SHRA POSSIBLE AT BWG AFTER 22Z. --SCHOTT PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIF CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ AVIATION (18Z TAFS)... SCT TO NUMEROUS SHOWERS WILL STREAM EWD THRU THE AFTN ALONG AND EITHER SIDE OF OH RIVER. STILL A CONVECTIVE THREAT BUT CG LIGHTNING ACTIVITY GRADUALLY DIMINISHING AT THIS TIME. KLVX VWP PROFILE SHOWS UNIFORM SWLY FLOW IN LOW-LEVELS WITH ONLY MODEST INCREASE IN SPEED WITH HEIGHT...THUS LOW-LEVEL WIND SHEAR NO LONGER A SIGNIFICANT HAZARD. CIGS MAY OCCASIONALLY FALL INTO MVFR CATEGORY BUT GENERALLY CIGS EXPECTED ABOVE 3KFT (VFR) DURING FCST PD. AS SHORTWAVE TO OUR N PULLS OUT...PRECIP SHOULD BE MORE SCT LATE TNGT AND EARLY FRI...BEFORE MODELS SHOW NEXT SURGE OF MOISTURE AND PRECIP ARRIVING FRI AFTN. TWF LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 729 PM EDT THU MAR 22 2007 .EVENING UPDATE... WEAK SURFACE WAVE MOVING ALONG THE BOUNDARY WELL TO THE NORTH ACROSS CENTRAL IL AND IN...LITTLE IF ANY SHRA ANYWHERE ACROSS THE FORECAST AREA. EVIDENT TREND ON THE VIS SAT AND REGIONAL RADARS THAT SLOW AND STEADY CLEARING OF CONVECTIVE DEBRIS FROM THE DAY...WITH BEST OMEGAS AND ANY INSTABILITY TO THE NORTH OF THE REGION. MID LEVEL CLOUDS DECREASING IN COVERAGE..WITH THINNING OF THE THICK CI FROM EARLIER STORMS. RUC AND 18Z RUNS OF GFS AND NAM LEADS ME TO LOWER POPS TO ISOLATED NORTH AND TO END ANYWHERE ALONG OR SOUTH OF THE OHIO RIVER FOR THE REST OF THE NIGHT. WITH SOME LESSENING OF THE SOUTHERLY WINDS AND SOME CLEARING NOW EXPECTED..WILL MONITOR FOR ANY HINT OF FOG DEVELOPMENT OVERNIGHT. --SCHOTT && .AVIATION DISCUSSION (00Z TAFS)... GRADUAL CLEARING APPEARS TO BE DEVELOPING IN THE LATEST VIS SAT LOOP...NOTHING OF ANY SIGNIFICANCE LOOKS TO EFFECT AVIATION CONCERNS THROUGH DAYBREAK FRIDAY. MODEST LOW LEVEL JET DEVELOPS TONIGHT BUT DOESN`T REACH THE 20 KNOTS GREATER THAN SFC WINDS TO MENTION IN THE TAFS...BUT 20 TO 25 KTS AROUND 1500 TO 2000 FEET LOOKS LIKELY OVERNIGHT. VFR CONDITIONS AT ALL THREE TAFS SITES LOOKS AS A GOOD BET THROUGH THE PERIOD...SOME SCATTERED SHOWER AND THUNDERSTORM ACTIVITY LOOKS TO PUSH SOUTH INTO THE NORTHERN TAF SITES OF SDF AND LEX AFTER 14 TO 18Z...WITH SHRA POSSIBLE AT BWG AFTER 22Z. --SCHOTT && .PREV DISCUSSION... /ISSUED 300 PM EDT THU MAR 22 2007/ SHORT TERM (TONIGHT AND FRIDAY)... SHORT RANGE MODEL GUIDANCE IN REASONABLE AGREEMENT FOR TNGT AND FRI. CURRENTLY SHORTWAVE IS PUSHING EWD OVER SERN CANADA JUST N OF GRT LAKES. SHORTWAVE TROF ACRS GRT LAKES HELPED CREATE SHWR ACTIVITY OVER OH VALLEY WITHIN DIFFLUENT FLOW ALOFT AND MODEST WARM ADVECTION. PRECIP HAS DIMINISHED OVER OUR AREA THIS AFTN...BUT AXIS OF SHWRS AND TSTMS STILL ACTIVE OVER SRN IL INTO FAR NWRN KY. WESTERLY FLOW ALOFT SUGGESTS SOME OF THESE SHWRS COULD PUSH BACK INTO NRN PARTS OF FCST AREA TNGT...SO WILL CONT WITH CHC/SCT PRECIP. SOUNDINGS SUGGEST ONLY MARGINAL INSTABILITY ALOFT SO STILL A FEW RUMBLES OF THUNDER PSBL TNGT BUT NOT EXPECTING SIGNIF CNVCTN AT THIS TIME. FLOW PTRN PROGGED TO REMAIN WESTERLY ON FRI AS SFC FRONTAL BOUNDARY REMAINS LUST TO OUR NORTH. BOTH 12 UTC GFS AND NAM-WRF ARE FCSTG AREA OF INCREASING VERT MOTION AND PRECIP COMING OUT OF THE SRN PLAINS TNGT (AHEAD OF DEEP SWRN U.S. UPR LOW) AND INTO MID MS VALLEY FRI MRNG BEFORE TURNING EWD INTO LOWER OH VALLEY FRI AFTN AND EVNG. THIS WOULD BRING INCREASING CHCS OF PRECIP BACK ACRS PARTS OF CNTRL KY AND S-CNTRL IN FRI AFTN/EVNG. AGAIN INSTABILITY MARGINAL BUT EMBEDDED CNVCTN STILL EXPECTED ALONG WITH POTENTIAL FOR SOME TRAINING PRECIP ELEMENTS AND LOCALLY HEAVY RAINFALL NEAR TOP OF FLAT RIDGE AXIS ALOFT OVER OH VALLEY. CLOUDS AND SCT PRECIP THIS AFTN HAVE KEPT TEMPS LOWER ACRS NRN HALF OF FCST AREA. TEMPS TNGT SHOULD NOT FALL THAT FAR...AND WILL FCST MINS AT OR ABV GUIDANCE...WHICH WAS THE CASE LAST NGT/THIS MRNG. ON FRI...CLOUDS AND INCREASING RAIN CHCS ACRS THE NORTH AGAIN POSE A TEMP FCST CHALLENGE. MAV AND FWC BASED MOS SHOWING LOWER HI TEMPS THAN MET. GFS AND NAM-WRF MODEL SFC TEMPS ARE CONSISTENT WITH THEIR OWN CLOUD AND PRECIP FCST. GIVEN POP/CLOUD FCST IN GRIDS FOR FRI... HAVE LOWERED MAX TEMPS A FEW DEGREES. IF PRECIP DOES NOT MATERIALIZE AS MUCH AS EXPECTED OR CLOUDS ARE LESS DENSE...THEN HI TEMP VALUES WILL BE CLOSER TO HIGHER MET VALUES ON FRI. TWF LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... ECMWF CONTINUES TO BE THE MOST CONSISTENT MODEL AND HAS SOME SUPPORT FROM THE UKMET. WILL GENERALLY FOLLOW ECMWF FOR MOST OF EXTENDED. IN THE EARLY PERIODS NAM SUPPORTS SOME SUPPORT FOR HIGHER RH ALONG THE FRONT. FRIDAY NIGHT THROUGH SUNDAY NIGHT.. A FRONTAL BOUNDARY WILL BE NEARLY STATIONARY FROM WEST TO EAST ACROSS NORTHERN KENTUCKY TO CENTRAL ILLINOIS. SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE AREA FRIDAY NIGHT WITH THE MOST NUMEROUS SHOWERS ACROSS THE NORTHERN PARTS OF THE FORECAST AREA AND CONSIDERABLY LOWER CHANCES NEAR THE TENNESSEE BORDER. THE SOUTHERLY BREEZES WILL KEEP WARM...MOIST AND UNSTABLE AIR OVER THE REGION...THUS WILL KEEP THUNDER IN THE FORECAST. ON SATURDAY THE FRONT WILL MOVE NORTH AS A WARM FRONT. THE SHOWERS WILL GRADUALLY COME TO AN END. THE TIMING OF THE ENDING OF THE RAIN AND CLOUDS DECREASING WILL AFFECT HOW WARM TEMPERATURES WILL GET. WILL KEEP TEMPS ACROSS THE FAR NORTHERN COUNTIES A LITTLE COOLER AS THIS AREA WILL BE THE LAST TO CLEAR. REST OF AREA SHOULD GET WELL INTO THE 70S. ON SUNDAY ENTIRE FORECAST AREA WILL BE WELL IN THE WARM SECTOR AND HIGHS COULD TOP 80 IN MANY LOCATIONS. MONDAY THROUGH THURSDAY... ON MONDAY CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA WILL STILL BE IN THE WARM SECTOR WITH A COLD FRONT DROPPING SOUTHEAST INTO SOUTHERN ILLINOIS BY TUESDAY MORNING. WILL ALLOW WIDELY SCATTERED THUNDERSTORMS TO DEVELOP MONDAY AFTERNOON AND SCATTERED STORMS MONDAY NIGHT THROUGH TUESDAY. THE NEXT CHANCE OF THUNDERSTORMS WILL COME WEDNESDAY NIGHT THROUGH THURSDAY AS WARM FRONT MOVES NORTH THROUGH THE AREA. HAVE STAYED CLOSE TO OR A LITTLE WARMER THAN HPC GUIDANCE TEMPERATURES. SCHOLZ AVIATION (18Z TAFS)... SCT TO NUMEROUS SHOWERS WILL STREAM EWD THRU THE AFTN ALONG AND EITHER SIDE OF OH RIVER. STILL A CONVECTIVE THREAT BUT CG LIGHTNING ACTIVITY GRADUALLY DIMINISHING AT THIS TIME. KLVX VWP PROFILE SHOWS UNIFORM SWLY FLOW IN LOW-LEVELS WITH ONLY MODEST INCREASE IN SPEED WITH HEIGHT...THUS LOW-LEVEL WIND SHEAR NO LONGER A SIGNIFICANT HAZARD. CIGS MAY OCCASIONALLY FALL INTO MVFR CATEGORY BUT GENERALLY CIGS EXPECTED ABOVE 3KFT (VFR) DURING FCST PD. AS SHORTWAVE TO OUR N PULLS OUT...PRECIP SHOULD BE MORE SCT LATE TNGT AND EARLY FRI...BEFORE MODELS SHOW NEXT SURGE OF MOISTURE AND PRECIP ARRIVING FRI AFTN. TWF LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1048 AM EDT THU MAR 22 2007 .SHORT TERM /REST OF TODAY/... AREA MORNING UPPER AIR SOUNDINGS SHOW LAYERED MOISTURE THROUGH MUCH OF THE COLUMN. SFC OBS/SATL DATA CONFIRMS SCT-BKN MULTILAYERED CLOUDS ACRS FORECAST AREA THIS LATE MORNING BUT THE CLOUD PATCHES APPEAR TO BE BREAKING AND THINNING. THEREFORE EXPECT SKY CONDITION WILL AVERAGE PTSUNNY DURING THE AFTN. INSOLATION SHUD BE SUFFICIENT TO ALLOW TEMPS TO REACH FCSTD VALUES RANGING FROM M60S ACRS THE EASTERN SHORE TO M70S OVER PIEDMONT...BUT OF COURSE COOLER WHERE FLOW IS ONSHORE. LTL IF ANY CHANGES NEEDED TO FCST ATTM BUT UPDATED FCST TO REFRESH PRODUCTS. .MARINE UPDATE... DECIDED TO ADD SCA FOR THE CHESAPEAKE BAY WTRS FROM SMITH POINT TO NEW POINT COMFORT...WITH 15-20 KT WINDS AND 2-3 FT WAVES. RUC AND NAM MODELS SUGGEST INCRSG SFC WINDS AFTER 18Z. SOUNDINGS SHOW AROUND 15 KT AT SFC UNDER WEAK INVERSION WITH 25-30 KTS ABOVE INVERSION. EXPECT ENOUGH MIXING TO ALLOW 20 KT GUSTS DOWN TO SFC. STRONGER LOW LEVEL INVERSION TO SOUTH OF NEW POINT COMFORT SO OPTED NOT TO GO FOR SCA FOR SOUTHERN BAY BUT STEADY 15 KT. ON CSTL WTRS...EXPECT 15-20 KT SOUTH WINDS FROM FENWICK DOWN TO PARRAMORE WITH LONGER FETCH BUILDING SEAS TO SCA CRITERIA AFTER 2 PM. DIFFICULT FCST FOR THE WEEKEND WITH BACKDOOR COLD FRONT SAT/SAT NGT. HAVE DECIDED TO GO CLOSER TO NAM/UKMET (GFS IS OUTLIER)...KEEPING SW FLOW SRN ZONES ON SAT...ELY FLOW ACRS THE NORTH. THEN...FRONT CLEARS ENTIRE MARINE AREA SAT NGT/SUN...WITH NNE FLOW AND POSSIBLE SMALL CRAFT CONDITIONS AT THAT TIME. && .PREV DISCUSSION... /ISSUED 513 AM EDT THU MAR 22 2007/ SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... CURRENTLY...HIGH PRESSURE CONTINUES TO PUSH OFFSHORE WHILE A COLD FRONT ADVANCES EAST THROUGH THE WESTERN GREAT LAKES AND MIDWEST REGIONS. THE MAIN FORECAST CONERN TODAY WILL BE WITH CLOUD COVER EXTENT (DEPTH) AND THUS IMPACT ON TEMPS. GFS/NAM ARE IN FAIRLY CLOSE ACCORD IN THE SHORT TERM (THROUGH TONIGHT). BOTH INDICATE THE COLD FRONT DROPPING TO NEAR THE MASON- DIXON LINE BY MIDNIGHT TONIGHT...BECOMING MORE W-E ORIENTED AS THE ASSOCIATED UPPER LEVEL VORT LOBE ENCOUNTERS A ZONAL/FLAT UPPER RIDGE. PRE-FRONTAL FORCING/MOISTURE IS INSUFFICIENT FOR POPS ACROSS THE FCST AREA TODAY. AS FOR SKY COVER...EXPECT THE LOWER CLOUDS TO SCOUR OUT LATER THIS MORNING/AFTN AS THE LOW LEVEL FLOW VEERS TOWARD THE S-SW RESULTING IN MORE APPRECIABLE WARMING (AND RELATIVE DRYING) WITHING THE 1000-850 MB LAYER. STILL EXPECT PERIODIC WAVES OF HIGHER BASED CLOUDS IN THE AFTN AS WE GET INTO THE WARM SECTOR...THUS HAVE WORDED PARTLY SUNNY. BASED ON RECENT TRENDS (YDAY)...HAVE GONE A FEW DEGREES HIGHER THAN MOS TODAY FOR HIGH TEMPS. THIS BASED ON THE LOW LEVEL WAA AND INCREASED SUNSHINE THIS AFTN (ANTICIPATED DEEPER MIXING WITH THE LATE MARCH SUN ANGLE). TONIGHT...FRONT DIPS INTO NRN VA AND THE NRN PTN OF THE DELMARVA. HAVE INCLUDED LOW (30-40%) POPS OVER THE NRN THIRD OF THE CWA CLOSEST TO THE FRONT...THOUGH ONCE AGAIN WITH THE FLATTENING UPPER FLOW (AND NEGLIGIBLE STRAIGHT UPPER JET FORCING)...DYNAMICS AND THUS MOISTURE DEPTHS REMAIN LACKING. S OF FVX-RIC-MFV...MOISTURE IS JUST TOO SHALLOW (PARTICULARLY IN LOW LEVELS) FOR POPS. FRIDAY...COMPARED TO THE NAM/UKMET/ECMWF...THE 00Z GFS IS TOO QUICK WITH THE INITIAL IMPULSE TRACKING FROM THE UPPER MIDWEST- OH VLY-MID ATLC REGION. SIDING MORE TOWARD A NAM/ECMWF BLEND... EXPECT A NW-SE DRAPED SURFACE FRONTAL BNDRY ACROSS THE FCST AREA... WITH THE FRONT TAKING ON THE TYPICAL "SAG" EAST TOWARD THE COOLER COASTAL WATERS. AS A RESULT EXPECT A LARGE TEMP GRADIENT FROM SW-NE... I.E. AROUND 80/LOWER 80S INLAND TO AROUND 60 ALONG THE LOWER ERN SHORE. WILL ALSO MAINTAIN MORE EXTENSIVE CLOUD COVER/LOW POPS OVER THE N-NE ZONES ALONG AND N OF THE PROJECTED FRONTAL ZONE. SATURDAY...GFS IS MUCH COOLER WITH THE LOWER LEVELS COMPARED TO THE OTHER MODELS...BASICALLY A CONSEQUENCE OF THIS MODEL BEING TOO PROGRESSIVE WITH THE INITIAL UPPER SHORTWAVE/WEAK SURFACE LOW ALONG THE STATIONARY FRONT. GFS (MAV) MOS GUIDANCE IN FACT IS SOME 20+ DEGREES COOLER WITH HIGH TEMPS OVER INLAND LOCALES COMPARED TO THE NAM (MET) GUIDANCE! FOR NOW WILL CONTINUE TO LEAN MORE TOWARD THE NAM/ ECMWF...WHICH DOES NOT DROP THE FRONT S OF THE LOWER DELMARVA UNTIL LATE IN THE DAY. BASED ON THESE PROJECTIONS...EXPECT ANOTHER DAY WITH A SIGNIFICANT TEMPERATURE GRADIENT FROM SW (80-85) TO AREAS ALONG THE ATLANTIC SIDE OF THE LOWER MD ERN SHORE (LOW-MID 50S). LONG TERM /SUNDAY THROUGH WEDNESDAY/... BASED ON THE LATEST NAM/ECWMF TRENDS...AND WITH THE LOWER CONFIDENCE IN THE GFS SAT-SUN...DID NOT MAKE TOO MANY CHANGES TO THE FCSTS DURING THE EXTENDED PERIODS. HIGH PRESSURE BUILDING FROM THE N AND EVENTUALLY NE (OFFSHORE) ON SUNDAY WILL MAKE FOR A COOLER DAY OVER THE NERN PTNS OF THE FCST AREA...THOUGH AGAIN EXPECT TEMPS TO REMAIN MUCH MILDER AS YOU HEAD FARTHER SW. TOWARD PETERSBURG/FARMVILLE/SOUTH HILL. AVIATION...VARIABLE CONDITIONS EARLY THIS MORNING...HAVE MVFR CIGS NORTH AND WEST...VFR SOUTH. FLOW TURNS TO S OR SW LATER TODAY WITH INCREASING WIND SPEEDS BY AFTN...AND MAINLY VFR CONDS. MVFR CIGS MAY HANG TOUGH ON THE ERN SHORE THRU 16-18Z. CONTINUED VFR TONIGHT AS MIXING SHOULD INHIBIT SIGNIFICANT FOG FORMATION. MARINE...GRADIENT INCREASES FROM SOUTH TO SOUTHWEST LATER TODAY. CHILLY BAY WATERS WILL MAKE IT DIFFICULT TO EFFICIENTLY MIX THESE WINDS DOWN TO THE SFC...SO OPTED TO KEEP CONDITIONS ON THE BAY & SOUND BELOW SMALL CRAFT (ALTHOUGH IT WILL BE CLOSE LATER THIS AFTN). ON COASTAL WATERS...INCREASING SOUTHERLY FLOW (NEAR 20 KTS BY AFTN) WILL LIKELY BRING SEAS TO MARGINAL SMALL CRAFT CONDITIONS (5 FT WAVES OFFSHORE) N OF PARRAMORE ISL...FROM LATER IN THE AFTN THROUGH ERLY MRNG THU. DIFFICULT FCST FOR THE WEEKEND WITH BACKDOOR COLD FRONT SAT/SAT NGT. HAVE DECIDED TO GO CLOSER TO NAM/UKMET (GFS IS OUTLIER)...KEEPING SW FLOW SRN ZONES ON SAT...ELY FLOW ACRS THE NORTH. THEN...FRONT CLEARS ENTIRE MARINE AREA SAT NGT/SUN...WITH NNE FLOW AND POSSIBLE SMALL CRAFT CONDITIONS AT THAT TIME. FIRE WEATHER...LIGHT SE TO S FLOW THIS MRNG...WITH GUSTY SOUTH...SOUTHWEST WINDS INCREASING BY AFTN FOR MUCH OF INLAND VA. HOWEVER...NOT REALLY A DOWNSLOPE FLOW SO RH VALUES DO NOT DROP OFF THAT MUCH...WITH MOST LOCATIONS BOTTOMING OUT 35-45% AT THE DRIEST. FARTHER EAST...COOLER TEMPERATURES WILL TEND TO INHIBIT MIXING SOMEWHAT SO WINDS LIKELY STAY MORE FROM DUE SOUTH AT 15 KTS OR LESS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM EDT FRIDAY FOR ANZ630-631-650-652. && $$ SHORT TERM UPDATE...CULLEN/FOSTER md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 415 PM EDT FRI MAR 23 2007 .DISCUSSION... .SHORT TERM (TONIGHT AND SAT)... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW NEARLY ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. IN THIS FAST FLOW...SHORTWAVE OF INTEREST IN THE SHORT TERM IS OVER SRN SASKATCHEWAN/ERN MT/WRN ND. RADARS SHOW DECENT COVERAGE OF ECHOES ACROSS ND/SRN MANITOBA ASSOCIATED WITH THIS SHORTWAVE...AND THERE HAVE BEEN A FEW OBS THAT HAVE INDICATED -SHRA IN NRN ND/SE SASKATCHEWAN/SRN MANITOBA TODAY. WELL TO THE W... SHORTWAVE THAT DROPPED OUT OF THE WESTERLIES 2-3 DAYS AGO OVER THE W COAST AND BECAME A MID LEVEL LOW IS NOW CENTERED JUST S OF AZ. THIS SYSTEM WILL BE OF INTEREST TO FCST HERE LATE IN THE UPCOMING WEEKEND AS IT GETS KICKED NE BY NEXT TROF APPROACHING THE W COAST. MODELS ARE IN GOOD AGREEMENT STRENGTHENING UPSTREAM SHORTWAVE A BIT AS IT MOVES TO UPPER MI/LAKE SUPERIOR SAT MORNING. WITH AIRMASS AHEAD OF APPROACHING SHORTWAVE RELATIVELY DRY PER 12Z KBIS/KINL SOUNDINGS...IT BECOMES THE TYPICAL QUESTION OF WHETHER FORCING WILL BE SUFFICIENT TO MOISTEN THE DRY COLUMN TO ALLOW PCPN TO REACH THE SFC. BEST COMBINATION OF LOW CONDENSATION PRES DEFICITS AND ASCENT ON THE 290K AND 295K SURFACES PASSES ACROSS THE NRN FCST AREA...BUT ANOTHER AREA OF MOIST ASCENT DEVELOPS OVER THE SE AND ERN FCST AREA AS WELL. THE NRN AREA WOULD APPEAR TO BE MORE LIKELY TO SEE PCPN AS IT WILL BE ON THE CYCLONIC SIDE OF STRENGTHENING JET ASSOCIATED WITH SHORTWAVE. TOUGH TO SAY WHETHER FORCING IS SUFFICIENT TO OVERCOME THE DRY AIR...BUT GIVEN MODEL TRENDS FOR THIS SHORTWAVE TO BE STRONGER...WILL INTRODUCE LOW CHC POPS ACROSS THE N TONIGHT. NAM/GFS FCST SOUNDINGS SUGGEST PTYPE WILL BE LIQUID...AND SFC TEMPS SHOULD STAY JUST ABOVE FREEZING TO PREVENT FZRA. OVER THE ERN FCST AREA...MODELS SUGGEST THAT THE NRN EXTENT OF THE DEEP MOISTURE TO THE S MAY SLIP INTO THAT AREA (NOTE SATURATED PROFILE ON 12Z KDVN SOUNDING). WILL THUS ALSO INTRODUCE CHC POPS OVER THE E AS WELL. WILL LINGER CHC POPS OVER THE NCNTRL/E EARLY SAT. OTHERWISE...WITH MODELS INDICATING AGGRESSIVE DRYING THRU MOST OF THE COLUMN SAT IN THE WAKE OF SHORTWAVE...WOULD EXPECT SKIES TO CLEAR OUT NICELY FROM W TO E DURING THE DAY. AS WEAK HIGH PRES SLIDES ACROSS THE AREA DURING THE AFTN...LAKE BREEZES SHOULD BE THE RULE BY MID/LATE AFTN NEAR LAKE SUPERIOR AND LAKE MICHIGAN. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE MID/UPPER 50S IN THE INTERIOR. .LONG TERM(SAT NIGHT THROUGH THU) MAIN FCST CONCERNS ARE SHRA/TSRA POTENTIAL LATE SUN INTO MON AND AGAIN BY WED/THU. SAT NIGHT...WITH THE SFC RDG...MOSTLY CLEAR SKIES AND VERY DRY AIRMASS IN PLACE OVER THE AREA(PWAT AOB 0.25 INCH) AND LIGHT WINDS FOR MOST OF THE NIGHT...FAVORABLE RADIATIONAL COOLING CONDITIONS SHOULD ALLOW TEMPS TO DROP INTO THE MID TO UPPER 20S INLAND...A BIT BLO GUIDANCE. HOWEVER...SOME INCREASE IN MID/HIGH CLOUDS AND SE DOWNSLOPE WINDS LATE FAR WEST COULD BRING CLIMBING TEMPS BEFORE SUNRISE. SUN INTO SUN NIGHT...MDLS ARE IN GENERAL AGREEMENT IN LIFTING A SHRTWV...REMNANTS OF THE BAHA/SW US CLOSED LOW...INTO THE WRN GREAT LAKES. THE UKMET WAS SLOWER/STRONGER WITH THE SYSTEM THAN THE GFS AND THE WEAKER/FASTER CANADIAN GLOBAL GEM. FCST GENERALLY LEANED TOWARD THE GFS. INITIAL BATCH OF SHRA/TSRA COULD DEVELOP WITH STRONG WAA AS THE 925-850 MB THETA-E RDG ARC INTO W UPR MI AND SPREAD E LATE. OTHERWISE...THE MAIN FORCING MOVES IN TOWARD 06Z/MON. EVEN THOUGH SHRTWV PATH WOULD SEEM TO FAVOR THE WRN CWA...DECENT 700-300 MB QVECTOR CONV SPREADS ACRS UPPER MI...SUPPORTING GOING LIKELY POPS SUN NIGHT. WITH THE AMPLIFYING PATTERN...STRONG SRLY FLOW(900-850 MB WINDS AOA 40 KT) BRINGING GULF MOISTURE INTO THE AREA MAY PUSH 900-850 MB DEWPOINTS INTO THE 10C-12C RANGE. 900 MB ELEVATED CAPE INTO THE 300-500 J/KG RANGE WILL DECENT CHANCE FOR TSTMS. EVEN WITH SOME BRIEF HEAVY DOWNPOURS POSSIBLE...THE PROGRESSIVE SYSTEM SHOULD LIMIT GENERAL PCPN AMOUNTS TO LESS THAN AN A HALF INCH. MON...EXPECT SHRA/TSRA TO END OVER THE WEST EARLY AND E BY AFTERNOON AS THE SFC TROF MOVES THROUGH AND SHRTWV RDGING/QVECTOR DIV BUILD IN. SOME SUNSHINE WITH WRLY FLOW AND 900-925 MB TEMPS FCST NEAR 10C SHOULD ALLOW TEMPS TO CLIMB TO AROUND 60 OR THE LOW 60S...CLOSE TO RECORD HIGHS. FOR NOW...KEPT TEMPS FAIRLY CONSERVATIVE...AT OR SLIGHTLY ABOVE GUIDANCE BUT WOULD NOT BE SURPRISED IF READINGS ADJUSTED UPWARD LATER IF A DECENT AMOUNT OF SUNSHINE DEVELOPS. TUE-FRI...MDLS SUGGEST ANOTHER WRN CONUS TROF WILL MOVE TOWARD THE CNTRL CONUS AND GREAT LAKES. SIGNIFICANT DIFFERENCES DEVELOP THOUGH BY LATE IN THE WEEK IN HANDLING THE TROF. THE 06Z/12Z GFS AND ENSEMBLE ARE MORE PROGRESSIVE IN BRINGING A SHRTWV AND SFC TROF/FRONT THROUGH THE UPPER GREAT LAKES EVEN AS THE MID LEVEL LOW LINGERS TO THE NW. THE ECMWF KEEPS THE TROF TO THE WEST. EVEN WITH THE LARGE UNCERTAINTY...SHRA/TSRA CHANCES STILL SEEM WARRANTED GIVEN POTENTIAL FOR THE FRONT TO MOVE IN WITH DECENT MOISTURE INFLOW AHEAD OF THE SYSTEM. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON(SHORT TERM) JLB(LONG TERM) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1100 AM EDT FRI MAR 23 2007 .UPDATE... MID CLOUDS CONTINUE TO LINGER LATE THIS MORNING OVER THE ERN FCST AREA...AND NEW CLOUD DEVELOPMENT IS OCCURRING OVER NCNTRL UPPER MI. CLOUDS ARE DEVELOPING IN AN AREA OF PERSISTENT ISENTROPIC ASCENT AS VIEWED ON 290K SFC (ROUGHLY 750-800MB) PER 12Z RUC. ASCENT SLACKENS DURING THE AFTN...SO CLOUDS SHOULD TEND TO THIN OUT SOME LATER IN THE AFTN. AS FOR TEMPS...12Z KINL/KGRB SOUNDINGS AND MORNING TAMDAR SOUNDING FROM KSAW SUPPORT RAISING HIGH TEMPS. KINL/KGRB SOUNDINGS YIELD HIGHS IN THE MID 50S TO AROUND 60F IF MIXED LAYER BUILDS TO 850MB WHILE KSAW SOUNDING SUPPORTS HIGHS IN THE LWR 50S. RAISED HIGHS TO THE LWR END OF THOSE VALUES GIVEN SOME CLOUD COVER. TEMPS WILL BE CONSIDERABLE COOLER NEAR LAKE MICHIGAN UNDER LIGHT SRLY FLOW...AND THE COOLING SHOULD EXTEND ACROSS ALL OF THE ERN FCST AREA. LAKE BREEZE SHOULD DEVELOP OFF LAKE SUPERIOR EXCEPT FOR AREAS E OF MARQUETTE AS SRLY FLOW SHOULD BE SUFFICIENT THRU THE AFTN TO PREVENT DEVELOPMENT THERE. && .PREV DISCUSSION (ISSUED AT 530 AM EDT)... MAIN FCST CONCERNS IN SHORT TERM ARE CLOUDS/TEMPS THEN FOCUS WILL BE ON TIMING OF NEXT CHC OF RAIN/THUNDERSTORMS FOR SUN AFTERNOON. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. ONE SHORTWAVE IS MOVING THROUGH THE UPR GREAT LAKES EARLY THIS MORNING WHILE ANOTHER IS UPSTREAM OVER SRN ALBERTA. SHORTWAVE MOVING THROUGH UPR GREAT LAKES PRODUCED A FEW FLURRIES THIS MORNING NORTH OF LAKE SUPERIOR IN AREA OF WEAK Q-VECT CONV AND ISENTROPIC ASCENT. MODEL SNDGS CONSISTENT IN SHOWING LINGERING MOISTURE AROUND 850 MB IN WAKE OF SHORTWAVE SO KEPT IN A BIT MORE CLOUD COVER TODAY IN ANTICIPATION OF STRATOCU DEVELOPING DURING THE DAY. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE LOW/MID 50S OVER THE WRN INTERIOR. SRLY FLOW WILL KEEP TEMPS MUCH COOLER OVER THE ERN FCST AREA NEAR AND DOWNWIND OF LAKE MICHIGAN. LOCAL COOLING SHOULD ALSO OCCUR NEAR LAKE SUPERIOR OVER THE W AND NCNTRL AREAS MID/LATE AFTN WHERE BOUNDARY LAYER WINDS WILL BE LIGHTER. FROM MUNISING EWD...SRLY FLOW MAY STRONG ENOUGH 10-15 KT TO SUPRESS LAKE BREEZE DEVELOPMENT. NEXT SHORTWAVE FROM ALBERTA IS DUE TO MOVE INTO THE UPR GREAT LAKES LATE FRI NIGHT AND SAT. UPR DIV IN RRQ OF 100 KT 3H JET SHOULD PRODUCE SOME MID CLOUDS PER MODEL SNDGS BUT OTHERWISE MODEL SNDGS LOOK PRETTY DRY AT LOW LEVELS. WEAK PRES GRADIENTS WITH SFC HIGH OVERHEAD WILL ALLOW FOR LAKE BREEZES TO DEVELOP SAT OFF BOTH LAKES SUPERIOR AND MICHIGAN...KEEPING TEMPS COOLER (40S) ALONG LAKESHORE AREAS. MIXING TO AROUND 850 MB OVER THE WESTERN INTERIOR WILL ALLOW MAX TEMPS TO REACH NEAR TO MID 50S. SAT NIGHT...INFLUENCE OF SFC HIGH JUST TO THE NE OF LAKE SUPERIOR WILL ALLOW FOR LIGHT WIND AND GENERALLY CLEAR TO PARTLY CLOUDY SKIES. EXPECT LOWS TO REACH INTO THE 20S OVER THE INTERIOR...CLOSER TO COOLER GFS MOS GUIDANCE. MODELS STILL IN GOOD AGREEMENT SHOWING UPR LOW EJECTING OUT OF THE PLAINS AND INTO THE UPR GREAT LAKES SUN NIGHT INTO MON. AN INCREASING RIBBON OF MOISTURE/ISENTROPIC ASCENT ON THE 300K SFC... A 40KT H85 JET...AND PWATS AROUND AN INCH ARE MAIN TRIGGERS FOR SHOWERS LATE SUN INTO SUN NIGHT. NEG 850-500 MB THETA-E LAPSE RATES COULD ALSO RESULT IN THUNDER. BUMPED UP POPS TO LIKELY SUN NIGHT WITH ARRIVAL OF SFC WARM FRONT AND UPR TROUGH. DEPARTURE OF SHORTWAVE AND ASSOC SFC TROF/WARM FRONT SHOULD TAPER OFF RAIN CHCS BY MON AFTERNOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON (UPDATE) VOSS (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 530 AM EDT FRI MAR 23 2007 .DISCUSSION... MAIN FCST CONCERNS IN SHORT TERM ARE CLOUDS/TEMPS THEN FOCUS WILL BE ON TIMING OF NEXT CHC OF RAIN/THUNDERSTORMS FOR SUN AFTERNOON. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. ONE SHORTWAVE IS MOVING THROUGH THE UPR GREAT LAKES EARLY THIS MORNING WHILE ANOTHER IS UPSTREAM OVER SRN ALBERTA. SHORTWAVE MOVING THROUGH UPR GREAT LAKES PRODUCED A FEW FLURRIES THIS MORNING NORTH OF LAKE SUPERIOR IN AREA OF WEAK Q-VECT CONV AND ISENTROPIC ASCENT. MODEL SNDGS CONSISTENT IN SHOWING LINGERING MOISTURE AROUND 850 MB IN WAKE OF SHORTWAVE SO KEPT IN A BIT MORE CLOUD COVER TODAY IN ANTICIPATION OF STRATOCU DEVELOPING DURING THE DAY. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE LOW/MID 50S OVER THE WRN INTERIOR. SRLY FLOW WILL KEEP TEMPS MUCH COOLER OVER THE ERN FCST AREA NEAR AND DOWNWIND OF LAKE MICHIGAN. LOCAL COOLING SHOULD ALSO OCCUR NEAR LAKE SUPERIOR OVER THE W AND NCNTRL AREAS MID/LATE AFTN WHERE BOUNDARY LAYER WINDS WILL BE LIGHTER. FROM MUNISING EWD...SRLY FLOW MAY STRONG ENOUGH 10-15 KT TO SUPRESS LAKE BREEZE DEVELOPMENT. NEXT SHORTWAVE FROM ALBERTA IS DUE TO MOVE INTO THE UPR GREAT LAKES LATE FRI NIGHT AND SAT. UPR DIV IN RRQ OF 100 KT 3H JET SHOULD PRODUCE SOME MID CLOUDS PER MODEL SNDGS BUT OTHERWISE MODEL SNDGS LOOK PRETTY DRY AT LOW LEVELS. WEAK PRES GRADIENTS WITH SFC HIGH OVERHEAD WILL ALLOW FOR LAKE BREEZES TO DEVELOP SAT OFF BOTH LAKES SUPERIOR AND MICHIGAN...KEEPING TEMPS COOLER (40S) ALONG LAKESHORE AREAS. MIXING TO AROUND 850 MB OVER THE WESTERN INTERIOR WILL ALLOW MAX TEMPS TO REACH NEAR TO MID 50S. SAT NIGHT...INFLUENCE OF SFC HIGH JUST TO THE NE OF LAKE SUPERIOR WILL ALLOW FOR LIGHT WIND AND GENERALLY CLEAR TO PARTLY CLOUDY SKIES. EXPECT LOWS TO REACH INTO THE 20S OVER THE INTERIOR...CLOSER TO COOLER GFS MOS GUIDANCE. MODELS STILL IN GOOD AGREEMENT SHOWING UPR LOW EJECTING OUT OF THE PLAINS AND INTO THE UPR GREAT LAKES SUN NIGHT INTO MON. AN INCREASING RIBBON OF MOISTURE/ISENTROPIC ASCENT ON THE 300K SFC... A 40KT H85 JET...AND PWATS AROUND AN INCH ARE MAIN TRIGGERS FOR SHOWERS LATE SUN INTO SUN NIGHT. NEG 850-500 MB THETA-E LAPSE RATES COULD ALSO RESULT IN THUNDER. BUMPED UP POPS TO LIKELY SUN NIGHT WITH ARRIVAL OF SFC WARM FRONT AND UPR TROUGH. DEPARTURE OF SHORTWAVE AND ASSOC SFC TROF/WARM FRONT SHOULD TAPER OFF RAIN CHCS BY MON AFTERNOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 PM EDT THU MAR 22 2007 .SHORT TERM (TONIGHT AND FRIDAY)... MAIN FCST ISSUE IN THE SHORT TERM IS POSSIBILITY OF SOME -SN TONIGHT. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS THE NRN CONUS/SRN CANADA. SHORTWAVE THAT PASSED ACROSS THE UPPER LAKES EARLIER TODAY IS NOW OVER THE ONTARIO/QUEBEC BORDER. NEXT SHORTWAVE IN THE FAST FLOW IS OVER NW ND. MID CLOUDS ASSOCIATED WITH SHORTWAVE WERE SPREADING ACROSS NRN MN...AND HIGH CLOUDS HAVE ALREADY SPREAD ACROSS ALL OF UPPER MI THIS AFTN. RADARS SHOW A DECENT AREA OF RETURNS ACROSS FAR NE ND/NW MN AND SRN MANITOBA. SFC OBS THAT REPORT VSBY ARE SPARSE IN THAT AREA...SO DIFFICULT TO KNOW HOW MUCH PCPN IS REACHING THE GROUND. HOWEVER...IN THE LAST FEW HRS...A COUPLE OF OBS IN SRN MANITOBA HAVE REPORTED 1-4SM IN -SN. WELL TO THE W...SHORTWAVE THAT DROPPED OUT OF THE WESTERLIES A DAY OR TWO AGO OVER THE W COAST HAS CLOSED OFF INTO A MIDLEVEL LOW CENTERED JUST S OF CA. THIS SYSTEM WILL BE OF INTEREST TO FCST HERE LATE IN THE UPCOMING WEEKEND AS IT GETS KICKED NE BY NEXT TROF APPROACHING THE W COAST. UPSTREAM SHORTWAVE WILL RACE E...CROSSING UPPER MI/LAKE SUPERIOR BTWN 03Z-09Z. BASED ON THE DARKENING SEEN ON WATER VAPOR IMAGERY... THE GFS HAS A BETTER HANDLE ON SHORTWAVE THAN THE WEAKER NAM. LATEST RUC AND 12Z REGIONAL CANADIAN ALSO SUPPORT THE GFS. OVERLAP OF MODEST DEEP LAYER QVECTOR CONVERGENCE AND MOIST ISENTROPIC ASCENT (CONDENSATION PRES DEFICITS UNDER 20MB) ON THE 290K SFC (AROUND 700MB) LINES UP WELL WITH WHERE RADAR RETURNS ARE PRESENT IN NE ND/NW MN AND SRN MANITOBA. STRONGER ISENTROPIC ASCENT IS INDICATED FARTHER S...BUT AIRMASS IS DRIER THERE. LATEST RUC IS VERY SIMILAR TO THE GFS WITH REGARD TO PROGRESSION OF QVECTOR CONVERGENCE/ISENTROPIC ASCENT THRU 06Z. FORCING/ISENTROPIC ASCENT IS TO SHIFT THRU NE MN BEFORE WEAKENING AS IT CROSSES UPPER MI/LAKE SUPERIOR TONIGHT. WITH ANTECEDENT DRY AIR TO OVERCOME...THE WEAKENING FORCING SUGGESTS PCPN THAT IS OCCURRING UPSTREAM WILL TEND TO DISSIPATE AS IT NEARS AND THEN MOVES ACROSS THE FCST AREA. ON THE OTHER HAND...GIVEN THE APPEARANCE ON WATER VAPOR IMAGERY...SHORTWAVE MAY NOT WEAKEN AS FAST AS MODELS INDICATE. SO...SITUATION IS CERTAINLY STILL WORTHY OF SLIGHT CHC/LOW CHC POPS OVER NW LAKE SUPERIOR AND ACROSS THE KEWEENAW. FCST WETBULB ZERO PROFILES INDICATE ANY PCPN THAT OCCURS WILL BE SNOW. FOLLOWING SHORTWAVE...CANADIAN/GFS SHOW MOISTURE LINGERING AROUND 850MB ON FRI...ESPECIALLY OVER THE CNTRL/ERN FCST AREA. SO THERE SHOULD BE A FAIR AMOUNT OF STRATOCU DEVELOPING DURING THE DAY. MIXING TO 850-800MB ON FCST SOUNDINGS YIELDS HIGHS IN THE LOW/MID 50S. HOWEVER...SRLY FLOW WILL KEEP TEMPS MUCH COOLER NEAR AND DOWNWIND OF LAKE MICHIGAN. LOCAL COOLING SHOULD ALSO OCCUR NEAR LAKE SUPERIOR OVER THE W AND OVER THE NCNTRL MID/LATE AFTN AS BOUNDARY LAYER WINDS SLACKEN. FROM MUNISING EWD...SRLY FLOW MAY BE SUFFICIENT THRU THE DAY TO PREVENT LAKE BREEZE DEVELOPMENT. .LONG TERM (FRIDAY NIGHT THROUGH NEXT THURSDAY)... CONTINUITY IN MODEL SOLUTIONS IS POOR CURRENTLY MAINLY DUE TO ZONAL WEST TO EAST UPPER FLOW ALONG CANADA/UNITED STATES BORDER. IN RECENT MODEL RUNS...IT APPEARED SHORTWAVE CURRENTLY OFF SHORE OF BRITISH COLUMBIA WAS TO MOVE EAST AND ARRIVE OVR ONTARIO AND UPR LAKES FRI NIGHT INTO EARLY SAT. ALSO...THE WAVE WAS PROGGED TO SHEAR OUT AS IT CAME EAST. NOW...A TREND IS EMERGING THAT RESULTS IN STRONGER WAVE NOT COMING THROUGH UNTIL SAT. NAM MOST EMPHATIC WITH THIS IDEA WHILE UKMET/GFS AND LATEST ECMWF ARE WEAKER. SHORTWAVE ALONG WITH DIVERGENCE FM RRQ OF H3 OVR ONTARIO SHOULD PRODUCE CONSIDERABLE MID CLOUDS. HOWEVER...SOUNDINGS FM GFS AND EVEN NAM ARE VERY DRY BLO H85 SO HAVE KEPT A DRY FCST. MIXING HEIGHTS MAY BE LIMITED DUE TO CLOUDS AND LIGHT WINDS SO LOWERED TEMPS SLIGHTLY. AT THE SFC...RIDGE DRIFTING OVER UPR LAKES WILL MOVE TO THE LOWER GREAT LAKES SAT NIGHT INTO SUN. RETURN FLOW AS HIGH DEPARTS WILL ONLY STRENGTHEN THROUGH MOST OF THE UPCOMING WEEK. IT IS FEASIBLE THAT SAT NIGHT WILL BE THE LAST ONE FOR A WHILE WITH A GOOD PORTION OF CWA EXPERIENCING MIN TEMPS BLO FREEZING. UPR LOW OVR SOUTHWEST EJECTS INTO PLAINS SUN AND LIFTS TOWARD UPR GREAT LAKES SUN NIGHT INTO MON. UKMET/GFS/ECMWF IN GOOD AGREEMENT HERE. NAM IS MUCH SLOWER WITH TROUGH EJECTION AND WAS NOT PREFERRED DUE TO EVEN STRONGER KICKER SHORTWAVE TROUGH BARRELLING INTO WEST COAST AS EARLY AS SUN. LARGE AREA OF H85-H7 WARM AIR ADVECTION... 40KT H85 JET...AND PWATS ECLIPSING AN INCH (250-300 PCT OF NORMAL) ARE MAIN TRIGGERS FOR PCPN SUN INTO SUN NIGHT. WARMING H85 TEMPS COMBINED WITH COOL H5 TEMPS AROUND -15C RESULT IN STEEPENING MID LEVEL LAPSE RATES AND POSSIBILITY OF THUNDER. MAIN SFC WARM FRONT AND UPR TROUGH DO NOT ARRIVE UNTIL LATE SUN NIGHT INTO MON WHICH IS WHEN BEST COVERAGE TO SHOWERS/THUNDERSTORMS IS EXPECTED. 00Z GFS EVEN INDICATED SOME SFC BASED INSTABILITY AHEAD OF PRIMARY COLD FRONT MOVING THROUGH MON EVENING. ECMWF MUCH QUICKER WITH FROPA. ALTHOUGH MOST PCPN WILL BE DONE BY MON NIGHT...KEPT A SMALL CHANCE IN GRIDS FOR TUE AS SECONDARY SFC TROUGH MOVES THROUGH PER HPC AND H5 COLD POOL (-20C AT H5) ALSO ROTATES THROUGH. BRIEF RIDGING BOTH ALOFT AND AT SFC FOR WED...THEN DEEP TROUGH CONTINUES TO DEVELOP OVR MUCH OF WESTERN CONUS. SW FLOW DEVELOPING ALOFT...AND EVENTUALLY AT SFC...LEADS TO AN INCREASE IN RAIN CHANCES LATE NEXT WEEK. TEMPS WILL REMAIN ABOVE NORMAL. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1037 AM EDT THU MAR 22 2007 .UPDATE... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A POTENT SHORTWAVE RACING E ACROSS ERN LAKE SUPERIOR AND ONTARIO. SHARP DRYING/SUBSIDENCE IN THE WAKE OF SHORTWAVE IS LEADING TO A DECREASE IN CLOUD COVER ACROSS THE FCST AREA THIS MORNING. 00Z/12Z KINL SOUNDINGS SHOWED THE INCOMING DRY AIR NICELY AS PRECIPITABLE WATER DROPPED FROM 0.68 TO 0.15 INCHES...AND 12Z SOUNDING INDICATED DWPT DEPRESSIONS OF 15-25C FROM 840MB TO 550MB. A PERIOD OF GUSTY WINDS IS ALSO FOLLOWING THE STRONG SHORTWAVE. WINDS WERE BEING AIDED BY 4-5MB/3HR PRES RISE MAX THAT WAS QUICKLY MOVING E ACROSS THE UPPER LAKES. CORE OF PRES RISES IS NOW OVER CNTRL LAKE SUPERIOR/CNTRL UPPER MI...SO STRONGEST WINDS HAVE JUST ABOUT PASSED THE AREA. NEXT SHORTWAVE IS HEADING ESE THRU SRN SASKATCHEWAN. MID/HIGH CLOUDS ASSOCIATED WITH SHORTWAVE ARE ALREADY STREAMING E THRU ND INTO NRN MN. INHERITED FCST IS IN GOOD SHAPE FOR THE AFTN AND ONLY REQUIRES MINOR ADJUSTMENTS BASED ON MORNING TRENDS. SOME STRATOCU WILL BE AROUND FOR A FEW MORE HRS...MAINLY ACROSS THE N...ASSOCIATED WITH 850MB THERMAL TROF AND LINGERING LOW-LEVEL MOISTURE. STRATOCU SHOULD BE GONE BY MID/LATE AFTN...BUT ALREADY MID/HIGH CLOUDS ASSOCIATED WITH NEXT SHORTWAVE WILL BE SLIPPING INTO THE FCST AREA FROM THE W. AS FOR TEMPS...MIXING TO 800-850MB ON 12Z KINL SOUNDING SUGGESTS HIGH TEMPS IN THE UPPER 30S/LWR 40S ARE ON TRACK OVER THE W AND N. WNW DOWNSLOPING WIND WILL RESULT IN MAX TEMPS SEVERAL DEGREES HIGHER OVER PORTIONS OF THE CNTRL FCST AREA...ESPECIALLY SCNTRL. AS FOR WINDS...WILL MAINTAIN GALE WARNING OVER ERN LAKE SUPERIOR FOR A FEW MORE HRS WITH EXPECTATION OF GALE FORCE GUSTS. OTHERWISE...WINDS WILL CONTINUE TO DIMINISH OVER THE ENTIRE FCST AREA THRU THE DAY AS PRES RISE SHIFTS E OF THE AREA AND SFC HIGH PRES RIDGE OVER MN DRIFTS E. && .PREV DISCUSSION (ISSUED AT 400 AM EDT)... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STRG SHRTWV NEAR LK WINNIPEG EMBEDDED IN ZONAL FLOW ALF ALG THE CNDN BORDER...WITH ANOTHER SHRTWV PRESENT OVER ND. THREE DISTINCT AREAS OF PCPN NOTED AT THE START OF SHIFT. THE FIRST WAS A BAND OF SHRA MOVING INTO WRN LK SUP JUST AHEAD OF COLD FNT IN DPVA/DEEP LYR H85-3 QVECTOR CNVGC ASSOCIATED WITH ND SHRTWV. LLVL MSTR LINGERS BEHIND THIS FNT WITH SC CIGS OBSVD BACK TO THE RED RIVER VALLEY...WHERE DRIER AIR NOTED ON THE BIS SDNG IS WORKING EWD. STRONGER COLD FNT ASSOCIATED WITH SHRTWV OVER LK WINNIPEG MOVING TOWARD THE MN AT 03Z...BUT LTL PCPN OBSVD ALG THIS BNDRY DESPITE SHARPER THERMAL CONTRAST. SECOND CLUSTER OF SHRA WITH EMBEDDED TSRA EXTENDS FM NW WI INTO IA WHERE DPVA/DEEP LYR H85-3 QVECTOR CNVGC/SFC COLD FNT INTERSECTING HIER H85 DWPTS AOA 8C SURGING NEWD IN ADVANCE OF FNT...MSTR NOT AVBL TO BAND FARTHER N IN WRN LK SUP. RAOBS/PROFILERS SHOW H85 SW WINDS AOA 50 KTS AHEAD OF THIS CLUSTER. LARGEST AREA OF SHRA PRESENT OVER ERN WI/LK MI/NW LWR MI AT NOSE OF STRONGEST H85-7 WINDS JUST AHEAD OF WEAK SHRTWV NOTED ON RUC ANALYSIS. SCT SHRA/TSRA ON NRN FRINGE OF THIS AREA ARE IMPACTING THE ERN CWA...BUT FOR THE MOST PART THESE SHRA/TSRA ON TRACK TO MISS THE FA. OTRW...LTL PCPN NOTED OVER THE FA RIGHT NOW...BUT RETURN OF HIER LLVL MSTR OVER MELTING SN HAS CAUSED QUITE A BIT OF ST/FOG...WITH VSBYS AOB 1/4SM AT PLACES ACRS MAINLY THE SCNTRL AND E. UPSTREAM...ANOTHER SHRTWV MOVING THRU BRITISH COLUMBIA. MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND EVOLUTION OF PCPN AREAS AS LATEST RUC/LARGER SCALE MODELS SHOW SHRTWVS OVER ND AND LK WINNIPEG PHASING OVERNGT. FOCUS AFTER COLD FROPA EARLY THIS MRNG SHIFTS TO WINDS/TEMPS. AS SHRTWVS BEGIN TO MERGE TO A 40-UNIT VORT MAX OVER FAR NRN LK SUP BY 12Z THU...EXPECT SHRA AREAS OVER WRN LK SUP/WI TO MERGE OVER THE SCNTRL/ERN CWA WITH SOME LOCALLY HEAVY RA THERE WHERE MSTR CNVGC PHASES BETTER WITH DPVA/FALLING HGTS/DEEP QVECTOR CVNGC BEFORE ACCELERATING INCRSGLY KATAFNT TYPE COLD FNT DRIVES E UNDER JET SURGE REGION OF DEEPENING SHRTWV. WITH RAPID INFLUX OF DRY AIR EXPECTED AS H85 W WINDS INCRS UP TO 50KT...LOOK FOR PCPN/DENSE FOG TO END SOON AFTR COLD FROPA WITH INTENSE DRY ADVCTN/SUBSIDENCE. 00Z RUC/NAM INDICATE DRYING WL REACH ERY ARND 12Z...SO MOST IF NOT ALL PCPN WL BE OVER BY EARLY TDAY. WL CARRY LINGERING SHRA OVER THE ERN COUNTIES EARLY...OTRW HAVE REMOVED POPS ALTOGETHER AS NAM/RUC FCST SDNGS FOLLOWING THE FROPA ARE QUITE DRY. WL EVALUATE NEED TO KEEP GOING DENSE FOG ADVY GOING CLOSE TO FCST ISSUANCE...BUT ANTICIPATE DROPPING ADVY FOR MOST OF THE FA BY FCST ISSUANCE. GFS FCST SDNGS SHOW MORE LLVL MSTR...BUT PREFER THE DRIER LOOK TO THE RUC/NAM FCSTS GIVEN MORE DRYING OBSVD UPSTREAM OVER NW MN/ANTICIPATED DRY SURGE BEHIND DEEPENING SHRTWV. OTRW...LOOK FOR GUSTY WINDS THIS MRNG BEHIND THE BNDRY WITH 35KT WINDS WITHIN THE MIXED LYR TO DIMINISH A BIT THIS AFTN WITH ARRIVAL OF HI PRES RDG. ALTHOUGH PRES GRADIENT SEEMS TO DIMINISH WITH APRCH OF RDG...MIXING/DEEPENING PBL WITH PLENTY OF SUNSHINE IN LLVL CAD SHOULD TAP STRONGER WINDS ALF TO MAINTAIN GUSTINESS THRU THE DAY. MIXING TO H85 ON NAM FCST SDNGS SUGS HI TEMPS WL REACH ARND 45 OVER THE SE COUNTIES...WHERE NW FLOW WL BE DOWNSLOPING. LOOK FOR AN INCRS IN HI CLD LATE TDAY IN ADVANCE OF NEXT SHRTWV NOW MOVING INTO BRITISH COLUMBIA FCST TO MOVE TOWARD NW MN LATE TDAY. FOR TNGT...SHRTWV OVER THE NRN PLAINS PROGGED TO DRIFT ACRS THE UPR GRT LKS...AND GFS/NAM/UKMET SHOW INCRSG MID LVL MSTR. ALTHOUGH LLVLS APPEAR WL BE TOO DRY FOR ANY PCPN...GFS AND ESPECIALLY THE NAM GENERATE SOME GENERALLY LGT QPF OVER THE NW AND LK SUP. NAM ACTUALLY SHOWS SOME SHARP H85-7 FGEN WITH SOME MODEST ISENTROPIC LIFT IN ADVANCE OF THE SHRTWV. SINCE GFS/UKMET ARE MUCH WEAKER WITH FCST DYNAMICS BUT WV IMAGERY INDICATES A WELL DEFINED SHRTWV IN BRITISH COLUMBIA...WL CARRY SLGT CHC -SHSN (FCST WBZ PROFILES SUG ANY PCPN WOULD BE SN) ACRS THE NW CWA ON CYC SIDE OF NAM FCST H3 JET MAX/BEST H85-7 FGEN. EXPECT THE LOWEST MIN TEMPS OVER THE SCNTRL WHERE THE CLDS WL BE THINNEST. FOLLOWING DEPARTURE OF SHRTWV EARLY FRI...SFC-H85 RDG AXIS/MID LVL DRYING FCST TO DOMINATE. GFS/NAM BOTH SHOW SOME HIER DWPTS AT H85 LINGERING HOWEVER...SO EXPECT BKN DIURNAL SC TO DVLP DURING DAY. MIXING TO H85 ON GFS/NAM FCST SDNGS YIELDS HI TEMPS NEAR 55. WITH LGT SW FLOW...EXPECT LK BREEZES/AFTN COOLING TO DVLP MAINLY NEAR LK MI. SOME CONSIDERABLE MODEL DISAGREEMENTS BEGIN TO SHOW IN THE FRI NGT/SAT PDS...NOT SURPRISING CONSIDERING FAST ZONAL FLOW FCST TO PREVAIL. GFS SHOWS A MUCH DEEPER SHRTWV ARRIVING LATE FRI NGT AND GENERATING SGNFT PCPN ON SAT. WL SIDE WITH THE MAJORITY UKMET/ ECWMF/CNDN/NAM THAT SHOW A MUCH WEAKER SHRTWV SHEARING BY ON FRI NGT FOLLOWED BY RDGING ON SAT. OPTED TO REMOVE POPS FRI NGT AND KEEP SAT DRY. WITH H85 TEMPS APRCHG 6C ON SAT...EXPECT TEMPS OVER THE INLAND TO RISE WELL INTO THE 50S TO NEAR 60 PER MIXING TO H8 ON NAM FCST SDNGS. WITH SFC HI CENTER TO THE SE AND CWA IN SYNOPTIC SW FLOW... EXPECT THE MOST SGNFT LK MODERATION OFF LK MI. BUT RELATIVELY WEAK FLOW AND SFC HTG INLAND SHOULD ALLOW LK BREEZES OFF SUPERIOR AS WELL. COORDINATED WITH GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING E HALF OF LAKE SUPERIOR. && $$ ROLFSON (UPDATE) KC (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 AM EDT THU MAR 22 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STRG SHRTWV NEAR LK WINNIPEG EMBEDDED IN ZONAL FLOW ALF ALG THE CNDN BORDER...WITH ANOTHER SHRTWV PRESENT OVER ND. THREE DISTINCT AREAS OF PCPN NOTED AT THE START OF SHIFT. THE FIRST WAS A BAND OF SHRA MOVING INTO WRN LK SUP JUST AHEAD OF COLD FNT IN DPVA/DEEP LYR H85-3 QVECTOR CNVGC ASSOCIATED WITH ND SHRTWV. LLVL MSTR LINGERS BEHIND THIS FNT WITH SC CIGS OBSVD BACK TO THE RED RIVER VALLEY...WHERE DRIER AIR NOTED ON THE BIS SDNG IS WORKING EWD. STRONGER COLD FNT ASSOCIATED WITH SHRTWV OVER LK WINNIPEG MOVING TOWARD THE MN AT 03Z...BUT LTL PCPN OBSVD ALG THIS BNDRY DESPITE SHARPER THERMAL CONTRAST. SECOND CLUSTER OF SHRA WITH EMBEDDED TSRA EXTENDS FM NW WI INTO IA WHERE DPVA/DEEP LYR H85-3 QVECTOR CNVGC/SFC COLD FNT INTERSECTING HIER H85 DWPTS AOA 8C SURGING NEWD IN ADVANCE OF FNT...MSTR NOT AVBL TO BAND FARTHER N IN WRN LK SUP. RAOBS/PROFILERS SHOW H85 SW WINDS AOA 50 KTS AHEAD OF THIS CLUSTER. LARGEST AREA OF SHRA PRESENT OVER ERN WI/LK MI/NW LWR MI AT NOSE OF STRONGEST H85-7 WINDS JUST AHEAD OF WEAK SHRTWV NOTED ON RUC ANALYSIS. SCT SHRA/TSRA ON NRN FRINGE OF THIS AREA ARE IMPACTING THE ERN CWA...BUT FOR THE MOST PART THESE SHRA/TSRA ON TRACK TO MISS THE FA. OTRW...LTL PCPN NOTED OVER THE FA RIGHT NOW...BUT RETURN OF HIER LLVL MSTR OVER MELTING SN HAS CAUSED QUITE A BIT OF ST/FOG...WITH VSBYS AOB 1/4SM AT PLACES ACRS MAINLY THE SCNTRL AND E. UPSTREAM...ANOTHER SHRTWV MOVING THRU BRITISH COLUMBIA. MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND EVOLUTION OF PCPN AREAS AS LATEST RUC/LARGER SCALE MODELS SHOW SHRTWVS OVER ND AND LK WINNIPEG PHASING OVERNGT. FOCUS AFTER COLD FROPA EARLY THIS MRNG SHIFTS TO WINDS/TEMPS. AS SHRTWVS BEGIN TO MERGE TO A 40-UNIT VORT MAX OVER FAR NRN LK SUP BY 12Z THU...EXPECT SHRA AREAS OVER WRN LK SUP/WI TO MERGE OVER THE SCNTRL/ERN CWA WITH SOME LOCALLY HEAVY RA THERE WHERE MSTR CNVGC PHASES BETTER WITH DPVA/FALLING HGTS/DEEP QVECTOR CVNGC BEFORE ACCELERATING INCRSGLY KATAFNT TYPE COLD FNT DRIVES E UNDER JET SURGE REGION OF DEEPENING SHRTWV. WITH RAPID INFLUX OF DRY AIR EXPECTED AS H85 W WINDS INCRS UP TO 50KT...LOOK FOR PCPN/DENSE FOG TO END SOON AFTR COLD FROPA WITH INTENSE DRY ADVCTN/SUBSIDENCE. 00Z RUC/NAM INDICATE DRYING WL REACH ERY ARND 12Z...SO MOST IF NOT ALL PCPN WL BE OVER BY EARLY TDAY. WL CARRY LINGERING SHRA OVER THE ERN COUNTIES EARLY...OTRW HAVE REMOVED POPS ALTOGETHER AS NAM/RUC FCST SDNGS FOLLOWING THE FROPA ARE QUITE DRY. WL EVALUATE NEED TO KEEP GOING DENSE FOG ADVY GOING CLOSE TO FCST ISSUANCE...BUT ANTICIPATE DROPPING ADVY FOR MOST OF THE FA BY FCST ISSUANCE. GFS FCST SDNGS SHOW MORE LLVL MSTR...BUT PREFER THE DRIER LOOK TO THE RUC/NAM FCSTS GIVEN MORE DRYING OBSVD UPSTREAM OVER NW MN/ANTICIPATED DRY SURGE BEHIND DEEPENING SHRTWV. OTRW...LOOK FOR GUSTY WINDS THIS MRNG BEHIND THE BNDRY WITH 35KT WINDS WITHIN THE MIXED LYR TO DIMINISH A BIT THIS AFTN WITH ARRIVAL OF HI PRES RDG. ALTHOUGH PRES GRADIENT SEEMS TO DIMINISH WITH APRCH OF RDG...MIXING/DEEPENING PBL WITH PLENTY OF SUNSHINE IN LLVL CAD SHOULD TAP STRONGER WINDS ALF TO MAINTAIN GUSTINESS THRU THE DAY. MIXING TO H85 ON NAM FCST SDNGS SUGS HI TEMPS WL REACH ARND 45 OVER THE SE COUNTIES...WHERE NW FLOW WL BE DOWNSLOPING. LOOK FOR AN INCRS IN HI CLD LATE TDAY IN ADVANCE OF NEXT SHRTWV NOW MOVING INTO BRITISH COLUMBIA FCST TO MOVE TOWARD NW MN LATE TDAY. FOR TNGT...SHRTWV OVER THE NRN PLAINS PROGGED TO DRIFT ACRS THE UPR GRT LKS...AND GFS/NAM/UKMET SHOW INCRSG MID LVL MSTR. ALTHOUGH LLVLS APPEAR WL BE TOO DRY FOR ANY PCPN...GFS AND ESPECIALLY THE NAM GENERATE SOME GENERALLY LGT QPF OVER THE NW AND LK SUP. NAM ACTUALLY SHOWS SOME SHARP H85-7 FGEN WITH SOME MODEST ISENTROPIC LIFT IN ADVANCE OF THE SHRTWV. SINCE GFS/UKMET ARE MUCH WEAKER WITH FCST DYNAMICS BUT WV IMAGERY INDICATES A WELL DEFINED SHRTWV IN BRITISH COLUMBIA...WL CARRY SLGT CHC -SHSN (FCST WBZ PROFILES SUG ANY PCPN WOULD BE SN) ACRS THE NW CWA ON CYC SIDE OF NAM FCST H3 JET MAX/BEST H85-7 FGEN. EXPECT THE LOWEST MIN TEMPS OVER THE SCNTRL WHERE THE CLDS WL BE THINNEST. FOLLOWING DEPARTURE OF SHRTWV EARLY FRI...SFC-H85 RDG AXIS/MID LVL DRYING FCST TO DOMINATE. GFS/NAM BOTH SHOW SOME HIER DWPTS AT H85 LINGERING HOWEVER...SO EXPECT BKN DIURNAL SC TO DVLP DURING DAY. MIXING TO H85 ON GFS/NAM FCST SDNGS YIELDS HI TEMPS NEAR 55. WITH LGT SW FLOW...EXPECT LK BREEZES/AFTN COOLING TO DVLP MAINLY NEAR LK MI. SOME CONSIDERABLE MODEL DISAGREEMENTS BEGIN TO SHOW IN THE FRI NGT/SAT PDS...NOT SURPRISING CONSIDERING FAST ZONAL FLOW FCST TO PREVAIL. GFS SHOWS A MUCH DEEPER SHRTWV ARRIVING LATE FRI NGT AND GENERATING SGNFT PCPN ON SAT. WL SIDE WITH THE MAJORITY UKMET/ ECWMF/CNDN/NAM THAT SHOW A MUCH WEAKER SHRTWV SHEARING BY ON FRI NGT FOLLOWED BY RDGING ON SAT. OPTED TO REMOVE POPS FRI NGT AND KEEP SAT DRY. WITH H85 TEMPS APRCHG 6C ON SAT...EXPECT TEMPS OVER THE INLAND TO RISE WELL INTO THE 50S TO NEAR 60 PER MIXING TO H8 ON NAM FCST SDNGS. WITH SFC HI CENTER TO THE SE AND CWA IN SYNOPTIC SW FLOW... EXPECT THE MOST SGNFT LK MODERATION OFF LK MI. BUT RELATIVELY WEAK FLOW AND SFC HTG INLAND SHOULD ALLOW LK BREEZES OFF SUPERIOR AS WELL. COORDINATED WITH GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING LAKE SUPERIOR. && $$ KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1217 PM CDT FRI MAR 23 2007 .UPDATE... UPDATED FOR 18Z AVIATION DISCUSSION. && .AVIATION... MAIN CONCERNS FOR 18Z TAFS INVOLVE AREA OF STRATUS MIGRATING NORTHWARD THIS AFTN AND FOG POTENTIAL IN THE WEST TOWARD MORNING. NAM AND RUC BOTH POINT TOWARD MSP/RNH/EAU BEING MOST AFFECTED...WITH MSP SEEING THE EARLIEST ARRIVAL. OTHERWISE...IT WILL BE A BATTLE BETWEEN MID LEVEL CLDS AT AXN AND STC AND THE INFUSION OF LOW LEVEL MSTR FOR FOG DEVELOPMENT. HAVE PUT SOME MVFR VSBYS IN AT AXN DURING THE FAVORED TIME NEAR DAWN...BUT WITH MID CLDS HANGING AROUND STC LONGER...KEPT THIS SITE VFR. RWF WILL NOT HAVE THE MID/UPR CLDS TO DEAL WITH SO INCLUDED CONSIDERABLE VSBY RESTRICTIONS OVRNGT AND EARLY MRNG. && .PREV DISCUSSION... /ISSUED 255 AM CDT FRI MAR 23 2007/ DISCUSSION... IN THE NEAR TERM...A SPLIT UPPER AIRFLOW REGIME WILL PERSIST ACROSS THE CONUS THROUGH SATURDAY MORNING. THIS WEATHER PATTERN WILL PROVIDE SOME MILD AND DRY WEATHER ACROSS THE UPPER MIDWEST THROUGH SATURDAY. THE LATEST WATER VAPOR SATELLITE PICTURE...SHOWED A WELL-DEFINED UPPER LOW CENTERED OVER BAJA. MEANWHILE...A STRONG UPPER JET EXTENDS FROM THE WESTERN PACIFIC INTO MEXICO. THIS SYSTEM WILL BEGIN TO LIFT SLOWLY NORTHEAST OVER THE SOUTHERN AND CENTRAL ROCKIES. A NEARLY STATIONARY SURFACE FRONTAL BOUNDARY...OVER SOUTHERN IOWA AND NORTHERN ILLINOIS...WILL ALSO SLOWLY MOVE NORTHWARD AS A WARM FRONT OVER THE WEEKEND. THIS FRONTAL BOUNDARY WILL BE OR HAS BEEN THE MAIN FOCUS FOR TSRA. THE EUROPEAN MODEL HAS BEEN CONSISTENT IN THE OVERALL WEATHER PATTERN...WHILE THE GFS AND NAM MODELS SEEN LITTLE TOO FAST. AIRMASS WILL BECOME QUITE UNSTABLE ON SUNDAY AS THE UPPER LOW LIFTS NORTHWARD OVER THE NORTHERN PLAINS. WARM FRONT IS FORECAST TO ADVANCE NORTH OVER SOUTHERN MINNESOTA. FORECAST PARAMETERS ARE INDICATING AT LEAST SLIGHT RISK OF SEVERE STORMS OVER SOUTHERN MINNESOTA SUNDAY AFTERNOON AND EVENING. WIND FIELDS ARE FORECAST TO BE QUITE STRONG BY MID SUNDAY AFTERNOON ACROSS MUCH OF OUR CWA. THIS SHOULD BE SUFFICIENT TO PROVIDE FAVORABLE SHEAR FOR ORGANIZED STORMS...INCLUDING SUPERCELLS WITH HAIL/WIND DAMAGE AND POSSIBLE TORNADOES. QUESTION...IS WHETHER MUCH OF OUR CONVECTION...WILL STAY ELEVATED OR WILL IT BECOME SURFACE BASE OVER SOUTHERN MINNESOTA LATE AFTERNOON AND EVENING...IF THE SURFACE FRONTAL BOUNDARY LIFTS FURTHER NORTHWARD THAN ANTICIPATED. RIGHT NOW...STORM PREDICTION CENTER HAS THE ENTIRE CWA OUTLOOKED IN A SLIGHT RISK FOR SUNDAY. THE LATEST EXTENDED MODELS CONTINUE TO INDICATE AN UNSETTLED WEATHER PATTERN OVER THE UPPER MIDWEST THROUGH MID WEEK. ANOTHER IN A SERIES OF LONGWAVE TROUGH WILL AGAIN AMPLIFY OVER WESTERN U.S. BEFORE LIFTING NORTH OVER THE UPPER MIDWEST...WITH ANOTHER ROUND OF STRONG TO SEVERE STORMS EXPECTED...ESPECIALLY WEDNESDAY. MADE SOME CHANGES TO PREVIOUS FORECAST...RAISED TEMPS OVER THE NEXT FEW DAYS...BOTH MIN/MAX TEMPS AND INCREASE POPS OVER SOUTHWEST HALF OF CWA LATE SATURDAY NIGHT AND SUNDAY. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 915 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY) LATEST SATELLITE IMAGERY SHOWS LINGERING UPPER RIDGE OVER THE REGION...WHICH IS CONTINUING TO CUT OFF LOW LEVEL GULF MOISTURE ACROSS THE REGION. REMOVED PATCHY MORNING FOG IN THE SOUTH AND PUT IN A LITTLE MORE CLOUD COVER FOR PARTLY TO MOSTLY SUNNY SKIES FROM THE HIGH CLOUDS SPILLING IN FROM THE WEST. THE REST OF FORECAST APPEARS TO BE ON TRACK WITH TEMPERATURES QUICKLY RISING TO THE 70S BY NOON BEFORE REACHING THE LOWER 80S THIS AFTERNOON./17/ .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI/HBG FOR SATURDAY MORNING. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA FOR SATURDAY MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT./17/ && .PREVIOUS DISCUSSION...252 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY THROUGH SATURDAY)...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH SATURDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL NOSE INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW OVER BAJA. THIS LOW IS PROGGED TO MOVE TO THE NORTHEAST OVER THE FOUR CORNERS REGION DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO SPREAD OVERHEAD FROM THE WEST BUT WL BE WELL ABOVE NORMAL EACH DAY...IN THE LOWER 80S THIS AFTERNOON AND SATURDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)...THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA INTO MONDAY...CONTINUING TO DEFLECT POTENTIAL SHORTWAVE ENERGY. BY LATE MONDAY AND TUESDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION...THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. WITH PASSAGE OF THE TROUGH THE MID LEVEL RIDGE IS FORECAST TO REBUILD OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER. THERE ARE STILL INDICATIONS IN THE MODELS THAT A MORE ACTIVE PATTERN WILL TAKE SHAPE OVER THE LOWER MS VALLEY REGION BY NEXT FRIDAY AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS AND FORCE A BREAKDOWN OF THE RIDGE. THE GFS/ ECMWF ARE CONSISTENT IN SHOWING THIS BREAK-DOWN...AND WILL KEEP THE CHANCE POPS OFFERED BY MEX MOS. /EC/ && .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI THIS MORNING AND AGAIN SATURDAY MORNING. IFR CONDITIONS ARE EXPECTED TO DEVELOP AROUND 11Z AT HBG AGAIN THIS MORNING AND SATURDAY MORNINGS. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA EACH MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 82 54 84 55 / 2 2 3 3 MERIDIAN 83 52 85 54 / 2 2 2 2 VICKSBURG 82 56 84 57 / 3 2 3 3 HATTIESBURG 82 54 84 54 / 3 2 2 5 NATCHEZ 81 56 83 58 / 3 2 3 4 GREENVILLE 81 57 83 57 / 7 2 3 3 GREENWOOD 83 56 85 57 / 6 2 3 3 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 915 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY) LATEST SATELLITE IMAGERY SHOWS LINGERING UPPER RIDGE OVER THE REGION...WHICH IS CONTINUING TO CUT OFF LOW LEVEL GULF MOISTURE ACROSS THE REGION. REMOVED PATCHY MORNING FOG IN THE SOUTH AND PUT IN A LITTLE MORE CLOUD COVER FOR PARTLY TO MOSTLY SUNNY SKIES FROM THE HIGH CLOUDS SPILLING IN FROM THE WEST. THE REST OF FORECAST APPEARS TO BE ON TRACK WITH TEMPERATURES QUICKLY RISING TO THE 70S BY NOON BEFORE REACHING THE LOWER 80S THIS AFTERNOON./17/ .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI FOR SATURDAY MORNING. IFR CONDITIONS ARE EXPECTED TO DEVELOP AROUND 11Z AT HBG FOR SATURDAY MORNING. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA FOR SATURDAY MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT./17/ && .PREVIOUS DISCUSSION...252 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY THROUGH SATURDAY)...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH SATURDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL NOSE INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW OVER BAJA. THIS LOW IS PROGGED TO MOVE TO THE NORTHEAST OVER THE FOUR CORNERS REGION DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO SPREAD OVERHEAD FROM THE WEST BUT WL BE WELL ABOVE NORMAL EACH DAY...IN THE LOWER 80S THIS AFTERNOON AND SATURDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)...THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA INTO MONDAY...CONTINUING TO DEFLECT POTENTIAL SHORTWAVE ENERGY. BY LATE MONDAY AND TUESDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION...THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. WITH PASSAGE OF THE TROUGH THE MID LEVEL RIDGE IS FORECAST TO REBUILD OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER. THERE ARE STILL INDICATIONS IN THE MODELS THAT A MORE ACTIVE PATTERN WILL TAKE SHAPE OVER THE LOWER MS VALLEY REGION BY NEXT FRIDAY AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS AND FORCE A BREAKDOWN OF THE RIDGE. THE GFS/ ECMWF ARE CONSISTENT IN SHOWING THIS BREAK-DOWN...AND WILL KEEP THE CHANCE POPS OFFERED BY MEX MOS. /EC/ && .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI THIS MORNING AND AGAIN SATURDAY MORNING. IFR CONDITIONS ARE EXPECTED TO DEVELOP AROUND 11Z AT HBG AGAIN THIS MORNING AND SATURDAY MORNINGS. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA EACH MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 82 54 84 55 / 2 2 3 3 MERIDIAN 83 52 85 54 / 2 2 2 2 VICKSBURG 82 56 84 57 / 3 2 3 3 HATTIESBURG 82 54 84 54 / 3 2 2 5 NATCHEZ 81 56 83 58 / 3 2 3 4 GREENVILLE 81 57 83 57 / 7 2 3 3 GREENWOOD 83 56 85 57 / 6 2 3 3 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 252 AM CDT FRI MAR 23 2007 .SHORT TERM...(TODAY THROUGH SATURDAY)...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH SATURDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL NOSE INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW OVER BAJA. THIS LOW IS PROGGED TO MOVE TO THE NORTHEAST OVER THE FOUR CORNERS REGION DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO SPREAD OVERHEAD FROM THE WEST BUT WL BE WELL ABOVE NORMAL EACH DAY...IN THE LOWER 80S THIS AFTERNOON AND SATURDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)...THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA INTO MONDAY...CONTINUING TO DEFLECT POTENTIAL SHORTWAVE ENERGY. BY LATE MONDAY AND TUESDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION...THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. WITH PASSAGE OF THE TROUGH THE MID LEVEL RIDGE IS FORECAST TO REBUILD OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER. THERE ARE STILL INDICATIONS IN THE MODELS THAT A MORE ACTIVE PATTERN WILL TAKE SHAPE OVER THE LOWER MS VALLEY REGION BY NEXT FRIDAY AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS AND FORCE A BREAKDOWN OF THE RIDGE. THE GFS/ ECMWF ARE CONSISTENT IN SHOWING THIS BREAK-DOWN...AND WILL KEEP THE CHANCE POPS OFFERED BY MEX MOS. /EC/ && .AVIATION...VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT GWO/GTR/GLH. MVFR VISIBILITIES MAY DEVELOP AROUND 11Z AT JAN/MEI THIS MORNING AND AGAIN SATURDAY MORNING. IFR CONDITIONS ARE EXPECTED TO DEVELOP AROUND 11Z AT HBG AGAIN THIS MORNING AND SATURDAY MORNINGS. AFTER 15Z...VFR CONDITIONS WILL PREVAIL ACROSS THE WHOLE AREA EACH MORNING. THERE MAY BE A SCT-BKN DECK DEVELOP EACH AFTERNOON...BUT CEILINGS WILL REMAIN WELL ABOVE 3KFT. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 82 54 84 55 / 2 2 3 3 MERIDIAN 83 52 85 54 / 2 2 2 2 VICKSBURG 82 56 84 57 / 3 2 3 3 HATTIESBURG 82 54 84 54 / 3 2 2 5 NATCHEZ 81 56 83 58 / 3 2 3 4 GREENVILLE 81 57 83 57 / 7 2 3 3 GREENWOOD 83 56 85 57 / 6 2 3 3 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 935 AM CDT THU MAR 22 2007 .SHORT TERM...LATEST SATELLITE IMAGERY SHOWS THE REGION UNDER AN UPPER RIDGE...WHICH IS CONTINUING OUR LONG ROUND OF DRY WEATHER. SHOULD GET SOME SCATTERED CLOUDS MOSTLY IN THE FORM OF HIGH LEVEL CLOUDS FOR THIS AFTERNOON. THE FOG HAS LIFTED OVER OUR THE SOUTHEAST ZONES...SO HAVE ALLOWED THE DENSE FOG ADVISORY TO EXPIRE. CURRENT HIGHS IN THE LOWER 80S SEEMS TO BE ON TRACK. SO WILL MAKE NO OTHER CHANGES TO THE ZONES./17/ .AVIATION...PATCHES OF LIFR CIGS/VSBY WILL BE POSSIBLE IN AREAS ALONG AND S OF HIGHWAY 84 FOR FRIDAY MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME AREAWIDE BY 15Z FRIDAY./17/ .PREVIOUS DISCUSSION... TODAY THROUGH FRIDAY...GRADIENT WINDS HAVE CONTINUED OVER MUCH OF CWA THIS MORNING WITH THE EXCEPTION OF SOUTHEAST MISSISSIPPI LAST HOUR. PINE BELT AIRPORT WAS REPORTING VISIBILITY RESTRICTIONS ALREADY. WL CONTINUE TO MONITOR OUR SOUTHEAST ZONES FOR AN ADVISORY AGAIN THIS MORNING...BUT CURRENTLY EXPECTING ANY DENSE FOG DEVELOPMENT TO REMAIN PATCHY. ELSE...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH FRIDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL BUILD INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW DROPPING SOUTH OFF THE SOUTHERN CALIFORNIA COAST. THIS LOW IS PROGGED TO MOVE OVER BAJA DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. SOME MID AND HIGH LEVEL CLOUDS WILL SPREAD OVERHEAD FROM THE WEST BUT WL STILL REACH WELL ABOVE NORMAL...AROUND 80 DEGREES THIS AFTERNOON AND FRIDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ FRIDAY NIGHT THROUGH NEXT WEEK... THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA THIS WEEKEND...TENDING TO DEFLECT ANY POTENTIAL SHORTWAVE TROUGHS. WITH THAT IN MIND...THE GFS SEEMS A LITTLE TOO QUICK IN INCREASING RAIN CHANCES SUNDAY AND SUNDAY NIGHT AND WILL KEEP THE FORECAST DRY. BY MONDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION... THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. THE MID LEVEL RIDGE REBUILDS OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER FOR THE FORECAST AREA. THERE ARE INDICATIONS THAT A MORE ACTIVE PATTERN COULD TAKE SHAPE OVER THE LOWER MS VALLEY REGION NEXT WEEKEND AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS. THE GFS/UKMET/ECMWF ARE ALL IN AGREEMENT ON THIS SCENARIO...BUT PERSISTENCE CERTAINLY ARGUES AGAINST IT. /EC/ .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 230 AM CDT THU MAR 22 2007 .DISCUSSION... TODAY THROUGH FRIDAY...GRADIENT WINDS HAVE CONTINUED OVER MUCH OF CWA THIS MORNING WITH THE EXCEPTION OF SOUTHEAST MISSISSIPPI LAST HOUR. PINE BELT AIRPORT WAS REPORTING VISIBILITY RESTRICTIONS ALREADY. WL CONTINUE TO MONITOR OUR SOUTHEAST ZONES FOR AN ADVISORY AGAIN THIS MORNING...BUT CURRENTLY EXPECTING ANY DENSE FOG DEVELOPMENT TO REMAIN PATCHY. ELSE...WARM TEMPERATURES AND DRY WEATHER WILL CONTINUE THROUGH FRIDAY. AT THE SURFACE AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE FROM THE ATLANTIC WILL BE OVER THE SOUTHEAST STATES MAINTAINING SOUTHEAST TO SOUTH LOW LEVEL FLOW OVER OUR CWA. ALOFT HIGH PRESSURE OVER THE WESTERN GULF WILL BUILD INLAND OVER OUR CWA AS WELL. LATEST SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUT OFF LOW DROPPING SOUTH OFF THE SOUTHERN CALIFORNIA COAST. THIS LOW IS PROGGED TO MOVE OVER BAJA DURING THE NEXT 36HRS AND HELP STRENGTHEN THE RIDGING IN THE WESTERN GULF. THE RIDGING SURFACE AND ALOFT OVER OUR CWA WILL HELP KEEP THE PRECIPITATION OCCURRING OVER THE SOUTHERN PLAINS TO OUR WEST. SOME MID AND HIGH LEVEL CLOUDS WILL SPREAD OVERHEAD FROM THE WEST BUT WL STILL REACH WELL ABOVE NORMAL...AROUND 80 DEGREES THIS AFTERNOON AND FRIDAY AT MOST SITES. OVERNIGHT LOWS WILL BE ABOVE NORMAL AS WELL TONIGHT WITH MOST SITES BOTTOMING OUT IN THE LOW TO MID 50S. /22/ FRIDAY NIGHT THROUGH NEXT WEEK... THE MID LEVEL RIDGE WILL HOLD TOUGH OVER THE FORECAST AREA THIS WEEKEND...TENDING TO DEFLECT ANY POTENTIAL SHORTWAVE TROUGHS. WITH THAT IN MIND...THE GFS SEEMS A LITTLE TOO QUICK IN INCREASING RAIN CHANCES SUNDAY AND SUNDAY NIGHT AND WILL KEEP THE FORECAST DRY. BY MONDAY...THE RIDGE IS FORECAST TO BREAK DOWN ENOUGH TO ALLOW DEEPER MOISTURE TO MOVE IN...AND WITH THE APPROACH OF A SRN STREAM PERTURBATION... THE CHANCE POPS INDICATED BY GFS MOS SEEM REASONABLE. THE MID LEVEL RIDGE REBUILDS OVER THE AREA FOR THE MID WEEK BRINGING A RETURN TO WARM AND DRY WEATHER FOR THE FORECAST AREA. THERE ARE INDICATIONS THAT A MORE ACTIVE PATTERN COULD TAKE SHAPE OVER THE LOWER MS VALLEY REGION NEXT WEEKEND AS STRONG WESTERLIES CARVE OUT A TROUGH OVER THE WRN/CNTRL CONUS. THE GFS/UKMET/ECMWF ARE ALL IN AGREEMENT ON THIS SCENARIO...BUT PERSISTENCE CERTAINLY ARGUES AGAINST IT. /EC/ && .AVIATION...PATCHES OF LIFR CIG/VSBY WILL BE POSSIBLE IN AREAS ALONG AND S OF HIGHWAY 84 THIS MORNING AND AGAIN FRIDAY MORNING. VFR CONDITIONS ARE EXPECTED TO RESUME AREAWIDE BY 15Z EACH MORNING. /22/ && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM: 22 LONG TERM: EC ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 414 PM CDT FRI MAR 23 2007 .DISCUSSION (FRI THROUGH SUN)... MOST OF THE PRECIP HAS NOW EXITED THE CWA THIS AFTERNOON WITH THE COMPLEX OF STORMS ACROSS SOUTHEASTERN KANSAS INTO CENTRAL MISSOURI NOW TRAINING JUST SOUTH OF LINN/BUTLER/BATES COUNTIES. A FEW LIGHT SHOWERS JUST NORTH OF THE KC METRO AREA WITH A FEW ADDITIONAL SHOWERS TRAILING BACK FURTHER WEST TOWARDS TOPEKA. THIS ACTIVITY APPEARS TO BE ASSOCIATED WITH A WEAK DISTURBANCE NEAR H7 AS NOTED VIA RUC MOISTURE PROG. AS THIS SPREADS EASTWARD...MAY SEE A FEW ADDITIONAL SHOWERS DEVELOP ACROSS NE KS AND NW MO THROUGH THE REMAINDER OF THE AFTERNOON. STATIONARY FRONTAL BOUNDARY NOW LOCATED NEAR OR JUST NORTH OF THE MO/IA BORDER THIS AFTERNOON WITH SOME BREAKS IN THE CLOUD DECK NOTED VIA VIS SATELLITE NEAR THE BOUNDARY. MODEL CONSENSUS KEEPS HIGHEST QPF CLOSER TO THE FRONT OVERNIGHT COINCIDENT WITH HIGHER LOW LEVEL MOISTURE CONTENT AND SOMEWHAT STRONGER 295-300K ISENTROPIC ASCENT. HOWEVER...APPEARS CORE OF LLJ WILL REMAIN SOUTH AND WEST OF THE AREA ACROSS THE SOUTHERN PLAINS WITH AFOREMENTIONED BOUNDARY MORE DIFFUSE OVERNIGHT. NONETHELESS...HAVE EDGED POPS UP ACROSS THE AREA WITH HIGHER AMOUNTS ACROSS THE NORTHERN COUNTIES...ALTHOUGH CONFIDENCE IS NOT HIGH WITH REGARDS TO PRECIP PLACEMENT. ATTENTION THEN TURNS TO MAIN UPPER LEVEL LOW AS IT EJECTS ACROSS THE CENTRAL PLAINS THIS WEEKEND. TOUGH TO GAGE PRECIP EPISODES WITH SEVERAL WAVES EMBEDDED WITHIN SOUTHWESTERLY FLOW. 60KT H5 JET PROGGED TO EMERGE ACROSS CENTRAL KS TOMORROW AFTERNOON AND EVENING. BELIEVE STRONGEST CONVECTIVE ACTIVITY WILL REMAIN TO OUR WEST CLOSER TO STRONGER JET DYNAMICS. HOWEVER...DEPENDING ON AMOUNT OF HEATING RECEIVED TOMORROW AFTERNOON...CANNOT RULE OUT THUNDERSTORM ACTIVITY DEVELOPING ALONG AND SOUTH OF OLD BOUNDARY. UPPER LOW TO THEN SWING INTO NORTH CENTRAL NE AND SOUTH CENTRAL SD BY SUNDAY MORNING. MODELS DIFFER A BIT ON PLACEMENT OF JET DURING THE AFTERNOON. HOWEVER...APPEARS JET AXIS WILL ALIGN FROM CENTRAL IA SOUTHWARD INTO NORTHERN MISSOURI. AS THIS OCCURS...DRYLINE WILL PUSH INTO EASTERN KS DURING THE AFTERNOON SUNDAY AND ACT AS THE FOCUS FOR THUNDERSTORM DEVELOPMENT. STILL A BIT FAR OUT...BUT IF DYNAMICS COME TOGETHER AND SUFFICIENT THERMODYNAMICS ARE REALIZED...SOME SEVERE ACTIVITY WILL BE POSSIBLE. OTHERWISE...WILL CONTINUE WITH WARM MOIST PATTERN AS SOUTHERN FLOW CONTINUES WITH THE BOUNDARY REMAINING TO THE NORTH. DEROCHE EXTENDED DISCUSSION (MON THROUGH FRI)... THE UNSETTLED WEATHER PATTERN LOOKS TO PERSIST THROUGH NEXT WEEK. SEGMENTS OF THE MID/UPPER TROUGH WILL CONTINUE TO EJECT NORTHEAST OVER THE EASTERN RIDGE EARLY NEXT WEEK. MEANWHILE THE ASSOCIATED MID/UPPER WEAKNESS WILL TRACK EAST ACROSS THE SOUTHERN/GULF STATES. THE FORECAST AREA WILL BE BETWEEN THESE TWO PORTIONS OF THE UPPER SYSTEM...WITH RELATIVELY WEAK/ELONGATED SHORTWAVE ENERGY ADVANCING ACROSS THE AREA. AS A RESULT...HAVE CONTINUED LOW END SHOWER AND THUNDERSTORM CHANCES ON MONDAY OF NEXT WEEK. UNSEASONABLY WARM TEMPERATURES WILL CONTINUE THROUGH MID WEEK NEXT WEEK...WITH SHORTWAVE RIDGING PROGRESSING ACROSS THE MIDWEST. ANOTHER MID/UPPER TROUGH WILL ENTER THE WESTERN CONUS EARLY NEXT WEEK...AND IS EXPECTED TO EVENTUALLY LIFT NORTHEAST ACROSS THE ROCKIES AND TOWARD THE NORTHERN PLAINS. THE ATTENDANT SURFACE COLD FRONT IS FORECAST TO REACH THIS FORECAST AREA LATE WEDNESDAY INTO THURSDAY...AND BRING AN INCREASED CHANCE FOR MORE SHOWER AND THUNDERSTORM ACTIVITY. STOFLET AVIATION... MOST OF THE MORNING SHOWER ACTIVITY HAS EXITED THE TAF SITES AND IS NOW MAINLY CONFINED ALONG AND SOUTH OF A PLEASANTON TO SEDALIA LINE. OTHER CONCERN IS WITH LOW CLOUD DECK EXTENDING FROM SOUTHEAST KS INTO NORTHEAST MISSOURI. WITH FETCH OF LOW LEVEL MOISTURE CONTINUING THROUGH THE EARLY AFTERNOON...CURRENT THINKING IS THAT CLOUD DECK SHOULD STICK AROUND THROUGH THE SHORT TERM. DAYTIME HEATING HAS ALLOWED SOME BREAKS FURTHER NORTH ACROSS NORTHEAST KS AND SOUTHEAST NB WITH HIGHER CEILINGS ACROSS NORTHERN MO. THEREFORE...DECIDED TO BRING IN A BIT HIGHER CEILINGS BY MID AFTERNOON AS SOME MIXING TAKES SHAPE. HOWEVER...WILL HAVE TO KEEP AN EYE ON THINGS AS VARIANCE OF CLOUD DECK AND EXTENT OF MIXING REMAINS IN QUESTION. IN ADDITION...FAIRLY ACTIVE PATTERN COUNTING WITH CONTINUING DIFFICULTY IN PINPOINTING EXACT TIMING OF PRECIP. LEFT MENTION OUT ATTM WITH LOW CONFIDENCE AND WILL CONTINUE TO MONITOR FOR ANY UPSTREAM DEVELOPMENT. HOWEVER...CURRENT THINKING IS THAT PRECIP CHANCES WILL REMAIN LOW THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING WITH HIGHER CHANCES DEVELOPING DURING THE MORNING HOURS. DEROCHE && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 215 PM CDT FRI MAR 23 2007 .DISCUSSION... CONVECTION CONTINUES TO EXPAND WITH THE ORIENTATION SHIFTING MORE WEST TO EAST. DECENT LOW LEVEL MOISTURE TRANSPORT CONTINUES TO FEED INTO BROAD DIFFLUENCE ALOFT AHEAD OF A MID LEVEL SHEAR AXIS. ORIGINATION POINT OF CONVECTION IN SE KS/NE OK HAS SHIFTED VERY LITTLE OVER THE PAST SEVERAL HOURS. WHAT WAS ONCE A SW TO NE ORIENTATION HAS SHIFTED A BIT MORE TOWARDS A W-E AXIS...PARTIALLY DUE TO A SLIGHT VEER IN THE 925/850MB WIND DIRECTIONS PER THE LATEST RUC INITIALIZATIONS. PRECIPITATION CHANCES TONIGHT WILL BE TIED MAINLY TO THE EVOLUTION AND MOVEMENT OF THE ONGOING CONVECTION. GIVEN MOIST ENVIRONMENT... GOOD SUPPORT ALOFT GIVEN UPPER DIFFLUENCE AND THE MID LEVEL SHEAR AXIS...HAVE OPTED TO EXPAND CATEGORICAL POPS EASTWARD AND NORTHWARD. GAGAN/FOSTER NOT MUCH CHANGE IN THE OVERALL PATTERN AS WE HEAD INTO THE WEEKEND. OUR REGION WILL REMAIN UNDER THE INFLUENCE OF A DEEP SOUTHWESTERLY FLOW BETWEEN AN UPPER RIDGE ANCHORED OVER THE SOUTHEASTERN U.S. AND CUT OFF LOW OVER THE DESERT SOUTHWEST. THE UPPER LOW IN THE SOUTHWEST U.S. WILL LIFT NORTH NORTHEAST AROUND THE PERIPHERY OF THE RIDGE THIS WEEKEND. THIS WILL INDUCE THE DEVELOPMENT OF A SURFACE LOW ACROSS THE HIGH PLAINS. AS A RESULT A WARM FRONT WILL DEVELOP OR STRENGTHEN WHICH WE MAY BE SEEING THE ORIGINS NOW ACROSS SOUTHERN MISSOURI. MODELS HAVE TRENDED STRONGER WITH UPPER RIDGING INTO THE OZARKS THIS WEEKEND AND THUS KEEP PRECIPITATION CHANCES MAINLY TO THE WEST OF THE AREA. ALL OF THE OZARKS REGION AND OSAGE PLAINS WILL BE ENVELOPED BY THE WARM SECTOR SATURDAY AND SUNDAY. MORE SUNSHINE AND INCREASING SOUTHERLY FLOW SHOULD PUSH TEMPERATURES TO AROUND 80 DEGREES. IF NEAR FULL SUNSHINE DEVELOPS WOULD NOT BE SURPRISED TO SEE LOWER OR EVEN MIDDLE 80S IN A FEW SPOTS. NEXT IN SERIES OF SHORTWAVES WILL LIFT NORTHEAST TOWARD THE AREA EARLY NEXT WEEK PROVIDING A CHANCE OF SCATTERED CONVECTION. BETTER CHANCES OF THUNDERSTORMS WILL ARRIVE LATER WEDNESDAY OR THURSDAY OF NEXT WEEK AS A MORE SIGNIFICANT UPPER TROUGH SWINGS EAST ACROSS THE ROCKIES. FOSTER && .AVIATION... FOR THE 18Z TAF PACKAGE...PRIMARY CONCERNS REVOLVE AROUND CONVECTION FOR THIS AFTERNOON. RAINFALL HAS QUICKLY EXPANDED EASTWARD...COMING IN ABOUT AN HOUR EARLIER THAN EXPECTED AT SGF. RADAR TRENDS AND SHORT TERM FORECAST GUIDANCE SUGGESTS THAT THE CORRIDOR FROM JLN TO SGF WILL BE IN FOR A WET AFTERNOON. PERIODS OF SHRA/TSRA ARE EXPECTED. CIG/VIS WILL FLUCTUATE FROM VFR TO MVFR WITH THE PASSAGE OF MORE SUBSTANTIAL CELLS/DOWNPOURS. FREQUENT LIGHTNING IS ALSO EXPECTED. TIMING THE ENDING OF THIS RAINFALL IS PROVING PROBLEMATIC AND HAVE KEPT PREDOMINATE TSRA AT BOTH JLN AND SGF THROUGH THE LATE AFTERNOON. WILL MONITOR RADAR TRENDS TO SEE IF THE WEST TO EAST AXIS OF SHRA/TSRA BEGINS TO SHIFT NORTH/EAST. AFTER THE RAIN ENDS...GENERALLY VFR CONDITIONS ARE EXPECTED. SUBSEQUENT TAFS WILL NEED TO MONITOR THE POTENTIAL FOR LIGHT FOG IN THE WAKE OF THIS RAINFALL. AT THIS POINT...CONTINUED 30-40KT WINDS IN THE LOW LEVELS JUST OFF THE SFC WOULD LIKELY PRECLUDE THIS FROM OCCURRING. GUSTY WINDS ARE EXPECTED TO DEVELOP SATURDAY MORNING AS MIXING BEGINS. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO SGF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1245 PM CDT FRI MAR 23 2007 .UPDATE... CONVECTION CONTINUES TO EXPAND WITH THE ORIENTATION SHIFTING MORE WEST TO EAST. HAVE ONCE AGAIN UPDATED THE FORECAST TO ACCOUNT FOR THE LATEST RADAR TRENDS. DECENT LOW LEVEL MOISTURE TRANSPORT CONTINUES TO FEED INTO BROAD DIFFLUENCE ALOFT AHEAD OF A MID LEVEL SHEAR AXIS. ORIGINATION POINT OF CONVECTION IN SE KS/NE OK HAS SHIFTED VERY LITTLE OVER THE PAST SEVERAL HOURS. WHAT WAS ONCE A SW TO NE ORIENTATION HAS SHIFTED A BIT MORE TOWARDS A W-E AXIS...PARTIALLY DUE TO A SLIGHT VEER IN THE 925/850MB WIND DIRECTIONS PER THE LATEST RUC INITIALIZATIONS. THE HEAVIEST RAINFALL CONTINUES FROM CHEROKEE COUNTY INTO LAWRENCE COUNTY. STREET FLOODING HAS BEEN REPORTED IN THE PAST HALF HOUR VIA CHEROKEE EMERGENCY MGMT AND WITH HEAVY RAINFALL CONTINUING FOR THE NEXT FEW HOURS REPORTS SUCH AS THESE ARE EXPECTED TO INCREASE. WILL ALTER ORIENTATION OF POTENTIAL FLOODING IN THE HWO WITH THE 100PM ISSUANCE TO INCLUDE AREAS FROM CHEROKEE COUNTY THROUGH GREENE COUNTY WITH HEAVY RAINFALL ELSEWHERE. GIVEN MOIST ENVIRONMENT...GOOD SUPPORT ALOFT GIVEN UPPER DIFFLUENCE AND THE MID LEVEL SHEAR AXIS...HAVE OPTED TO EXPAND CATEGORICAL POPS EASTWARD. LOOKS LIKE A WET AFTERNOON. GAGAN && .PREVIOUS DISCUSSION... //1055 AM CDT FRI MAR 23 2007// FORECAST UPDATED TO ACCOUNT FOR THE LATEST RADAR TRENDS. AXIS OF SHRA/TSRA HAS DEVELOPED ALONG A MID/UPPER LEVEL SHEAR AXIS EXTENDING FROM NE MO THROUGH SE KS AND INTO NE TX. DECENT MOISTURE TRANSPORT IS NOTED IN THE LOW LEVELS OF THE ATMOSPHERE...WITH THETA-E RIDGING TO THE TUNE OF 328K NOSING INTO WEST CENTRAL MISSOURI. THE MOST CONCENTRATED AREAS OF SHRA/TSRA CURRENTLY RESIDES OVER JASPER COUNTY MO AND CHEROKEE COUNTY MO. ADDITIONAL...MORE SCATTERED ACTIVITY EXTENDS FARTHER EAST ON THE NE PERIPHERY OF THE BEST LOW LEVEL MOISTURE TRANSPORT VECTORS (AS VIEWED THROUGH THE LATEST RUC INITIALIZATIONS). WITH PWS FROM THE MORNING KSGF SOUNDING AROUND 1.15 INCHES AND KIS IN EXCESS OF 30...THIS ACTIVITY WILL BE EFFICIENT IN RAINFALL PRODUCTION. METARS ACROSS SE KS CORRELATE WELL TO 1-HR RAINFALL RATES. WITH THE RADAR CURRENTLY INDICATING HOURLY RAINFALL AMOUNTS BETWEEN ONE AND TWO INCHES...A FLASH FLOOD THREAT EXISTS. THE PRIMARY CONCERN REMAINS EXTREME SE KS AND WESTERN MO WHERE FLASH FLOOD GUIDANCE VALUES REMAIN LOW FROM RECENT RAINS. INDICATIONS ARE THAT WHILE THIS AREA OF RAINFALL WILL REMAIN ELONGATED AND RATHER NARROW...THE SLOW MOVEMENT OF THE SHEAR AXIS WILL PROMOTE TRAINING CONVECTION IN AN AREA WITH LOWER TOLERANCE FOR HEAVY RAINFALL AMOUNTS. ALL PRODUCTS HAVE BEEN UPDATED AND SENT. && .AVIATION... FOR THE 18Z TAF PACKAGE...PRIMARY CONCERNS REVOLVE AROUND CONVECTION FOR THIS AFTERNOON. RAINFALL HAS QUICKLY EXPANDED EASTWARD...COMING IN ABOUT AN HOUR EARLIER THAN EXPECTED AT SGF. RADAR TRENDS AND SHORT TERM FORECAST GUIDANCE SUGGESTS THAT THE CORRIDOR FROM JLN TO SGF WILL BE IN FOR A WET AFTERNOON. PERIODS OF SHRA/TSRA ARE EXPECTED. CIG/VIS WILL FLUCTUATE FROM VFR TO MVFR WITH THE PASSAGE OF MORE SUBSTANTIAL CELLS/DOWNPOURS. FREQUENT LIGHTNING IS ALSO EXPECTED. TIMING THE ENDING OF THIS RAINFALL IS PROVING PROBLEMATIC AND HAVE KEPT PREDOMINATE TSRA AT BOTH JLN AND SGF THROUGH THE LATE AFTERNOON. WILL MONITOR RADAR TRENDS TO SEE IF THE WEST TO EAST AXIS OF SHRA/TSRA BEGINS TO SHIFT NORTH/EAST. AFTER THE RAIN ENDS...GENERALLY VFR CONDITIONS ARE EXPECTED. SUBSEQUENT TAFS WILL NEED TO MONITOR THE POTENTIAL FOR LIGHT FOG IN THE WAKE OF THIS RAINFALL. AT THIS POINT...CONTINUED 30-40KT WINDS IN THE LOW LEVELS JUST OFF THE SFC WOULD LIKELY PRECLUDE THIS FROM OCCURRING. GUSTY WINDS ARE EXPECTED TO DEVELOP SATURDAY MORNING AS MIXING BEGINS. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO SGF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1055 AM CDT FRI MAR 23 2007 .UPDATE... FORECAST UPDATED TO ACCOUNT FOR THE LATEST RADAR TRENDS. AXIS OF SHRA/TSRA HAS DEVELOPED ALONG A MID/UPPER LEVEL SHEAR AXIS EXTENDING FROM NE MO THROUGH SE KS AND INTO NE TX. DECENT MOISTURE TRANSPORT IS NOTED IN THE LOW LEVELS OF THE ATMOSPHERE...WITH THETA-E RIDGING TO THE TUNE OF 328K NOSING INTO WEST CENTRAL MISSOURI. THE MOST CONCENTRATED AREAS OF SHRA/TSRA CURRENTLY RESIDES OVER JASPER COUNTY MO AND CHEROKEE COUNTY MO. ADDITIONAL...MORE SCATTERED ACTIVITY EXTENDS FARTHER EAST ON THE NE PERIPHERY OF THE BEST LOW LEVEL MOISTURE TRANSPORT VECTORS (AS VIEWED THROUGH THE LATEST RUC INITIALIZATIONS). WITH PWS FROM THE MORNING KSGF SOUNDING AROUND 1.15 INCHES AND KIS IN EXCESS OF 30...THIS ACTIVITY WILL BE EFFICIENT IN RAINFALL PRODUCTION. METARS ACROSS SE KS CORRELATE WELL TO 1-HR RAINFALL RATES. WITH THE RADAR CURRENTLY INDICATING HOURLY RAINFALL AMOUNTS BETWEEN ONE AND TWO INCHES...A FLASH FLOOD THREAT EXISTS. THE PRIMARY CONCERN REMAINS EXTREME SE KS AND WESTERN MO WHERE FLASH FLOOD GUIDANCE VALUES REMAIN LOW FROM RECENT RAINS. INDICATIONS ARE THAT WHILE THIS AREA OF RAINFALL WILL REMAIN ELONGATED AND RATHER NARROW...THE SLOW MOVEMENT OF THE SHEAR AXIS WILL PROMOTE TRAINING CONVECTION IN AN AREA WITH LOWER TOLERANCE FOR HEAVY RAINFALL AMOUNTS. ALL PRODUCTS HAVE BEEN UPDATED AND SENT. GAGAN && .PREVIOUS DISCUSSION... //303 AM CDT FRI MAR 23 2007// THE UNSEASONABLY WARM AND UNSETTLED PATTERN WILL PERSIST THROUGH MUCH OF THE SEVEN DAY FORECAST PERIOD. UNUSUAL FOR THE TIME OF YEAR...NO COLD FRONTS OR MAJOR WEATHER SYSTEMS ARE EXPECTED TO PASS OVERHEAD. HOWEVER...DUE TO AN EXTENDED PERIOD OF GULF INFLUX...SCATTERED CLUSTERS OF SHOWERS AND THUNDERSTORMS ARE IN THE OFFING FOR THE NEXT SEVERAL DAYS. THEREFORE...THE PRIMARY FORECAST CONCERN IN THIS MORNINGS ANALYSIS WAS PRECIP CHANCES IN BOTH THE SHORT AND LONG TERM TIME FRAMES. ONE ITEM TO NOTE...BECAUSE OF EAST TO NORTHEAST FLOW OVER MUCH OF THE GULF OF MEXICO...A RATHER HOMOGENEOUS AIRMASS WILL CONTINUE FROM THE GULF INTO MID AMERICA. DRY ADVECTION FROM THE ATLANTIC REGIONS CONTINUE TO LIMIT DEEP RICH MOISTURE FROM MATERIALIZING WITHIN THE WESTERN GULF SOURCE REGION. THEREFORE...DESPITE THE LONG PERIOD OF SOUTHERLY FLOW...INSTABILITY WILL REMAIN UNUSUALLY LIMITED FOR STRONG TO SEVERE CONVECTION THE NEXT FEW DAYS. SHORT TERM (TODAY - SUNDAY NIGHT)... A SYNOPTIC SCALE CYCLONE CENTERED OVER THE BAJA OF CALIFORNIA CONTINUES TO INFLUENCE THE OVERALL PATTERN OVER THE SOUTHERN PLAINS AND MISSOURI OZARKS REGION. A BELT OF SUBTROPICAL MOISTURE EXTENDS AROUND THE EASTERN FLANK OF THE CYCLONE...AND IS CORRELATED WITH LARGE SCALE LIFT MAINLY IN THE FORM OF JET STREAM LEVEL DIFFLUENCE. A FEW CLUSTERS OF CONVECTION WITHIN THE PACIFIC MOISTURE PLUME APPEAR TO BE CORRELATED WITH ENHANCED AREAS OF UPPER LEVEL DIFFLUENCE...WHICH IS VERIFIED BY THE SOUTHERN PLAINS PROFILER NETWORK WHEN ANALYZING 250 MB WIND VECTOR MEASUREMENTS. ONE OF THESE CONVECTIVE CLUSTERS IS CURRENTLY IMPACTING EXTREME SOUTHEAST KANSAS AND SOUTHWEST MISSOURI. DUE TO LIMITED INSTABILITY...THE PRIMARY HAZARDS WITH THIS CLUSTER APPEARS TO BE MODERATE TO HEAVY RAIN...ALONG WITH A FEW CLOUD TO GROUND LIGHTNING STRIKES. TIMING OF THIS CONVECTIVE CLUSTER AND HOW IT EVOLVES WITH RESPECT TO AREAL COVERAGE WAS THE INITIAL FORECAST CONCERN FOR TODAYS PERIOD. EXTRAPOLATION WITH THE CLUSTERS CURRENT MOVEMENT SUGGESTS THAT AFTER 12Z...THE PRECIPITATION SHIELD WILL BE OVER MUCH OF SOUTH CENTRAL AND CENTRAL MISSOURI. RAIN WILL LIKELY END IN THE SPRINGFIELD METRO AREA SOMETIME BETWEEN 6 - 8AM. THEREFORE WILL ADJUST MORNING POPS TO REPRESENT THIS EXTRAPOLATION...WITH LIKELY TO CATEGORICAL POPS OVER THE EASTERN HALF OF THE CWA...THEN TAPERING THE GRID TO SLIGHT CHANCES OUT WEST. IT`S LIKELY THAT THE CLUSTER WILL LOSE SOME OF IT`S LOW LEVEL FORCING WITH NOCTURNAL VEERING OF LOW LEVEL WINDS. BOTH THE WRF AND THE GFS INDICATE A SECOND CLUSTER OF CONVECTION TO IMPACT THE OZARKS THIS AFTERNOON. AGAIN...THE ONLY KINEMATIC MECHANISM TO CAUSE THIS APPEARS TO BE AN AREA OF ENHANCED UPPER DIFFLUENCE CURRENTLY BECOMING MORE ORGANIZED NEAR ABILENE TEXAS. HOW THIS FORECASTED BAND OF FORCING WILL IMPACT THE OZARKS REMAINS VERY QUESTIONABLE. QPF FIELDS FROM THE WRF AND GFS ARE VERY INCONSISTENT AND NOT IMPRESSIVE AT ALL. HOWEVER MOS GUIDANCE SUGGEST CATEGORICAL POPS IN ALL LOCATIONS. WILL ADJUST THE AFTERNOON POP GRID TO 50 POPS DUE TO THE UNCERTAINTY ON HOW THIS EVOLVES. ONE ELEMENT THAT WE DO KNOW FOR SURE IS THAT CONSIDERABLE CLOUD COVER WILL EXIST THROUGH THE ENTIRE DAY...WHICH WILL HAVE SOME IMPACTS ON TEMPERATURES. WITH EARLY MORNING TEMPERATURES STARTING OUT IN THE LOW TO MID 60S...DESPITE CLOUD COVER AND PRECIP READINGS SHOULD WARM INTO THE 70S IN MOST LOCATIONS. HEADING INTO THE WEEKEND...THE BAJA LOW WILL FILL WHILE THE MAIN CIRCULATION SHIFTS INTO THE HIGH PLAINS. MASS AND MOISTURE FIELDS FROM THE GFS INDICATE THAT THE AXIS OF SUBTROPICAL MOISTURE SHIFTS EAST OF THE CWA...HOWEVER...LOW LEVEL JET AND WARM CONVEYOR BELT PROCESSES OCCUR BY SATURDAY MORNING. THIS WILL YIELD MORE AREAS OF CONVECTIVE CLUSTERS SOMEWHERE ALONG THE SOUTHERN/CENTRAL PLAINS CORRIDOR. RESIDUAL CLUSTERS WILL LIKELY SHIFT EASTWARD DURING THE DAY ON SATURDAY...POSSIBLY IMPACTING THE CWA. WILL KEEP ONGOING THUNDERSTORM CHANCES GOING IN THE GRIDS DUE TO SIGNALS FROM BOTH THE GFS AND WRF FOR INCREASED INSTABILITY WITHIN THIS PERIOD. NOT MUCH CHANGE IN THE LARGE SCALE PATTERN CAN BE ANALYZED WITHIN MODEL DATA. THEREFORE SINCE WE WILL REMAIN UNDER THIS EXTENDED WARM/MOISTURE ADVECTION REGIME...WILL KEEP THUNDERSTORM CHANCES GOING THROUGH SUNDAY NIGHT. LONG TERM (MONDAY - THURSDAY)... AN UPPER LEVEL WEAKNESS...BASICALLY THE RESIDUAL TROUGHING FROM THE ONGOING BAJA CYCLONE IS SUGGESTED TO GRADUALLY PASS THROUGH THE AREA MONDAY OR TUESDAY. NOT MUCH OF A RESPONSE OCCURS AT THE SURFACE AS THE OZARKS REMAINS UNDER SOUTHERN FLOW. COOLING ALOFT MAY PROMOTE INCREASED INSTABILITY...ESPECIALLY TUESDAY AFTERNOON. WILL KEEP ONGOING TSTORM CHANCES ON TUESDAY LOOK GOOD AND MADE LITTLE CHANGE. MEDIUM RANGE MODELS INDICATE THAT LONG WAVE TROUGHING WILL REDEVELOP ACROSS THE WESTERN THIRD OF THE CONUS. THIS WILL REINFORCE THE UNSETTLED PATTERN AND OFFER A CONTINUATION OF UNSEASONABLY WARM TEMPERATURES. I MADE A FEW ADJUSTMENTS TO TEMPERATURES BY WARMING THESE GRIDS BY SEVERAL DEGREES IN THE EXTENDED. ECMWF HAS BEEN PERFORMING THE BEST OVER THE PAST FEW WEEKS...WHICH SHOWS ENERGY APPROACHING THE NATIONS MID SECTION BY THURSDAY. THE GFS IS NOT MUCH DIFFERENT WITH A SIMILAR SOLUTION. THEREFORE NO ADJUSTMENTS TO THESE ONGOING THUNDERSTORM CHANCES WERE NEEDED. CRAMER && .AVIATION... TAF SITES WERE AMENDED EARLIER TO GAUGE RAINFALL/TS TIMING. IT APPEARS THAT CIGS/VIS WILL WAVER FROM VFR TO MVFR WITH THE ON AGAIN...OFF AGAIN HEAVIER CONVECTIVE ELEMENTS. RAINFALL WILL PERSIST AT JLN INTO THE EARLY AFTERNOON. AT SGF...CONFIDENCE IS A LITTLE LOWER IN TIMING DUE TO THE SLOW EASTWARD DRIFT OF CONVECTION...AN ESTIMATED TIMING IS PROVIDED IN THE LATEST TAF TARGETING THE EARLY TO MID AFTERNOON HOURS. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO SGF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 800 PM CDT WED MAR 21 2007 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... COLD FRONT HAS MOVED INTO SOUTHEASTERN NEBRASKA AND NORTH CENTRAL KANSAS WITH A LINE OF THUNDERSTORMS DEVELOPING ALONG THE FRONT FROM NEAR CONCORDIA NORTHEAST TO SOUTH OF OMAHA. REPORTS FROM OAX INDICATED NUMEROUS THREE QUARTER TO ONE AND ONE QUARTER HAIL REPORTS WITH THIS LINE. MLCAPES AROUND 1500-2000 J/KG...STEEP MID LEVEL LAPSE RATES AND SFC-6KM SHEAR FROM 30-40 KNOTS WILL CONTINUE TO SUPPORT THE THREAT OF HAIL AS THE THUNDERSTORMS MOVE EAST INTO EXTREME NORTHWEST MISSOURI. THE LINE OF THUNDERSTORMS WILL CONTINUE TO MOVE SOUTH AND EAST THROUGH THE NIGHT WITH THE SEVERE WEATHER THREAT GRADUALLY DIMINISHING. LATEST RUC AND NAM SUGGEST THAT THE CAP OVER THE CWA WILL GRADUALLY ERODE...BUT WITH THE LACK OF INSOLATION...SBCAPE AND MUCAPE DROP TO 1000-1250 J/KG BETWEEN 09-12Z. SHEAR WILL REMAIN MARGINAL THROUGH THE NIGHT. THE LINE OF CONVECTION IS EXPECTED TO REACH A KANSAS CITY TO PRINCETON LINE BY 08Z. BY 12Z...ONLY SMALL HAIL IS EXPECTED. DB && .PREVIOUS DISCUSSION... 331 PM... VERY CHALLENGING FORECAST THROUGH THE EARLY PERIODS AS LARGE SCALE PATTERN CHANGE HAS PLACED THE LOWER MISSOURI VALLEY REGION IN A FAVORED AREA FOR REPEATED PRECIPITATION EVENTS. 19Z SURFACE ANALYSIS DEPICTS A SEASONABLY MOIST WARM SECTOR AIRMASS OVER THE CWA THIS AFTERNOON...CHARACTERIZED BY DEWPOINTS APPROACHING 60 DEGREES. RUC SOUNDINGS SHOW THAT AN ELEVATED MIXED LAYER WITH STEEP MID-LEVEL LAPSE RATES HAS OVERSPREAD THE REGION...LEAVING THE AREA CAPPED ABOVE AN EXTENSIVE STRATUS CANOPY. PACIFIC COLD FRONT/DRYLINE STRETCHED FROM NORFOLK TO KEARNEY NEBRASKA...AND PER VISIBLE SATELLITE IMAGERY HAS BEEN PRECEDED BY AN INTERESTING GRAVITY WAVE. SHORT MODEL PROGS COLLABORATE WELL WITH OBSERVATIONAL DATA...SHOWING THAT CONVECTION WILL LIKELY DEVELOP OVER SE NEBRASKA IN THE NEXT SEVERAL HOURS WHERE BETTER SURFACE CONVERGENCE IS FOCUSED ALONG THE ADVANCING FRONT AND JUST EAST OF THE ANALYZED SURFACE LOW. ATTENDANT SEVERE THREAT APPEARS TO BE PRIMARILY IN THE FORM OF DAMAGING LINE SEGMENTS WITH ATTENDANT LARGE HAIL AS STEEP MID LEVEL LAPSE RATES COUPLE WITH INCREASING UNIDIRECTIONAL SHEAR AFTER DARK. CERTAINLY STORMS MOVING TOWARD THE NORTHEAST WOULD HAVE THE GREATER THREAT FOR SEVERE. THE QUESTION REMAINS AS TO HOW LONG THE THREAT WILL PERSIST AFTER DARK...AND CURRENT THINKING IS THAT IT MAY TAKE SOME TIME FOR CONVECTION TO WIND DOWN AS LOW LEVEL INSTABILITY IS MAINTAINED BY A WELL MIXED BOUNDARY LAYER AND EXTENSIVE CLOUD COVER. INCREASED LIKELIHOOD OF SEVERE WEATHER REMAINS PRIMARY FOCUSED IN AREAS NORTH AND WEST OF A KANSAS CITY TO TRENTON LINE. SURFACE FRONT WILL BEGIN TO STALL SOMEWHERE ALONG EAX/SGF CWA BORDER TOMORROW MORNING...AND WAFFLE OVER THE NEXT SEVERAL DAYS AS A SERIES OF MID LEVEL DISTURBANCES ARE EJECTED FROM A DEEP UPPER LOW ENTRENCHED IN THE BAJA. VERY UNUSUAL FLOW PATTERN FOR THIS TYPE OF YEAR...BUT THE QUALITY AND DEPTH OF MOISTURE THAT PERSISTS THROUGH THE WEEKEND CERTAINLY RAISES A RED FLAG THAT CUMULATIVE RAINFALL TOTALS COULD LEAD TO FLOODING BY THE WEEKEND. EVEN MORE CHALLENGING WILL BE THE TEMPERATURES AS THE QUASI-STATIONARY BOUNDARY COULD LEAD TO LARGE ERRORS DEPENDING ON ITS DAY TO DAY PLACEMENT AND PROPAGATION. WHERE PERIODIC SUNSHINE IS ABLE TO MANIFEST BETWEEN THESE SYSTEMS...RAPID WARMING INTO THE UPPER 60S-MID 70S COULD OCCUR GIVEN BALMY MID LEVEL TEMPERATURES BENEATH WEAK 500MB RIDGING AND SOUTHWEST UPPER FLOW. EQUALLY POSSIBLE ARE HIGHS IN THE 50S WHERE MCS INDUCED PRECIPITATION/CLOUD DEBRIS KEEP READINGS NEARLY WET BULBED. BOOKBINDER VERY LITTLE CHANGE TO PREVIOUS THINKING REGARDING THE PROGRESS OF THE CLOSED BAJA LOW INTO THE CNTRL CONUS THIS WEEKEND. ECMWF STILL REMAINS THE MODEL OF CHOICE...ALTHOUGH THE OPERATIONAL GFS AND GFS ENSEMBLES HAVE STEADILY BEEN TRENDING TOWARDS THIS SOLUTION THE PAST SEVERAL RUNS. BEFORE THE MAIN BRUNT OF MIDLEVEL ENERGY EJECTS TOWARDS THE REGION LATE SUNDAY...NUMEROUS WEAK SHORTWAVES WILL RIDE OVER THE RIDGE AXIS WHOSE WRN PERIPHERY SHOULD ALIGN ALONG THE LOWER MISSOURI RIVER VALLEY. EACH PASSING SHORTWAVE WILL INVIGORATE LIFT ASSOCIATED WITH WAA ABOVE THE BOUNDARY LAYER...AND LEAD TO SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS. HAVE TRIMMED POPS SLIGHTLY FOR THE SAT NIGHT TIME PERIOD AS SFC AND LOW LEVEL FRONT APPEARS AS IF IT WILL LIFT NORTH OF MISSOURI KEEPING FOCUSING MECHANISM FURTHER NORTH OF THE AREA. SOME CONCERN THAT PRE-EXISTING CONVECTION GENERATED OVER THE HIGH PLAINS WILL DRIFT INTO THE AREA ASSISTED BY A STRENGTHENING NOCTURNAL LLJ...SO HAVE CONTINUED A 30-40 PERCENT POP RANGE. MODELS CONTINUE TO ADVERTISE THE POSSIBILITY OF A POTENT WEATHER SCENARIO FOR SUNDAY. AS WITH PREVIOUS MODEL RUNS...ECMWF LIFTS THE UPPER WAVE A LITTLE FURTHER WEST OF THE AREA SHEARED MORE SO OVER THE RIDGE AXIS. REGARDLESS...AS THE WAVE EJECTS INTO THE CNTRL PLAINS...INCREASING H5/H7 LAPSE RATES IN EXCESS OF 6C/KM WILL ADVECT INTO THE AREA OVERTOP OF INCREASING MODIFIED GULF MOISTURE LEADING TO HEIGHTENED INSTABILITY WITH MUCAPES FORECAST AOA 1000 J/KG. AT THE SAME TIME...STRENGTHENING WINDS ALOFT WILL LEAD TO 0-6KM BULK SHEAR VECTORS AOA 50KT WITH THE REGION SITUATED UNDER THE FAVORABLE LEFT FRONT EXIT REGION OF A 90+ KT UPPER JET. OTHER THAN THE UPPER WAVE AND LOW LEVEL FOCUSING MECHANISM PLACEMENT...MAIN UNCERTAINTY APPEARS TO BE TIED TO ANY MORNING CONVECTION CONTAMINATING THE MODIFIED AIRMASS PROHIBITING FULL AFTERNOON DESTABILIZATION. AFTER THE UPPER WAVE MOVES NORTHEAST OF THE AREA INTO THE GREAT LAKES...A SFC FRONT WILL SAG THROUGH THE AREA...HOWEVER ONCE AGAIN STALL JUST SOUTH OF THE FORECAST AREA AS ANOTHER LARGE CHUNK OF ENERGY ESTABLISHES A LONGWAVE TROUGH OVER THE WRN CONUS. PREFER A SOLUTION SLOWER THAN THE OPERATIONAL GFS WHICH PUSHES THIS LONGWAVE FEATURE EAST INTO THE INTERMOUNTAIN REGION BY NEXT WEDNESDAY. FOLLOWED CLOSER TO THE GFS ENSEMBLE MEAN IN THIS RESPECT WHICH KEEPS THE AREA MAINLY DRY...ALBEIT QUITE WARM FOR THE END OF THE FORECAST PERIOD. 21 && .AVIATION... VFR CEILINGS ARE EXPECTED THIS EVENING WITH THE LINE OF CONVECTION REACHING STJ AROUND 07Z. THE CONVECTION WILL LAST LESS THAN 2 HOURS. AN ISOLATED STORM MAY BE MARGINALLY SEVERE WITH A HAIL THREAT. THE CEILINGS AND VISIBILITIES ARE EXPECTED TO BE MVFR...POSSIBLY VERY BRIEFLY IFR. THE THUNDERSTORMS WILL MOVE SOUTHEAST INTO THE KANSAS CITY AREA BETWEEN 08Z AND 10Z. ONCE THE THUNDERSTORMS MOVE SOUTHEAST OF THE AIRPORTS AND THE COLD FRONT MOVES THROUGH...VFR CEILINGS ARE EXPECTED AFTER 10Z AT STJ AND AFTER 12Z AT MKC AND MCI. ANOTHER ROUND OF THUNDERSTORMS IS POSSIBLE DURING THE AFTERNOON HOURS ON THURSDAY. DB && EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO EAX mo