AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 402 AM MDT MON AUG 20 2007 .SHORT TERM... TODAY AND TONIGHT) SHORT TERM CONCERNS INCLUDE WARM TEMPERATURES AND THE POTENTIAL FOR A STRONG STORM OR TWO ACROSS THE FAR SE PLAINS LATE THIS AFTERNOON. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING WEAK TO MODERATE WESTERLY FLOW ALOFT ACROSS THE STATE WITH FASTER ZONAL FLOW ACROSS THE NORTHERN TIER OF OF STATES AS A SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT CONTINUES TO MOVE ACROSS THE INTERMOUNTAIN WEST AND NORTHERN ROCKIES. WATER VAPOR IMAGERY ALSO INDICATING DRIER AIR EMBEDDED IN THE FLOW ALOFT MOVING ACROSS NORTHERN AND WESTERLY COLORADO ATTM. WESTERLY FLOW ALOFT ALSO OWNING TO LEE TROUGHING ACROSS THE EASTERN PLAINS THIS MORNING HELPING TO KEEP TEMPERATURES RATHER MILD THIS MORNING WITH CURRENT READINGS IN THE 60S AND 70S ACROSS THE PLAINS AND 50S TO LOWER 60S OVER THE HIGHER TERRAIN ATTM. TODAY AND TONIGHT...MODELS REMAIN CONSISTENT WITH KEEPING WARM AND DRIER WESTERLY FLOW ALOFT ACROSS THE AREA AS THE NORTHERN TIER SHORT WAVE CONTINUES ACROSS THE NORTHERN ROCKIES AND OVER THE NORTHERN HIGH PLAINS STATES THROUGH TONIGHT. MOVEMENT OF SYSTEM PUSHES LEE TROUGH OUT TO THE WESTERN KANSAS BORDER THIS AFTERNOON...WHERE MODEL SOUNDINGS ARE INDICATING A MODERATELY UNSTABLE ATMOSPHERE IN PLACE WITH CAPES BETWEEN 500-1500 J/KG...LIFTED INDICES BETWEEN -2C AND -4C AND INCREASING BULK SHEAR TO AROUND 25 KTS. MODEL SOUNDINGS ALSO CONTINUE TO INDICATE A HEALTHY CAP IN PLACE WITH H7 TEMPS BETWEEN 14C AND 18C...THOUGH WITH VERY WARM TEMPERATURES EXPECTED ALONG WITH POTENTIAL FOR CONVERGENCE ALONG LEE TROUGH POSSIBLY HELPING TO BREAK CAP...HAVE ADDED SLIGHT POPS ACROSS THE FAR SE PLAINS LATE THIS AFTERNOON AND EARLY EVENING. IF STORMS CAN GET GOING...COULD SEE THE POTENTIAL FOR MARGINALLY SEVERE HAIL ALONG WITH GUSTY WINDS TO AROUND 50 MPH. ACROSS THE REST...WITH THE WARM AND DRIER AIR ALOFT...EXPECTING MAINLY DRY CONDITIONS AND HAVE KEPT CURRENT SLIGHT POPS ACROSS THE HIGHER TERRAIN...AS CANT TOTALLY RULE OUT AN ISOLATED -TSRA/-SHRA WITH THE STRONG SOLAR HEATING. WITH LESS CONVECTIVE CLOUD COVER EXPECTED ALONG WITH WARM WESTERLY FLOW ALOFT...SHOULD SEE HIGHS SOME 6-12F ABOVE SEASONAL AVERAGES ACROSS THE REGION WITH TEMPERATURES REMAINING AT OR ABOVE NORMS TONIGHT. -MW .LONG TERM... (TUESDAY THROUGH SUNDAY) VERY WEAK SURFACE BOUNDARY OVER THE SOUTHEAST PLAINS TUESDAY AFTERNOON COULD PROVIDE A FOCUS FOR TSRA...ESPECIALLY IF NAM`S 60F DEWPOINTS VERIFY. FOR NOW...SPREAD THE LOW POPS FOR TSRA EASTWARD ALONG THE NM BORDER...MIGHT NEED TO ADJUST THEM FARTHER NORTH DEPENDING ON WHERE BOUNDARY WASHES OUT. ANOTHER HOT DAY AREAWIDE...WITH VERY LITTLE TEMPERATURE CHANGE NOTED AT 700 MB. STILL APPEARS STRONGER UPSLOPE SURGE WILL DEVELOP WEDNESDAY...THOUGH MODELS SEEM TO STALL THE BOUNDARY ALONG THE ARKANSAS RIVER...WHICH IS A LITTLE FARTHER NORTH THAN PREVIOUS RUNS. SHOULD SEE SOME INCREASE IN TSRA COVERAGE...WHICH IS COVERED WELL IN CURRENT GRIDS. STILL NOT MUCH COOLING NOTED...THOUGH MAXES OVER THE EAST SHOULD FALL A FEW DEGREES AS WINDS TAKE ON A MORE EASTERLY COMPONENT. BULK OF THE COOLER AIR AND PRECIPITATION NOW APPEARS TO ARRIVE LATE THURSDAY INTO FRIDAY...AS BOTH NAM AND GFS SHOW NICE 700 MB BAROCLINIC ZONE DROPPING SOUTH OVER THE STATE LATE THU AFTERNOON. GIVEN TIMING TROUBLES OF THE MODELS THE LAST FEW DAYS...LOW POPS AND SLIGHTLY COOLER TEMPS ARE FINE FOR NOW...THOUGH WOULDN`T BE SURPRISED IF FRIDAY TURNS OUT COOLER AND WETTER THAN CURRENT SET OF GRIDS PORTRAY...AFTER ALL...THE COLORADO STATE FAIR STARTS FRIDAY...WHICH SEEMS TO GUARANTEE A LEAST A FEW DAYS OF WET WEATHER. && .AVIATION...VFR CONDITIONS EXPECTED FOR ALL TAF SITES WITH DRIER AND WARM AIR ALOFT ACROSS THE AREA. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/10 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 357 AM MDT SUN AUG 19 2007 .SHORT TERM... (TODAY AND TONIGHT) MAIN SHORT TERM CONCERN IS THE AMOUNT OF CONVECTION ACROSS THE HIGHER TERRAIN. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING GENERALLY WEAK WEST TO SOUTHWEST FLOW ALOFT ACROSS THE REGION WITH FASTER ZONAL FLOW CONTINUING ACROSS THE NORTHERN TIER AS UPPER LEVEL HIGH PRESSURE PERSISTS ACROSS SOUTHERN NEW MEXICO ATTM. WATER VAPOR IMAGERY ALSO INDICATING MINOR SHORT WAVE EMBEDDED IN THE WESTERLY FLOW MOVING INTO WESTERN WYOMING WITH DRIER AIR ALOFT MOVING ACROSS EASTERN UTAH AND INTO WESTERN COLORADO ATTM. CURRENT OBSERVATIONS AND SATELLITE INDICATING IFR STRATUS ACROSS THE WESTERN TEXAS AND OKLAHOMA PANHANDLE INTO WESTERN KANSAS...WITH SOME PATCHY MVFR/IFR CIGS ACROSS EXTREME SE COLORADO ATTM. TODAY AND TONIGHT...NOT MUCH CHANGE IN CURRENT FORECAST THINKING AS MODELS REMAIN CONSISTENT WITH KEEPING DRIER WESTERLY ALOFT ACROSS MUCH OF THE REGION AS WESTERN WYOMING SHORT WAVE CONTINUES TO MOVE ACROSS THE NORTHERN ROCKIES THROUGH TONIGHT. WITH ENOUGH RESIDUAL MOISTURE ALONG WITH DAYTIME HEATING...CANT RULE OUT ISOLATED THUNDERSTORMS DEVELOPING ACROSS THE HIGHER TERRAIN THIS AFTERNOON AND EVENING AND HAVE KEPT THE BEST POPS ACROSS THE CENTRAL MTS WITH PROXIMITY TO PASSING WAVE. MODELS INDICATING SLIGHT WARMING ALOFT WITH H7 TEMPS PROGGED BETWEEN 14-18C...AND WITH LESS CONVECTIVE CLOUD COVER...SHOULD SEE HIGHS IN THE UPPER 80S TO UPPER 90S ACROSS THE PLAINS...WITH 60S TO LOWER 80S ACROSS THE HIGH TERRAIN. CONVECTION TO DIMINISH WITH THE SUN THIS EVENING WITH CLEARING SKIES THROUGH THE OVERNIGHT. MODELS INDICATING WARM AIR ALOFT PERSISTING ACROSS THE REGION...AND HAVE WARMED OVERNIGHT LOWS A TAD MAINLY ACROSS THE HIGHER ELEVATIONS. -MW .LONG TERM... (MONDAY THROUGH NEXT SATURDAY) WESTERLY FLOW INCREASES ACROSS THE AREA ON MONDAY...AS FIRST PIECE OF THE PACIFIC NORTHWEST UPPER TROUGH MOVES THROUGH THE NRN ROCKIES. SHOULD BE WARMER AND DRIER ALL AREAS AS WEST WINDS PUSH MOISTURE AXIS EASTWARD AND DOWNSLOPE FLOW DEVELOPS ON THE PLAINS. LEFT THE LOW POPS IN PLACE OVER THE MOUNTAINS FOR SOME ISOLATED AFTERNOON AND EVENING CONVECTION AS MODELS HAVE BEEN TOO QUICK TO DRY THE AIR MASS OUT THIS SUMMER. MIGHT SEE A WEAK NORTHERLY SURGE OVER THE PLAINS MONDAY AFTERNOON AS UPPER JET PUSHES OUT INTO THE PLAINS...BUT LITTLE IN THE WAY OF MOISTURE OR COOL AIR ASSOCIATED WITH IT. WESTERLY FLOW CONTINUES TUESDAY...WITH MORE SIGNIFICANT BOUNDARY DEVELOPING OVER NORTHEAST COLORADO BY TUESDAY EVENING AS MAIN UPPER JET PUSHES ACROSS THE NORTHERN PLAINS. SHOULD SEE FRONT PUSH THROUGH THE EAST BY MID-MORNING WEDNESDAY WITH A FAIRLY MOIST UPSLOPE SURGE DEVELOPING OVER THE PLAINS DURING THE DAY. EXPECT BEST CHANCE OF PRECIP OVER MUCH OF THE AREA TO BE WEDNESDAY AFTERNOON AND EVENING...WITH PERHAPS ENOUGH MOISTURE LINGERING FOR ANOTHER ROUND OF STORMS THURSDAY. SLIGHTLY COOLER TEMPS BOTH WED/THU BEHIND THE FRONT...THOUGH READINGS WILL ONLY FALL BACK TO NEAR SEASONAL NORMALS AS BULK OF THE COOLING REMAINS NORTH. && .AVIATION...PATCHY MVFR/IFR CIGS ACROSS EXTREME SE COLORADO TO QUICKLY BURN OFF THIS MORNING. LESS CONVECTION IS EXPECTED TODAY AS DRIER AIR ALOFT MOVES INTO THE REGION...THOUGH CANT RULE OUT ISOLATED THUNDERSTORMS ACROSS THE HIGHER TERRAIN...WITH VCTS POSSIBLE FOR KCOS TAF BETWEEN 22-02Z. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/10 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 303 AM EDT MON AUG 20 2007 .SYNOPSIS...DEAN IS STRENGTHENING AS IT ENTERS THE NW CARIBBEAN SEA WITH MAX SUSTAINED WINDS NOW AT 150 MPH, AT THE HIGH END OF CAT 4. THE UPPER LOW OVER THE WRN GULF CONTINUES TO MOVE STEADILY WWD AND SHOULD HAVE NO INFLUENCE OF THE FUTURE TRACK OF DEAN AS IT MOVES INTO DEEP S TX AND NE MEXICO BY MIDDAY. THIS WILL ALLOW THE DEEP LAYER RIDGE OFF THE GA/SC COAST TO BUILD WWD ALONG THE ERN GULF COAST, WITH THE AXIS JUST N OF THE FL BORDER FOR THE NEXT FEW DAYS, KEEPING DEAN SAFELY AT BAY. && .SHORT TERM...TODAY THROUGH WED. THE MAIN WX STORY OUTSIDE THE MARINE AREA WILL BE A RETURN TO NEAR RECORD-BREAKING HEAT. WITH DEEP-LAYER RIDGING IN PLACE, CONVECTION SHOULD BE INHIBITED AND TEMPS WILL SOAR. THIS SHOULD BE A FAMILIAR SCENARIO FOR MOST. INLAND AREAS WILL REACH THE UPPER 90S EACH OF THE NEXT SEVERAL DAYS. IN FACT, WE ARE GOING FOR 100 AT TLH ON WED, WHICH WOULD TIE THE RECORD FOR THAT DATE. THROUGH THE 19TH, THE AVERAGE TEMPERATURE FOR THE MONTH OF AUGUST IS HOVERING JUST OVER 85 DEGREES. THIS IS A ABOUT A DEGREE ABOVE THE CURRENT RECORD FOR HOTTEST AUGUST AT TLH, 84.2 IN 1999. LOOKING AT THE LONG RANGE FORECAST, THIS RECORD CERTAINLY LOOKS TO BE IN JEOPARDY, PENDING NO DIRECT IMPACTS FROM ANY TC. 1000-700 MB FLOW WILL BE SE AROUND 10 KT TODAY. WE BASED OUR POPS ON THIS REGIME (TYPE 6), BUT UNDERCUT THE CLIMO POPS AS THE PW ON THE MODIFIED RUC SOUNDING IS ONLY 1.30 INCHES. THIS EQUATES TO A 20 POP ONLY FOR THE PANHANDLE SEA BREEZE AREA, WITH SOME OF THIS WORKING INTO SE AL LATE IN THE DAY. ALSO INCLUDED A 20 POP OVER THE SE BIG BEND IN ANTICIPATION OF THE E COAST SEA BREEZE MAKING IT THAT FAR W BEFORE DAY`S END. THIS SAME BOUNDARY WARRANTS SLIGHT CHANCE POPS FOR THE ENTIRE BIG BEND THIS EVENING, AS WELL AS ADJACENT AREAS OF FAR SW GA. NO MENTIONABLE POPS WILL BE INCLUDED IN THE FORECAST FOR TUE-WED. .LONG TERM...WED NIGHT THROUGH SUN. THERE IS SOME UNCERTAINTY IN THIS PART OF THE FORECAST, THANKS TO ACTIVITY IN THE TROPICS. A TROPICAL WAVE NE OF THE LEEWARD ISLANDS IS BEING MONITORED BY NHC. WE HAVE GONE WITH THE GFS SOLUTION FOR NOW WHICH BRINGS THE FEATURE TO FL BY WED NIGHT INTO THU MORNING, WITH A WEAK LOW CENTER AIMING AT THE KEYS. THE LATEST (00Z MON) ECMWF BRINGS THIS SYSTEM WWD MORE SLOWLY, WITH THE LOW CIRCULATION FURTHER TO THE N, PASSING N OF THE BAHAMAS THU NIGHT. STAY TUNED. THE PERIOD WILL START OUT HOT AND DRY ON THU, THEN WE SHOW A VERY GRADUAL INCREASE IN POP, WITH NEAR CLIMO POPS BY SUN WHEN THE GFS SHOWS YET ANOTHER TROPICAL WAVE APPROACHING FL FROM THE E AND A FRONTAL SYSTEM MOVING INTO DIXIE FROM THE NW. && .MARINE...TODAY THROUGH FRI. NOT MUCH CHANGE FROM THE PREVIOUS FORECAST. THE FIRST COUPLE OF PERIODS WILL SEE DIURNAL FLUCTUATIONS TYPICAL OF ELY FLOW. AFTER THAT, THE MARINE AREA BEGINS TO COME UNDER THE INFLUENCE OF DISTANT, BUT POWERFUL HURRICANE DEAN. GIVEN THE VERY FAST FORWARD MOVEMENT OF DEAN AND THE LESS THAN IDEAL DYNAMIC FETCH POINTING WESTWARD, WILL SHOW A VERY SHARP GRADIENT IN SEA HEIGHTS FROM EAST TO WEST ACROSS OUR COASTAL WATERS DUE TO THE ANGULAR SPREADING OF SWELLS GENERATED BY THE HURRICANE AS IT PASSES S OF THE YUCATAN CHANNEL. OVER THE WESTERN WATERS...WILL MAX OUT OUR SEA HEIGHTS AROUND 5 TO 7 FEET FOR A SHORT PERIOD OF TIME LATE TUESDAY NIGHT AND INTO WEDNESDAY MORNING. EXPECT THE LONGER PERIOD ENERGY FROM THE SOUTH TO ONLY REACH HEIGHTS OF 3 TO 4 FEET (12-13S). THIS COMBINED WITH THE LOCALLY GENERATED WIND WAVES...THE OVERALL SEAS SHOULD RANGE FROM 5 TO 7 FEET DURING THIS SHORT TIME FRAME. ALTHOUGH THE CHANCES ARE VERY LOW WITH THE MOTION AND SPEED OF DEAN...OUR AREA COULD POSSIBLY RECEIVE SOME LONGER PERIOD ENERGY FROM THE SOUTHWEST AS DEAN MOVES ACROSS THE SOUTHWESTERN GOMEX TUESDAY NIGHT TROUGH WEDNESDAY. && .AVIATION...OTHER THAN POSSIBLE MVFR/IFR VSBYS DURING THE EARLY MORNING HOURS AROUND DAYBREAK PREVAILING VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. AFTERNOON SHOWERS AND THUNDERSTORMS WILL REMAIN SUPPRESSED AND VERY ISOLATED AT BEST. && .FIRE WEATHER...MIN RH WILL DIP TO NEAR 35 PERCENT EACH OF THE NEXT TWO AFTERNOONS OVER INLAND PORTIONS OF THE FL BIG BEND. DISPERSION VALUES WILL BE HIGH AS WELL. WHILE, WE ARE NOT FORECASTING RED FLAG CONDITIONS, DEW POINTS WILL NOT NEED TO MIX OUT MUCH MORE THAN FORECAST FOR US TO GET TO CRITERIA. WILL HAVE THE DAY SHIFT KEEP A CLOSE EYE ON THIS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 98 75 98 73 100 / 10 20 10 10 10 PANAMA CITY 95 78 95 79 95 / 20 10 10 10 10 DOTHAN 96 75 98 75 98 / 10 10 10 10 10 ALBANY 97 75 99 75 98 / 05 10 10 05 10 VALDOSTA 98 74 98 71 98 / 05 10 10 05 10 CROSS CITY 98 75 97 72 96 / 20 20 10 05 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ AVIATION...GIBBS MARINE...GIBBS/WOOL REST OF DISCUSSION...WOOL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 215 PM EDT SUN AUG 19 2007 .SHORT TERM...MSAS ANALYSIS SHOWS HIGH PRESSURE HAS SETTLED IN OFF THE CAROLINA COAST PROVIDING AN EASTERLY FLOW REGIME FOR THE AREA. OVER THE SOUTHERN SECTIONS OF THE FORECAST AREA...THERE ARE SUBTLE INDICATIONS OF A COASTAL TROUGH WHICH HAS RESULTED IN MOSTLY SPRINKLES WITH ISOLATED SHOWERS OVER COASTAL WATERS. FOR THE REMAINDER OF THIS AFTERNOON...THE MOST SIGNIFICANT OF THE SHORTWAVE ENERGY HAS LIFTED NORTH OF THE AREA AND RUC DIFFERENTIAL PVA ANALYSIS SHOWS A LARGE ARE OF SUBSIDENCE OVER THE ENTIRE FORECAST AREA. IN ADDITION...DRIER AIR NOTED ON THE WATER VAPOR STREAMING IN OFF THE ATLANTIC SHOULD HELP CURB CONVECTIVE DEVELOPMENT AND CURRENT 20 POPS LOOK SUFFICIENT. FOR MONDAY...500 MB HIGH STRENGTHENS FURTHER TO 596 DAM AND SETTLES DIRECTLY OVER NORTHEAST FLORIDA. THIS WILL CONTINUE TO KEEP POPS AT A MINIMUM WITH THE OCCASIONAL EARLY MORNING SOUTHERN COASTAL SHOWER ALWAYS A POSSIBILITY. THE REAL STORY WILL BE THE CONTINUED HOT TEMPS WITH MID 90S IN STORE FOR INLAND LOCATIONS. ALTHOUGH DEWPOINTS LOOK A LITTLE LOWER THAN PREVIOUS EVENT...WILL NEED TO MONITOR CLOSELY FOR POSSIBLE HEAT ADVISORIES THROUGHOUT THE WEEK. TUESDAY AND WEDNESDAY...AS DEAN PASSES WELL TO THE SOUTH OF FLORIDA...STACKED HIGH CONFIGURATION WILL BE A MAINSTAY OVER OUR AREA WITH NIL TO SLIGHT CHANCE POPS EACH DAY. .LONG TERM...MID AND UPPER LEVEL HIGH RETROGRADES WEST BY THE END OF THE WEEK AND SURFACE HIGH BREAKS DOWN WITH A TROUGH DIPPING DOWN FROM THE MID-ATLANTIC. ALL THIS POINTS TO SOME SLIGHT RELIEF FROM THE EXTREME HEAT AND POPS INCREASING...ESPECIALLY OVER THE NORTHERN SECTIONS. THERE ARE A COUPLE OF WEAK WAVES INDICATED BY THE GFS FOR THE WEEKEND WITH THE FIRST LOOKING TO IMPACT SOUTH FLORIDA EARLY SATURDAY AND GRADUALLY EXTEND NORTHWARD THROUGH SUNDAY. WAY TO FAR OUT TO GET INTO MANY DETAILS AND CURRENT SCT POPS IN THE GRIDS LOOK SUFFICIENT FOR NOW. && .AVIATION...VIS IMAGERY SHOWS SCT-BKN CU FIELD BUT CLOUDS ARE ABOVE 3000 FT. TONIGHT...BRIEF MVFR VIS POSSIBLE TOWARD MONDAY MORNING DUE TO INCREASED SUBSIDENCE ALOFT AND LIGHT BOUNDARY LAYER WINDS EXCEPT FOR SSI WHERE MIXING WILL BE MORE PREVALENT. && .MARINE...NO HEADLINES FOR NOW. IT HAS BEEN NOTED FOR THE PAST 12-18 HRS THAT SEAS HAVE INCREASED A BIT MAINLY DUE TO E TO SE SWELLS INCREASING BY 1-2 FT. HAVE ADJUSTED WNA WAVE GUIDANCE A BIT FOR NEXT 48 HRS AND STILL LOOKS LIKE A SMALL AREA OF 5-6 FT SEAS POSSIBLE OVER THE SE OFFSHORE WATERS FROM LATE MON INTO EARLY TUE. OTHERWISE...WINDS LOOK TO REMAIN AT OR BELOW 15 KT FOR THE PERIOD AT THIS TIME AND SEAS AT OR BELOW 5 FT. RIP CURRENT RISK TO REMAIN ELEVATED IN THE MODERATE CATEGORY AT LEAST THROUGH MID WEEK DUE TO ONSHORE FLOW AND ESE SWELLS. && .PRELIMINARY POINT TEMPS/POPS... AMG 71 96 72 96 / 20 10 10 0 SSI 79 90 78 89 / 10 10 10 0 JAX 74 93 74 93 / 20 10 10 10 SGJ 76 90 76 89 / 20 10 10 0 GNV 72 95 71 94 / 20 20 10 20 OCF 73 94 72 94 / 20 20 10 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ DEESE/SHASHY/WALKER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 730 PM EDT MON AUG 20 2007 .AVIATION... KIWX 88D SHOWS PCPN SCATTERED ACROSS THE AREA BUT BACK END NOW MOVING THROUGH KSBN. KFWA WILL SEE A FEW MORE HOURS OF SHOWERS BEFORE TAPERING TO DRIZZLE. SATELLITE SHOWS SOME BREAKS IN CLOUDS ACROSS IL IN AREA OF LOWER THETA E AIR. THIS LOWER THETA E AIR TO MOVE INTO NORTHERN INDIANA OVERNIGHT AS LOW LEVEL JET BECOMES ORIENTED MORE WEST SOUTHWEST AND LOSES FOCUS OVER BOUNDARY AND OUR AREA. LOW LEVEL MOISTURE REMAINS HIGH AND WIND FIELD WILL BE LIGHT SO EXPECT TRANSITION TO DRIZZLE THEN IFR FOG AND CIGS THROUGH THE NIGHT. PREVIOUS TAF HAD THIS TREND AND CONTINUED WITH IT. WAS OPTIMISTIC FOR CONDITIONS ON TUESDAY WITH IMPROVING TREND THROUGH THE DAY. TAF SITES IN WARM SECTOR NEAR STALLED FRONTAL BOUNDARY SO AFTERNOON CONVECTION POSSIBLE WITH ANY DAYTIME HEATING. ADDED CB GROUP FOR NOW. && SHORT TERM... TONIGHT THROUGH TUESDAY AFTERNOON... OVERALL SYNOPSIS ACROSS THE CONUS SHOWS STRONG RIDGING CENTERED OVER THE SOUTHEASTERN CONUS AND DESERT SOUTHWEST WITH NEARLY ZONAL FLOW ACROSS THE NORTHERN STATES...SMALL AMPLIFIED RIDGE FROM THE EXTREME NORTHWESTERN GREAT LAKES INTO HUDSON BAY. LAST BITS OF ERIN REMAIN ACROSS THE OZARKS. SURFACE FRONT REMAINS SITUATED FROM THE MOD VALLEY TO NEAR CHICAGO ACROSS NORTHERN INDIANA INTO CENTRAL OHIO. CURRENT RUC ANALYSIS SHOWS DECENT 30 TO 40 KT LOW LEVEL JET STILL DRIVING INTO THE BOUNDARY...THOUGH THE WINDS SEEM TO HAVE VEERED SOME TO THE WEST...POSSIBLY THE REASONING FOR THE LESSER AMOUNTS ACROSS THE NORTHERN PORTIONS OF THE FORECAST AREA TODAY. FLOODING CONCERNS ARE LESSENING QUICKLY ACROSS THE REGION. TONIGHT THE BEST FORCING APPEARS TO BE DRIFTING EAST OF THE REGION AS MODELS AND LATEST RUC ANALYSIS EACH SHOWS THE BETTER FRONTOGENETICAL FORCING ACROSS NORTHERN OHIO AND PARTS EAST. COMBINED WITH THE MOISTURE ROBBING EFFECTS OF CONVECTION ACROSS CENTRAL INDIANA THE RAINFALL AMOUNTS SHOULD BE LOWER THAN PREVIOUS THINKING. BECAUSE OF THESE FACTORS WILL BE DROPPING THE FLOOD WATCH ACROSS THE ENTIRE REGION. RIVER FLOODING WILL BE THE MAIN CONCERN THE NEXT FEW DAYS. MORE SOUTHERLY FLOW ACROSS THE REGION AT THE SURFACE HAS BROUGHT DEWPOINTS UP INTO THE MID TO UPPER 60S ACROSS MUCH OF THE REGION...LOW TEMPS WILL NOT DROP MUCH BELOW THE UPPER 60S FOR MUCH OF THE AREA...OUTSIDE OF THE FAR NW COUNTIES NEAR HILLSDALE MI WHERE MID TO LOWER 60S WILL BE POSSIBLE. TUESDAY THE FRONT SHOULD LIFT SLIGHTLY NORTH FURTHER INTO THE GREAT LAKES...WITH WARMER AND MOIST AIR MOVING INTO THE REGION. ALL DAY PRECIP LOOKS UNLIKELY...BUT MORE SCATTERED ACTIVITY DOES. AFTERNOON HEATING WILL DROP LI`S TO AROUND -5 OR -6 WITH SURFACE BASED CAPES NEARING 2000 TO 2500 J/KG BY MID AFTERNOON. SCATTERED AFTERNOON THUNDERSTORMS WILL DEVELOP...WITH VERY LOCALIZED HEAVY RAINFALL POSSIBLE. WITH THE COVERAGE OF STORMS NOT NEARLY AS GREAT...SOME NUISANCE FLOODING AND QUICK FLASH FLOODING MAY OCCUR BUT A NEED FOR A FLOOD WATCH IS UNWARRANTED AT THIS TIME FOR THIS ACTIVITY. HIGHS WILL REBOUND TO MORE SEASONAL LEVELS...ONLY LIMITED BY THE CLOUD COVER AS H850 TEMPS JUMP TO NEAR 20C ACROSS THE AREA. HIGHS WILL PUSH INTO THE 80S WITH SOME UPPER 80S POSSIBLE ACROSS THE SOUTHERN COUNTIES. && .LONG TERM... BEGINNING OF FCST PERIOD SHOULD FEATURE DIMINISHING CHANCES OF PRECIP AS FRONTAL BOUNDARY LIFTS NORTH OF THE AREA AND WHATS LEFT OF ERIN SHIFTS EASTWARD. HAVE TRENDED GRIDS TUE NITE THROUGH WED MORNING ACCORDINGLY WITH DRY FCST OVER ALL BUT NORTHERN CWA BY 12Z WED. THIS WILL HAVE OUR CWA IN WARM SECTOR...WARM HUMID AND VERY UNSTABLE AIRMASS COMBINED WITH AMPLE LOW LEVEL MOISTURE FROM RECENT RAINS SHOULD BE SUFFICIENT TO TRIGGER SCT TSRA BY THE AFTERNOON HOURS ON WED DESPITE THE LACK OF ANY APPARENT LARGER SCALE FOCUS AND FORCING. MODELS INDICATING PREVAILING SW FLOW WITH OUR AREA IN WARM SECTOR THROUGH THURSDAY...SUGGESTING THE POTENTIAL FOR A MORE SUSTAINED 1 TO 2 DAY PERIOD OF DRY WEATHER DEVELOPING IN THIS TIME FRAME...BUT FOR NOW WILL KEEP SMALL CHANCE POPS FROM CURRENT FCST AND SEE IF MODELS CONTINUE THIS TREND. NO MAJOR CHANGES IN REMAINDER OF EXTENDED AS MEDIUM RANGE MODELS INDICATE COLD FRONT TO MOVE THROUGH ON SAT BRINGING DRY FCST TO THE AREA DAYS 6 AND 7. WARMING TREND EXPECTED MID WEEK AS FRONTAL BOUNDARY LIFTS NORTH ALLOWING TEMPS TO REACH NEAR 90...WITH LOWER 90S POSSIBLE WED AND THUR IF ANY APPRECIABLE AMOUNT OF SUN. WITH DEWPOINTS AROUND 70F HEAT INDICES COULD APPROACH 100 WED AND THU AFTN IF L90S ARE REALIZED. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SCHOTT/LASHLEY LONG TERM....LOGSDON AVIATION...LASHLEY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 306 PM EDT MON AUG 20 2007 SHORT TERM... TONIGHT THROUGH TUESDAY AFTERNOON... OVERALL SYNOPSIS ACROSS THE CONUS SHOWS STRONG RIDGING CENTERED OVER THE SOUTHEASTERN CONUS AND DESERT SOUTHWEST WITH NEARLY ZONAL FLOW ACROSS THE NORTHERN STATES...SMALL AMPLIFIED RIDGE FROM THE EXTREME NORTHWESTERN GREAT LAKES INTO HUDSON BAY. LAST BITS OF ERIN REMAIN ACROSS THE OZARKS. SURFACE FRONT REMAINS SITUATED FROM THE MOD VALLEY TO NEAR CHICAGO ACROSS NORTHERN INDIANA INTO CENTRAL OHIO. CURRENT RUC ANALYSIS SHOWS DECENT 30 TO 40 KT LOW LEVEL JET STILL DRIVING INTO THE BOUNDARY...THOUGH THE WINDS SEEM TO HAVE VEERED SOME TO THE WEST...POSSIBLY THE REASONING FOR THE LESSER AMOUNTS ACROSS THE NORTHERN PORTIONS OF THE FORECAST AREA TODAY. FLOODING CONCERNS ARE LESSENING QUICKLY ACROSS THE REGION. TONIGHT THE BEST FORCING APPEARS TO BE DRIFTING EAST OF THE REGION AS MODELS AND LATEST RUC ANALYSIS EACH SHOWS THE BETTER FRONTOGENETICAL FORCING ACROSS NORTHERN OHIO AND PARTS EAST. COMBINED WITH THE MOISTURE ROBBING EFFECTS OF CONVECTION ACROSS CENTRAL INDIANA THE RAINFALL AMOUNTS SHOULD BE LOWER THAN PREVIOUS THINKING. BECAUSE OF THESE FACTORS WILL BE DROPPING THE FLOOD WATCH ACROSS THE ENTIRE REGION. RIVER FLOODING WILL BE THE MAIN CONCERN THE NEXT FEW DAYS. MORE SOUTHERLY FLOW ACROSS THE REGION AT THE SURFACE HAS BROUGHT DEWPOINTS UP INTO THE MID TO UPPER 60S ACROSS MUCH OF THE REGION...LOW TEMPS WILL NOT DROP MUCH BELOW THE UPPER 60S FOR MUCH OF THE AREA...OUTSIDE OF THE FAR NW COUNTIES NEAR HILLSDALE MI WHERE MID TO LOWER 60S WILL BE POSSIBLE. TUESDAY THE FRONT SHOULD LIFT SLIGHTLY NORTH FURTHER INTO THE GREAT LAKES...WITH WARMER AND MOIST AIR MOVING INTO THE REGION. ALL DAY PRECIP LOOKS UNLIKELY...BUT MORE SCATTERED ACTIVITY DOES. AFTERNOON HEATING WILL DROP LI`S TO AROUND -5 OR -6 WITH SURFACE BASED CAPES NEARING 2000 TO 2500 J/KG BY MID AFTERNOON. SCATTERED AFTERNOON THUNDERSTORMS WILL DEVELOP...WITH VERY LOCALIZED HEAVY RAINFALL POSSIBLE. WITH THE COVERAGE OF STORMS NOT NEARLY AS GREAT...SOME NUISANCE FLOODING AND QUICK FLASH FLOODING MAY OCCUR BUT A NEED FOR A FLOOD WATCH IS UNWARRANTED AT THIS TIME FOR THIS ACTIVITY. HIGHS WILL REBOUND TO MORE SEASONAL LEVELS...ONLY LIMITED BY THE CLOUD COVER AS H850 TEMPS JUMP TO NEAR 20C ACROSS THE AREA. HIGHS WILL PUSH INTO THE 80S WITH SOME UPPER 80S POSSIBLE ACROSS THE SOUTHERN COUNTIES. && .LONG TERM... BEGINNING OF FCST PERIOD SHOULD FEATURE DIMINISHING CHANCES OF PRECIP AS FRONTAL BOUNDARY LIFTS NORTH OF THE AREA AND WHATS LEFT OF ERIN SHIFTS EASTWARD. HAVE TRENDED GRIDS TUE NITE THROUGH WED MORNING ACCORDINGLY WITH DRY FCST OVER ALL BUT NORTHERN CWA BY 12Z WED. THIS WILL HAVE OUR CWA IN WARM SECTOR...WARM HUMID AND VERY UNSTABLE AIRMASS COMBINED WITH AMPLE LOW LEVEL MOISTURE FROM RECENT RAINS SHOULD BE SUFFICIENT TO TRIGGER SCT TSRA BY THE AFTERNOON HOURS ON WED DESPITE THE LACK OF ANY APPARENT LARGER SCALE FOCUS AND FORCING. MODELS INDICATING PREVAILING SW FLOW WITH OUR AREA IN WARM SECTOR THROUGH THURSDAY...SUGGESTING THE POTENTIAL FOR A MORE SUSTAINED 1 TO 2 DAY PERIOD OF DRY WEATHER DEVELOPING IN THIS TIME FRAME...BUT FOR NOW WILL KEEP SMALL CHANCE POPS FROM CURRENT FCST AND SEE IF MODELS CONTINUE THIS TREND. NO MAJOR CHANGES IN REMAINDER OF EXTENDED AS MEDIUM RANGE MODELS INDICATE COLD FRONT TO MOVE THROUGH ON SAT BRINGING DRY FCST TO THE AREA DAYS 6 AND 7. WARMING TREND EXPECTED MID WEEK AS FRONTAL BOUNDARY LIFTS NORTH ALLOWING TEMPS TO REACH NEAR 90...WITH LOWER 90S POSSIBLE WED AND THUR IF ANY APPRECIABLE AMOUNT OF SUN. WITH DEWPOINTS AROUND 70F HEAT INDICES COULD APPROACH 100 WED AND THU AFTN IF L90S ARE REALIZED. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SCHOTT LONG TERM....LOGSDON in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 127 PM EDT MON AUG 20 2007 .AVIATION... TAF PERIOD CONCERNS ARE DEALING WITH THE LOW CEILINGS AND VSBY FROM RAINFALL THROUGH MOST OF THE PERIOD. BETTER CHANCES FOR IFR CONDITIONS AT FWA AND THE SOUTHERN PORTIONS OF THE FORECAST AREA THROUGH THE REST OF THE AFTERNOON AND EARLY EVENING...LESSER SO ACROSS THE SBN TAF SITE AND NORTH. FWA AND AREAS ACROSS THE SOUTHERN FORECAST AREA WILL SEE PERIODS OF SHOWERS AND THUNDERSTORMS THROUGH AT LEAST 00-06Z CREATING MVFR AND IFR CONDITIONS. CIGS WILL LOWER OVERNIGHT AND WINDS WILL LIGHTEN FROM THE SOUTH AS THE FRONT MOVES SLIGHTLY FURTHER NORTH INTO THE SOUTHERN GREAT LAKES. CONDITIONS SHOULD BECOME MORE VFR LIKELY DURING THE LATE MORNING OR EARLY AFTERNOON TUESDAY WITH SOME LINGERING SCATTERED SHOWERS/T-STORMS POSSIBLE. CIGS SHOULD RISE TO WELL ABOVE VFR LIMITS BY 16-18Z. && .PREV DISCUSSION... /ISSUED 1104 AM EDT MON AUG 20 2007/ UPDATE... CONTINUED DEVELOPMENT OF SHOWERS AND THUNDERSTORMS DUE TO LOW LEVEL JET INTERACTION ACROSS THE STATIONARY BOUNDARY WHICH LINGERS FROM NEAR THE NORTH END OF CHICAGO TO ACROSS NORTHERN INDIANA AND INTO CENTRAL OHIO. RUC 80 SHOWS STRONG 850-700 MB FRONTOGENSIS JUST TO THE NORTHEAST OF THE AREA...WITH BEST FORCING JUST TO THE SOUTH OF THAT REGION ACROSS THE FORECAST AREA. PERIODS OF HEAVY RAINFALL WILL CONTINUE THROUGH THE AFTERNOON...CREATING OR WORSENING FLOODING PROBLEMS ACROSS THE REGION. WILL CONTINUE THE FLOOD WATCH FOR THE ENTIRE AREA. ACROSS THE FAR SOUTHERN PORTIONS OF THE REGION INTO CENTRAL INDIANA SOME PARTIAL CLEARING LATE THIS MORNING INTO THE AFTERNOON HAVE PUSHED LI`S TO -3 AND STARTED TO ERODE ANY CIN...WILL HAVE TO WATCH FOR THE POSSIBILITY OF STRONGER STORMS ACROSS THE FAR SOUTHERN COUNTIES THROUGH THE AFTERNOON AND EVENING HOURS. MAY TWEAK TO DEWPOINTS...SLIGHTLY HIGHER THAN PREVIOUS THINKING...ALSO ADJUSTED AFTN TEMPS UP ACROSS THE SOUTHERN ZONES WITH MID 80S POSSIBLE THERE. PREV DISCUSSION... /ISSUED 645 AM EDT MON AUG 20 2007/ SHORT TERM... TODAY AND TONIGHT COMPLICATED SHORT TERM PERIOD. 8Z RADAR IMAGERY SHOWING HEAVY BAND OF TSRA MOVING NE OVER NRN INDIANA DROPPING HEAVY RAINFALL UP TO AN INCH TO AN INCH AND A HALF PER HOUR. STRONG H85 LLJ AND SHRT/WV PASSING JUST TO THE S OF FA HAVE SPARKED THIS DEVELOPMENT NORTH OF THE STATIONARY FRONT DRAPED OVER NRN IL/CENTRAL IN AT 8Z. EXPECT CONVECTION TO CONTINUE AND MOVE NE THROUGH THE MORNING HOURS INTO LWR MI/NW OH WITH THE FRONT CLOSE BEHIND. ATTENTION IS THEN FOCUSED ON DEVELOPING SHRT/WV FROM REMNANTS OF TD ERIN OVER SW MO SHOWN ON IR IMAGERY AT 8Z. MODELS IN GOOD AGREEMENT OF STRENGTHENING CONVECTION WITH THIS WAVE WHICH WILL MOVE NE AND INTERACT WITH FRONT PROGGED TO BE OVER FA THIS AFTERNOON. BEST SVR POTENTIAL LOOKS TO BE OVER SE CWA CLOSER TO PASSING VORT MAX AND BEST CAPE. HOWEVER...THE PRIMARY THREAT STILL LOOKS TO BE HEAVY RAINFALL WITH VERY MOIST BL...DEEP WARM CLOUD LAYER...AND LONG THIN CAPE. THEREFORE HAVE EXTENDED FLOOD WATCH TILL 10Z TONIGHT. PRECIP CHANCES WILL GRADUALLY BE ON THE DECREASE LATE TONIGHT AFTER PASSAGE OF SHRT/WV. KEPT MAX TEMPS FOR TODAY 4 TO 5 DEGREES BELOW GUIDANCE AS TEMPS STRUGGLED TO MAKE IT TO THE MID 60S YESTERDAY...AND ABUNDANT CLOUD COVER/PRECIP SHOULD INHIBIT DIURNAL RISE TODAY. LONG TERM... E-W ORIENTED STNRY FRONT IS EXPECTED TO BE OVER THE AREA AT THE START OF THE LONG TERM PD (12Z TUE) WITH REMNANTS OF ERIN MOVG OFF TO OUR THE EAST. THIS SHOULD RESULT IN CONTINUED SHOWERS AND TSTMS IN THE AREA TUE, BUT EXPECT COVERAGE WILL NOT BE AS EXTENSIVE AS THE PREVIOUS 24HRS. FLOW ALOFT OVER THE AREA SHOULD BACK A BIT FROM W TO SW TUE-TUE NIGHT AS A SHRTWV MOVES INTO THE UPR MIDWEST. THIS IS EXPECTED TO CAUSE THE STNRY FRONT TO LIFT NORTH OF THE AREA BY WED MORNING. SCATTERED SHOWERS AND TSTMS TUE SHOULD DIMINISH IN AREAL COVERAGE FURTHER TUE NIGHT AS THE FRONT MOVES NORTH OF THE CWA. WARM SECTOR EXPECTED TO BECOME QUITE UNSTABLE ON WEDNESDAY RESULTING IN SCT TSTMS REDEVELOPING DURING THE DAY. GFS INDICATES A WIND SHIFT TO NW OVER THE AREA WED WHICH APPEARS TO BE THE RESULT OF CONVECTIVE FEEDBACK ALONG CDFNT APPROACHING FROM THE NW. PREFER NAM HANDLING OF THIS FEATURE KEEPING WINDS SW THRU THU. THIS CDFNT EXPECTED TO MOVE THROUGH THE AREA THU NGT WITH TSTMS ALONG AND AHEAD OF IT IN THE CONTINUED UNSTABLE AIRMASS ENHANCING POPS ACROSS THE CWA. ANOTHER WAVE IS EXPECTED TO MOVE ENE ALONG THE FRONT FRI NGT AND SAT KEEPING SHOWERS AND TSTMS IN THE AREA. FRONT SHOULD FINALLY MOVE WELL SOUTH OF THE AREA WITH HIGH PRESSURE AND DRIER AIRMASS MOVG INTO THE CWA SAT NGT AND SUNDAY. TEMPS ARE EXPECTED TO WARM CONSIDERABLY INTO THE U80S-L90S BY WED AS THE FRONT APPROACHES. TROPICAL AIRMASS ENHANCED BY RECENT HEAVY RAINFALL SHOULD RESULT IN DEWPOINTS IN THE L70S AND AFTN HEAT INDICES IN THE M-U90S. AVIATION... IFR CONDITIONS ARE EXPECTED MUCH OF THIS TAF PD. 35KT SWLY LLJ OVERRUNNING STNRY SFC FRONT OVER CENTRAL IL/IN WAS CAUSING WIDESPREAD TSTM OVER NRN IL/IN THIS MORNING. EXPECT THIS ACTIVITY WILL WANE AS LLJ GOES THROUGH DIURNAL WKNG/VEERING. CLOUDS WILL LIMIT HEATING TODAY, BUT STILL SHOULD BE SOME DIURNAL DESTABILIZATION AGAIN THIS AFTN. REMNANTS OF ERIN OVER MO WILL LIFT NE ACROSS INDIANA THIS EVENING PRECEEDED/ACCOMPANIED BY SHRA/TSRA AT THE TERMINALS. AS THIS WAVE MOVES AWAY FROM THE AREA LATE TONIGHT LIGHT WINDS AND MOIST AIRMASS SHOULD ALLOW STRATUS/FOG TO FORM. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH THROUGH LATE TONIGHT FOR INZ003>009-012>018-020- 022>027-032>034. MI...FLOOD WATCH THROUGH LATE TONIGHT FOR MIZ077>081. OH...FLOOD WATCH THROUGH LATE TONIGHT FOR OHZ001-002-004-005-015-016- 024-025. LM...NONE. && $$ SHORT TERM...TAYLOR LONG TERM....LAMMERS AVIATION/UPDATE...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1104 AM EDT MON AUG 20 2007 .UPDATE... CONTINUED DEVELOPMENT OF SHOWERS AND THUNDERSTORMS DUE TO LOW LEVEL JET INTERACTION ACROSS THE STATIONARY BOUNDARY WHICH LINGERS FROM NEAR THE NORTH END OF CHICAGO TO ACROSS NORTHERN INDIANA AND INTO CENTRAL OHIO. RUC 80 SHOWS STRONG 850-700 MB FRONTOGENSIS JUST TO THE NORTHEAST OF THE AREA...WITH BEST FORCING JUST TO THE SOUTH OF THAT REGION ACROSS THE FORECAST AREA. PERIODS OF HEAVY RAINFALL WILL CONTINUE THROUGH THE AFTERNOON...CREATING OR WORSENING FLOODING PROBLEMS ACROSS THE REGION. WILL CONTINUE THE FLOOD WATCH FOR THE ENTIRE AREA. ACROSS THE FAR SOUTHERN PORTIONS OF THE REGION INTO CENTRAL INDIANA SOME PARTIAL CLEARING LATE THIS MORNING INTO THE AFTERNOON HAVE PUSHED LI`S TO -3 AND STARTED TO ERODE ANY CIN...WILL HAVE TO WATCH FOR THE POSSIBILITY OF STRONGER STORMS ACROSS THE FAR SOUTHERN COUNTIES THROUGH THE AFTERNOON AND EVENING HOURS. MAY TWEAK TO DEWPOINTS...SLIGHTLY HIGHER THAN PREVIOUS THINKING...ALSO ADJUSTED AFTN TEMPS UP ACROSS THE SOUTHERN ZONES WITH MID 80S POSSIBLE THERE. && .PREV DISCUSSION... /ISSUED 645 AM EDT MON AUG 20 2007/ SHORT TERM... TODAY AND TONIGHT COMPLICATED SHORT TERM PERIOD. 8Z RADAR IMAGERY SHOWING HEAVY BAND OF TSRA MOVING NE OVER NRN INDIANA DROPPING HEAVY RAINFALL UP TO AN INCH TO AN INCH AND A HALF PER HOUR. STRONG H85 LLJ AND SHRT/WV PASSING JUST TO THE S OF FA HAVE SPARKED THIS DEVELOPMENT NORTH OF THE STATIONARY FRONT DRAPED OVER NRN IL/CENTRAL IN AT 8Z. EXPECT CONVECTION TO CONTINUE AND MOVE NE THROUGH THE MORNING HOURS INTO LWR MI/NW OH WITH THE FRONT CLOSE BEHIND. ATTENTION IS THEN FOCUSED ON DEVELOPING SHRT/WV FROM REMNANTS OF TD ERIN OVER SW MO SHOWN ON IR IMAGERY AT 8Z. MODELS IN GOOD AGREEMENT OF STRENGTHENING CONVECTION WITH THIS WAVE WHICH WILL MOVE NE AND INTERACT WITH FRONT PROGGED TO BE OVER FA THIS AFTERNOON. BEST SVR POTENTIAL LOOKS TO BE OVER SE CWA CLOSER TO PASSING VORT MAX AND BEST CAPE. HOWEVER...THE PRIMARY THREAT STILL LOOKS TO BE HEAVY RAINFALL WITH VERY MOIST BL...DEEP WARM CLOUD LAYER...AND LONG THIN CAPE. THEREFORE HAVE EXTENDED FLOOD WATCH TILL 10Z TONIGHT. PRECIP CHANCES WILL GRADUALLY BE ON THE DECREASE LATE TONIGHT AFTER PASSAGE OF SHRT/WV. KEPT MAX TEMPS FOR TODAY 4 TO 5 DEGREES BELOW GUIDANCE AS TEMPS STRUGGLED TO MAKE IT TO THE MID 60S YESTERDAY...AND ABUNDANT CLOUD COVER/PRECIP SHOULD INHIBIT DIURNAL RISE TODAY. LONG TERM... E-W ORIENTED STNRY FRONT IS EXPECTED TO BE OVER THE AREA AT THE START OF THE LONG TERM PD (12Z TUE) WITH REMNANTS OF ERIN MOVG OFF TO OUR THE EAST. THIS SHOULD RESULT IN CONTINUED SHOWERS AND TSTMS IN THE AREA TUE, BUT EXPECT COVERAGE WILL NOT BE AS EXTENSIVE AS THE PREVIOUS 24HRS. FLOW ALOFT OVER THE AREA SHOULD BACK A BIT FROM W TO SW TUE-TUE NIGHT AS A SHRTWV MOVES INTO THE UPR MIDWEST. THIS IS EXPECTED TO CAUSE THE STNRY FRONT TO LIFT NORTH OF THE AREA BY WED MORNING. SCATTERED SHOWERS AND TSTMS TUE SHOULD DIMINISH IN AREAL COVERAGE FURTHER TUE NIGHT AS THE FRONT MOVES NORTH OF THE CWA. WARM SECTOR EXPECTED TO BECOME QUITE UNSTABLE ON WEDNESDAY RESULTING IN SCT TSTMS REDEVELOPING DURING THE DAY. GFS INDICATES A WIND SHIFT TO NW OVER THE AREA WED WHICH APPEARS TO BE THE RESULT OF CONVECTIVE FEEDBACK ALONG CDFNT APPROACHING FROM THE NW. PREFER NAM HANDLING OF THIS FEATURE KEEPING WINDS SW THRU THU. THIS CDFNT EXPECTED TO MOVE THROUGH THE AREA THU NGT WITH TSTMS ALONG AND AHEAD OF IT IN THE CONTINUED UNSTABLE AIRMASS ENHANCING POPS ACROSS THE CWA. ANOTHER WAVE IS EXPECTED TO MOVE ENE ALONG THE FRONT FRI NGT AND SAT KEEPING SHOWERS AND TSTMS IN THE AREA. FRONT SHOULD FINALLY MOVE WELL SOUTH OF THE AREA WITH HIGH PRESSURE AND DRIER AIRMASS MOVG INTO THE CWA SAT NGT AND SUNDAY. TEMPS ARE EXPECTED TO WARM CONSIDERABLY INTO THE U80S-L90S BY WED AS THE FRONT APPROACHES. TROPICAL AIRMASS ENHANCED BY RECENT HEAVY RAINFALL SHOULD RESULT IN DEWPOINTS IN THE L70S AND AFTN HEAT INDICES IN THE M-U90S. AVIATION... IFR CONDITIONS ARE EXPECTED MUCH OF THIS TAF PD. 35KT SWLY LLJ OVERRUNNING STNRY SFC FRONT OVER CENTRAL IL/IN WAS CAUSING WIDESPREAD TSTM OVER NRN IL/IN THIS MORNING. EXPECT THIS ACTIVITY WILL WANE AS LLJ GOES THROUGH DIURNAL WKNG/VEERING. CLOUDS WILL LIMIT HEATING TODAY, BUT STILL SHOULD BE SOME DIURNAL DESTABILIZATION AGAIN THIS AFTN. REMNANTS OF ERIN OVER MO WILL LIFT NE ACROSS INDIANA THIS EVENING PRECEEDED/ACCOMPANIED BY SHRA/TSRA AT THE TERMINALS. AS THIS WAVE MOVES AWAY FROM THE AREA LATE TONIGHT LIGHT WINDS AND MOIST AIRMASS SHOULD ALLOW STRATUS/FOG TO FORM. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH THROUGH LATE TONIGHT FOR INZ003>009-012>018-020- 022>027-032>034. MI...FLOOD WATCH THROUGH LATE TONIGHT FOR MIZ077>081. OH...FLOOD WATCH THROUGH LATE TONIGHT FOR OHZ001-002-004-005-015-016- 024-025. LM...NONE. && $$ UPDATE...SCHOTT SHORT TERM/AVIATION...TAYLOR LONG TERM....LAMMERS in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 735 PM EDT SUN AUG 19 2007 .AVIATION... MODELS CONTINUE TO STRUGGLE HANDLING THIS VERY DIFFICULT AND CHAOTIC CONVECTION PATTERN. WEAK FRONT REMAINS WELL SOUTH OF MOST MODEL DEPICTIONS FOR 00Z. RUC PROBABLY BEST AND EVEN THIS LOOKS TOO FAR NORTH WITH ITS PLACEMENT OF BEST LIFT AND QPF COMPARED TO LATEST SATELLITE AND RADAR TRENDS. WITH VERY COOL LOW LEVEL EASTERLY FLOW IN PLACE AND ELEVATED CONVECTION NORTH OF BOUNDARY...FEEL IT WILL BE DIFFICULT FOR NORTHWARD MOVEMENT ESPECIALLY OVERNIGHT. WITH LOW LEVEL JET EXPECTED TO INCREASE OVERNIGHT AND SHORT WAVE SEEN IN WATER VAPOR EXITING NORTHEAST MISSOURI...EXPECT ADDITIONAL DEVELOPMENT OF CONVECTION THROUGH THE NIGHT ACROSS OUR AREA...ESPECIALLY NORTHERN INDIANA. TAFS ARE IN LINE WITH CURRENT OBSERVATIONS. PERSISTENT LOW LEVEL EASTERLY FLOW WITH DEEP AND WARM SOUTHWEST FLOW ABOVE TO LIKELY KEEP LOW CLOUDS LOCKED IN. CONFINED TSRA TO BEST WINDOW WITH SHORT WAVE APPROACHING AND LLJ OVERNIGHT. WILL UPDATE AS NEEDED. && .SHORT TERM... TONIGHT AND TOMORROW OPERATIONAL MODELS HAVING DIFFICULTIES DEALING WITH REMNANTS OF ERIN...CREATING ISSUES WITH MOISTURE AND PLACEMENT OF INGREDIENTS FOR HEAVY RAINFALL PRODUCTION ACROSS THE REGION. TO MITIGATE THE DIFFERENCES THE 09Z SREF LOOKS TO BE A FAIRLY SOLID SOLUTION HANDLING THE LEFTOVERS FROM ERIN A LITTLE MORE SMOOTHLY THAN EITHER THE OPERATIONAL GFS OR NAM. CONSTANT LOW CLOUD COVER AND OCCASIONAL PRECIP HAS KEPT TEMPS IN CHECK ACROSS THE NORTHERN TWO THIRDS OF THE FORECAST AREA THIS AFTERNOON. NEARLY STATIONARY BOUNDARY RESIDES ALONG A LINE FROM CENTRAL IA TO NEAR KLAF TO NEAR DAYTON/COLUMBUS OHIO. CURRENT WATER VAPOR IMAGERY SHOWS ERIN BEING SHEARED RAPIDLY AND MOISTURE BEING TRANSPORTED NORTH TOWARDS THE REGION...PWATS REMAIN SOMEWHAT ABOVE 2 INCHES THROUGH THE PERIOD. LITTLE MOVEMENT TO THE PLACEMENT OF THE FRONTAL BOUNDARY THROUGH THE PERIOD...NEARLY CONSTANT MODERATE LOW LEVEL JET PUSHING ACROSS THE BOUNDARY ENHANCING THE PRECIP. MODELS SEEM TO HAVE A SLIGHT NORTHERLY BIAS WITH THE PLACEMENT OF THE PRECIP AND HAVE MADE ADJUSTMENTS ACCORDINGLY. SHRTWV MOVING FROM MS VALLEY LOOKS TO MOVE ACROSS THE REGION TONIGHT ALLOWING FOR PERIODS OF MODERATE TO HEAVY RAINFALL. LOCALIZED HEAVY RAINFALL TOTALS OF 2 TO 4 INCHES WILL BE POSSIBLE OVERNIGHT. HAVE EXPANDED THE FLOOD WATCH TO ACROSS THE ENTIRE FORECAST AREA...ALSO EXTENDED THE TIMEFRAME THROUGH EARLY MONDAY EVENING (00Z TUES). SIMILAR CONDITIONS OF LOW LEVEL JET MOVING ACROSS THE FRONTAL BOUNDARY AND AMPLE MOISTURE CONTINUE INTO MONDAY AFTERNOON. KEPT HIGH POPS THROUGH THE PERIOD...STARTING TO DECREASE THROUGH THE AFTERNOON FROM WEST TO EAST. TEMPERATURES OVERNIGHT WILL REMAIN SOMEWHAT STEADY ACROSS THE SOUTHWESTERN MI/ AND EXTREME NE IN AND NW OH COUNTIES TONIGHT...ONLY DROPPING A FEW DEGREES...THE REST OF THE AREA WILL HAVE TEMPS FALL TO JUST ABOVE SEASONAL AVGS. AFTERNOON TEMPS MONDAY ARE CONTROLLED BY THE CLOUD COVER AND PRECIP...HAVE WENT TOWARDS THE COOL SIDE OF MOS...UNDERCUTTING SLIGHTLY ACROSS THE NORTHEAST COUNTIES. DECENT GRADIENT FROM NORTHEAST TO SOUTHWEST ACROSS THE REGION...WITH AREAS NEAR MONTICELLO IN APPROACHING 80 OR SLIGHTLY ABOVE AND HILLSDALE MI AREA STRUGGLING TO REACH THE UPPER 60S. && .LONG TERM... TOMORROW NIGHT THROUGH SUNDAY NOT REALLY MANY CHANGES TO THE LONG TERM PART OF THE FORECAST. OVERALL STILL LOOKING TO BE A WET WEEK. MONDAY NIGHT THE FRONT WILL STILL BE HANGING AROUND THE AREA HELPING WITH THE LIFT...AND WITH ABUNDANT MOISTURE IN THE AREA...WILL BE CONTINUING THE RAIN CHANCES. SOMEWHAT OF A QUESTION ON WHEN THE RAIN WILL OCCUR ON TUESDAY AND TUESDAY NIGHT AS MODELS HAVE SWITCHED AROUND A LITTLE IN THE TIMING OF THE FRONT FINALLY LIFTING NORTHWARD TO THE NORTHEAST OF THE CWA. THE FRONT IS PROGGED TO MOVE NORTHEAST OF THE CWA BY WEDNESDAY MORNING. AT THIS POINT IN TIME WILL NOT TRY TO PIN DOWN ANY PERIODS OF RAIN...SO WILL LEAVE THE BLANKETED RAIN CHANCES FOR TUESDAY AND TUESDAY NIGHT. IF THIS CURRENT TREND CONTINUES THEN A GOOD PORTION OF WEDNESDAY COULD BE DRY AS WELL AS WE ARE IN BETWEEN FRONTS...AWAITING A COLD FRONT FROM THE NORTHWEST. GFS DID HAVE THE COLD FRONT MOVING IN ON WEDNESDAY BUT NOW SEEMS TO BE SLOWING IT DOWN. ALSO WANT TO SEE SOME MORE CONSISTENCY FOR THURSDAY AND FRIDAY...FOR NOW THE GFS IS STALLING OUT THE COLD FRONT JUST TO OUR NORTHWEST THURSDAY/THURSDAY NIGHT AND THEN MOVING THE FRONT INTO THE CWA ON FRIDAY. THIS WILL HOLD IF THE UPPER HIGH OVER THE EAST COAST IS STRONG ENOUGH TO HOLD OFF THE FRONT. THIS FRONT IS THEN PROGGED TO HANG AROUND INTO SATURDAY. THEN THE MODELS FINALLY MOVE A HIGH PRESSURE INTO THE CWA ON SUNDAY. NO CHANGES FOR THE END OF THIS WEEK AS THAT PERIOD IS SEVERAL DAYS OFF YET AND MODELS ARE NOT TOO CONSISTENT YET. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH THROUGH MONDAY EVENING FOR INZ003>009-012>018-020- 022>027-032>034. MI...FLOOD WATCH THROUGH MONDAY EVENING FOR MIZ077>081. OH...FLOOD WATCH THROUGH MONDAY EVENING FOR OHZ001-002-004-005-015- 016-024-025. LM...NONE. && $$ SHORT TERM...SCHOTT/LASHLEY LONG TERM....LOTHAMER AVIATION...LASHLEY in AREA FORECAST DISCUSSION...UPDATED FOR TAFS NATIONAL WEATHER SERVICE DES MOINES IA 1150 PM CDT SUN AUG 19 2007 .SYNOPSIS... NEARLY STATIONARY FRONT WOBBLING NORTH ACROSS THE STATE LATE THIS AFTERNOON WITH TROPICAL MOISTURE FEED WELL IN PLACE ONCE AGAIN. THUNDERSTORMS CONTINUE TO DEVELOP NORTH OF BOUNDARY ACROSS SOUTHERN MN AND ARE HEADING EAST ALONG H850 FRONTAL ZONE. OVER SOUTHERN SECTIONS OF THE FORECAST AREA...CONTINUE TO SEE INFLUX OF OLD ERIN MOISTURE WITH AREAS OF THUNDERSTORMS INCREASING. MAINTAINING FLASH FLOOD WATCH TONIGHT ACROSS THE NORTH WHERE ADDITIONAL RAINFALL EXPECTED. SOUTHERN PORTIONS CAN TAKE A FEW INCHES WITH LESS IMPACT EXPECTED THERE. .SHORT TERM...TONIGHT... DEEP TROPICAL MOISTURE PLUME CONTINUES TO STREAM NORTH INTO THE STATE TNT. THOUGH THE GREATEST LIFT INITIALLY APPEARS TO BE ALONG AND NORTH OF THE IA-MN BORDER...RUC MODEL HAS COME AROUND TO SHOW INCREASING LIFT WITH STRONGER AND MORE NORTHERLY MOISTURE TRANSPORT OVER THE ENTIRE FORECAST AREA THIS EVENING AND GRADUALLY SHIFTING THE GREATER MOISTURE TRANSPORT MORE EAST NORTHEAST BY 03Z LATER THIS EVENING. H700 WAVE OVER THE DAKOTAS SHOULD HELP KEEP PATTERN PROGRESSIVE OVER THE NORTH THOUGH SOME STORMS EXPECTED TO FIRE INTO THE WARM SECTOR THIS EVENING ALONG THE FRONTAL BOUNDARY AS IT DRIFTS SOUTHEAST WITH TIME. THIS MAY MITIGATE SOME HYDRO ISSUES OVER THE NORTH BUT WILL HOLD ONTO FLASH FLOOD WATCH DUE TO FACT THAT LITTLE IF ANY ADDITIONAL RAINFALL TNT WILL CAUSE PROBLEMS. OLD ERIN STILL A PROBLEM...AS MOISTURE TRANSPORT AND PLUME WILL CROSS THE SOUTHEAST THIRD OF FORECAST AREA THROUGH 06Z...WITH SOME HEAVY RAINFALL POSSIBLE THERE. GFS/NAM MUCH FARTHER EAST WITH TRACK THIS EVENING...AND AM FOLLOWING RUC MORE CLOSELY. FFG RUNNING HIGHER SOUTHEAST COUNTIES WITH VALUES GENERALLY IN THE 2.5 TO 3.5 RAINFALL SO WILL NOT EXTEND WATCH ANY FARTHER SOUTH ATTM THOUGH SOME TOTALS MAY COME IN ABOVE TWO INCHES IN SOME CASES. H700 WAVE NORTH WILL LIFT EAST AFTER 06Z AND RAINFALL SHOULD DIMINISH AT THAT TIME. ACROSS THE SOUTH EXPECT THE RAIN TO DIMINISH BETWEEN THE 04 AND 08Z TIMEFRAME AS OLD ERIN SPINS EAST BY MORNING. FOLLOWING THAT...FOG MAY BECOME AN ISSUE IN THE WAKE OF THE THESE SYSTEMS AS WINDS REMAIN LIGHT BY MORNING. WITH GO WITH AREAS OF FOG FOR NOW. .LONG TERM...MONDAY THROUGH SUNDAY ACTIVE WEATHER PATTERN TO CONTINUE FOR THE WORK WEEK AS THE SURFACE BOUNDARY IS NEVER FORECAST TO LEAVE IOWA UNTIL FRIDAY NIGHT. SEVERAL ROUNDS OF CONVECTIVE WEATHER ARE LIKELY TO OCCUR...WITH HIGHEST PROBABILITIES OVER NORTHERN IOWA WHERE SOME HEAVY RAINS HAVE ALREADY FALLEN...MAKING LOCAL FLOODING THE BIGGEST THREAT FOR THE WEEK. WESTERLY FLOW ALOFT WILL PROVIDE ENOUGH SHEAR AT TIMES FOR ISOLATED SEVERE WEATHER. CONDITIONS SOUTH OF THE FRONT WILL REMAIN TROPICAL WITH HIGHS CLOSE TO 90 AND DEWPOINTS WELL INTO THE 70S. TEMPERATURES A BIT MORE PROBLEMATIC NORTH SINCE THERE IS A SLIM POSSIBILITY THAT COOLER AND DRIER AIR COULD SLIP IN FOR A SHORT SPELL. SPECIFICALLY...AFTER TONIGHT HEAVY RAIN CHANCES APPEAR TO BE MOST LIKELY WITH CONVECTIVE COMPLEXES THAT ARE EXPECTED TO DEVELOP MONDAY EVENING AND MOVING ACROSS NORTHERN IOWA...WITH REPEAT ACTION POSSIBLE ACROSS THE SAME AREA TUESDAY NIGHT. RETURN FLOW OF COPIOUS MOISTURE AND THETA-E ADVECTION IS RAPID ACROSS THIS AREA AS A SERIES OF SHORT WAVES COMES OUT IN THE WLY FLOW ALOFT. DIFFICULT TO SEE ENOUGH OF A BREAK IN THIS PATTERN THROUGH THURSDAY NIGHT...SO CHANCES FOR THUNDERSTORMS REMAIN IN THE FORECAST THROUGH FRIDAY. LONGER RANGE MODELS AGREE THAT A RIDGE WILL BUILD SOMEWHAT TO THE WEST PUSHING A SURFACE HIGH INTO IOWA AND THE UPPER MIDWEST FOR FRIDAY AND SATURDAY...WHICH SHOULD END THE PERSISTENT RAIN CHANCES AND DROP TEMPERATURES AND DEWPOINTS BACK TO COMFORTABLE LEVELS. ALL OF THESE RAIN CHANCES LEAVE THE POSSIBILITY OF ADDITIONAL FLASH FLOOD WATCHES AND POSSIBLE RIVER FLOODING EVENTUALLY FOR THE NORTHERN HALF OF THE STATE. CEDAR RIVER IS NOW EXPECTED TO REACH BANK FULL...AND COULD GO HIGHER IF RAINS TARGET THE SAME AREAS FOR A COUPLE OF DAYS IN A ROW. .AVIATION...20/06Z STATIONARY BOUNDARY MEANDERS THROUGH THE STATE. STORMS WITH HEAVY RAINFALL LEAVING VERY MOIST AIRMASS WITH FOG LIKELY. FREQUENT IFR CONDITIONS NORTHERN HALF OF IOWA THROUGH MORNING. MVFR CLOUDS AROUND 3000 FEET TODAY. && .DMX WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH THROUGH 4 AM MONDAY IAZ004>007-IA015>017-IA023>028-IA035>039-IA049>050- && $$ SHORT TERM...REV LONG TERM...JUNGBLUTH AVIATION...FORSTER ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 339 PM CDT MON AUG 20 2007 .DISCUSSION... THE LATEST WATER VAPOR SATELLITE IMAGERY ALONG WITH THE 12Z UPPER AIR MAPS SHOWED AN UPPER LEVEL TROUGH MOVING EASTWARD INTO THE NORTHERN AND CENTRAL PLAINS. A BROAD UPPER RIDGE WAS LOCATED ACROSS THE SOUTHERN CONUS. A SECOND UPPER LEVEL TROUGH WAS LOCATED ACROSS THE PACIFIC NORTHWEST. THE 19Z SURFACE MAP SHOWED A WEAK COLD FRONT EXTENDING FROM EASTERN CO...NORTHEAST ACROSS NORTHWEST KS...INTO WEST CENTRAL NE THEN NORTHEAST INTO A SURFACE LOW OVER SOUTHEAST SD. A SURFACE TROUGH EXTENDED FROM NORTH CENTRAL NE...SOUTH-SOUTHWEST INTO NORTH CENTRAL KS. DEWPOINTS ACROSS MUCH OF EASTERN KS WERE IN THE MID 70S AND COMBINED WITH TEMPERATURES IN THE UPPER 90S ACROSS THE WESTERN COUNTIES AND MID 70 DEWPOINTS ACROSS THE EASTERN COUNTIES WAS CAUSING HEAT INDICES TO REACH 108 TO 112 DEGREES ACROSS MOST OF THE CWA WITH THE EXCEPTION OF THE FAR NORTHEAST COUNTIES. THEREFORE A HEAT ADVISORY WAS ISSUED FOR MOST OF THE CWA THROUGH 700 PM. TONIGHT...SURFACE BASED STORMS THAT DEVELOP ALONG THE SURFACE TROUGH OR WEAK COLD FRONT LATE THIS AFTERNOON AND EARLY EVENING ACROSS EAST CENTRAL NE AND CENTRAL KS WILL PROBABLY MOVE EAST INTO THE NORTHWEST COUNTIES OF THE CWA LATER THIS EVENING. ONE OF THE BIG QUESTIONS IS THE AMOUNT OF COVERAGE FROM THESE STORMS. THE NAM MODEL SHOWS AN MCS DEVELOPING ACROSS EASTERN NE...WHICH WOULD THEN PROPAGATE SOUTH-SOUTHWEST ACROSS MOST OF THE EASTERN COUNTIES OF THE CWA FROM LATE THIS EVENING THROUGH THE EARLY MORNING HOURS OF TUESDAY. MEANWHILE...THE RUC AND GFS HAVE SCATTERED TO NUMEROUS THUNDERSTORMS DEVELOPING ALONG THE FRONT AND MOVING THEM EAST AND SOUTHEAST INTO THE NORTHWEST COUNTIES OF THE CWA LATE THIS EVENING BEFORE WEAKENING THEM AS THEY MOVE INTO THE CENTRAL COUNTIES DURING THE EARLY MORNING HOURS OF TUESDAY. GIVEN LOWER TO MID 70 DEWPOINTS ALONG WITH SURFACE TEMPERATES IN THE MID 90S TO AROUND 100 DEGREES HAVE CAUSED MLCAPES TO INCREASE 3-4,000 J/KG ACROSS EASTERN KS AND SOUTHEAST NE THIS AFTERNOON. THE VERTICAL WINDSHEAR PROFILES SHOW SOME TURNING FROM THE SURFACE TO 850MB...AND 30KTS OF WESTERLY FLOW ABOVE 600 MB. THUS SOME STORMS THAT DEVELOP ACROSS NORTH CENTRAL KS AND EASTERN NE THIS AFTERNOON AND EVENING MAY BECOME SEVERE WITH DAMAGING OUTFLOW WINDS BEING THE PRIMARY HAZARD. THE 0 DEGREE ISOTHERM HEIGHTS ARE ABOVE 16,000 FEET THUS THE HAIL MAY ONLY GET TO QUARTER SIZE IN THUNDERSTORMS WITH MID-LEVEL ROTATION. HEAVY RAINFALL MAY ALSO BE POSSIBLE GIVEN PW`S OF 1.75 TO 2.0 INCHES. ATTM I KEPT THE HIGHEST POPS 40 PERCENT ACROSS THE NORTHERN COUNTIES. THIS MAY NEED TO BE UPDATED IF THE NAM SOLUTION IS CORRECT ABOUT DEVELOPING AN MCS ACROSS EASTERN NE. ATTM I`M LEANING MORE TO THE GFS MODEL. LOWS TONIGHT WILL BE IN THE MID 70S ACROSS THE CWA. TUESDAY...THE UPPER RIDGE WILL CONTINUE ACROSS THE SOUTHERN CONUS. A BROAD UPPER LEVEL TROUGH WILL SET UP ACROSS THE NORTHERN HIGH PLAINS. MINOR 5H TROUGHS MAY RIDE ACROSS THE CENTRAL PLAINS ON THE NORTHERN PERIPHERY OF THE 5H RIDGE ACROSS THE SOUTHERN CONUS. DEEP 850MB MOISTURE WILL CONTINUE IN PLACE AND COMBINED WITH AFTERNOON HEATING WILL CAUSE MLCAPES TO ONCE AGAIN REACH THE 3 TO 4,000 J/KG LEVEL. THE CAP MAY BE STRONG ENOUGH TO SUPPRESS DEEP MOIST CONVECTION UNTIL LATE TUESDAY AFTERNOON. THERE MAY BE AN OUTFLOW BOUNDARY ALONG THE NE BORDER FROM THUNDERSTORMS OVERNIGHT THAT MAY HELP ENHANCE SURFACE CONVERGENCE ACROSS THE NORTHERN COUNTIES OF THE CWA. OTHERWISE...STORMS MAY DEVELOP FARTHER WEST ALONG THE SURFACE TROUGH/COLD FRONT ACROSS WESTERN AND CENTRAL KS. SOME OF THESE THUNDERSTORMS MAY REACH THE NORTHWEST COUNTIES BY EARLY EVENING. HIGHS WILL BE IN THE UPPER 90S ACROSS THE WESTERN COUNTIES WITH MID 90S ACROSS THE EASTERN COUNTIES OF THE CWA. HEAT INDICES MAY REACH ABOVE 105 DEGREES ACROSS THE CWA DURING THE AFTERNOON HOURS. I WILL LET THE NEXT SHIFT DETERMINE IF A HEAT ADVISORY WILL BE NEEDED. SINCE CONVECTION THIS MORNING COULD LEAVE CLOUD COVER ACROSS THE NORTHERN AND EASTERN COUNTIES ON TUESDAY. TUESDAY NIGHT THROUGH FRIDAY...NEARLY STATIONARY SURFACE BOUNDARY REMAINS THE FOCUS FOR CONVECTIVE INITIATION THROUGH THIS TIME PERIOD. THE BOUNDARY EXTENDS FROM NORTHWEST KANSAS THROUGH SOUTHEAST NEBRASKA AND INTO IOWA. HOWEVER...THE LOCATION OF THE BOUNDARY WILL CERTAINLY BE IMPACTED BY CONVECTION DURING THIS PERIOD. HAVE KEPT HIGHEST POPS IN THE NORTHERN PORTION OF THE CWA THROUGH THE END OF THE WORK WEEK. HIGH TEMPERATURES THROUGH THE PERIOD WILL BE MAINLY IN THE 90S...BUT A BIT COOLER FRIDAY AS MORE CLOUD COVER IS ANTICIPATED. UPPER LEVEL TROUGH MOVES OUT OF THE ROCKIES LATE FRIDAY AND PUSHES THE FRONT SOUTH THROUGH THE CWA FRIDAY NIGHT. HAVE INCREASED POPS OVER THE SOUTHERN PORTION OF THE CWA FRIDAY NIGHT. TIMING WITH THE FROPA HAS BEEN FAIRLY CONSISTENT OVER THE PAST FEW MODEL RUNS. SURFACE HIGH PRESSURE BUILDS OVER NORTHEAST KS BEHIND THE FRONT ON SATURDAY WITH SURFACE DEWPOINTS EXPECTED TO BE IN THE LOW TO MID 60S ALONG WITH HIGHS IN THE 80S SHOULD MAKE FOR A PLEASANT DAY SATURDAY. PROGRESSIVE FLOW PATTERN ALLOWS SOUTHERLY RETURN FLOW TO DEVELOP SUNDAY WITH TEMPERATURES GRADUALLY WARMING THROUGH MONDAY. NEXT FRONTAL BOUDARY SETS UP IN WESTERN KANSAS AND CENTRAL NEBRASKA WITH CONVECTION EXPECTED TO REMAIN MAINLY TO OUR NORTH AND WEST. KEPT SLIGHT CHANCE POPS IN FOR MONDAY WITH MOIST LOW LEVEL AIRMASS IN PLACE AND FEW WEAK WAVES IN THE FLOW. && .AVIATION... MAY SEE ISOLATED TO SCATTERED THUNDERSTORMS MOVE INTO THE TAF SITES LATER THIS EVENING. ATTM I PLACED IN VCTS BUT IF AN MCS WERE TO DEVELOP AND MOVE SOUTHEAST ACROSS THE CWA WE COULD SEE A PERIOD OF TIME WHERE THUNDERSTORMS MAY MOVE ACROSS THE TAF SITES LATE THIS EVENING AND DURING THE EARLY MORNING HOURS OF TUESDAY. OTHERWISE... EXPECT MOSTLY CLEAR SKIES. SOUTH AND SOUTHEASTERLY WINDS OF 5 TO 10 KTS ARE EXPECTED THROUGH THE NIGHT. THE SOUTHERLY WINDS WILL INCREASE TO 10 TO 20 KTS DURING THE AFTERNOON HOURS. MAY SEE SOME MID-LEVEL CLOUDS THIS MORNING AND THEN A FEW BOUNDARY LAYER CU DEVELOPING IN THE AFTERNOON HOURS WITH BASES OF 4,000 FEET. && .TOP WATCHES/WARNINGS/ADVISORIES...HEAT ADVSY IN EFFECT UNTIL 7 PM THIS EVENING FOR ALL FAR NORTHEAST CWA. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1141 AM MDT MON AUG 20 2007 .UPDATE...IN EASTERN ZONES ISOLATED CONVECTION HAS ALREADY STARTED...THUS THE POPS FOR LATE THIS AFTERNOON WERE MOVED UP TO 17Z. MEANWHILE...IN EASTERN COLORADO...WITH MIXING DEW POINTS HAVE DROPPED TO THE LOWER 40S AND IN SOME CASES 30S. LATEST FORECAST HAS RH VALUES AS LOW AS 18 PERCENT...IN ADDITION WINDS ARE BREEZY NOW...BUT SHOULD DIMINISH THROUGH THE AFTERNOON. THEREFORE A RED FLAG WARNING HAS NOT BEEN ISSUED...BUT THIS WILL BE WATCHED CLOSELY AS THE AFTERNOON CONTINUES. && .PREV DISCUSSION... /ISSUED 1008 AM MDT MON AUG 20 2007/ .UPDATE...LATEST SURFACE ANALYSIS SHOWS TROUGH BISECTING GLD CWA. AFTERNOON CONVERGENCE ALONG THE TROUGH EXTENDS FROM THE SURFACE THROUGH 700MB ACCORDING TO THE RUC. ML CAPE VALUES EAST OF THE TROUGH ARE RELATIVELY HIGH...UP TO 1900 J/KG IN GLD CWA...AND VALUES OF CIN LOOK TO BE LOW. HOWEVER...WV IMAGERY SHOWS A DRY TONGUE OVER THE REGION...THOUGH THERE IS A PUSH OF MOIST AIR FURTHER TO THE NORTHWEST THAT SHOULD MAKE ITS WAY INTO THE REGION THIS AFTERNOON. CONSIDERING ALL OF THIS...SLIGHT CHANCE HAS BEEN ADDED TO EASTERN ZONES FOR LATE THIS AFTERNOON...BEGINNING AT 21Z. && .PREV DISCUSSION... /ISSUED 349 AM MDT MON AUG 20 2007/ .DISCUSSION...SHORT TERM CONCERNS ARE TEMPERATURES FOLLOWED BY THE POSSIBILITY OF THUNDERSTORMS EACH DAY DURING THE LATTER PART OF THE WORK WEEK. CONTINUE TO EXPECT HOT AND DRY CONDITIONS TODAY THROUGH TOMORROW ACROSS THE TRI-STATE REGION WITH THE CHANCE OF THUNDERSTORMS INCREASING BEGINNING TUESDAY EVENING. MODELS CONTINUE ON TRACK TO DAMPEN OUT THE REMAINDER OF THE UPPER RIDGE AS A NEGATIVELY TILTED TROUGH MOVES EAST ALONG THE U.S./CANADIAN BORDER TODAY AND TONIGHT. A SHORT WAVE TROUGH EXTENDING SOUTH INTO THE CENTRAL HIGH PLAINS IS EXPECTED TO HELP IN THE DEVELOPMENT OF THUNDERSTORMS IN THE VICINITY OF THE STATIONARY TROUGH THAT EXTENDS THROUGH NEBRASKA AND IN THE VICINITY OF THE SURFACE LEE TROUGH AND THESE FEATURES INTERSECTION POINT LATE TODAY. AHEAD OF THE SURFACE LEE TROUGH...DEWPOINTS ARE IN THE UPPER 60S AND LOWER 70S EXTEND FROM OKLAHOMA INTO CENTRAL NEBRASKA. THIS MOISTURE COMBINED WITH THE HOT TEMPERATURES AND UPPER SHORT WAVE EXPECTED JUST TO THE EAST OF THE TRI-STATE REGION SHOULD KEEP OUR FORECAST AREA HOT AND DRY TODAY THROUGH TUESDAY. IT APPEARS BY LATE TUESDAY THE FRONTAL BOUNDARY AND LEE SURFACE TROUGH WILL BE IN POSITION ACROSS THE TRI-STATE REGION WITH A SURFACE LOW PRESSURE CENTER DEEPENING NEAR THE CENTRAL PORTION OF THE KANSAS/COLORADO BORDER. THIS SHOULD MOVE THE PREFERRED AREA FOR THUNDERSTORM DEVELOPMENT INTO THE EASTERN SECTIONS OF THE FORECAST AREA. WITH THE BOUNDARY REMAINING IN THE REGION THROUGH THE END OF THE WEEK...WE COULD SEE CONTINUED THUNDERSTORM DEVELOPMENT ACROSS THE TRI-STATE REGION THROUGH FRIDAY NIGHT UNTIL THE FRONT FINALLY MOVES SOUTH OF THE REGION ON SATURDAY AND HIGH PRESSURE MOVES INTO PLACE ACROSS THE NORTHERN AND CENTRAL PLANS STATES. && .AVIATION...VFR CONDITIONS ARE ANTICIPATED TODAY AND TONIGHT ACROSS THE TRI-STATE REGION WITH ISOLATED TO WIDELY SCATTERED THUNDERSTORMS FURTHER NORTH AND EAST OVER SOUTH CENTRAL NEBRASKA AND CENTRAL KANSAS WHERE ABUNDANT LOW LEVEL MOISTURE IS AVAILABLE IN CLOSER PROXIMITY TO A COUPLE OF SURFACE BOUNDARIES. && && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JOHNSON/LOCKHART ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1008 AM MDT MON AUG 20 2007 .UPDATE...LATEST SURFACE ANALYSIS SHOWS TROUGH BISECTING GLD CWA. AFTERNOON CONVERGENCE ALONG THE TROUGH EXTENDS FROM THE SURFACE THROUGH 700MB ACCORDING TO THE RUC. ML CAPE VALUES EAST OF THE TROUGH ARE RELATIVELY HIGH...UP TO 1900 J/KG IN GLD CWA...AND VALUES OF CIN LOOK TO BE LOW. HOWEVER...WV IMAGERY SHOWS A DRY TONGUE OVER THE REGION...THOUGH THERE IS A PUSH OF MOIST AIR FURTHER TO THE NORTHWEST THAT SHOULD MAKE ITS WAY INTO THE REGION THIS AFTERNOON. CONSIDERING ALL OF THIS...SLIGHT CHANCE HAS BEEN ADDED TO EASTERN ZONES FOR LATE THIS AFTERNOON...BEGINNING AT 21Z. && .PREV DISCUSSION... /ISSUED 349 AM MDT MON AUG 20 2007/ .DISCUSSION...SHORT TERM CONCERNS ARE TEMPERATURES FOLLOWED BY THE POSSIBILITY OF THUNDERSTORMS EACH DAY DURING THE LATTER PART OF THE WORK WEEK. CONTINUE TO EXPECT HOT AND DRY CONDITIONS TODAY THROUGH TOMORROW ACROSS THE TRI-STATE REGION WITH THE CHANCE OF THUNDERSTORMS INCREASING BEGINNING TUESDAY EVENING. MODELS CONTINUE ON TRACK TO DAMPEN OUT THE REMAINDER OF THE UPPER RIDGE AS A NEGATIVELY TILTED TROUGH MOVES EAST ALONG THE U.S./CANADIAN BORDER TODAY AND TONIGHT. A SHORT WAVE TROUGH EXTENDING SOUTH INTO THE CENTRAL HIGH PLAINS IS EXPECTED TO HELP IN THE DEVELOPMENT OF THUNDERSTORMS IN THE VICINITY OF THE STATIONARY TROUGH THAT EXTENDS THROUGH NEBRASKA AND IN THE VICINITY OF THE SURFACE LEE TROUGH AND THESE FEATURES INTERSECTION POINT LATE TODAY. AHEAD OF THE SURFACE LEE TROUGH...DEWPOINTS ARE IN THE UPPER 60S AND LOWER 70S EXTEND FROM OKLAHOMA INTO CENTRAL NEBRASKA. THIS MOISTURE COMBINED WITH THE HOT TEMPERATURES AND UPPER SHORT WAVE EXPECTED JUST TO THE EAST OF THE TRI-STATE REGION SHOULD KEEP OUR FORECAST AREA HOT AND DRY TODAY THROUGH TUESDAY. IT APPEARS BY LATE TUESDAY THE FRONTAL BOUNDARY AND LEE SURFACE TROUGH WILL BE IN POSITION ACROSS THE TRI-STATE REGION WITH A SURFACE LOW PRESSURE CENTER DEEPENING NEAR THE CENTRAL PORTION OF THE KANSAS/COLORADO BORDER. THIS SHOULD MOVE THE PREFERRED AREA FOR THUNDERSTORM DEVELOPMENT INTO THE EASTERN SECTIONS OF THE FORECAST AREA. WITH THE BOUNDARY REMAINING IN THE REGION THROUGH THE END OF THE WEEK...WE COULD SEE CONTINUED THUNDERSTORM DEVELOPMENT ACROSS THE TRI-STATE REGION THROUGH FRIDAY NIGHT UNTIL THE FRONT FINALLY MOVES SOUTH OF THE REGION ON SATURDAY AND HIGH PRESSURE MOVES INTO PLACE ACROSS THE NORTHERN AND CENTRAL PLANS STATES. && .AVIATION...VFR CONDITIONS ARE ANTICIPATED TODAY AND TONIGHT ACROSS THE TRI-STATE REGION WITH ISOLATED TO WIDELY SCATTERED THUNDERSTORMS FURTHER NORTH AND EAST OVER SOUTH CENTRAL NEBRASKA AND CENTRAL KANSAS WHERE ABUNDANT LOW LEVEL MOISTURE IS AVAILABLE IN CLOSER PROXIMITY TO A COUPLE OF SURFACE BOUNDARIES. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JOHNSON/LOCKHART ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1131 AM CDT SUN AUG 19 2007 .UPDATE... MAIN CONCERN WILL CONTINUE TO BE MOVEMENT OF TROPICAL DEPRESSION ERIN AND TSRA CHANCES ASSOCIATED WITH IT FOR AREAS ACROSS SOUTH CENTRAL AND SOUTHEAST KANSAS. CURRENT SATELLITE ANALYSIS AND RADAR TRENDS SUGGEST THAT TD ERIN IS MAKING A GENERAL EASTWARD MOVEMENT. CURRENT 12Z MODELS NOT HANDLING THIS VERY WELL...WITH THE LATEST SHORT TERM RUC HAVING THE BEST HANDLE ON ITS MOVEMENT WHICH TAKES IT MORE EAST-NORTHEAST RATHER THAN NORTH. THIS MORE EASTWARD MOVEMENT WILL HAVE A BIG IMPACT ON POPS AND POSSIBLE SEVERE CHANCES FOR SOUTHEAST KANSAS. CURRENT THINKING IS THAT MOST OF THE CONVECTION WILL STAY SOUTH OR EAST OF THE AREA...BUT CIRRUS SHIELD WITH THIS SYSTEM IS THINNING SOME...WHICH WILL ALLOW MORE HEATING IN SOUTHEAST KS. LOTS OF LOW LEVEL MOISTURE AROUND...SO ANY INCREASED HEATING WILL INCREASE INSTABILITY ACROSS THIS AREA FOR A SCATTERED SEVERE CHANCE. SO WILL CONTINUE WITH SEVERE MENTION IN THIS AREA FOR NOW...AS HIGHER INSTABILITY AND CURRENT DIRECTIONAL SHEAR LOOKS FAVORABLE FOR A SEVERE WEATHER CHANCE. LOW LCL VALUES COULD LEAD TO AN ISOLATED TORNADO THREAT...BUT MAIN CONCERN WILL BE WET MICROBURST POTENTIAL. SEVERE THREAT LOOKS TO DROP OFF TONIGHT AS DIRECTIONAL SHEAR WANES SOME AS SYSTEM MOVE EAST. WILL ALSO MAKE SOME ADJUSTMENTS TO POPS FOR CEN KS AS A MORE EASTWARD MOVEMENT KEEPS PRECIP CHANCES TO THE EAST OF THIS AREA. .AVIATION... FOR 18Z TAF SUITE. MAIN CONCERN WILL BE FOR THE KCNU TAF SITE AS SOME SEVERE CONVECTION IS STILL POSSIBLE IF HEATING CAN MATERIALIZE. SO WILL CONTINUE THIS MENTION IN KCNU. WILL ALSO KEEP A VCTS IN KICT AND KHUT AS SOME ISOLATED TSRA COULD ROTATE NORTH INTO THIS AREA FOR THE AFTERNOON AREAS. LOTS OF LOW LEVEL MOISTURE AROUND...SO STILL COULD SEE SOME MVFR CEILINGS FOR THE KICT/KCNU AND KHUT SITES UNTIL SUNSET. KETCHAM && .PREV DISCUSSION... /ISSUED 619 AM CDT SUN AUG 19 2007/ UPDATE... AVIATION...12Z TAFS [RSL/SLN/HUT/ICT/CNU] IFR/MVFR STRATUS WILL CONTINUE TO AFFECT CENTRAL KS SITES UNTIL MID-LATE MORNING WHEN HEATING/MIXING SHOULD ALLOW IT TO DISSIPATE. T.D. ERIN OVER CENTRAL OK EARLY THIS AM...PROGGED TO MOVE NEWD ACROSS FAR SOUTHEASTERN KS LATER THIS PM/TONIGHT ALTHOUGH IT APPEARS TO BE MOVING DUE EAST AT THIS TIME. THIS TRACK WILL BRING HIGH SHOWER/T-STORM PROBABILITY TO CNU SITE MAINLY AFTER 23Z...WITH CONVECTION MORE ISOLD AT HUT/ICT TODAY. STRONG WIND GUSTS POSSIBLE WITH TS PARTICULARY AT CNU THIS EVE. JMC PREV DISCUSSION... /ISSUED 313 AM CDT SUN AUG 19 2007/ DISCUSSION... SYNOPSIS... TSRA POTENTIAL TO INCREASE TODAY & TONIGHT OVER ESPECIALLY SE KS AS REMNANTS OF "ERIN" CONTINUE NE MIGRATION FROM OK ACROSS SC & SE KS. WITH MID-UPR LOW ASSOCIATED WITH "ERIN" MOVING NE ACROSS CENTRAL OK DEEP-LAYER DIRECTIONAL SHEAR WILL INCREASE MARKEDLY OVER ESPECIALLY SE KS. THEREFORE AN INCREASED POTENTIAL FOR SEVERE THUNDERSTORMS TO EXIST OVER AREAS ALONG & SE OF THE TURNPIKE. WITH TROPICAL AIRMASS INCREASING GRIP ON THE REGION AS EVIDENCED BY SFC DEWPOINTS OF ~75F MIGRATING DUE NORTH ACROSS ERN OK AS WELL AS PRECIPITABLE WATERS OF ~2.5 INCHES...+RA A CERTAINTY IN SE KS BOTH TODAY & TONIGHT. TODAY & TONIGHT: PER "SYNOPSIS" HAVE INCREASED POPS CONSIDERABLY OVER SE KS TO ~70% TSRA WITH "POSSIBLY SEVERE" DESCRIPTOR APPLIED. MULTIPLE THREATS EXIST: DAMAGING WINDS...VERY HEAVY RAINS AND EVEN A COUPLE TORNADOES. (IN FACT TORNADO WATCH #616 JUST WENT INTO EFFECT FOR CENTRAL OK TIL 8 AM CDT.) SOAKED AIRMASS DICTATES LOWERING MAXES A FEW DEGREES ALL AREAS...ESPECIALLY SC & SE KS. AS REMNANTS OF ERIN CONTINUE NE TREK ACROSS SE KS SHRA/TSRA POTENTIAL TO GRADUALLY IN WEST-EAST MANNER IN CENTRAL & SC KS WITH NUMEROUS SHRA/EMBEDDED TSRA CONTINUING OVER SE KS MOST OF THE NIGHT. MON: AS PREVIOUSLY MENTIONED TROPICAL SYSTEM VACATES SE KS PREMISES SHRA TO LINGER INTO THE MORNING WITH LITTLE ADDITIONAL RAINFALL RESULTING. TUE-FRI: FORECAST FOCUS SHIFTS TOWARD FAST WLY MID-UPR DECK FLOW ACROSS NRN PLAINS WITH EMBEDDED SHORTWAVES EJECTING E. BEHAVIOR & TRACKS OF THE FEATURES BEARS WATCHING AS ATTENDANT COLD FRONT WILL KNOCK ON DOORS IN CENTRAL KS FROM TUE NIGHT THROUGH WED NIGHT. SE THRUST OF MID-LVL SHORTWAVES APPEARS LACKING. AS SUCH APPEARS FRONT MAY STALL & PERHAPS RETREAT NWD AS WARM FRONT WED NIGHT. UNTIL BEHAVIOR OF THE FRONT COMES INTO BETTER FOCUS...HAVE FELT IT PRUDENT TO ASSIGN 20-30% POPS TO CENTRAL KS BOTH TUE & WED NIGHTS. AVIATION... 06Z TAF UPDATE...SHOWERS AND A FEW THUNDERSTORMS COULD AFFECT SOUTHERN KANSAS DURING THE EARLY MORNING HOURS. THE ACTIVITY IS EXPECTED TO BECOME MORE WIDESPREAD DURING THE LATE MORNING AND AFTERNOON HOURS. OTHERWISE...LOW CLOUDS WITH POSSIBLE IFR CEILINGS ARE EXPECTED TO FILL IN ACROSS CENTRAL AND SOUTH CENTRAL KANSAS AROUND SUNRISE. THE CEILINGS SHOULD GRADUALLY IMPROVE BY LATE MORNING OVER THE AREA BUT THE RAIN AND THUNDERSTORMS WILL REMAIN OVER THE REGION. && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 87 73 94 75 / 50 20 0 0 HUTCHINSON 88 72 96 74 / 30 20 0 10 NEWTON 87 73 95 74 / 40 20 10 10 ELDORADO 86 73 94 74 / 60 40 10 0 WINFIELD-KWLD 87 74 94 75 / 60 40 10 0 RUSSELL 92 70 96 74 / 20 10 0 10 GREAT BEND 92 70 96 74 / 20 10 0 10 SALINA 90 72 97 74 / 30 10 0 10 MCPHERSON 88 72 96 74 / 30 10 0 10 COFFEYVILLE 88 73 89 74 / 80 60 30 0 CHANUTE 88 73 90 73 / 80 60 30 0 IOLA 88 73 91 73 / 70 70 30 10 PARSONS-KPPF 88 73 89 73 / 80 60 30 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PADUCAH KY 921 PM CDT SUN AUG 19 2007 .UPDATE... MINOR UPDATE FOR CONVECTION/SENSIBLE WEATHER TRENDS OVERNIGHT. && .DISCUSSION... CONVECTION THAT DEVELOPED ALONG THE DIFFERENTIAL HEATING BOUNDARY OVER SOUTHEAST MISSOURI AND WESTERN KENTUCKY HAS MOVED OUT THE WFO PAH FORECAST AREA AS OF 02Z MON /9 PM SUNDAY/. THE CIRRUS SHIELD FROM THE OK/ERN KS CONVECTION PERSISTED OVER A LARGE PART OF THE WFO PAH FORECAST AREA...INHIBITING INSOLATION FROM ALLOWING CONVECTIVE TEMPERATURES TO BE REACHED IN THE RELATIVELY MOST AIR...COMPARED TO SATURDAY. THE MAIN FOCUS FOR ANY ADDITIONAL PRECIPITATION DEVELOPMENT THROUGH MIDNIGHT AND INTO THE OVERNIGHT HOURS WILL BE FROM LIFT/WEAK SHEAR ASSOCIATED THE CIRCULATION FROM THE REMNANTS OF ERIN. AT 9 PM...THIS CIRCULATION WAS CENTERED OVER EXTREME NERN OK...WITH THE PRECIPITATION SHIELD EXTENDING THROUGH SWRN MO AND NWRN AR. RUC/NAM GUIDANCE SUGGEST THAT AFTER A LULL IN CONVECTION BETWEEN 10 PM SUNDAY THROUGH 4AM MONDAY...NEW CONVECTIVE ACTIVITY SHOULD REFIRE INTO THE AREA...WITH THE BEST CHANCES OVER SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS THROUGH DAYBREAK MONDAY. SUBTLE ADJUSTMENTS TO CLOUD COVER/TEMPERATURES/DEWPOINTS/AND WINDS MADE TO REFLECT THE APPROACH OF THE REMNANTS OF ERIN INTO MO OVERNIGHT. && .PREV DISCUSSION... /ISSUED 250 PM CDT SUN AUG 19 2007/ DISCUSSION... MAIN FORECAST CONCERNS ARE PRECIP CHANCES EARLY IN THE WEEK...THEN AGAIN LATE IN THE WEEK. REMNANTS OF ERIN CONTINUE TO SIT OVER EASTERN OKLAHOMA. AS THIS FEATURE/UPPER SHORT WAVE MOVE SLOWLY EAST OR NORTHEAST...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE...WITH NGM MOST GENEROUS WITH PRECIP ACROSS OUR AREA...AND GFS THE LEAST. THOUGH GFS/NAM/NGM DISAGREE IN COVERAGE AND POPS...OVERALL CONSENSUS DOES LEAN TOWARD BETTER CHANCES ACROSS NORTHERN AND WESTERN PORTIONS OF THE PAH FORECAST AREA TONIGHT THROUGH MONDAY NIGHT. WENT WITH CHANCE POPS NORTHWEST TO SLIGHT CHANCE POPS SOUTHEAST THROUGH MONDAY NIGHT...WHICH BASICALLY LEANS MOST TOWARD THE NAM SOLUTION AT THIS POINT. DUE TO LOW CONFIDENCE IN THE NEAR TERM FORECAST...ADJUSTMENTS MAY BE NEEDED OVER THE NEXT 24 HOURS AS HOPEFULLY THE MODELS GET A BETTER HANDLE ON THE SITUATION. MID WEEK INDICATES ANOTHER BRIEF PERIOD OF WELL ABOVE NORMAL TEMPERATURES. AN UPPER HIGH PRESSURE SYSTEM WILL BUILD OVER THE SOUTHEASTERN UNITED STATES AND KEEP OUR REGION IN VERY WARM SOUTHWEST FLOW THROUGH FRIDAY. AT THIS TIME...IT LOOKS LIKE HIGH TEMPS TUESDAY THROUGH FRIDAY WILL CLIMB IN TO THE MIDDLE TO UPPER 90S. FRIDAY NIGHT A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST. A COMPROMISE OF THE FASTER ECMWF AND THE SLOWER GFS KEEPS A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS NORTHERN PORTIONS OF THE PAH FORECAST AREA FRIDAY NIGHT...WITH CHANCES SPREADING SOUTHEAST ACROSS THE ENTIRE FA FOR SATURDAY...AND ENDING NORTHWEST TO SOUTHEAST SATURDAY NIGHT. LATEST MEX INDICATES TEMPERATURES MAY COOL TO ALMOST NEAR NORMAL BEHIND THE FRONT. FOR NEAR TERM TEMPS..STAYED IN THE BALL PARK OF MAV AND MET GUIDANCE...LEANING TOWARD WARMER MAV GUIDANCE FOR SOUTHEAST HALF OF COUNTIES FOR TUESDAY AND COOLER MET FOR NORTHWEST...THEN TOWARD WARMER MAV OVERALL FOR WEDNESDAY. IN THE EXTENDED...STAYED WITHIN A COUPLE OF DEGREES OF LATEST MEX GUIDANCE...WHICH ONLY REQUIRED SOME MINOR CHANGES. AVIATION... EXPECT DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS TO CONTINUE ACROSS THE REGIONS AND LAST INTO THE EVENING HOURS. AFTER STORMS DIE OUT...ONLY EXPECT SCT MID-HIGH CONVECTIVE CLOUD DEBRIS. OTHERWISE ANY RESTRICTED VSBYS SHOULD IMPROVE RAPIDLY AFTER SUNRISE WITH A PM CU FIELD 4-5K FT LEADING TO ISOLD CB/TSRA DEVELOPMENT ALONG TWEB ROUTES. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ SHORT TERM...SMITH AVIATION...GM ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 417 PM EDT MON AUG 20 2007 .SYNOPSIS... A WARM FRONT WILL MEANDER ACROSS CENTRAL VIRGINIA TONIGHT INTO WEDNESDAY MORNING. SEVERAL SPOKES OF ENERGY WILL RIDE ALONG THE FRONT THROUGH MIDWEEK...PROVIDING A CHANCE FOR SCATTERED SHOWERS AND THUNDERSTORMS. THE FRONT WILL DISSIPATE WEDNESDAY AFTERNOON...WITH HIGH PRESSURE TAKING CONTROL INTO LATE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... LATEST SFC AND SATL ANALYSIS DEPICTS MEANDERING WARM FRONT DRAPED ACROSS APPROX THE RTE 460 CORRIDOR. SKIES ARE SLOWLY CLEARING INTO CNTRL VA RIGHT NOW...BUT STILL A TREMENDOUS GRDNT ACRS THE CWA...MID 90S ALONG NC BORDER...AND STILL ONLY IN 70S AT RICHMOND. RUC SHOWS THE FRONT LIFTING A LITTLE FARTHER NWD THIS EVENG...WITH AMPLE CAPE MAKING TO ABOUT THE I-64 CORRIDOR. MARGINALLY DECENT 0-6KM SHEAR VALUES. SLGT RISK FOR STRONG TO SEVERE STORMS WILL STILL BE POSSIBLE MAINLY ACRS SRN 1/2 OF ZONES THIS EVENG...ALTHOUGH AREAS A BIT FARTHER MAY SEE SOME TSTMS AS WELL BY LATER IN THE EVENG. HAVE GONE WITH SCTD TSTMS MOST ZONES...BEST CHANCES BEING 8PM THROUGH ERLY AM HRS WHEN BEST FORCING/LOW LVL MSTR CONV PROGGED TO TRACK ACRS THE REGION. KEEPING TSTM MENTION OUT OF THE ERN SHORE. LOWS MAINLY UPR 60S TO LWR 70S. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...NEARLY STATIONARY FRONT/BNDRY TO CONTINUE TO AFFECT THE REGION BOTH TUE AND WED. REMNANTS OF ERIN TO ADD TO THE MSTR ON TUE/TUE NGT. HAVE FOLLOWED SREF MEANS FOR OVERALL POSITION OF THE BNDRY. THIS IS A COMPROMISE BETWN THE GFS AND NAM WHICH FLIP FLOP ON THEIR POSITIONS TUE AND WED. FOR TUE...THE GFS IS COOLER AND WETTER/KEEPING BNDRY FARTHER SOUTH...AND NAM IS WARMER/DRIER... PLACING NEARLY ALL OF THE CWA IN WARM SECTOR TUE. AS FOR POPS...HAVE GONE LKLY IN THE NORTH/SCTD FARTHER SOUTH. BEST FORCING LOOKS TO BE AFTN/EVENG. WED...BOTH MODELS INDICATE NE FLOW...BUT GFS/MAV IS AS MUCH AS 15 DEGREES WARMER THAN THE NAM/MET WITH SFC TEMPERATURES. BLENDED THE TEMPS HERE....AND WENT WITH 30% POPS ALL AREAS BY AFTN. KEPT TSTMS OUT OF THE FCST ALONG CSTL ZONES W/ STABLE LOW LYRS. && .LONG TERM/THURSDAY THROUGH MONDAY... LATEST RUNS OF GFS/ECMWF CONTINUE TO SHOW THE PERSISTENT MID LEVEL RIDGE ACRS GULF COAST STATES...GRADUALLY EXPANDING N AND E INTO THE MID ATLC THU INTO THE UPCOMING WEEKEND. APPEARS AS IF YET ANOTHER MINI HEAT WAVE (SEE CLIMO SECTION) WILL ENVELOP THE REGION...MAINLY FRI/SAT/ AND PERHAPS INTO SUNDAY. HAVE BUMPED INLAND TEMPS UP TO 97-99F FOR HIGHS FRI AND SAT. FLOW MAY BE A BIT MORE SLY (RATHER THAN SW) ALONG COASTL ZONES AT LEAST INTO FRI. THIS WILL LIKELY KEEP TEMPS SOMEWHAT COOLER CSTL ZONES UNTIL THE WEEKEND. AS FOR PRECIP...WILL HAVE THE USUAL SMALL CHC (20%) DURING AFTN/EVENG...BUT NO TRIGGER OTHER THAN DAYTIME HTG SO HAVE NOT GONE ANY HIGHER AT THIS PT UNTIL TIMING OF NXT COLD FRONT CAN BE DETERMINED ERLY NXT WEEK. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... SBY ASOS CONTS OTS...SO HAVE USED SURROUNDING OBS TO BEST ESTIMATE A FCST TDY GIVEN PSN OF FRNT. OTW...12Z TAFS WILL FEATURE THE TYPICAL ERLY MORN LOW ST AND BR DUE TO LL MSTR LEFT OVR FROM LASTS NITE RAIN. WND FCST THE BIGGEST CHALLENGE TDY AS FRNTL BNDRY PLAYS HAVOC WITH WND DRCTN / SPEEDS. KEPT CB IN MOST LCTNS AFTR 18Z DUE TO TSTRM CHC MOST AREAS S OF BNDRY. MORE SHOWERY PCPN XPCTD AT SBY. MORE FOG XPCTD AGAIN TONITE...SPCLLY IF SKIES CLEAR. && .MARINE... SCA HAS BEEN DROPPED FOR BAY. TWEEKED WNDS FOR 7 AM UPDATE AS PER CRNT OBS WRT FRNTL PSN. OTW... ANTHR VRY CHALLENGING CWF TDY AS PSN OF FRNTL BNDRY WILL PLAY HAVOC WITH WNDS. SAID BNDRY PROGGED TO SAG S TO A PSN ACROSS THE LWR CHES BAY AND CSTL WTRS THIS AFTRN WITH WEAK WAVES OF LOW PRS FROM TSTRMS ADDING ADDNTL WND CONCERNS. FIRST SUCH WAVE CRNTLY MOVG ACROSS LWR MD ERN SHORE WITH ANTHR WAVE XPCTD A BIT FRTHR S THIS AFTRN. THIS BNDRY STALLS THIS EVE B4 SLOWLY LIFTG BACK N AS A WRM FRNT LATER TONITE (JUST HOW FAR N IS YET ANTHR CONCERN). DUE TO INCRG NE WND FLOW BEHIND BNDRY...WILL CONT SCA FLAGS FOR MD CSTL WTRS WHERE SEAS SHOULD RESPOND TO THE INCRG ONSHORE FLOW. WILL KEEP SCA GOING FOR CURRITUCK SND AND MOUTH OF CHES BAY NXT FEW HRS PER CRNT W-SW WND BTWN 15-20 KTS. && .CLIMATE... WITH MORE HEAT EXPECTED FRI INTO SUNDAY...LOOKS PROBABLE THAT BOTH RIC AND NORFOLK WILL END UP IN TOP 10 HOTTEST AUG ON RECORD. CURRENTLY IF AUG ENDED NOW...RICHMOND AUG 2007 WOULD BE 2ND HOTTEST. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 6 AM EDT WEDNESDAY FOR ANZ650. && $$ SYNOPSIS...BROWN NEAR TERM...BROWN SHORT TERM...BROWN LONG TERM...BROWN AVIATION...KCS MARINE...25 CLIMATE...BROWN md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1139 AM EDT MON AUG 20 2007 .SYNOPSIS... A WARM FRONT WILL MEANDER ACROSS CENTRAL VIRGINIA TODAY INTO TUESDAY. SEVERAL SPOKES OF ENERGY WILL RIDE ALONG THE FRONT THROUGH MIDWEEK...PROVIDING A CHANCE FOR SCATTERED SHOWERS AND THUNDERSTORMS. THE FRONT WILL DISSIPATE WEDNESDAY...WITH HIGH PRESSURE TAKING CONTROL INTO LATE WEEK. && .NEAR TERM /THROUGH TONIGHT/... LATEST SFC AND SATL ANALYSIS DEPICTS MEANDERING WARM FRONT DRAPED ACROSS APPROX THE RTE 460 CORRIDOR. EARLIER ACTIVITY HAS SINCE DISSIPATED...WITH ONLY ABOUT A 20% OF PRECIP OVER THE NXT FEW HRS. MSNNY SKIES SRN TIER OF CWA...MCDY FOR REMAINDER OF THE AREA. THIS WILL CREATE A STRG THERMAL GRADIENT JUST N OF THE VA/NC BORDER. RUC SHOWS AMPLE CAPE AFTER 2-3PM...ALONG WITH MARGINALLY DECENT 0-6KM SHEAR VALUES. ALTHOUGH SPC HAS DROPPED SLGT RISK...STRONG TO SEVERE STORMS WILL STILL BE POSSIBLE MAINLY ACRS SRN 1/3 OF ZONES LATE THIS AFTN AND EVENG. HIGHS TODAY WILL RANGE FROM MID 90S FAR S/SW...TO THE UPPER 70S MD SHORE. ACRS NORFOLK...MAY SEE TEMPS HELD DOWN A LITTLE AS WINDS SHIFT TO NNE LATER IN AFTN. AS WITH PRVS SHIFTS...GFS SOLN IS BASIS FOR THIS FORECAST SUITE. BELIEVE THAT GFS SOLN IS MUCH MORE REASONABLE...AND IN LINE WITH UKMET/GGEM GUIDANCE. THIS WL TRANSLATE TO A RATHER LARGE THERMAL GRADIENT ACROSS THE FORECAST AREA TODAY. XPCT A SHOWERY...CLOUDY AND RATHER UNPLEASANT DAY WEATHERWISE ACROSS THE EASTERN SHORE AND THE NORTHERN QUARTER OF THE CWA...WITH STEADILY DECREASING CLOUDS (AND POPS) IN ADDITION TO WARMER CONDITIONS AS WE PUSH FURTHER SOUTH INTO CENTRAL AND SOUTHERN CWA. MOST OF THE REGION WL SEE HIGHS JUMP INTO THE U80S TO L90S...WITH WARMER HIGHS IN THE MID 90S ALONG THE VA/NC BORDER AND INTO INTERIOR NE NC. OVER THE EASTERN SHORE...HOWEVER...TEMPERATURES WL STRUGGLE TO RISE INTO THE U70S TO L80S ON RATHER GUSTY N TO NE WNDS. BOUNDARY WL BE MEANDERING BACK TO THE SOUTH AS THE DAY PROGRESSES...AS A SERIES OF MIDLVL S/W ENERGY STREAMS ALONG THE FRONT. THIS WL KEEP SHRAS IN THE FORECAST FOR THE NORTHERN HALF OF THE AREA TDA AND TNGT. ADDITIONALLY...CONVERGENCE ALONG THE FRONT AND VERY MOIST AIRMASS IVOF SOUTHWARD DIVING FRONTAL BOUNDARY WL LKLY BE ABLE TO FIRE A FEW ISO/SCT THUNDERSTORMS BY MID AFTN. 0-3KM AND 0-6KM BULK SHEAR APPEARS...AT THE LEAST...ADEQUATE FOR ISOLATED TSTM DVLPMNT THIS AFTN. SOUTHERN THIRD OF CWA HAS BEEN OUTLOOKED AS SLGT RISK IN RESPONSE TO THIS THREAT. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... DETERMINING FRONTAL POSITION CONTINUES TO BE A BIG FORECAST CHALLENGE THROUGH SHORT TERM...AND WL PLAY AN IMPORTANT ROLE IN SENSIBLE WX FOR THE MIDWK. ANOTHER COMPLICATION WL BE THE REMNANTS OF TS ERIN. WHEREAS THE NAM BRINGS THE HEAVIEST RAINFALL WELL NORTH OF THE REGION INTO CENTRAL PA AND NY/NJ AREA TUESDAY AFTN/NGT...THE GFS SOLN BRINGS THIS BEST SLUG OF MOISTURE ACROSS S PA...AND INTO LOWER MD EASTERN SHORE THRU TUESDAY NGT. PWATS APPROACHING/OVR 2 INCHES ACROSS THE ENTIRE CWA DURING THIS TIMEFRAME...SO FELT COMPELLED TO HELD ON TO LOW CHC POPS EVERYWHERE. HOWEVER...CONFINED BEST POPS OVER NORTHERN HALF OF THE CWA AS PER MODEL TREND. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... LONG TERM SEEMS TO BE CHARACTERIZED BY A GRADUAL RETURN TO THE COMMON REFRAIN: SEASONALLY WARM CONDITIONS AND DIURNALLY DRIVEN TSTMS. LATEST RUNS OF GFS/ECMWF CONTINUE TO SHOW THE PERSISTENT MID LEVEL RIDGE ACRS GULF COAST STATES...GRADUALLY BUILDING BACK TWDS MID ATLC GOING INTO NEXT WKND. MEANWHILE SFC HIGH PRESSURE OFF THE NJ TO NEW ENGLAND COAST WILL RETREAT FARTHER NE. HAVE CONTINUED TREND TO BECOME DRIER AND WARMER WITH EACH DAY...SLGT CHC POPS WED...(AND THURSDAY OVER PIEDMONT) WITH TEMPERATURES WARMING BACK INTO 90S FOR ALMOST ALL OF THE CWA FRI THROUGH SUNDAY. && .AVIATION /16Z MONDAY THROUGH FRIDAY/... SBY ASOS CONTS OTS...SO HAVE USED SURROUNDING OBS TO BEST ESTIMATE A FCST TDY GIVEN PSN OF FRNT. OTW...12Z TAFS WILL FEATURE THE TYPICAL ERLY MORN LOW ST AND BR DUE TO LL MSTR LEFT OVR FROM LASTS NITE RAIN. WND FCST THE BIGGEST CHALLENGE TDY AS FRNTL BNDRY PLAYS HAVOC WITH WND DRCTN / SPEEDS. KEPT CB IN MOST LCTNS AFTR 18Z DUE TO TSTRM CHC MOST AREAS S OF BNDRY. MORE SHOWERY PCPN XPCTD AT SBY. MORE FOG XPCTD AGAIN TONITE...SPCLLY IF SKIES CLEAR. && .MARINE... SCA HAS BEEN DROPPED FOR BAY. TWEEKED WNDS FOR 7 AM UPDATE AS PER CRNT OBS WRT FRNTL PSN. OTW... ANTHR VRY CHALLENGING CWF TDY AS PSN OF FRNTL BNDRY WILL PLAY HAVOC WITH WNDS. SAID BNDRY PROGGED TO SAG S TO A PSN ACROSS THE LWR CHES BAY AND CSTL WTRS THIS AFTRN WITH WEAK WAVES OF LOW PRS FROM TSTRMS ADDING ADDNTL WND CONCERNS. FIRST SUCH WAVE CRNTLY MOVG ACROSS LWR MD ERN SHORE WITH ANTHR WAVE XPCTD A BIT FRTHR S THIS AFTRN. THIS BNDRY STALLS THIS EVE B4 SLOWLY LIFTG BACK N AS A WRM FRNT LATER TONITE (JUST HOW FAR N IS YET ANTHR CONCERN). DUE TO INCRG NE WND FLOW BEHIND BNDRY...WILL CONT SCA FLAGS FOR MD CSTL WTRS WHERE SEAS SHOULD RESPOND TO THE INCRG ONSHORE FLOW. WILL KEEP SCA GOING FOR CURRITUCK SND AND MOUTH OF CHES BAY NXT FEW HRS PER CRNT W-SW WND BTWN 15-20 KTS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR ANZ650. SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR ANZ633-652. && $$ SYNOPSIS...BROWN NEAR TERM...BROWN SHORT TERM...MAM LONG TERM...BROWN/MAM AVIATION...MPR MARINE...MPR md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1123 AM EDT SUN AUG 19 2007 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO MOVE OFF THE COAST TODAY. A WARM FRONT WILL DEVELOP OVER THE AREA THIS AFTERNOON AND STALL ACROSS NORTHERN VIRGINIA THROUGH TUESDAY. A SERIES OF LOW PRESSURE SYSTEMS WILL SLIDE EAST ALONG THE FRONT KEEPING THE AREA UNSETTLED THROUGH MUCH OF THE WEEK. A WARMER AND MORE HUMID AIRMASS WILL RETURN FOR THE END OF THE WEEK. && .NEAR TERM /UNTIL NOON TODAY/... STATIONARY FRONT BISECTING CWA LATE THIS MORNING WITH CLOUDY SKIES AND LIGHT SHRAS TO THE NORTH AND SUNNY SKIES TO THE SOUTH. GFS/RUC MODELS SHOW WEAK ISENTROPIC LIFT CONTINUING THRU THE AFTERNOON. NOT MUCH MOVEMENT TO THE FRONT EXPECTED IN THE NEXT 18 HRS. MAYBE AN ISOLD TSRA IN THE SW AS INSTABILITY BUILDS BUT NOT MUCH IN THE WAY OF FORCING && .SHORT TERM /NOON TODAY THROUGH 6 PM MONDAY/... OVERRUNNING PRECIP...NORTH OF BOUNDARY...WILL MOVE ACROSS NORTHERN ZONES TONIGHT. TRENDED FROM HIGH LIKELY TO LOW CHC POPS NORTH TO SOUTH. A SFC LOW APPEARS TO SLIDE EAST ALONG THE BOUNDARY MONDAY AFTN. I WILL ASSUME THE BOUNDARY WILL BE STATIONED ACROSS SOUTHERN ZONES. AS A RESULT CONTINUED THE WET WX BUT WILL ALSO KEEP A MENTION OF THUNDER GIVEN ADDITIONAL FORCING FROM SFC LOW. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... MONDAY NIGHT THROUGH WEDNESDAY A WAVY FRONT WILL REMAIN ACROSS THE MID ATLANTIC THROUGH TUESDAY NIGHT. SEVERAL WEAK WAVES APPEAR TO TRACK ALONG THE FRONT...BRINGING THE BEST RAINFALL CHANCES THE REGION HAS SEEN FOR QUITE SOME TIME. PRECIPITABLE WATER VALUES RISE TO NEAR 2 INCHES...WELL ABOVE THE NORMAL OF 1.1 INCHES. PRECIPITATION CHANCES WILL COME WITH HARD-TO-TIME WEAK WAVES MOVING ALONG THE FRONTAL BOUNDARY. GUIDANCE STILL SHOWS THAT THE NORTHERN HALF OF THE FORECAST AREA HAS THE BEST CHANCE OF SEEING NOTICEABLE PRECIPITATION WHILE THE SOUTHERN HALF OF THE FORECAST AREA COULD BE LEFT HIGH AND DRY. OVERALL...INCOMING CLOUD COVER ASSOCIATED WITH THE FRONT WILL SPREAD NORTH AND SOUTH RATHER FAR...AND THIS SHOULD HELP TO KEEP TEMPERATURES WELL BELOW NORMAL. THURSDAY THROUGH SATURDAY... HIGH PRESSURE WILL BUILD ONCE THE FRONT HAS EXITED THE REGION...BRINGING A RETURN TO A MORE TYPICAL WARM AND HUMID AIRMASS. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS THRU 00Z MON. SHOULD SEE CEILINGS GRADUALLY LOWER DURING THE DAY. EXPECT MVFR CEILINGS AND VISIBILITIES DUE TO CLOUDS AND LIGHT PRECIP STARTING THIS EVENING. TSTMS POSSIBLE MON. THE NEARLY STATIONARY FRONTAL BOUNDARY WILL LINGER THROUGH LATE TUESDAY INTO EARLY WEDNESDAY...MAINTAINING CHANCES OF MVFR AND EVEN TEMPORARY IFR CEILINGS AND VISIBILITIES WITH SHOWERS AND THUNDERSTORMS POSSIBLE THROUGHOUT. HIGHEST CHANCES FOR PROLONGER MVFR OR IFR CONDITIONS WILL BE FOR THE WASHINGTON...BALTIMORE...AND MARTINSBURG TERMINALS. && .MARINE... WARM FRONT DEVELOPING ACROSS THE NORTHERN BAY TODAY. SOUTH OF THE FRONT...SOUTHERLY CHANNELING WINDS INCREASE TO A LOW END SCA SO HAVE ISSUED SCA FOR THIS AFTERNOON AND EVENING FOR THE LOWER BAY. WRF-ARW INDICATES A BNDRY ACROSS THE NORTHERN BAY WHICH DRIFTS SOUTH THIS EVENING. LIGHT...10 KNOTS OR LESS...AND VARIABLE WIND DIRECTIONS EXPECTED OVER THE WATERS WITH A NEARLY STATIONARY...WAVY FRONTAL BOUNDARY OVER THE REGION. CONSISTENT CHANCES OF SHOWERS AND THUNDERSTORMS REMAIN THROUGH TUESDAY WITH THE BOUNDARY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ UPDATE...ROSA LONG TERM...SAR md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1101 AM EDT SUN AUG 19 2007 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OFF THE COAST TODAY...AS A WARM FRONT MOVES BACK NORTH INTO THE AREA THIS AFTERNOON. THE FRONT WILL STALL OVER THE NORTHERN MID ATLANTIC REGION MONDAY AND TUESDAY. THIS WILL PROVIDE ANOTHER CHANCE FOR SCATTERED SHOWERS AND THUNDERSTORMS. WEAK HIGH PRESSURE WILL THEN TAKE CONTROL THROUGH THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LATEST SATL SHOWING ZONE OF ISENTROPIC LIFT/LOW CLOUD BANK ACRS THE PIEDMNT. RUC DEPICTS THIS WELL IN 300-305K LEVEL...AND TRACKS THIS FARTHER TO THE NE BY MID AFTN. IN ADDITION...CAN SEE CU POPPING ACRS CSTL CAROLINAS. HAVE ADDED 30% POP TO THE FCST FOR MD ZONES...AND 20% MUCH OF INTERIOR AREAS. MAY STAY CLDY ALL DAY FAR NORTHEAST. FOR TEMP FCST TRENDED HIGHS DOWN ANOTHER DEGREE OR TWO ACRS NRN ZONES WHERE MORE CLOUDS WILL STAY ARND ALL DAY. BEST RAIN CHANCE EASILY COMES TNGT. ISENTROPIC UPGLIDE DEPICTED BY BOTH MODELS ALONG AND NORTH OF FRONT...RESULTING IN HIGH CHC TO LKLY POPS OVER NORTHERN TIER OF CWA (LKU TO WAL AND NORTH)...WITH SILENT POPS OVER SOUTHERN THIRD OF CWA. RAIN DOES APPEAR AS IF IT WL BE A (VERY MUCH WELCOME) LGT AND STRATIFORM RAINFALL...SO CHOSE TO STICK WITH SHRA VICE TSRA. USED A MAV/FWC BLEND FOR LOWS THIS EVENING...RESULTING IN LOWS IN THE U60S/ARND 70. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... DETERMINING FRONTAL POSITION HAS PROVED TO BE THE BIGGEST FORECAST CHALLENGE THROUGH MONDAY EVENING. MODELS SEEM TO POINT TWDS FRONT REMAINING NEARLY STATIONARY/WAVERING SLIGHTLY THROUGH MON NGT...WITH INCREASINGLY MOIST AIR MASS CARRING OVER TO BEGIN THE WORK WEEK. GENERAL TREND OF INCREASING CLDS MONDAY HAS BEEN KEPT IN TACT. GIVEN THIS THICKER CLOUD COVER...ESPECIALLY OVER THE NORTH...TEMPERED MOS VALUES SLIGHTLY FOR MAX T MONDAY. THIS YIELDED QUITE A THERMAL GRADIENT. U80S/NR 90 OVER THE NW...WITH L/M90S ELSEWHERE INLAND. MEANWHILE...TEMPS ONLY IN UPPER 70S/L80S IN MD. && .LONG TERM /TUESDAY THROUGH SATURDAY/... LATEST RUNS OF GFS/ECMWF CONTINUE TO SHOW THE PERSISTENT MID LEVEL RIDGE ACRS GULF COAST STATES...WHICH WILL KEEP HURRICANE DEAN WELL TO OUR SOUTH (SEE LATEST OFFICIAL FCST FROM NHC/TPC FOR DETAILS). TUE AND WED...MID ATLC REMAINS IN BETWEEN SFC HIGH PRESSURE ACRS NEW ENGLAND...AND WEAK HIGH PRESSURE ACRS SC/GA. GFS/ECMWF MEAN POSITION OF SFC TROUGH/STATIONARY FRONT IS ACRS NRN PORTION OF THE CWA BOTH DAYS. HAVE CHC POPS NORTH...SCHC SOUTH BOTH DAYS. TEMPS AGAIN MUCH COOLER ACRS NE ZONES. FRONT LOOKS TO LIFT FARTHER NORTH LATE WED...AND FOR PERIOD THU THROUGH SAT HAVE GONE WITH JUST 20% DIURNAL TSTMS (OR LESS) AND HIGHER TEMPS MAINLY BACK INTO THE 90S CWA WIDE. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... SC CLOUD DECK AND ASSCTD -RA MOVG SE FROM DC AREA THIS AM...ALTHOUGH ECHOES HAVE BEEN WEAKENING. DESPITE THIS...DECIDED TO ADD A 2 HR TEMPO PRD FOR -RA THIS AM AT SBY. GAVE RIC MORE CLOUDS NXT FEW HRS AS WELL. MODELS CONT THE WETTER TREND AT SBY TONITE...SO TRENDED THE SBY TAF MORE PESSIMISTIC WRT CLOUD COVER/VSBY IN -RA AT SBY (MVFR RANGE). RIC MAY SEE BKN SC DECK...BUT LTL IN WAY OF PCPN. && .MARINE... WNDS SLOWLY INCRG PAST HR OR SO. WILL HAVE TO BE WATCHED FOR PSBL SCA ACROSS CURRITUCK SND THIS AFTRN. OTW...VRY CHALLENGING FCST THIS AM AS INCRG WNDS AND SEAS WILL RESULT IN SCA CONDITIONS AS VARIOUS TIMES ACROSS MARINE AREA FOR THE NXT SVRL DAYS. ALL MODELS NOW INCRS S-SE FLOW (BTWN 15-20 KTS) OVR CHES BAY THIS AFTRN. SO..IN COORD WITH LWX...HAVE HOISTED SCA`S FOR CHES BAY THRU ERLY EVE. GRDNT SLOWER TO INCRS ACROSS CURRITUCK SND... SO HELD BACK ON SCA THERE UNTIL AFTR MIDNITE...BUT CONT IT THRU MOST OF MON. BUFKIT SHOWNG GUST PTNTL UP TO 25 KTS ACROSS NRN CSTL WTRS AFTR MIDNITE TONITE AS WELL AS INCRG SEAS TO 5 FT. SO...IN COORD WITH PHL...HAVE HOISTED SCA FOR MD CSTL WTRS LATE TONITE THRU MON. ENDED FLAGS MON AFTRN AS FIRST EVENT ENDS. NXT EVENT WILL BE NRLY SURGE BEHIND FRNT LATE MON AFTRN. WILL NOT HEADLINE FOR THIS EVENT ATTM (AS IT WILL PRBLY LEAD TO SOME CONFUSION AS TO JUST WHEN SCA`S END AND BEGIN). WILL LET LATER SHIFTS DECIDE THIS. SUFFICE IT TO SAY THAT ANTHR 4-6 HR NRLY SURGE XPCTD DOWN CHES BAY LATER MON...BUT CONFIDENCE RTHR LOW ATTM AS TO THE EXACT HRS THIS OCCURS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 3 AM TO 6 PM EDT MONDAY FOR ANZ650. SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT THIS EVENING FOR ANZ630>632. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EDT MONDAY FOR ANZ633. && $$ SYNOPSIS...BROWN NEAR TERM...BROWN SHORT TERM...MAM LONG TERM...BROWN/MAM AVIATION...MPR MARINE...MPR/KCS md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1037 PM EDT MON AUG 20 2007 .UPDATE... MAIN FCST ISSUE IS POTENTIAL OF SHRA OVER THE W AND SW OVERNIGHT. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A COUPLE OF SHORTWAVES OF NOTE UPSTREAM. FIRST IS OVER WRN WI AND THE SECOND EXTENDS FROM SRN SASKATCHEWAN TO ERN ND. SHORTWAVE OVER WRN WI HAS TRIGGERED SCT SHRA/TSRA IN WI WITH THUNDER AS CLOSE AS ABOUT 35 MILES S OF KIWD. HOWEVER...PCPN HAS YET TO ACTUALLY REACH UPPER MI...AND RADAR TRENDS THIS EVENING SUGGEST A TENDENCY FOR PCPN TO DEVELOP MORE TO THE S WITH TIME WHILE THE NRN PORTION DISSIPATES. NET RESULT IS A SE MOTION. GUESS THAT`S NO SURPRISE GIVEN THE DROUGHT PATTERN THAT DOMINATES THE FCST AREA. SINCE WI SHORTWAVE IS INDICATED TO WEAKEN BY ALL GUIDANCE... INCLUDING 00Z RUC...AS IT HEADS E AND SINCE A PERSISTENT E TO SE FLOW WILL MAINTAIN A FEED OF DRY AIR...DOUBT THAT PCPN WILL MAKE MUCH PROGRESS INTO FCST AREA OVERNIGHT. AREAS ALONG THE WI BORDER APPEAR TO HAVE THE BEST OPPORTUNITY TO SEE SOME PCPN GIVEN BETTER MOISTURE DEPTH INDICATED BY 00Z KGRB SOUNDING. EVENING RADAR TRENDS ALSO SUPPORT THIS THINKING. TAIL END OF SHORTWAVE FROM SASKATCHEWAN TO ERN ND MAY SUPPORT SOME SHRA OVER WRN LAKE SUPERIOR...MAINLY LATE IN THE NIGHT. SO...FOR THE UPDATE...WILL INCLUDE LOW POPS ALONG THE WI BORDER AREAS AND OVER WRN LAKE SUPERIOR. WILL KEEP THE REST OF THE FCST AREA DRY FOR THE OVERNIGHT. SINCE THERE IS A LACK OF INSTABILITY IN UPPER MI AND SHORTWAVE WILL BE WEAKENING...WILL REMOVE MENTION OF THUNDER. && .PREV DISCUSSION (ISSUED AT 421 PM EDT)... SHORT TERM (TONIGHT AND TUE)... PLENTY OF LOW CLOUDS HAVE REMAINED ACROSS THE SOUTHWESTERN PORTIONS OF THE CWA...MAINLY TO THE SOUTH AND WEST OF THE CMX TO SAW SITES. UNDER THE DENSE LOWER CLOUDS...MORNING DRIZZLE WAS NOTICED ON THE RADAR ACROSS PORTIONS OF SOUTH CENTRAL UPPER MICHIGAN. THIS PRECIPITATION WAS ABLE TO DRY UP QUICKLY LATE THIS MORNING AND EARLY THIS AFTERNOON. AM CONTINUING TO WATCH THE PROGRESSION OF OUR NEXT WEATHER MAKER...IN THE FORM OF A SURFACE LOW OVER WESTERN SASKATCHEWAN...SLOWLY PROGRESSING NORTHEASTWARD AND INTO WESTERN MANITOBA BY THE END OF THE PERIOD. CONFIDENCE IN THIS FORECAST PERIOD HAS INCREASED SLIGHTLY SINCE THE OVERNIGHT HOURS AS THE NEAR TERM MODELS HAVE COME INTO A LITTLE BETTER AGREEMENT WITH THE ONSET OF SHOWERS AND THUNDERSTORM ACTIVITY FOR TUESDAY. THE 12Z NAM HAS SLOWED DOWN THE INCOMING TROUGH/COLD FRONT. FOLLOWING SUIT THE 12Z GFS HAS DONE SOMETHING SIMILAR...BUT STILL NOT QUITE AS SLOW AS THE NAM. BOTH HAVE LINED UP CLOSER TO MY INITIAL THINKING...WHICH WAS A CONTINUATION OF THE EXISTING SETUP...DROUGHT EQUALS DROUGHT. THEREFORE...WAS THINKING THAT THE WESTERN CWA WOULD ONCE AGAIN RECEIVE THE GREATEST CHANCE OF SIGNIFICANT PRECIPITATION...WHILE THE EAST WILL BE LUCKY TO GET MORE THAN A TENTH OF AN INCH OUT OF THIS SYSTEM. SIMILAR TO PREVIOUS SYSTEMS...A SPLITTING OF THE PRECIPITATION IS EXPECTED. HAVE ADDED LIKELY POPS TO THE WESTERN PORTIONS OF THE AREA...MAINLY JUST WESTERN LAKE SUPERIOR. LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... FOR TUE NIGHT...TRIMMED BACK POPS WITH PWATS DROPPING AFTER 00Z WED...AND INCREASED STABILITY WITH THE LOSS OF DIURNAL HEATING. LOCALLY RUN WRF-ARW HAS ONLY THE SINGLE BAND OF PRECIP STRETCHING ACROSS THE UPPER PENINSULA...AND HAS THINGS CLEARING OUR OF THE CENTRAL BY 00Z WED AND OUT OF THE FAR EAST BY 06Z. 12Z NAM/GFS BOTH TRY TO BRING UP A SECOND PRECIP LOBE AFTER 06Z...H85 THETA E RIDGE CONTINUES TO SET UP JUST TO THE SOUTH OF THE CWFA AND OVER SOUTHERN WI WITH ENERGY FROM FIRST SHORTWAVE TRACKING JUST TO THE NORTH OF THE CWFA AND THE SECOND RIPPLING THROUGH THE KGRB AREA AROUND 12Z WED. MUCH LIKE THINGS HAVE BEEN GOING OVER THE LAST SEVERAL WEEKS...THE BULK OF THE PRECIP MISSES UPPER MI. ON WED AND WED NIGHT...DIRTY LITTLE SHORTWWAVE PUSHES ACROSS CWFA AND KEEPS THE PICTURE MUDDLED FOR PRECIP CHANCES. Q-VECTOR CONVERGENCE AGAIN LOOKS TO THE NORTH AND SOUTH OF THE CWFA AND THE JET DYNAMICS HIT BEST OVER ONTARIO. BY THU...BEST MID LEVEL ENERGY AGAIN BECOMES FOCUSED TO OUR SOUTH WITH DRIER AIR AND SUBSIDENCE OVER THE WESTERN LAKE AND INTO THE NORTHWESTERN COUNTIES. THE CURRENT WX GRID DEPICTS THIS SCENARIO WELL...SO WILL ESSENTIALLY LEAVE THIS UNTOUCHED. ON FRI...LOLLYGAGGING FRONT TO THE SE OF THE CWFA...AND THEN ADVANCING SYSTEM MOVING IN FROM THE SOUTHWEST. WILL KEEP THE CHANCE POPS IN THE SE CWFA FOR THE TIMEFRAME...BUT KEEP THE NORTHERN PORTIONS DRY. FOR SAT...IF YOU BELIEVE THE 00Z GEFS...THINGS LOOK GOOD FOR THE OPEN HOUSE WITH FRONTAL PASSAGE MORE PROGRESSIVE THAN PRIOR SOLUTIONS WITH COLD FRONT SOUTH OF THE CWFA BY 00Z FRI. DRIER AIR MOVING IN BEHIND THE FRONT SHOULD LIMIT PRECIP CHANCES IN THE NORTH...SAVE FOR LAKE EFFECT CLOUDS WITH A NORTHERLY WIND. A SECOND SYSTEM EXTENDING UP FROM THE PLAINS MAY BRING SOME PRECIP CHANCES TO THE SOUTHERN PORTION OF THE CWFA ON SAT...DEBATED WHETHER TO ADD POPS...BUT KEPT FORECAST DRY ATTM GIVEN UNCERTAINTY IN HOW FAR SOUTH SYSTEM WILL BE. FOR SUN AND MON...MORE UNCERTAINLY CURRENTLY EXISTS WITH MODELS DIVERGING BETWEEN TROUGHINESS AND RIDGINESS OVER THE EASTERN PORTION OF THE CONUS...WITH ENSEMBLE SOLUTIONS POINTING TOWARD A FAIRLY ZONAL FLOW OVER THE EATERN CONUS AND A SURFACE HIGH BUILDING INTO THE GREAT LAKES REGION. ATTM...WILL KEEP THE EXTENDED FORECAST DRY WITH NEAR CLIMO TEMPS. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... DRY LOW-LEVEL E TO SE FLOW HAS BEEN VERY EFFECTIVE AT PREVENTING MVFR CIGS OVER FAR W AND SW UPPER MI FROM EDGING E DURING THE AFTN. IN FACT...THERE HAS BEEN SOME RETREAT OF THE MVFR CLOUD DECK IN THE LAST FEW HRS. FCST CHALLENGE WILL BE DETERMINING WHEN THESE CLOUDS WILL ADVANCE E TO KCMX/KSAW. OPTED TO DELAY MVFR CLOUD ARRIVAL FROM PREVIOUS FCST GIVEN RECENT TRENDS AND PERSISTENT DRY FLOW FROM THE SE (MVFR CLOUDS SHOULD ARRIVE LATE IN THE NIGHT/TUE MORNING). PLENTY OF LOW END MVFR AND IFR CIGS DOMINATE LARGE PORTIONS OF WI AND MN. APPROACHING TROF TUE SHOULD EASILY SWEEP THESE LOW MVFR CIGS E TO KCMX/KSAW. FOR NOW...KEPT CIGS ABOVE IFR RANGE...BUT WOULD NOT BE SURPRISED TO SEE CIGS DROP INTO THAT RANGE MID/LATE AFTN ESPECIALLY IF PERSISTENT -SHRA OCCUR. AS FOR PCPN...WHILE CONFIDENCE IS NOT HIGH ON PCPN OCCURRING...IT IS SUFFICIENT AT THE MOMENT TO INCLUDE PREVAILING -SHRA IN THE MID/LATE AFTN. WITH LIMITED INSTABILITY... THUNDER POTENTIAL IS MINIMAL AND WILL NOT BE INCLUDED. SHOULD PERSISTENT -SHRA OCCUR...MAY SEE SOME VSBY RESTRICTION INTO THE MVFR RANGE DUE TO FOG LATE IN THE AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER JAMES BAY AND A TROUGH MOVING EASTWARD FROM THE WESTERN DAKOTAS WILL MAINTAIN AN EAST TO SOUTHEASTERLY WIND OF 15 TO 25 KT ON LAKE SUPERIOR THROUGH TONIGHT. WINDS WILL DIMINISH BELOW 20 KT ON WESTERN LAKE SUPERIOR TUE...BUT REMAIN AS HIGH AS 25 KT ON EASTERN LAKE SUPERIOR UNTIL LATE TUE AFTERNOON WHEN THE TROUGH APPROACHES THE CENTRAL PORTION OF THE LAKE. LOOK FOR WINDS TO REMAIN BELOW 20 KT ACROSS LAKE SUPERIOR THROUGH THE REST OF THE PERIOD AS A WEAK PRESSURE GRADIENT EXISTS...ESPECIALLY WITH HIGH PRESSURE BUILDING IN ON TEMPORARILY ON FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SHORT TERM...KF LONG TERM...JLL AVIATION...ROLFSON MARINE...KF/KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 150 PM EDT MON AUG 20 2007 .UPDATE... AFTER COORDINATION WITH THE IMET ON THE SLEEPER LAKE FIRE AND LOOKING AT 09Z RUC/06Z NAM SOUNDINGS...HAVE RAISED TEMPERATURES TO NEAR 75 AND LOWERED DEWPOINTS INTO THE MID 40S FOR THE NORTHEAST FIRE WEATHER ZONE. IR SATELLITE LOOP AND MODEL SOUNDINGS SHOW HIGH CLOUDS THINNING OUT ACROSS THIS ZONE IN THE AFTERNOON...WHICH SHOULD ALLOW TEMPERATURES TO GET HIGHER THAN THE PREVIOUS FORECAST...THUS RESULTING IN LOWER DEWPOINTS. GIVEN THE TEMPS AND DEWPOINTS MENTION ABOVE...RELATIVE HUMIDITIES WILL BE LOWERED BY 20-25 PERCENT FROM THE EARLIER FIRE WEATHER FORECAST ISSUED. DAY SHIFT WILL HAVE TO MONITOR DEWPOINTS THIS AFTERNOON SINCE WIND SPEEDS ARE FORECAST TO BE 15 TO 20 MPH FROM A SE DIRECTION...NOT GOOD FOR THE SLEEPER LAKE FIRE. IF DEWPOINTS DROP A FEW MORE DEGREES...SAY EITHER UPPER 30S TO AROUND 40...A RED FLAG WARNING WILL BE REQUIRED. IN ADDITION...AFTER COORDINATION WITH THE MICHIGAN DNR AND APX...WILL BE ISSUING A WILDFIRE POTENTIAL STATEMENT FOR EASTERN ALGER...NORTHERN SCHOOLCRAFT...LUCE AND CHIPPEWA COUNTIES. && .DISCUSSION...(ISSUED AT 447 AM EDT MON AUG 20) UPPER AIR PATTERN CONSISTS OF A 500 MB TROUGH MOVING INTO THE NORTHERN ROCKIES...TROUGHING IN THE CENTRAL PLAINS ASSOCIATED WITH THE REMAINS OF ERIN...RIDGING ACROSS THE SOUTHWEST AND SOUTHEAST U.S. AND SOUTH CENTRAL CANADA AND TROUGHING ACROSS NEW ENGLAND. NEXT WEATHER MAKER OF NOTE WILL BE THE SHORTWAVE IN THE NORTHERN ROCKIES WHICH WILL AFFECT THE AREA TUE WITH MORE SHORTWAVES FOR WED AND WED NIGHT. A SHORTWAVE ACROSS THE CORNBELT SHOULD STAY TO THE SOUTH OF AREA TODAY AND KEEP THE PCPN ASSOCIATED WITH IT SOUTH OF THE AREA AS WELL AS AIRMASS IS VERY DRY OVER MOST OF THE CWA EXCEPT ACROSS MENOMINEE COUNTY. NAM SEEMS TO FAR NORTH WITH ITS QPF FIELD THIS EVENING AND IT HAS QPF INTO SOUTHERN CWA ALL DAY TODAY WHICH SEEMS OVERDONE. NAM BRINGS IN SOME 850-500 MB Q-VECTOR CONVERGENCE LATE TONIGHT ALONG WITH SOME MOISTURE WITH THE Q-VECTOR CONVERGENCE AND MOISTURE MOVING ACROSS THE CWA ON TUE WITH MORE SHORTWAVE ENERGY ARRIVING TUE NIGHT AND WED WITH MORE MOISTURE AGAIN AND THEN HAS A COLD FRONT MOVE TO THE SOUTH AND STALL OUT WITH MOISTURE REMAINING TO THE SOUTH OF THE CWA WED NIGHT. GFS HAS ADVERTISED THIS SCENARIO AS WELL. THIS FORECAST WAS PARTICULARLY DIFFICULT WITH THE NAM AND GFS HANDLING THE QPF DIFFERENTLY FROM EACH OTHER WITH THE GFS HAVING CONVECTIVE FEEDBACK ISSUES AND THE NAM SEEMED TOO SLOW WITH THINGS. WENT WITH A BLEND OF THE TWO MODELS WHICH WAS CLOSE TO THE CURRENT FORECAST WITH A FEW MINOR CHANGES. CONFIDENCE IN THIS FORECAST IS LOW AND WOULD NOT BE SURPRISED IF THE CWA GETS SPLIT WITH THE PCPN WITH SOME GOING NORTH AND MORE OF IT STAYING TO THE SOUTH AND WEST. WILL HAVE TO SEE HOW THIS PANS OUT...BUT CONFIDENCE STILL IS NOT VERY HIGH YET WITH MODEL INCONSISTENCIES AND CONVECTIVE FEEDBACK ISSUES. FOR THIS MORNING...KEPT IN POPS ALONG THE WISCONSIN BORDER COUNTIES AS SOME RAIN HAS MADE IT IN THERE AS KMNM HAS PICKED UP .27 INCH THROUGH 4 AM EDT THIS MORNING FOR THIS WHOLE EVENT. EVEN KIMT AND KLNL HAVE PICKED UP SOME PCPN AS WELL AND LOOK FOR THIS TO CONTINUE THIS MORNING AS THERE ARE SOME SHOWERS HEADING EAST ACROSS ERN MN AND NORTHERN WI. BY THIS AFTERNOON...SHORTWAVE ENERGY TO THE SOUTH WILL BE OUT OF THE AREA AND THINGS SHOULD DRY OUT. FEEL THERE WILL BE PLENTY OF MID AND HIGH LEVEL CLOUDS TODAY AND THIS SHOULD KEEP TEMPERATURES DOWN A BIT TODAY ACROSS MOST OF THE AREA AND LOWERED HIGHS A BIT TO ACCOUNT FOR LESS SUN. WITH MORE CLOUDS TONIGHT...LOWS SHOULD ALSO BE A BIT WARMER AND WENT CLOSE TO ADJMAV FOR LOWS AND HIGHS. KEPT SLOWER TIMING OF POPS TONIGHT AND TUE GOING. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... BOTH SAW AND CMX CONTINUE TO FLIRT WITH MVFR CEIGS THIS AFTERNOON...AS THE DENSE CLOUD DECK TO THE SOUTHWEST HAS ATTEMPTED TO INVADE. HOWEVER...DRIER AIR IS WINNING OUT...ESPECIALLY AT CMX. THESE BORDERLINE VFR TO MVFR CEIGS WILL CONTINUE THROUGH THE PERIOD. HAVE ADDED THE MENTION OF PRECIPITATION AT CMX LATE IN THE PERIOD AS THE TROUGH/COLD FRONT NEARS. STILL EXPECT SAW TO REMAIN DRY THROUGH AT LEAST 18Z AS SHOWER AND POSSIBLE THUNDERSTORM ACTIVITY WEAKENS AND DIVIDES OVER THE CWA. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER JAMES BAY AND A TROUGH MOVING EASTWARD FROM THE WESTERN DAKOTAS WILL MAINTAIN A 15 TO 25 KT WIND ON LAKE SUPERIOR THROUGH TONIGHT...SWITCHING FROM THE E TODAY TO THE SE TONIGHT. THE AREA FROM THE APOSTLE ISLANDS TO DULUTH COULD EVEN SEE SOME 30 KT GUSTS THIS MORNING DUE TO FUNNELING EFFECTS. WINDS WILL DIMINISH BELOW 20 KT ON WESTERN LAKE SUPERIOR TUE...BUT REMAIN AS HIGH AS 25 KT ON EASTERN LAKE SUPERIOR UNTIL LATE TUE AFTERNOON WHEN THE TROUGH APPROACHES THE CENTRAL PORTION OF THE LAKE. LOOK FOR WINDS TO REMAIN BELOW 20 KT ACROSS LAKE SUPERIOR THROUGH THE REST OF THE PERIOD AS A WEAK PRESSURE GRADIENT EXISTS...ESPECIALLY WITH HIGH PRESSURE BUILDING IN ON FRI. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...AJ DISCUSSION...MICHELS AVIATION...KF MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1022 AM EDT MON AUG 20 2007 .UPDATE...WELL...RAIN ENDED UP SPREADING A BIT FARTHER NORTH THAN EARLIER THOUGHT...GENERALLY FOLLOWING ALONG AND SOUTH OF THE M-32 CORRIDOR...BUT DON`T BELIEVE TOO MANY FOLKS MINDED A LITTLE WATER. FARTHER NORTH PENETRATION INTO THE RESIDUAL DRY AIRMASS APPEARS COMPLIMENTS OF MORE SUBSTANTIAL ISENTROPIC ASCENT/FRONTOTGENETICAL FORCING...WITH REGIONAL PROFILERS SHOWING H85 JET REVVING ACROSS REMAINING TIGHT BAROCLINIC ZONE (+18C AT KILX COMPARED TO +8/+9C AT KBUF/KINL - NO APX RAOB PER RRS UPGRADE). 12Z RUC APPEARS TO HAVE A GOOD HANDLE ON AXIS OF FRONTOGENESIS IN THE 700-600MB LAYER...RESPONSIBLE FOR DECENT PRECIP BAND CUTTING ACROSS THE CENTRAL CWA. IN ADDITION...PRONOUNCED SHORTWAVE NOTED ON WATER VAPOR PICS CUTTING THROUGH EASTERN WISCONSIN GIVING A BOOST TO OVERALL COVERAGE. THE BIGGEST FORECAST CONCERN FOR TODAY IS OBVIOUSLY PLACEMENT OF PRECIP INTO THE AFTERNOON HOURS (IF ANY) AS WELL AS CLOUD COVER AND ITS EFFECT ON HIGH TEMPERATURES. CURRENT AREA OF PRECIP WILL BE ON THE WANE OVER THE NEXT FEW HOURS AS FRONTOGENESIS/LIFT WEAKENS IN RESPONSE TO DIURNAL VEERING OF THE LOW LEVEL JET...AND SHORTWAVE QUICKLY PROGRESSES THROUGH CENTRAL MICHIGAN. HOWEVER...SIMILAR TO THE PAST FEW DAYS...CANNOT TOTALLY RULE OUT LINGERING SCATTERED SHOWERS THROUGH THE AFTERNOON ACROSS THE FAR SOUTH IN CLOSER PROXIMITY TO DEEPER MOISTURE AND WEAKLY CONFLUENT FLOW. OTHERWISE...FAIRLY DEEP LAYER RIDGING (SFC-700MB) SLIDING SOUTHEAST FROM JAMES BAY WILL REINFORCE DEEP EAST/SOUTHEASTERLY FLOW ACROSS NORTHERN MICHIGAN BY EARLY AFTERNOON...WHICH SHOULD DRIVE THE LOWER CLOUD DECK BACK SOUTH ONCE AGAIN AS DRY AIR (EVIDENT JUST OFF TO THE EAST/NORTHEAST) ERODES THE LOW LEVEL MOISTURE FROM SOUTH TO NORTH. ALL THE WHILE...INCREASINGLY CONFLUENT FLOW AROUND 700MB SHOULD HELP MAINTAIN A MID CLOUD DECK ACROSS MUCH OF THE AREA THROUGH THE AFTERNOON...SO WILL CALL IT JUST PLAIN CLOUDY SOUTH WHERE LOW CLOUDS LIKELY TO LINGER THE MAJORITY OF THE DAY...TO BECOMING PARTLY CLOUDY NORTH WITH DRYING (HOPEFULLY) WINNING OUT. AS FAR AS TEMPERATURES ARE CONCERNED...EXPECT ANOTHER RELATIVELY TIGHT GRADIENT FROM SOUTHWEST TO NORTHEAST...WITH HIGHS STRUGGLING TO REACH THE LOW 60S WHERE CLOUDS LINGER...TO THE LOW (AND PERHAPS MID) 70S UP NORTH GIVEN EXTRA INSOLATION COUPLED WITH H85 TEMPS REBOUNDING TO AROUND 10C BY 21Z PER MODEL DEPICTION. ON THE MARINE SIDE...WILL CONTINUE SMALL CRAFT ADVISORIES FOR THE WHOLE HURON SHORELINE AS WELL AS ACROSS THE STRAITS GIVEN TIGHTENING GRADIENT WITH SOUTHEAST PUSH OF HIGH PRESSURE AND EXPECTED RESPONSE OF BOUNDARY LAYER WIND FIELD TO AROUND 20-25 KNOTS PER NAM GUIDANCE. CHANNELING OF THE WIND WILL ALSO COME INTO PLAY THROUGH THE NARROW SHORELINE...WITH GUSTIER WINDS ALSO EXPECTED IN COASTAL CONVERGENCE REGIME ALONG THE COAST OF MACKINAC COUNTY. LAWRENCE && .PREV DISCUSSION... /ISSUED 717 AM EDT MON AUG 20 2007/ AVIATION...STATIONARY FRONT ACROSS THE OHIO VALLEY COMBINED WITH MOISTURE STREAMING INTO THE REGION FROM THE GULF (INCLUDING THE REMNANTS OF TD ERIN) WILL PRODUCE A FAIRLY WIDESPREAD SWATH OF RAINFALL TODAY. SHARP CUTOFF OF RAINFALL EXPECTED TO BE ALONG A LINE FROM CVX TO GLR TO SPT. TVC SHOULD BE THE ONLY TAF SITE IN NRN LOWER MICHIGAN IMPACTED BY THESE SHOWERS AND MVFR CIGS AND VSBYS THAT WILL ACCOMPANY THEM. OVERALL VFR CONDITIONS AND BKN MID-HIGH CLOUD COVER ARE ANTICIPATED FOR PLN/APN. WINDSPEED AT ALL THREE TAF SITES WILL INCREASE OUT OF THE E/SE TODAY. DISCUSSION... /ISSUED 355 AM EDT MON AUG 20 2007/ STATIONARY FRONT EXTENDS FROM THE CENTRAL PLAINS INTO HE OHIO VALLEY EARLY THIS MORNING. 850-700 MB TROUGH AXIS STRETCHES FROM NRN WISCONSIN INTO CENTRAL LOWER MICHIGAN. TIGHT BAROCLINIC ZONE STRETCHES ACROSS SRN LOWER MICHIGAN AND OHIO (+8C H8 TEMP ACROSS NRN MICHIGAN...+20C NEAR CINCINNATI)...WITH A BAND OF 850-500 MB F-GEN EXTENDING THRU NRN MICHIGAN AND WISCONSIN. GULF MOISTURE CONTINUES TO STREAM INTO THE VCNTY OF THE STATIONARY FRONT...ENHANCED BY THE REMNANTS OF TD ERIN. LIFT AND MOISTURE IS PRODUCING A LARGE AREA OF PRECIP ALONG AND NORTH OF THE BOUNDARY. MAIN FORECAST ISSUES OVER THE NEXT 48 HOURS REVOLVE AROUND CHANCES OF PRECIP FROM THIS SYSTEM...AND JUST HOW FAR NORTH PRECIP CHANCES WILL REACH WITH HIGH PRESSURE/DRY AIR TO THE NORTH AND THE FRONT AND ASSOCIATED MOISTURE TO THE SOUTH. TODAY AND TONIGHT...AREA OF DPVA AND ENHANCED MOISTURE AHEAD OF THE UPSTREAM SHORT WAVE WILL MOVE THRU LOWER MICHIGAN THIS MORNING. BEST CHANCES OF PRECIP WILL REMAIN FOCUSED ACROSS CENTRAL AND SRN LOWER MICHIGAN ALONG THE TIGHT BAROCLINIC ZONE AND AXIS OF DEEP MOISTURE NORTH OF THE STATIONARY BOUNDARY. TIGHT MOISTURE GRADIENT WILL REMAIN IN PLACE TODAY ACROSS NRN LOWER MICHIGAN WITH DRY HIGH PRESSURE REMAINING CENTERED NORTH OF MICHIGAN OVER ONTARIO... MAINTAINING DRY EASTERLY FLOW ACROSS OUR CWA. THIS WILL BE THE MAIN PLAYER IN HOLDING THE RAIN SHIELD AT BAY FOR LOCATIONS NORTH OF A LINE FROM GRAND TRAVERSE BAY TO GRAYLING TO OSCODA. LOCATIONS SOUTH OF THIS LINE WILL CONTINUE TO SEE SCT-NMRS SHRA THRU THIS MORNING. CHANCE POPS WILL PERSIST FOR SRN SECTIONS OF THE CWA INTO THE AFTERNOON AND EVENING...BUT SHORT WAVE WILL BE WELL EAST OF THE REGION...SO CHANCES OF PRECIP WILL BE SMALL AND MAINLY DRIVEN BY WEAK ISENTROPIC ASCENT WELL NORTH OF THE FRONT. LACK OF SUFFICIENT INSTABILITY (SURFACE-BASED OR ALOFT) WILL PRECLUDE CHANCES OF THUNDER...SO WILL CONTINUE TO LEAVE OUT OF THE FORECAST FOR TODAY THRU THIS EVENING. INCREASINGLY SHALLOW MOISTURE AND LOSS OF ISENTROPIC LIFT SHOULD BRING ANY CHANCES OF PRECIP TO AN END BY MIDNIGHT OR SO. HOWEVER...SHALLOW MOISTURE WILL MAINTAIN PARTLY TO MOSTLY CLOUDY SKIES OVERNIGHT. TEMPS TODAY WILL BE GREATLY LIMITED BY CLOUD COVER AND PRECIP...WITH AFTERNOON HIGHS ONLY WARMING INTO THE UPPER 60S AND LOWER 70S (COOLER IN THE SRN HALF OF THE CWA IN PROXIMITY TO CHANCES OF PRECIP AND THICKER CLOUD COVER). LOW TEMPS TONIGHT WILL COOL BACK INTO THE UPPER 50S TO AROUND 60 DEGREES. TUESDAY AND TUESDAY NIGHT...BREAK IN THE ACTION WILL PERSIST INTO TUESDAY MORNING AS HIGH PRESSURE AND LOW LEVEL DRY AIR REMAIN IN CONTROL. UPSTREAM WARM FRONT AND NARROW BAND OF ASSOCIATED MOISTURE WILL REACH WRN SECTIONS OF OUR CWA TUESDAY AFTERNOON...WORKING ITS WAY THRU OUR CWA TUESDAY NIGHT. NRN SECTIONS OF THE CWA MAY FINALLY GET A CHANCE FOR PRECIP FROM THIS FEATURE AS BEST MOISTURE AND DPVA VIA A SHORT WAVE ALIGN WITH THE FRONT MOVE THRU THE NRN HALF OF THE CWA. WILL KEEP A CHANCE OF SHRA/TSRA IN THE FORECAST FOR THE ENTIRE CWA...BUT FOCUS SLIGHTLY BETTER POPS ACROSS THE NORTH OVERNIGHT. WILL INCLUDE THE MENTION OF THUNDER AS A NARROW BAND OF INSTABILITY LIFT WILL ACCOMPANY THE SHORT WAVE. HIGH TEMPS TUESDAY AFTERNOON WILL BE IN THE LOWER TO MID 70S...LIMITED BY THICKENING CLOUD COVER AS THE FRONT APPROACHES. LOW TEMPS OVERNIGHT WILL ONLY COOL INTO THE LOWER TO MID 60S WITH LOW LEVEL WAA COMMENCING BEHIND THE WARM FRONT. WEDNESDAY THROUGH FRIDAY...CHALLENGING FORECAST AS MODEL DERIVED CONVECTIVE COMPLEXES CONTINUE TO PLAY HAVOC WITH TIMING AND STRENGTH OF SYSTEMS SLATED TO CROSS THE NORTHERN LAKES IN QUASI-ZONAL MID AND UPPER LEVEL FLOW ON NORTHERN PERIPHERY OF STRONG SOUTHEAST CONUS MID LEVEL RIDGING. GIVEN THESE UNCERTAINTIES...WILL CONTINUE CONSERVATIVE THEME AND MAKE FEW...IF ANY...CHANGES THROUGH THIS PERIOD. WEDNESDAY...WEAK COLD/OCCLUDED FRONT STILL SLATED TO APPROACH NORTHERN MICHIGAN WEDNESDAY. HOWEVER...GROWING EVIDENCE IN LATEST GUIDANCE...ESPECIALLY LATEST NAM-WRF AND ECMWF MODELS...THAT FRONT MAY STALL BEFORE ENTERING THE NORTHERN LAKES. AT THE OTHER END OF THE SPECTRUM IS THE LATEST GFS...WHICH SPAWNS A CONVECTIVELY INDUCED SURFACE LOW OVER SOUTHERN WISCONSIN LATER TUESDAY NIGHT WHICH CROSSES NORTHERN MICHIGAN WEDNESDAY. GIVEN THESE UNCERTAINTIES...FELT BEST COURSE OF ACTION WAS TO LEAVE GOING LOW POPS ALONE FOR SHOWERS AND THUNDERSTORMS. 850MB TEMPERATURES IN THE LOW TO MID TEENS SUPPORTS HIGH TEMPERATURES IN THE UPPER 70S TO MID 80S. WEDNESDAY NIGHT THROUGH THURSDAY...IF SLOWER SOLUTIONS ARE CORRECT...THE THREAT OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THIS PERIOD AS FRONTAL ZONE SLOWLY PUSHES EAST INTO THE AREA. AS STATED...WOULD LIKE TO SEE SOME MORE CONSISTENCY BEFORE GOING IN THIS DIRECTION WITH THE FORECAST. COULD EASILY SEE THE ADDITION OF POPS FOR PART...OR ALL...OF THIS TIME FRAME IN SUBSEQUENT FORECASTS. THURSDAY NIGHT THROUGH SATURDAY...HOW SYSTEM BEHAVES DURING THE MIDWEEK WILL HAVE A GREAT BEARING ON HOW THINGS PLAY OUT FOR LATER IN THE WEEK/EARLY NEXT WEEKEND. POTENTIAL FOR A RELATIVELY ACTIVE PERIOD OF WEATHER AND SOME MUCH NEEDED RAINFALL...AS WAVES OF LOW PRESSURE RIDE UP THE FRONTAL ZONE. EXACTLY WHERE THIS FRONT WILL RESIDE REMAINS THE ELUSIVE ANSWER. MSB && .APX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 136 AM EDT MON AUG 20 2007 UPDATED AVIATION SECTION FOR THE 06Z TAF ISSUANCE .SHORT TERM (TONIGHT AND MON)... LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW RIDGING OVER THE CENTRAL CONUS EXTENDING UP INTO SOUTH CENTRAL CANADA. THIS RIDGE IS BRACKETED BY UPPER LOWS/TROUGHING ALONG THE NORTHWEST COAST AND OVER EASTERN QUEBEC. A SHARPLY DEFINED SHORTWAVE TROUGH CAN BE SEEN ROTATING THROUGH WASHINGTON AND OREGON...AND THIS IS THE NEXT SIGNIFICANT SHORTWAVE FEATURE EXPECTED TO AFFECT THE AREA...ALTHOUGH IT WILL LOSE SOME OF ITS LUSTER AS IT WORKS EASTWARD THROUGH THE UPPER RIDGE. RADAR IMAGERY CONTINUES TO SHOW A WNW-ESE ORIENTED AREA OF PCPN WITH EMBEDDED CONVECTION FROM SOUTHERN MINNESOTA THROUGH NORTHERN INDIANA AND NORTHWEST OHIO. THIS ACTIVITY CORRELATES WELL WITH AN AREA OF 850-700MB FRONTOGENESIS AND CONVECTIVE INSTABILITY SHOWN BY THE 12Z NAM AND GFS. SOME LIGHTER SHOWERS ARE JUST SOUTH OF THE CWFA OVER NORTHEAST WISCONSIN...AND THERE IS A SLIGHT CHANCE THEY COULD CLIP MENOMINEE COUNTY LATE THIS AFTERNOON OR THIS EVENING...BUT CURRENT OBSERVED TRENDS WOULD KEEP THEM OUT OF THE AREA. MAIN SHORT TERM FORECAST CONCERN IS THE POSSIBILITY OF PCPN AS WELL AS ASSOCIATED TEMPERATURE AND CLOUD COVER ISSUES AS THE WARM FRONTAL BOUNDARY CONTINUES TO LURK TO OUR SOUTH. UTILIZED A COMBINATION OF THE NAM AND GFS...WHICH ARE REASONABLY SIMILAR THROUGH TOMORROW. THE WARM FRONTAL BOUNDARY IS NOT EXPECTED TO MAKE MUCH IF ANY NORTHWARD PROGRESS THROUGH MONDAY. THE NAM AND GFS DO MANAGE TO NUDGE IT SLIGHTLY NORTH LATE TONIGHT AND EARLY MONDAY...WHICH COULD BRING THE SHARP GRADIENT IN CLOUD COVER A BIT FARTHER NORTH...SO ALLOWED FOR SOME INCREASE IN CLOUD COVER DURING THAT TIME FRAME. AS FAR AS PCPN GOES...CONTINUED TO LEAVE IT OUT OF THE FORECAST THROUGH MONDAY. THE FRONTAL BOUNDARY WILL REMAIN ACTIVE THROUGH MONDAY...WITH A PERSIST AREA OF GOOD 850-700MB FRONTOGENESIS INTERACTING WITH AN AREA OF NEGATIVE 850-500MB DIFFERENTIAL THETA-E AND GOOD LOW LEVEL MOISTURE. HOWEVER...THIS AXIS OF CONVERGENCE...FRONTOGENESIS...MOISTURE...AND CONVECTIVE INSTABILITY WILL REMAIN SOUTH OF OUR AREA. IF ANYTHING...THE PERSISTENT PCPN NORTH OF THE BOUNDARY SHOULD REINFORCE THE BOUNDARY AND HELP KEEP IT TIED UP TO THE SOUTH THROUGH MONDAY. IN ADDITION...THE DRY EASTERLY FLOW FROM THE SURFACE HIGH ANCHORED TO OUR NORTH AND EAST SHOULD HELP KEEP ANY RENEGADE SHOWERS AT THE NORTHERN EDGE OF THE ELEVATED FRONTAL BOUNDARY FROM PEELING OFF INTO OUR AREA. WILL HAVE HIGHER POPS NEAR THE WISCONSIN BORDER...BUT WILL KEEP THEM BELOW THE THRESHOLD OF MENTIONING ANY ACTUAL PCPN. IF RADAR TRENDS CHANGE...THEN THERE MAY BE THE NEED TO MENTION AN ISOLATED SHOWER IN SOUTHERN MENOMINEE COUNTY...BUT WILL LEAVE THAT OUT FOR NOW. .LONG DISCUSSION (MON NIGHT THRU SUN)... QUESTION FOR MON NGT IS WHETHER UPR LO OVER THE PAC NW DRIFTING ACRS SRN CAN CAN GENERATE ANY PCPN OVER THE CWA. CONSIDERING THE PERSISTENT NW FLOW ACRS ERN CAN THAT WL TEND TO HOLD DRY CNDN HI/ ANTECEDENT AIRMASS IN PLACE ACRS THE UPR GRT LKS AND THE PRESENCE OF PERSISTENT/ANNOYING BNDRY TO THE S THAT WL INTERCEPT MSTR RETURN IN ADVANCE OF SLUGGISH UPR LO MOVING ONLY INTO CNTRL CAN AT 12Z TUE... HAVE TENDED TO FOLLOW A SLOWER/DRIER NAM SCENARIO AND RESTRICT POPS TO THE FAR WRN CWA THRU 12Z TUE TO THE W OF MODEST H85 LLJ AXIS (ONLY UP TO 30 KTS) AS SHOWN BY THE BIT MORE PROGRESSIVE GFS. OTRW...RETURN OF HIER PWAT WL TRANSLATE INTO INCRSG MID/HI CLDS ABV LINGERING LLVL DRY AIR. EXPECT LOWEST MIN TEMPS OVER THE INTERIOR E CLOSER TO PERSISTENT HI CENTER/DRIER AIR. ON TUE...GUIDANCE SHOWS COMMA TAIL FEATURE ASSOCIATED WITH SLOW MOVING LO ACRS SCNTRL CAN SWINGING W-E ACRS THE CWA. OPTED TO LOWER GOING 40 POPS TO 30 EXCEPT OVER THE NW SINCE NAM/GFS/UKMET SHOW SHARPER DPVA/H85-3 QVECTOR CNVGC SHIFTING TO THE N OVER ONTARIO... CWA PROGGED TO FALL INTO UNFVRBL RIGHT EXIT OF H3 JET MAX MOVING THRU NRN MN IN SUPPORT OF CYC IN SCNTRL CAN... AND FCST SDNGS HINT AT DRY AIR TRYING TO HOLD IN WITH ABSENCE OF SGNFT HGT FALLS. LOWERED FCST MAX TEMPS CLOSER TO MUCH COOLER MOS GUIDANCE WITH EXPECTATION OF AT LEAST CONSIDERABLE CLD COVER AND LLVL SE FLOW. BEST CHC FOR WARMER TEMPS WL BE OVER THE W...WHERE CLDS MAY THIN LATE IN THE DAY FOLLOWING PASSAGE OF DEEPER COMMA TAIL MSTR TO THE E. ON TUE NGT/WED...12Z UKMET IS FASTER/DEEPER THAN GFS WITH SFC WAVE FCST TO RIDE ENEWD IN WSW FLOW ALF BTWN SLOW MOVING VORTEX ACRS SCNTRL CAN AND UPR RDG OVER THE SE STATES. CUT POPS BACK TO 20 OVER THE ENTIRE FA ON TUE EVNG BEFORE INCRSG POPS TO 30 AFT MIDNGT OVER THE SCNTRL AND E TO ACCOUNT FOR POTENTIAL LO PRES WAVE THAT WOULD RIDE NEWD. MAINTAINED THE LOWER POPS OVER THE NW TO ACCOUNT FOR HIER PROBABILITY WAVE WL TRACK ALG PERSISTENT BNDRY FARTHER S. IN THE MEDIUM/EXTENDED PD FOLLOWING PCPN CHCS ON WED...HI PRES RDG LOOKS TO BE BLDG TOWARD THE FA ON THU. HOWEVER...CONSIDERING SFC FNT HANGS UP JUST TO THE SE OF THE FA...WARY ABOUT A DRY FCST... ESPECIALLY OVER THE SCNTRL AND E. IN FACT...12Z GFS SHOWS A SERIES OF WAVES RIDING ENEWD ON THIS BNDRY AND DUMPING QUITE A PIT OF PCPN ON AREAS SE OF CRYSTAL FALLS TO MQT. THEN QUESTIONS AS TO EXTENT OF SFC DVLPMNT/TRACK OF LO PRES IN THE CNTRL PLAINS FOR THE FRI-SAT TIME. 00Z ECWMF/GFS/UKMET/12Z CNDN SHOW A DEEPER UPR TROF DVLPG IN THE PLAINS WITH THE RESULT A SOMEWHAT DEEPER WAVE TRACKING FARTHER N TOWARD NRN LWR MI FRI NGT WITH DEEPER RH/CYC NE FLOW OVER THE CWA. 00Z CNDN/06Z GFS ON THE OTHER HAND ARE A BIT FLATTER WITH THE TROF/SFC WAVE AND SHOW DEEPER RH/MAIN BODY OF PCPN STAYING TO THE S. 12Z GFS HAS COMPLETELY SHIFTED GEARS AND SHOWS DRY HI PRES BLDG INTO THE AREA ON SAT FOLLOWING PASSAGE OF LAST WAVE ON THE FNT THU NGT. ALTHOUGH 00Z GFS REFCST GUIDANCE APPEARS TO SUPPORT THE 00Z CNDN/06Z GFS SCENARIO...NCEP MANUAL GUIDANCE INDICATES A PREFERENCE FOR THE DEEPER 00Z GFS/ECMWF/UKMET/12Z CNDN FCST. SO FOLLOWED THIS FCST SCENARIO...WITH EXPECTED TEMPS BLO NORMAL ESPECIALLY ON SAT WITH STEADY NE FLOW. THEN COOL/DRIER ON SUN WITH NW FLOW BTWN DEPARTING LO AND CNDN HI PRES BLDG TOWARD THE UPR MS VALLEY. COORDINATED WITH APX/GRB/LOT/DLH. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... MODELS SUGGEST THAT 925-850 MB MOISTURE OVER WI AND LAKE MI WILL PUSH NORTHWARD...AS ALREADY EVIDENT ON THE 02Z TAMDAR SOUNDING FROM SAW SHOWING NEARLY SATURATED CONDITIONS AROUND 4000 FT. SURFACE OBSERVATIONS CURRENTLY NEAR THE WI BORDER INDICATE 2500-3500 FT CIGS. THE NORTHWARD PROGRESSION SHOULD BE SLOW...DUE TO EASTERLY FLOW ADVECTING DRY AIR IN FROM ONTARIO. HAVE DECIDED TO LIFT CIGS INTO THE VFR CATEGORY IN THE AFTERNOON AT SAW DUE TO DAYTIME HEATING...BUT THEN BROUGHT THEM BACK DOWN TO MVFR IN THE EVENING AS COOLING OCCURS. SOMETHING SIMILAR COULD HAPPEN AT CMX...BUT EASTERLY WINDS UPSLOPING MAY PREVENT THAT FROM OCCURING. NO PCPN EXPECTED AT EITHER TAF SITE SINCE DEEPER MOISTURE SHOULD STAY SOUTH. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FCST ISSUANCE)... HIGH PRESSURE CENTERED TO THE NORTH AND EAST OF THE AREA WILL GRUDGINGLY SLIDE EAST OVER THE NEXT SEVERAL DAYS AS A WARM FRONT TO THE SOUTH TRIES TO LIFT NORTH. ALTHOUGH THE WARM FRONT WILL PROBABLY NOT MAKE IT NORTH INTO UPPER MICHIGAN...WE WILL EVENTUALLY SEE A COLD FRONTAL BOUNDARY SLIDE THROUGH BY LATE THURSDAY. WITH A HIGH TO THE EAST AND LOWER PRESSURE TO THE WEST...WE WILL GENERALLY SEE EASTERLY FLOW TONIGHT AND MONDAY GIVE WAY TO SOUTHERLY FLOW BY TUESDAY THROUGH THURSDAY. THE PRESSURE GRADIENT WILL BE TIGHTEST OVER THE NEXT 24 TO 36 HOURS WITH 15 TO 25 KT WINDS OVER MUCH OF THE LAKE DURING THAT TIME. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM DISCUSSION...TRH LONG TERM DISCUSSION...KC AVIATION...AJ MARINE...TRH mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 800 PM EDT SUN AUG 19 2007 .SHORT TERM DISCUSSION (TNGT THRU MON)...(ISSUED 335 PM EDT) LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW RIDGING OVER THE CENTRAL CONUS EXTENDING UP INTO SOUTH CENTRAL CANADA. THIS RIDGE IS BRACKETED BY UPPER LOWS/TROUGHING ALONG THE NORTHWEST COAST AND OVER EASTERN QUEBEC. A SHARPLY DEFINED SHORTWAVE TROUGH CAN BE SEEN ROTATING THROUGH WASHINGTON AND OREGON...AND THIS IS THE NEXT SIGNIFICANT SHORTWAVE FEATURE EXPECTED TO AFFECT THE AREA...ALTHOUGH IT WILL LOSE SOME OF ITS LUSTER AS IT WORKS EASTWARD THROUGH THE UPPER RIDGE. RADAR IMAGERY CONTINUES TO SHOW A WNW-ESE ORIENTED AREA OF PCPN WITH EMBEDDED CONVECTION FROM SOUTHERN MINNESOTA THROUGH NORTHERN INDIANA AND NORTHWEST OHIO. THIS ACTIVITY CORRELATES WELL WITH AN AREA OF 850-700MB FRONTOGENESIS AND CONVECTIVE INSTABILITY SHOWN BY THE 12Z NAM AND GFS. SOME LIGHTER SHOWERS ARE JUST SOUTH OF THE CWFA OVER NORTHEAST WISCONSIN...AND THERE IS A SLIGHT CHANCE THEY COULD CLIP MENOMINEE COUNTY LATE THIS AFTERNOON OR THIS EVENING...BUT CURRENT OBSERVED TRENDS WOULD KEEP THEM OUT OF THE AREA. MAIN SHORT TERM FORECAST CONCERN IS THE POSSIBILITY OF PCPN AS WELL AS ASSOCIATED TEMPERATURE AND CLOUD COVER ISSUES AS THE WARM FRONTAL BOUNDARY CONTINUES TO LURK TO OUR SOUTH. UTILIZED A COMBINATION OF THE NAM AND GFS...WHICH ARE REASONABLY SIMILAR THROUGH TOMORROW. THE WARM FRONTAL BOUNDARY IS NOT EXPECTED TO MAKE MUCH IF ANY NORTHWARD PROGRESS THROUGH MONDAY. THE NAM AND GFS DO MANAGE TO NUDGE IT SLIGHTLY NORTH LATE TONIGHT AND EARLY MONDAY...WHICH COULD BRING THE SHARP GRADIENT IN CLOUD COVER A BIT FARTHER NORTH...SO ALLOWED FOR SOME INCREASE IN CLOUD COVER DURING THAT TIME FRAME. AS FAR AS PCPN GOES...CONTINUED TO LEAVE IT OUT OF THE FORECAST THROUGH MONDAY. THE FRONTAL BOUNDARY WILL REMAIN ACTIVE THROUGH MONDAY...WITH A PERSIST AREA OF GOOD 850-700MB FRONTOGENESIS INTERACTING WITH AN AREA OF NEGATIVE 850-500MB DIFFERENTIAL THETA-E AND GOOD LOW LEVEL MOISTURE. HOWEVER...THIS AXIS OF CONVERGENCE...FRONTOGENESIS...MOISTURE...AND CONVECTIVE INSTABILITY WILL REMAIN SOUTH OF OUR AREA. IF ANYTHING...THE PERSISTENT PCPN NORTH OF THE BOUNDARY SHOULD REINFORCE THE BOUNDARY AND HELP KEEP IT TIED UP TO THE SOUTH THROUGH MONDAY. IN ADDITION...THE DRY EASTERLY FLOW FROM THE SURFACE HIGH ANCHORED TO OUR NORTH AND EAST SHOULD HELP KEEP ANY RENEGADE SHOWERS AT THE NORTHERN EDGE OF THE ELEVATED FRONTAL BOUNDARY FROM PEELING OFF INTO OUR AREA. WILL HAVE HIGHER POPS NEAR THE WISCONSIN BORDER...BUT WILL KEEP THEM BELOW THE THRESHOLD OF MENTIONING ANY ACTUAL PCPN. IF RADAR TRENDS CHANGE...THEN THERE MAY BE THE NEED TO MENTION AN ISOLATED SHOWER IN SOUTHERN MENOMINEE COUNTY...BUT WILL LEAVE THAT OUT FOR NOW. .LONG DISCUSSION (MON NGT THRU SUN)... QUESTION FOR MON NGT IS WHETHER UPR LO OVER THE PAC NW DRIFTING ACRS SRN CAN CAN GENERATE ANY PCPN OVER THE CWA. CONSIDERING THE PERSISTENT NW FLOW ACRS ERN CAN THAT WL TEND TO HOLD DRY CNDN HI/ ANTECEDENT AIRMASS IN PLACE ACRS THE UPR GRT LKS AND THE PRESENCE OF PERSISTENT/ANNOYING BNDRY TO THE S THAT WL INTERCEPT MSTR RETURN IN ADVANCE OF SLUGGISH UPR LO MOVING ONLY INTO CNTRL CAN AT 12Z TUE... HAVE TENDED TO FOLLOW A SLOWER/DRIER NAM SCENARIO AND RESTRICT POPS TO THE FAR WRN CWA THRU 12Z TUE TO THE W OF MODEST H85 LLJ AXIS (ONLY UP TO 30 KTS) AS SHOWN BY THE BIT MORE PROGRESSIVE GFS. OTRW...RETURN OF HIER PWAT WL TRANSLATE INTO INCRSG MID/HI CLDS ABV LINGERING LLVL DRY AIR. EXPECT LOWEST MIN TEMPS OVER THE INTERIOR E CLOSER TO PERSISTENT HI CENTER/DRIER AIR. ON TUE...GUIDANCE SHOWS COMMA TAIL FEATURE ASSOCIATED WITH SLOW MOVING LO ACRS SCNTRL CAN SWINGING W-E ACRS THE CWA. OPTED TO LOWER GOING 40 POPS TO 30 EXCEPT OVER THE NW SINCE NAM/GFS/UKMET SHOW SHARPER DPVA/H85-3 QVECTOR CNVGC SHIFTING TO THE N OVER ONTARIO... CWA PROGGED TO FALL INTO UNFVRBL RIGHT EXIT OF H3 JET MAX MOVING THRU NRN MN IN SUPPORT OF CYC IN SCNTRL CAN... AND FCST SDNGS HINT AT DRY AIR TRYING TO HOLD IN WITH ABSENCE OF SGNFT HGT FALLS. LOWERED FCST MAX TEMPS CLOSER TO MUCH COOLER MOS GUIDANCE WITH EXPECTATION OF AT LEAST CONSIDERABLE CLD COVER AND LLVL SE FLOW. BEST CHC FOR WARMER TEMPS WL BE OVER THE W...WHERE CLDS MAY THIN LATE IN THE DAY FOLLOWING PASSAGE OF DEEPER COMMA TAIL MSTR TO THE E. ON TUE NGT/WED...12Z UKMET IS FASTER/DEEPER THAN GFS WITH SFC WAVE FCST TO RIDE ENEWD IN WSW FLOW ALF BTWN SLOW MOVING VORTEX ACRS SCNTRL CAN AND UPR RDG OVER THE SE STATES. CUT POPS BACK TO 20 OVER THE ENTIRE FA ON TUE EVNG BEFORE INCRSG POPS TO 30 AFT MIDNGT OVER THE SCNTRL AND E TO ACCOUNT FOR POTENTIAL LO PRES WAVE THAT WOULD RIDE NEWD. MAINTAINED THE LOWER POPS OVER THE NW TO ACCOUNT FOR HIER PROBABILITY WAVE WL TRACK ALG PERSISTENT BNDRY FARTHER S. IN THE MEDIUM/EXTENDED PD FOLLOWING PCPN CHCS ON WED...HI PRES RDG LOOKS TO BE BLDG TOWARD THE FA ON THU. HOWEVER...CONSIDERING SFC FNT HANGS UP JUST TO THE SE OF THE FA...WARY ABOUT A DRY FCST... ESPECIALLY OVER THE SCNTRL AND E. IN FACT...12Z GFS SHOWS A SERIES OF WAVES RIDING ENEWD ON THIS BNDRY AND DUMPING QUITE A PIT OF PCPN ON AREAS SE OF CRYSTAL FALLS TO MQT. THEN QUESTIONS AS TO EXTENT OF SFC DVLPMNT/TRACK OF LO PRES IN THE CNTRL PLAINS FOR THE FRI-SAT TIME. 00Z ECWMF/GFS/UKMET/12Z CNDN SHOW A DEEPER UPR TROF DVLPG IN THE PLAINS WITH THE RESULT A SOMEWHAT DEEPER WAVE TRACKING FARTHER N TOWARD NRN LWR MI FRI NGT WITH DEEPER RH/CYC NE FLOW OVER THE CWA. 00Z CNDN/06Z GFS ON THE OTHER HAND ARE A BIT FLATTER WITH THE TROF/SFC WAVE AND SHOW DEEPER RH/MAIN BODY OF PCPN STAYING TO THE S. 12Z GFS HAS COMPLETELY SHIFTED GEARS AND SHOWS DRY HI PRES BLDG INTO THE AREA ON SAT FOLLOWING PASSAGE OF LAST WAVE ON THE FNT THU NGT. ALTHOUGH 00Z GFS REFCST GUIDANCE APPEARS TO SUPPORT THE 00Z CNDN/06Z GFS SCENARIO...NCEP MANUAL GUIDANCE INDICATES A PREFERENCE FOR THE DEEPER 00Z GFS/ECMWF/UKMET/12Z CNDN FCST. SO FOLLOWED THIS FCST SCENARIO...WITH EXPECTED TEMPS BLO NORMAL ESPECIALLY ON SAT WITH STEADY NE FLOW. THEN COOL/DRIER ON SUN WITH NW FLOW BTWN DEPARTING LO AND CNDN HI PRES BLDG TOWARD THE UPR MS VALLEY. COORDINATED WITH APX/GRB/LOT/DLH. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... THERE WILL CONTINUE TO BE A VERY SHARP GRADIENT IN CLOUD COVER AS YOU HEAD SOUTH OF UPPER MICHIGAN. THE CLOUDS TO THE SOUTH WILL TRY TO CREEP A BIT NORTH LATE TONIGHT AND EARLY MONDAY...BUT CEILINGS SHOULD REMAIN VFR...ALTHOUGH SOME MARGINAL MVFR CONDITIONS COULD SNEAK INTO KSAW TOWARD DAYBREAK. THE BETTER MOISTURE AND FORCING WITH THE WARM FRONTAL BOUNDARY WILL REMAIN SOUTH OF THE AREA...SO NO PCPN IS EXPECTED. && .MARINE (FOR 4 PM LAKE SUPERIOR FCST ISSUANCE)... HIGH PRESSURE CENTERED TO THE NORTH AND EAST OF THE AREA WILL GRUDGINGLY SLIDE EAST OVER THE NEXT SEVERAL DAYS AS A WARM FRONT TO THE SOUTH TRIES TO LIFT NORTH. ALTHOUGH THE WARM FRONT WILL PROBABLY NOT MAKE IT NORTH INTO UPPER MICHIGAN...WE WILL EVENTUALLY SEE A COLD FRONTAL BOUNDARY SLIDE THROUGH BY LATE THURSDAY. WITH A HIGH TO THE EAST AND LOWER PRESSURE TO THE WEST...WE WILL GENERALLY SEE EASTERLY FLOW TONIGHT AND MONDAY GIVE WAY TO SOUTHERLY FLOW BY TUESDAY THROUGH THURSDAY. THE PRESSURE GRADIENT WILL BE TIGHTEST OVER THE NEXT 24 TO 36 HOURS WITH 15 TO 25 KT WINDS OVER MUCH OF THE LAKE DURING THAT TIME. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM DISCUSSION...TRH LONG TERM DISCUSSION...KC AVIATION/MARINE...TRH mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 335 PM EDT SUN AUG 19 2007 .SHORT TERM DISCUSSION (TNGT THRU MON)... LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW RIDGING OVER THE CENTRAL CONUS EXTENDING UP INTO SOUTH CENTRAL CANADA. THIS RIDGE IS BRACKETED BY UPPER LOWS/TROUGHING ALONG THE NORTHWEST COAST AND OVER EASTERN QUEBEC. A SHARPLY DEFINED SHORTWAVE TROUGH CAN BE SEEN ROTATING THROUGH WASHINGTON AND OREGON...AND THIS IS THE NEXT SIGNIFICANT SHORTWAVE FEATURE EXPECTED TO AFFECT THE AREA...ALTHOUGH IT WILL LOSE SOME OF ITS LUSTER AS IT WORKS EASTWARD THROUGH THE UPPER RIDGE. RADAR IMAGERY CONTINUES TO SHOW A WNW-ESE ORIENTED AREA OF PCPN WITH EMBEDDED CONVECTION FROM SOUTHERN MINNESOTA THROUGH NORTHERN INDIANA AND NORTHWEST OHIO. THIS ACTIVITY CORRELATES WELL WITH AN AREA OF 850-700MB FRONTOGENESIS AND CONVECTIVE INSTABILITY SHOWN BY THE 12Z NAM AND GFS. SOME LIGHTER SHOWERS ARE JUST SOUTH OF THE CWFA OVER NORTHEAST WISCONSIN...AND THERE IS A SLIGHT CHANCE THEY COULD CLIP MENOMINEE COUNTY LATE THIS AFTERNOON OR THIS EVENING...BUT CURRENT OBSERVED TRENDS WOULD KEEP THEM OUT OF THE AREA. MAIN SHORT TERM FORECAST CONCERN IS THE POSSIBILITY OF PCPN AS WELL AS ASSOCIATED TEMPERATURE AND CLOUD COVER ISSUES AS THE WARM FRONTAL BOUNDARY CONTINUES TO LURK TO OUR SOUTH. UTILIZED A COMBINATION OF THE NAM AND GFS...WHICH ARE REASONABLY SIMILAR THROUGH TOMORROW. THE WARM FRONTAL BOUNDARY IS NOT EXPECTED TO MAKE MUCH IF ANY NORTHWARD PROGRESS THROUGH MONDAY. THE NAM AND GFS DO MANAGE TO NUDGE IT SLIGHTLY NORTH LATE TONIGHT AND EARLY MONDAY...WHICH COULD BRING THE SHARP GRADIENT IN CLOUD COVER A BIT FARTHER NORTH...SO ALLOWED FOR SOME INCREASE IN CLOUD COVER DURING THAT TIME FRAME. AS FAR AS PCPN GOES...CONTINUED TO LEAVE IT OUT OF THE FORECAST THROUGH MONDAY. THE FRONTAL BOUNDARY WILL REMAIN ACTIVE THROUGH MONDAY...WITH A PERSIST AREA OF GOOD 850-700MB FRONTOGENESIS INTERACTING WITH AN AREA OF NEGATIVE 850-500MB DIFFERENTIAL THETA-E AND GOOD LOW LEVEL MOISTURE. HOWEVER...THIS AXIS OF CONVERGENCE...FRONTOGENESIS...MOISTURE...AND CONVECTIVE INSTABILITY WILL REMAIN SOUTH OF OUR AREA. IF ANYTHING...THE PERSISTENT PCPN NORTH OF THE BOUNDARY SHOULD REINFORCE THE BOUNDARY AND HELP KEEP IT TIED UP TO THE SOUTH THROUGH MONDAY. IN ADDITION...THE DRY EASTERLY FLOW FROM THE SURFACE HIGH ANCHORED TO OUR NORTH AND EAST SHOULD HELP KEEP ANY RENEGADE SHOWERS AT THE NORTHERN EDGE OF THE ELEVATED FRONTAL BOUNDARY FROM PEELING OFF INTO OUR AREA. WILL HAVE HIGHER POPS NEAR THE WISCONSIN BORDER...BUT WILL KEEP THEM BELOW THE THRESHOLD OF MENTIONING ANY ACTUAL PCPN. IF RADAR TRENDS CHANGE...THEN THERE MAY BE THE NEED TO MENTION AN ISOLATED SHOWER IN SOUTHERN MENOMINEE COUNTY...BUT WILL LEAVE THAT OUT FOR NOW. .LONG DISCUSSION (MON NGT THRU SUN)... QUESTION FOR MON NGT IS WHETHER UPR LO OVER THE PAC NW DRIFTING ACRS SRN CAN CAN GENERATE ANY PCPN OVER THE CWA. CONSIDERING THE PERSISTENT NW FLOW ACRS ERN CAN THAT WL TEND TO HOLD DRY CNDN HI/ ANTECEDENT AIRMASS IN PLACE ACRS THE UPR GRT LKS AND THE PRESENCE OF PERSISTENT/ANNOYING BNDRY TO THE S THAT WL INTERCEPT MSTR RETURN IN ADVANCE OF SLUGGISH UPR LO MOVING ONLY INTO CNTRL CAN AT 12Z TUE... HAVE TENDED TO FOLLOW A SLOWER/DRIER NAM SCENARIO AND RESTRICT POPS TO THE FAR WRN CWA THRU 12Z TUE TO THE W OF MODEST H85 LLJ AXIS (ONLY UP TO 30 KTS) AS SHOWN BY THE BIT MORE PROGRESSIVE GFS. OTRW...RETURN OF HIER PWAT WL TRANSLATE INTO INCRSG MID/HI CLDS ABV LINGERING LLVL DRY AIR. EXPECT LOWEST MIN TEMPS OVER THE INTERIOR E CLOSER TO PERSISTENT HI CENTER/DRIER AIR. ON TUE...GUIDANCE SHOWS COMMA TAIL FEATURE ASSOCIATED WITH SLOW MOVING LO ACRS SCNTRL CAN SWINGING W-E ACRS THE CWA. OPTED TO LOWER GOING 40 POPS TO 30 EXCEPT OVER THE NW SINCE NAM/GFS/UKMET SHOW SHARPER DPVA/H85-3 QVECTOR CNVGC SHIFTING TO THE N OVER ONTARIO... CWA PROGGED TO FALL INTO UNFVRBL RIGHT EXIT OF H3 JET MAX MOVING THRU NRN MN IN SUPPORT OF CYC IN SCNTRL CAN... AND FCST SDNGS HINT AT DRY AIR TRYING TO HOLD IN WITH ABSENCE OF SGNFT HGT FALLS. LOWERED FCST MAX TEMPS CLOSER TO MUCH COOLER MOS GUIDANCE WITH EXPECTATION OF AT LEAST CONSIDERABLE CLD COVER AND LLVL SE FLOW. BEST CHC FOR WARMER TEMPS WL BE OVER THE W...WHERE CLDS MAY THIN LATE IN THE DAY FOLLOWING PASSAGE OF DEEPER COMMA TAIL MSTR TO THE E. ON TUE NGT/WED...12Z UKMET IS FASTER/DEEPER THAN GFS WITH SFC WAVE FCST TO RIDE ENEWD IN WSW FLOW ALF BTWN SLOW MOVING VORTEX ACRS SCNTRL CAN AND UPR RDG OVER THE SE STATES. CUT POPS BACK TO 20 OVER THE ENTIRE FA ON TUE EVNG BEFORE INCRSG POPS TO 30 AFT MIDNGT OVER THE SCNTRL AND E TO ACCOUNT FOR POTENTIAL LO PRES WAVE THAT WOULD RIDE NEWD. MAINTAINED THE LOWER POPS OVER THE NW TO ACCOUNT FOR HIER PROBABILITY WAVE WL TRACK ALG PERSISTENT BNDRY FARTHER S. IN THE MEDIUM/EXTENDED PD FOLLOWING PCPN CHCS ON WED...HI PRES RDG LOOKS TO BE BLDG TOWARD THE FA ON THU. HOWEVER...CONSIDERING SFC FNT HANGS UP JUST TO THE SE OF THE FA...WARY ABOUT A DRY FCST... ESPECIALLY OVER THE SCNTRL AND E. IN FACT...12Z GFS SHOWS A SERIES OF WAVES RIDING ENEWD ON THIS BNDRY AND DUMPING QUITE A PIT OF PCPN ON AREAS SE OF CRYSTAL FALLS TO MQT. THEN QUESTIONS AS TO EXTENT OF SFC DVLPMNT/TRACK OF LO PRES IN THE CNTRL PLAINS FOR THE FRI-SAT TIME. 00Z ECWMF/GFS/UKMET/12Z CNDN SHOW A DEEPER UPR TROF DVLPG IN THE PLAINS WITH THE RESULT A SOMEWHAT DEEPER WAVE TRACKING FARTHER N TOWARD NRN LWR MI FRI NGT WITH DEEPER RH/CYC NE FLOW OVER THE CWA. 00Z CNDN/06Z GFS ON THE OTHER HAND ARE A BIT FLATTER WITH THE TROF/SFC WAVE AND SHOW DEEPER RH/MAIN BODY OF PCPN STAYING TO THE S. 12Z GFS HAS COMPLETELY SHIFTED GEARS AND SHOWS DRY HI PRES BLDG INTO THE AREA ON SAT FOLLOWING PASSAGE OF LAST WAVE ON THE FNT THU NGT. ALTHOUGH 00Z GFS REFCST GUIDANCE APPEARS TO SUPPORT THE 00Z CNDN/06Z GFS SCENARIO...NCEP MANUAL GUIDANCE INDICATES A PREFERENCE FOR THE DEEPER 00Z GFS/ECMWF/UKMET/12Z CNDN FCST. SO FOLLOWED THIS FCST SCENARIO...WITH EXPECTED TEMPS BLO NORMAL ESPECIALLY ON SAT WITH STEADY NE FLOW. THEN COOL/DRIER ON SUN WITH NW FLOW BTWN DEPARTING LO AND CNDN HI PRES BLDG TOWARD THE UPR MS VALLEY. COORDINATED WITH APX/GRB/LOT/DLH. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... THERE WILL CONTINUE TO BE A VERY SHARP GRADIENT IN CLOUD COVER AS YOU HEAD SOUTH OF UPPER MICHIGAN. WITH THE EXCEPTION OF SOME DIURNAL CU AND HIGH CIRRUS...LOOK FOR VERY LITTLE IN THE WAY OF CLOUD COVER AT KCMX AND KSAW THROUGH THE DAY. THE CLOUDS TO THE SOUTH WILL TRY TO CREEP A BIT NORTH LATE TONIGHT AND EARLY MONDAY...BUT CEILINGS SHOULD REMAIN VFR...ALTHOUGH SOME MARGINAL MVFR CONDITIONS COULD SNEAK INTO KSAW TOWARD DAYBREAK. THE BETTER MOISTURE AND FORCING WITH THE WARM FRONTAL BOUNDARY WILL REMAIN SOUTH OF THE AREA...SO NO PCPN IS EXPECTED. && .MARINE (FOR 4 PM LAKE SUPERIOR FCST ISSUANCE)... HIGH PRESSURE CENTERED TO THE NORTH AND EAST OF THE AREA WILL GRUDGINGLY SLIDE EAST OVER THE NEXT SEVERAL DAYS AS A WARM FRONT TO THE SOUTH TRIES TO LIFT NORTH. ALTHOUGH THE WARM FRONT WILL PROBABLY NOT MAKE IT NORTH INTO UPPER MICHIGAN...WE WILL EVENTUALLY SEE A COLD FRONTAL BOUNDARY SLIDE THROUGH BY LATE THURSDAY. WITH A HIGH TO THE EAST AND LOWER PRESSURE TO THE WEST...WE WILL GENERALLY SEE EASTERLY FLOW TONIGHT AND MONDAY GIVE WAY TO SOUTHERLY FLOW BY TUESDAY THROUGH THURSDAY. THE PRESSURE GRADIENT WILL BE TIGHTEST OVER THE NEXT 24 TO 36 HOURS WITH 15 TO 25 KT WINDS OVER MUCH OF THE LAKE DURING THAT TIME. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM DISCUSSION...TRH LONG TERM DISCUSSION...KC AVIATION/MARINE...TRH mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 120 AM EDT SUN AUG 19 2007 .AVIATION...NOT MUCH HAS CHANGED SINCE THE 00Z TAF ISSUANCE. THE RAIN HAS CONTINUED TO MOVE SOUTH OF THE REGION. EXPECT VFR CONDITIONS TO PREVAIL FOR THE MAJORITY OF THIS TAF CYCLE WITH A MID TO UPPER LEVEL OVERCAST. A WAVE PUSHING ACROSS THE NORTHERN OHIO VALLEY MAY DROP CEILINGS TO MVFR AT KTVC TOMORROW EVENING. HOWEVER...EXPECT ANY RAIN TO REMAIN SOUTH OF THE TAF SITES THROUGH THE PERIOD. LUTZ/MSB && .UPDATE...ISSUED 1041 PM AS THE RADAR HAS BEEN SHOWING THIS EVENING...THE RAIN SHOWERS HAVE BEEN MOVING TO THE SOUTH AND EAST. TRIMMED THE RAIN FARTHER SOUTH AND MAY HAVE TO UPDATE AGAIN AS THE RAIN LOOKING UPSTREAM ARE SHOWING WIDELY SCATTERED SHOWERS AND SPRINKLES. OTHERWISE, THE TEMPERATURES LOOKS GOOD WITH THE CLOUD COVER THAT IS OVER THE REGION AND THE HIGH PRESSURE THAT IS KEEPING THE WINDS DOWN TONIGHT. LUTZ && .PREV DISCUSSION...ISSUED 328 PM ANOTHER NICE FALL-LIKE DAY ACROSS THE CWA WITH HIGH PRESSURE FULLY IN CONTROL WILL TRANSITION TO A BIT MORE TRICKY FORECAST OVERNIGHT. EARLY AFTERNOON ANALYSIS SHOWS A BUILDING LOW/ MID LEVEL RIDGE ACROSS THE SOUTHEAST STATES...WITH SURFACE RIDGING STILL CENTERED ACROSS NORTHERN MICHIGAN BUT BEGINNING TO SLIP EAST EVER-SO-SLOWLY. RETURN FLOW ON THE BACKSIDE OF SOUTHEAST RIDGE FULLY UNDERWAY...WITH ONGOING BROAD ISENTROPIC ASCENT CONTINUING TO DRIVE A RATHER EXPANSIVE AREA OF PRECIPITATION LIFTING THROUGH WISCONSIN. IT IS THIS AREA OF PRECIPITATION THAT REMAINS THE PRIMARY FORECAST CONCERN FOR TONIGHT...NAMELY WILL IT AFFECT THE CWA AND WHAT EFFECT WILL THE ADDITIONAL CLOUDS HAVE ON OVERNIGHT LOWS. QUICK LOOK AT REGIONAL RADAR MOSAIC SHOWS A BIT BETTER ORGANIZED AREA OF PRECIP THAN SUGGESTED BY THE 12Z MODEL GUIDANCE...OWING PRIMARILY TO APPARENT ADDED JET DIVERGENCE...WITH JET ENTRANCE REGION SLIPPING ACROSS FAR NORTHERN MINNESOTA...AS WELL AS A PRONOUNCED VORT PROGRESSING INTO WESTERN MINNESOTA PER RUC ANALYSIS/ WATER VAPOR PICS (REMNANTS OF LAST NIGHT`S CONVECTION OVER THE BLACK HILLS?). HAVE BEEN RATHER IMPRESSED AT PRECIP`S ABILITY TO OVERCOME DRY AIRMASS JUST TO THE WEST...WITH QUITE A FEW SITES GOING FROM BKN-OVC200 DOWN TO OVC070 WITH PRECIP IN AN HOUR...ALSO SUGGESTING FORCED ASCENT A BIT BETTER THAN MODELS CREDIT. THIS ALL LEADS TO A RATHER MURKY PRECIP FORECAST FOR THE APX CWA OVERNIGHT... AS THINKING HAS BEEN DRY AIR WOULD WIN OUT...AND IT DOES APPEAR THIS WILL WORK FOR THE NORTHERN HALF...BUT HAVE HAD TO RE-EVALUATE FARTHER SOUTH. OVERNIGHT...THE LIFT FOR PRECIP WILL CERTAINLY BE THERE...WITH DECENT 305-310K ISENTROPIC UPGLIDE (25-30 KNOTS UP THE SURFACE) ON THE INCREASE AS WARM ADVECTION COMMENCES...WITH DEEP LAYER (900-700MB) FRONTOGENETICAL FORCING IN PLACE AS WELL GIVEN TIGHT BAROCLINIC ZONE ACROSS THE MIDWEST/LOWER GREAT LAKES. HOWEVER...RH PROGS ON THESE SURFACES AND SFC-H85 THETA-E ALSO SHOW A SHARP CUTOFF TO DEEP MOISTURE...AS BOTH CONVECTION TO THE SOUTH TAKES OVER TONIGHT...AND DEEP LAYER SUBSIDENCE/DRYING THIS AFTERNOON AND EVENING (SFC-700MB RH LESS THAN 35%) HOLD FIRM. THUS...WHILE THE OVERALL TREND OF THE DRY AIR WINNING OUT STILL LOOKS OK...HAVE TRENDED POPS FARTHER NORTH THROUGH THE NIGHTTIME HOURS...IN LINE WITH THE 09Z SREF/12Z UKMET WHICH SEEM TO HAVE A BETTER HANDLE ON CURRENT PRECIP. STILL NOT TALKING ABOUT A WHOLE LOT OF RAIN...BUT ANY RAIN IS WELCOME AT THIS POINT. NO THREAT OF ANY THUNDER OWING TO LACK OF MOISTURE/INSTABILITY AS WELL AS FLAT MID-LEVEL LAPSE RATES. AS FOR TEMPERATURES...THESE ALSO TRICKY GIVEN UNCERTAIN DEGREE OF CLOUD COVER. CLOUDY CONDITIONS EXPECTED THRU THE NIGHT ACROSS THE SOUTH IN CLOSER PROXIMITY TO FORCING/BETTER MOISTURE...WHILE MAY VERY WELL SEE THINGS CLEAR OUT ACROSS THE NORTH WITH BETTER SUBSIDENCE. WILL HOLD NUMBERS UP ABOVE GUIDANCE VALUES ACROSS THE SOUTH WITH PLENTIFUL CLOUD COVER...BUT CONTINUE PREVIOUS IDEA OF RATHER COOL READINGS (LOWER 40S...IF NOT A FEW UPPER 30S) FAR NORTH GIVEN SFC RIDGE AXIS HOLDING IN WITH FLOW DECOUPLING AND RESIDUAL DRY AIRMASS STILL IN PLACE. LAWRENCE LONG TERM...RECENT PATTERN OF TROUGHS OVER THE EASTERN PACIFIC AND EASTERN CANADA/NEW ENGLAND...AND LOW AMPLITUDE RIDGING IN BETWEEN EXPECTED TO BECOME MORE PROGRESSIVE FOR THE COMING WEEK...AS PACIFIC TROUGH MOVES INLAND AND HEIGHTS RISE ACROSS THE GREAT LAKES. HIGH PRESSURE IN PLACE AT THE ONSET OF THE FORECAST PERIOD TODAY WILL SLIDE EAST/NORTHEAST...ELONGATED FRONTAL BOUNDARY STRETCHING FROM THE CENTRAL HIGH PLAINS SOUTHEAST ACROSS THE TENNESSEE VALLEY WILL SLOWLY LIFT NORTHWARD AS A WARM FRONT IN RESPONSE. THIS WARM FRONT NOT LIKELY TO EVEN REACH LOWER MI UNTIL LATER MONDAY...AND EVEN THEN WILL PROBABLY HANG ALONG THE SOUTHERN BORDER THROUGH THE FIRST PART OF THE WEEK. SINCE THIS BOUNDARY WILL BE THE MAIN FOCUS FOR CONVECTIVE DEVELOPMENT OVER THE NEXT SEVERAL DAYS...MAIN FORECAST CONCERNS FOR THE NEAR TERM PORTION OF THE FORECAST WILL BASICALLY DEAL WITH HOW FAR NORTH THE THREAT FOR RAIN WILL REACH. SUNDAY...EXPECT A GOOD DEAL OF CONVECTION TO BE GOING SOUTHWEST/ SOUTH OF THE FORECAST AREA TO START SUNDAY MORNING ALONG FRONTOGENETICALLY ACTIVE WARM FRONTAL ZONE WHICH IS EXPECTED TO EXTEND ACROSS SOUTHERN WI/FAR SOUTHERN LOWER MI (ACTUAL WARM FRONT WILL LIE ACROSS NORTHEAST IA/NORTHERN IL/CENTRAL IN). AXIS OF DEEPER MOISTURE WILL PROBABLY REMAIN MAINLY SOUTH OF THE FORECAST AREA AS WELL...NAM TRIES TO BRING MOISTURE/QPF FARTHER NORTH ALTHOUGH ITS PRESUMED MCS DEVELOPMENT LOOKS TO BE TOO FAR NORTH (AS DOES ITS WARM FRONTAL POSITION). BUT RELUCTANT TO COMPLETELY JUMP ONTO ONE SPECIFIC MODEL SOLUTION GIVEN WHAT IS CURRENTLY HAPPENING UPSTREAM TODAY...WILL SIMPLY EXPAND CURRENT RAIN CHANCES NORTH AND EAST A BIT TO ALLOW FOR A BIGGER MARGIN OF ERROR. CURRENT EXPECTATION IS THAT MOST OF THE PRECIP WILL BE SOUTH OF THE FORECAST AREA...ESPECIALLY IF MID LEVEL WINDS HAVE MORE OF A NORTHERLY COMPONENT. WILL GO DRY SUNDAY NIGHT WITH PRECIPITATION TO THE SOUTH ALONG THE WARM FRONT...AND POSSIBLY SOME WARM ADVECTION PRECIP ACROSS WI. MONDAY...WARM FRONT STILL WELL TO THE SOUTH...THOUGH SOME LOW/MID LEVEL WARM ADVECTION PUSHES INTO PARTS OF NORTHERN LOWER ALONG WITH SOME ATTENDANT DEEPER MOISTURE. WILL CONTINUE LOW CHANCE POPS SOUTH OF M-72 TO COVER THIS. OTHERWISE MAIN ACTION REMAINS SOUTH OF THE STATE...WITH PERHAPS THE REMNANTS OF T.D. "ERIN" GETTING SCOOPED UP AND INVOLVED WITH HAPPENINGS ALONG THE WARM FRONT ACROSS THE NORTHERN OHIO VALLEY. AT THIS POINT HOWEVER THIS DOES NOT APPEAR TO BE A THREAT FOR NORTHERN MI. EXTENDED PERIODS (TUESDAY THROUGH SATURDAY)...HEIGHT FALLS PROGRESSING ACROSS THE NORTHERN PLAINS WILL EVENTUALLY HELP LIFT THE WARM FRONT INTO THE STATE IN THE LATER TUESDAY TIME FRAME... FOLLOWED BY A COLD FRONT WEDNESDAY. CURRENT RAIN CHANCES FOR TUESDAY/WEDNESDAY LOOK REASONABLE GIVEN THIS PROGRESSION...THOUGH IF THE WARM FRONT TIMING IS SLOW AREAS FARTHER NORTH COULD END UP BEING DRY FOR MUCH OF TUESDAY...AND THAT IS A CONCERN THAT WILL NEED TO BE WATCHED. FORECAST GETS MORE COMPLICATED FOR THURSDAY AND BEYOND...ONCE COLD FRONT GOES THROUGH IT WILL EVENTUALLY SLOW DOWN AND PARALLEL UPPER FLOW. WHERE EXACTLY THE BOUNDARY HANGS UP WILL DETERMINE WHAT TYPE OF PRECIPITATION CHANCES WE END UP WITH... ASSUMING FRONT HANGS UP SOMEWHERE ACROSS LOWER MI/WI...WE COULD BE STARING AT CARRYING RAIN CHANCES EACH DAY FROM THURSDAY THROUGH SATURDAY. GIVEN THE RECENT EXPANDING DROUGHT CONDITIONS NOT EXACTLY COMFORTABLE WITH THAT. CURRENT FORECAST HAS RAIN CHANCES THURSDAY AND DRY FRIDAY...ACTUALLY THINK THE OPPOSITE MAY BE A BETTER WAY TO GO AND WILL PUSH THE FORECAST IN THAT DIRECTION DESPITE POTENTIAL FOR FLIP-FLOPPING OVER THE NEXT SEVERAL FORECAST CYCLES. TEMPERATURES THROUGH THE PERIOD WILL PROBABLY AVERAGE A BIT ABOVE NORMAL...MOSTLY DEPENDING ON CLOUD/PRECIPITATION COVERAGE EACH DAY. JPB && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 114 AM EDT SUN AUG 19 2007 UPDATED AVIATION SECTION FOR 06Z TAF ISSUANCE .UPDATE...(ISSUED AT 948 PM EDT SAT AUG 18) LATEST RADAR LOOP SHOWS BANDS OF SHOWERS STRETCHING FROM CENTRAL/SOUTHERN MN INTO SOUTHERN LOWER MICHIGAN BECOMING SMALLER WIDTH WISE...NOW MOSTLY CONCENTRATED ALONG AND SOUTH OF I-94. HOWEVER...THIS CONCENTRATED ZONE NOW CONSISTS OF HEAVIER SHOWERS AND THUNDERSTORMS...LIKELY DUE TO INCREASING SOUTHWEST WINDS AT 850MB NOTED ON THE BLUE RIVER WISCONSIN PROFILER (NOW 30-35KT) IMPINGING ON THE NEARLY STATIONARY FRONTAL BOUNDARY. PLENTY OF HEAT AND MOISTURE EXISTS SOUTH OF THE FRONTAL BOUNDARY TO SUSTAIN THE CONVECTION...ESPECIALLY WITH THE REMNANTS OF TROPICAL STORM ERIN BEING ADVECTED NORTHWARD WITHIN THE LOW LEVEL JET. CLOSER TO HOME...EXCEPT FOR A FEW OF THE SHOWERS BRUSHING THE MENOMINEE AREA BETWEEN 20-24Z...THE CWA REMAINS DRY WITH MID AND HIGH CLOUDS CROSSING. THESE CLOUDS ARE ALSO ASSOCIATED WITH THE MID-LEVEL FRONTOGENESIS AND RIGHT ENTRANCE REGION FORCING AIDING IN THE SHOWERS FARTHER TO THE SW. WITH THE SHOWERS DRYING UP FROM CENTRAL MN INTO EAST-CENTRAL WI...THERE IS CONCERN THAT PCPN MAY BE ENTIRELY DONE NOW MENOMINEE COUNTY (THE ONLY PLACE WITH -SHRA MENTION IN THE CWA). TWO THINGS COULD BE OCCURRING THAT IS CAUSING THE DIMINISHING OF SHOWERS: INCREASED CONVECTIVE ACTIVITY IN SOUTHERN MN AND SOUTHERN WI IS INHIBITING MOISTURE TRANSPORT TOWARDS NORTHERN WI AND/OR THE COMBINATION OF THE MID-LEVEL FRONTOGENETICAL AND UPPER LEVEL JET CIRCULATIONS ARE DRIVING DRIER AIR SOUTHWESTWARD. 20Z TAMDAR SOUNDING FROM CHIPPEWA COUNTY AIRPORT SHOWED A LOT OF DRY AIR IN THE 600-800MB LAYER (DEWPOINT DEPRESSIONS OF 20C OR MORE). GIVEN THAT THE UPPER LEVEL FLOW IS PROGGED TO REMAIN CONFLUENT WITH HEIGHTS RISING INTO SOUTH CENTRAL CANADA...AND TROUGHING IN NEW ENGLAND...THINK IT WILL BE HARD TO GET THE SHOWERS NORTHWARD. THE 18Z GFS CONCURS WITH THIS IDEA...AND THUS HAVE DECIDED TO REMOVE SHOWERS FROM THE FCST THROUGH 18Z MON. GOING TEMPS SEEM REASONABLE...THOUGH SINCE SKIES REMAIN CLEAR OUT EAST AND LOW PRECIPITABLE WATER THERE...HAVE DECIDED TO DROP TEMPS A FEW MORE DEGREES. PRECIPITABLE WATER VALUES ARE ABOUT 0.25 INCH HIGHER THAN LAST NIGHT...SUGGESTING LOWS SHOULD NOT GET AS COLD. && .SHORT TERM...(TONIGHT AND SUNDAY) MAIN FCST CONCERNS ARE PCPN CHANCES ALONG WITH CLOUDS/TEMPS. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF INTO THE PAC NW A RDG FROM THE PLAINS TO SASK AND A TROF FROM ERN CANADA INTO NRN NEW ENGLAND RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM WRN WI TO NRN IA WAS MOVING E. AT THE SFC...LOW PRES WAS LOCATED OVER SRN SD WITH A WARM FRONT EXTENDING THROUGH CNTRL IA TO ERN MO. THE COMBINATION OF UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF TH 250-300 JET AND 850-700 FGEN AND ASSOCIATED 305K-310K ISENTROPIC LIFT SUPPORTED A BROAD AREA OF RAIN FROM ERN MN THROUGH THE S 2/3 OF WI. TSRA WERE CONFINED TO A BAND CLOSER TO THE FRONT...FROM SRN MN INTO SW WI AND NRN IL. VIS IMAGERY SHOWED MID HIGH CLOUDS HAD THINNED OUT OVER THE NRN CWA WITH THE THICKER CLOUDS REMAINING NEAR THE WI BORDER. RADARS ALSO SHOWED RETURNS CREEPING FROM WI CLOSER TO THE BORDER BUT WITH SFC -RA REPORTS LAGGING FARTHER TO THE S DUE TO THE PRESENCE OF A SUBSTANTIAL 850-650 MB DRY LAYER PER 18Z KSAW TAMDAR SOUNDINGS AND EARLIER KRHI SOUNDING. WITH THE VERY DRY AIRMASS LINGERING TO THE NORTH AND CONFLUENT MID/UPPER LEVEL FLOW N OF THE AREA LEADING TO MAINLY E OR ESE SHIFT OF THE AFOREMENTIONED RAIN SUPPORTING DYNAMICS...ANY ADDITIONAL PROGRESS OF THE PCPN INTO UPPER MI FROM TONIGHT INTO EARLY SUN WILL BE MARGINAL. SO...LOWER END POPS WERE CONFINED TO MAINLY THE SRN HALF OF MENOMINEE COUNTY. ALTHOUGH THE MID/HIGH CLOUDS MAY REDUCE RADIATIONAL COOLING COMPARED TO LAST NIGHT...THEY SHOULD REMAIN THIN ENOUGH TO ALLOW INLAND TEMPS TO DROP INTO THE 40S. SIMILARLY...MAINLY THIN HIGH CLOUDS AGAIN SUNDAY AND DECENT SUNSHINE WITH 850 MB TEMPS AROUND 9C SUPPORTS MAX READINGS INTO THE LOWER 70S. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... STUBBORN PATTERN FINALLY BEGINS TO ERODE BY EARLY IN THE WORK WEEK...NEVERTHELESS SFC HIGH AND SOME MID LEVEL RIDGING WILL SHUNT THE BEST DYNAMICS SOUTH OF THE CWFA...SENDING THE PRECIP CHANCES SOUTH WITH IT THROUGH MONDAY. BROAD TROUGHING OVER THE WESTERN CONUS BEGINS TO SHIFT THE RIDGE EASTWARD...ALLOWING A SURFACE LOW OVER WEST CENTRAL CANADA TO DEEPEN WHILE REMAINING NEARLY STATIONARY FROM 00Z TUE TO 00Z WED. ENERGY WRAPPING AROUND THE LOW REACHES INTO THE NORTH CENTRAL PLAINS AND INTO THE UPPER GREAT LAKES. WARM FRONT IN CENTRAL WI BY TUE MORNING WARRANTS CONTINUED MENTION OF CHANCE POPS IN THE SOUTHERN CWFA OVERNIGHT MONDAY...ALTHOUGH ENERGY COULD AGAIN REMAIN MOSTLY SOUTH OF UPPER MI UNTIL TUESDAY AFTERNOON. WARM AND MOIST AIR ADVECTING INTO THE CWFA ON TUESDAY AHEAD OF THE TRAILING COLD FRONT ALSO LEND TO THE IDEA OF POSSIBLE SEVERE ACTIVITY WITH SOME OF DEVELOPING THUNDERSTORMS...ALTHOUGH THE BEST DYNAMICS AND MOST MOISTURE SUGGESTS THE GREATEST THREAT WOULD BE OVER THE EASTERN MN/WESTERN WI AREA. LOOKING AT SOME PARAMETERS MORE CLOSELY FOR THE TUESDAY AFTERNOON THROUGH EVENING TIMEFRAME SUGGESTS THAT SHOULD THUNDERSTORMS DEVELOP...SOME OF THE STORMS MAY BE SEVERE. BETWEEN 18Z TUE AND 06Z WED...0-6 BULK SHEAR OVER THE WESTERN COUNTIES AND LAKE SUPERIOR INCREASES FROM 30-35 KT TO THE 60S. AT THE SAME TIME...0-2 SHEAR TOPS OUT AROUND 30-40 KT WITH GOOD LOW LEVEL DIRECTIONAL SHEAR. KIMT HODOGRAPH SHOWS STRONG CLOCKWISE SPIN ALONG WITH AN LCL AROUND 1000 FT AT 21Z TUE. MUCAPES INCREASE DRAMATICALLY FROM WEST TO EAST ACROSS THE CWFA DURING THE DAY ON TUESDAY...PEAKING AROUND 2200 J/KG AT KIWD IN THE AFTERNOON. GIVEN THE UNCERTAINLY IN THE TIMING/CHANCE OF THUNDERSTORMS...NEVERMIND IF THEY COULD BE SEVERE OVER THE WEST/WEST CENTRAL...DID NOT INCREASE POPS THROUGH THE TIME PERIOD BUT MENTIONED IN HWO. MODELS SHOW MORE ZONAL FLOW BY THE DAY 6 TIMEFRAME...WITH SOME SHORTWAVES RIPPLING THROUGH...AND DIGGING UP A LOW FROM THE PLAINS AND EJECTING IT TOWARD THE UPPER GREAT LAKES...WITH RIDIGING OVER THE INTERMOUNTAIN WEST BY DAY 7. SO...GIVEN THE DECENT AGREEMENT...AT THIS POINT IT LOOKS LIKE THE OPEN HOUSE...SCHEDULED FOR SATURDAY...SHOULD BE GOOD TO GO...PROVIDED SHORTWAVES ROTATING AROUND THE BASE OF THE TROUGH REMAIN SOUTH OF THE CWFA. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... VFR CONDITIONS ARE EXPECTED TO PERSIST DUE TO LOW LEVEL DRY AIR HOLDING ON FROM HIGH PRESSURE JUST TO THE NE OF LAKE SUPERIOR. LOOK FOR A GENERAL EAST WIND...WITH INCREASING SPEED ON SUNDAY AS THE HIGH SHIFTS TO THE EAST AND A TROUGH DEVELOPS FROM NORTHERN IA INTO SRN WI. WINDS MAY BECOME GUSTY IN THE AFTERNOON AT BOTH TAF SITES AS INLAND WARMING CREATES LAKE BREEZES...ADDING ONTO THE WIND SPEED. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LIGHT SOUTHERLY WINDS WILL BACK TO THE E AND SE LATE THIS AFTERNOON AS THE HIGH DRIFTS TO THE E. AS LOW PRESSURE OVER THE NORTHERN HIGH PLAINS MOVES TOWARD THE REGION...EASTERLY WINDS WILL INCREASE OVER LAKE SUPERIOR LATE SUN AS HIGH PRES MOVES TOWARD JAMES BAY AND A LOW PRES TROUGH SPREADS INTO SRN MN AND SRN WI. WINDS INTO THE 15-25 KT RANGE ARE EXPECTED WITH THE HIGHEST WINDSPEED OVER THE FAR WRN LAKE FAVORED BY PRES UPSTREAM UPSTREAM PRES FALLS AND TERRAIN EFFECTS. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON WED AS LOW PRESSURE SYSTEM LIFTS NE OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...AJ SHORT TERM...JLB LONG TERM...JLL AVIATION...AJ MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1041 PM EDT SAT AUG 18 2007 .UPDATE...AS THE RADAR HAS BEEN SHOWING THIS EVENING, THE RAIN SHOWERS HAVE BEEN MOVING TO THE SOUTH AND EAST. TRIMMED THE RAIN FARTHER SOUTH AND MAY HAVE TO UPDATE AGAIN AS THE RAIN LOOKING UPSTREAM ARE SHOWING WIDELY SCATTERED SHOWERS AND SPRINKLES. OTHERWISE, THE TEMPERATURES LOOKS GOOD WITH THE CLOUD COVER THAT IS OVER THE REGION AND THE HIGH PRESSURE THAT IS KEEPING THE WINDS DOWN TONIGHT. LUTZ && .AVIATION...ISSUED 802 PM RAIN IS MAINLY SOUTH OF M-55 SO FOR THE SHORT TERM, TVC WILL STAY OUT OF THE RAIN, THOUGH SPRINKLES AREN`T OUT OF THE QUESTION. APN AND PLN ARE TOO FAR NORTH AT THIS POINT AS THE RAIN LOOKS TO BE FOLLOWING THE GFS CONFIGURATION TO THE QPF. MBL IS SHOWING 10SM, AND REPORTED 0.01 LAST HOUR SO FOR THE BALANCE OF THE NIGHT THE GOING FORECAST LOOKS GOOD. THIS LOOKS TO BE THINKING IN THE PUBLIC FORECAST AS WELL THROUGH SUNDAY EVENING SO WILL KEEP THE BULK OF THE FORECAST DRY WITH SHOWERS OR SPRINKLES NEAR TVC. THE WIND LOOKS TO REMAIN UNDER 10 KNTS FOR SUNDAY AS WELL. LUTZ && .PREV DISCUSSION...ISSUED 328 PM ANOTHER NICE FALL-LIKE DAY ACROSS THE CWA WITH HIGH PRESSURE FULLY IN CONTROL WILL TRANSITION TO A BIT MORE TRICKY FORECAST OVERNIGHT. EARLY AFTERNOON ANALYSIS SHOWS A BUILDING LOW/ MID LEVEL RIDGE ACROSS THE SOUTHEAST STATES...WITH SURFACE RIDGING STILL CENTERED ACROSS NORTHERN MICHIGAN BUT BEGINNING TO SLIP EAST EVER-SO-SLOWLY. RETURN FLOW ON THE BACKSIDE OF SOUTHEAST RIDGE FULLY UNDERWAY...WITH ONGOING BROAD ISENTROPIC ASCENT CONTINUING TO DRIVE A RATHER EXPANSIVE AREA OF PRECIPITATION LIFTING THROUGH WISCONSIN. IT IS THIS AREA OF PRECIPITATION THAT REMAINS THE PRIMARY FORECAST CONCERN FOR TONIGHT...NAMELY WILL IT AFFECT THE CWA AND WHAT EFFECT WILL THE ADDITIONAL CLOUDS HAVE ON OVERNIGHT LOWS. QUICK LOOK AT REGIONAL RADAR MOSAIC SHOWS A BIT BETTER ORGANIZED AREA OF PRECIP THAN SUGGESTED BY THE 12Z MODEL GUIDANCE...OWING PRIMARILY TO APPARENT ADDED JET DIVERGENCE...WITH JET ENTRANCE REGION SLIPPING ACROSS FAR NORTHERN MINNESOTA...AS WELL AS A PRONOUNCED VORT PROGRESSING INTO WESTERN MINNESOTA PER RUC ANALYSIS/ WATER VAPOR PICS (REMNANTS OF LAST NIGHT`S CONVECTION OVER THE BLACK HILLS?). HAVE BEEN RATHER IMPRESSED AT PRECIP`S ABILITY TO OVERCOME DRY AIRMASS JUST TO THE WEST...WITH QUITE A FEW SITES GOING FROM BKN-OVC200 DOWN TO OVC070 WITH PRECIP IN AN HOUR...ALSO SUGGESTING FORCED ASCENT A BIT BETTER THAN MODELS CREDIT. THIS ALL LEADS TO A RATHER MURKY PRECIP FORECAST FOR THE APX CWA OVERNIGHT... AS THINKING HAS BEEN DRY AIR WOULD WIN OUT...AND IT DOES APPEAR THIS WILL WORK FOR THE NORTHERN HALF...BUT HAVE HAD TO RE-EVALUATE FARTHER SOUTH. OVERNIGHT...THE LIFT FOR PRECIP WILL CERTAINLY BE THERE...WITH DECENT 305-310K ISENTROPIC UPGLIDE (25-30 KNOTS UP THE SURFACE) ON THE INCREASE AS WARM ADVECTION COMMENCES...WITH DEEP LAYER (900-700MB) FRONTOGENETICAL FORCING IN PLACE AS WELL GIVEN TIGHT BAROCLINIC ZONE ACROSS THE MIDWEST/LOWER GREAT LAKES. HOWEVER...RH PROGS ON THESE SURFACES AND SFC-H85 THETA-E ALSO SHOW A SHARP CUTOFF TO DEEP MOISTURE...AS BOTH CONVECTION TO THE SOUTH TAKES OVER TONIGHT...AND DEEP LAYER SUBSIDENCE/DRYING THIS AFTERNOON AND EVENING (SFC-700MB RH LESS THAN 35%) HOLD FIRM. THUS...WHILE THE OVERALL TREND OF THE DRY AIR WINNING OUT STILL LOOKS OK...HAVE TRENDED POPS FARTHER NORTH THROUGH THE NIGHTTIME HOURS...IN LINE WITH THE 09Z SREF/12Z UKMET WHICH SEEM TO HAVE A BETTER HANDLE ON CURRENT PRECIP. STILL NOT TALKING ABOUT A WHOLE LOT OF RAIN...BUT ANY RAIN IS WELCOME AT THIS POINT. NO THREAT OF ANY THUNDER OWING TO LACK OF MOISTURE/INSTABILITY AS WELL AS FLAT MID-LEVEL LAPSE RATES. AS FOR TEMPERATURES...THESE ALSO TRICKY GIVEN UNCERTAIN DEGREE OF CLOUD COVER. CLOUDY CONDITIONS EXPECTED THRU THE NIGHT ACROSS THE SOUTH IN CLOSER PROXIMITY TO FORCING/BETTER MOISTURE...WHILE MAY VERY WELL SEE THINGS CLEAR OUT ACROSS THE NORTH WITH BETTER SUBSIDENCE. WILL HOLD NUMBERS UP ABOVE GUIDANCE VALUES ACROSS THE SOUTH WITH PLENTIFUL CLOUD COVER...BUT CONTINUE PREVIOUS IDEA OF RATHER COOL READINGS (LOWER 40S...IF NOT A FEW UPPER 30S) FAR NORTH GIVEN SFC RIDGE AXIS HOLDING IN WITH FLOW DECOUPLING AND RESIDUAL DRY AIRMASS STILL IN PLACE. LAWRENCE LONG TERM...RECENT PATTERN OF TROUGHS OVER THE EASTERN PACIFIC AND EASTERN CANADA/NEW ENGLAND...AND LOW AMPLITUDE RIDGING IN BETWEEN EXPECTED TO BECOME MORE PROGRESSIVE FOR THE COMING WEEK...AS PACIFIC TROUGH MOVES INLAND AND HEIGHTS RISE ACROSS THE GREAT LAKES. HIGH PRESSURE IN PLACE AT THE ONSET OF THE FORECAST PERIOD TODAY WILL SLIDE EAST/NORTHEAST...ELONGATED FRONTAL BOUNDARY STRETCHING FROM THE CENTRAL HIGH PLAINS SOUTHEAST ACROSS THE TENNESSEE VALLEY WILL SLOWLY LIFT NORTHWARD AS A WARM FRONT IN RESPONSE. THIS WARM FRONT NOT LIKELY TO EVEN REACH LOWER MI UNTIL LATER MONDAY...AND EVEN THEN WILL PROBABLY HANG ALONG THE SOUTHERN BORDER THROUGH THE FIRST PART OF THE WEEK. SINCE THIS BOUNDARY WILL BE THE MAIN FOCUS FOR CONVECTIVE DEVELOPMENT OVER THE NEXT SEVERAL DAYS...MAIN FORECAST CONCERNS FOR THE NEAR TERM PORTION OF THE FORECAST WILL BASICALLY DEAL WITH HOW FAR NORTH THE THREAT FOR RAIN WILL REACH. SUNDAY...EXPECT A GOOD DEAL OF CONVECTION TO BE GOING SOUTHWEST/ SOUTH OF THE FORECAST AREA TO START SUNDAY MORNING ALONG FRONTOGENETICALLY ACTIVE WARM FRONTAL ZONE WHICH IS EXPECTED TO EXTEND ACROSS SOUTHERN WI/FAR SOUTHERN LOWER MI (ACTUAL WARM FRONT WILL LIE ACROSS NORTHEAST IA/NORTHERN IL/CENTRAL IN). AXIS OF DEEPER MOISTURE WILL PROBABLY REMAIN MAINLY SOUTH OF THE FORECAST AREA AS WELL...NAM TRIES TO BRING MOISTURE/QPF FARTHER NORTH ALTHOUGH ITS PRESUMED MCS DEVELOPMENT LOOKS TO BE TOO FAR NORTH (AS DOES ITS WARM FRONTAL POSITION). BUT RELUCTANT TO COMPLETELY JUMP ONTO ONE SPECIFIC MODEL SOLUTION GIVEN WHAT IS CURRENTLY HAPPENING UPSTREAM TODAY...WILL SIMPLY EXPAND CURRENT RAIN CHANCES NORTH AND EAST A BIT TO ALLOW FOR A BIGGER MARGIN OF ERROR. CURRENT EXPECTATION IS THAT MOST OF THE PRECIP WILL BE SOUTH OF THE FORECAST AREA...ESPECIALLY IF MID LEVEL WINDS HAVE MORE OF A NORTHERLY COMPONENT. WILL GO DRY SUNDAY NIGHT WITH PRECIPITATION TO THE SOUTH ALONG THE WARM FRONT...AND POSSIBLY SOME WARM ADVECTION PRECIP ACROSS WI. MONDAY...WARM FRONT STILL WELL TO THE SOUTH...THOUGH SOME LOW/MID LEVEL WARM ADVECTION PUSHES INTO PARTS OF NORTHERN LOWER ALONG WITH SOME ATTENDANT DEEPER MOISTURE. WILL CONTINUE LOW CHANCE POPS SOUTH OF M-72 TO COVER THIS. OTHERWISE MAIN ACTION REMAINS SOUTH OF THE STATE...WITH PERHAPS THE REMNANTS OF T.D. "ERIN" GETTING SCOOPED UP AND INVOLVED WITH HAPPENINGS ALONG THE WARM FRONT ACROSS THE NORTHERN OHIO VALLEY. AT THIS POINT HOWEVER THIS DOES NOT APPEAR TO BE A THREAT FOR NORTHERN MI. EXTENDED PERIODS (TUESDAY THROUGH SATURDAY)...HEIGHT FALLS PROGRESSING ACROSS THE NORTHERN PLAINS WILL EVENTUALLY HELP LIFT THE WARM FRONT INTO THE STATE IN THE LATER TUESDAY TIME FRAME... FOLLOWED BY A COLD FRONT WEDNESDAY. CURRENT RAIN CHANCES FOR TUESDAY/WEDNESDAY LOOK REASONABLE GIVEN THIS PROGRESSION...THOUGH IF THE WARM FRONT TIMING IS SLOW AREAS FARTHER NORTH COULD END UP BEING DRY FOR MUCH OF TUESDAY...AND THAT IS A CONCERN THAT WILL NEED TO BE WATCHED. FORECAST GETS MORE COMPLICATED FOR THURSDAY AND BEYOND...ONCE COLD FRONT GOES THROUGH IT WILL EVENTUALLY SLOW DOWN AND PARALLEL UPPER FLOW. WHERE EXACTLY THE BOUNDARY HANGS UP WILL DETERMINE WHAT TYPE OF PRECIPITATION CHANCES WE END UP WITH... ASSUMING FRONT HANGS UP SOMEWHERE ACROSS LOWER MI/WI...WE COULD BE STARING AT CARRYING RAIN CHANCES EACH DAY FROM THURSDAY THROUGH SATURDAY. GIVEN THE RECENT EXPANDING DROUGHT CONDITIONS NOT EXACTLY COMFORTABLE WITH THAT. CURRENT FORECAST HAS RAIN CHANCES THURSDAY AND DRY FRIDAY...ACTUALLY THINK THE OPPOSITE MAY BE A BETTER WAY TO GO AND WILL PUSH THE FORECAST IN THAT DIRECTION DESPITE POTENTIAL FOR FLIP-FLOPPING OVER THE NEXT SEVERAL FORECAST CYCLES. TEMPERATURES THROUGH THE PERIOD WILL PROBABLY AVERAGE A BIT ABOVE NORMAL...MOSTLY DEPENDING ON CLOUD/PRECIPITATION COVERAGE EACH DAY. JPB && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 948 PM EDT SAT AUG 18 2007 .UPDATE... LATEST RADAR LOOP SHOWS BANDS OF SHOWERS STRETCHING FROM CENTRAL/SOUTHERN MN INTO SOUTHERN LOWER MICHIGAN BECOMING SMALLER WIDTH WISE...NOW MOSTLY CONCENTRATED ALONG AND SOUTH OF I-94. HOWEVER...THIS CONCENTRATED ZONE NOW CONSISTS OF HEAVIER SHOWERS AND THUNDERSTORMS...LIKELY DUE TO INCREASING SOUTHWEST WINDS AT 850MB NOTED ON THE BLUE RIVER WISCONSIN PROFILER (NOW 30-35KT) IMPINGING ON THE NEARLY STATIONARY FRONTAL BOUNDARY. PLENTY OF HEAT AND MOISTURE EXISTS SOUTH OF THE FRONTAL BOUNDARY TO SUSTAIN THE CONVECTION...ESPECIALLY WITH THE REMNANTS OF TROPICAL STORM ERIN BEING ADVECTED NORTHWARD WITHIN THE LOW LEVEL JET. CLOSER TO HOME...EXCEPT FOR A FEW OF THE SHOWERS BRUSHING THE MENOMINEE AREA BETWEEN 20-24Z...THE CWA REMAINS DRY WITH MID AND HIGH CLOUDS CROSSING. THESE CLOUDS ARE ALSO ASSOCIATED WITH THE MID-LEVEL FRONTOGENESIS AND RIGHT ENTRANCE REGION FORCING AIDING IN THE SHOWERS FARTHER TO THE SW. WITH THE SHOWERS DRYING UP FROM CENTRAL MN INTO EAST-CENTRAL WI...THERE IS CONCERN THAT PCPN MAY BE ENTIRELY DONE NOW MENOMINEE COUNTY (THE ONLY PLACE WITH -SHRA MENTION IN THE CWA). TWO THINGS COULD BE OCCURRING THAT IS CAUSING THE DIMINISHING OF SHOWERS: INCREASED CONVECTIVE ACTIVITY IN SOUTHERN MN AND SOUTHERN WI IS INHIBITING MOISTURE TRANSPORT TOWARDS NORTHERN WI AND/OR THE COMBINATION OF THE MID-LEVEL FRONTOGENETICAL AND UPPER LEVEL JET CIRCULATIONS ARE DRIVING DRIER AIR SOUTHWESTWARD. 20Z TAMDAR SOUNDING FROM CHIPPEWA COUNTY AIRPORT SHOWED A LOT OF DRY AIR IN THE 600-800MB LAYER (DEWPOINT DEPRESSIONS OF 20C OR MORE). GIVEN THAT THE UPPER LEVEL FLOW IS PROGGED TO REMAIN CONFLUENT WITH HEIGHTS RISING INTO SOUTH CENTRAL CANADA...AND TROUGHING IN NEW ENGLAND...THINK IT WILL BE HARD TO GET THE SHOWERS NORTHWARD. THE 18Z GFS CONCURS WITH THIS IDEA...AND THUS HAVE DECIDED TO REMOVE SHOWERS FROM THE FCST. GOING TEMPS SEEM REASONABLE...THOUGH SINCE SKIES REMAIN CLEAR OUT EAST AND LOW PRECIPITABLE WATER THERE...HAVE DECIDED TO DROP TEMPS A FEW MORE DEGREES. PRECIPITABLE WATER VALUES ARE ABOUT 0.25 INCH HIGHER THAN LAST NIGHT...SUGGESTING LOWS SHOULD NOT GET AS COLD. && .SHORT TERM...(TONIGHT AND SUNDAY) MAIN FCST CONCERNS ARE PCPN CHANCES ALONG WITH CLOUDS/TEMPS. WV IMAGERY AND RUC ANALYSIS INDICATED A TROF INTO THE PAC NW A RDG FROM THE PLAINS TO SASK AND A TROF FROM ERN CANADA INTO NRN NEW ENGLAND RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A WEAK SHORTWAVE TROUGH FROM WRN WI TO NRN IA WAS MOVING E. AT THE SFC...LOW PRES WAS LOCATED OVER SRN SD WITH A WARM FRONT EXTENDING THROUGH CNTRL IA TO ERN MO. THE COMBINATION OF UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF TH 250-300 JET AND 850-700 FGEN AND ASSOCIATED 305K-310K ISENTROPIC LIFT SUPPORTED A BROAD AREA OF RAIN FROM ERN MN THROUGH THE S 2/3 OF WI. TSRA WERE CONFINED TO A BAND CLOSER TO THE FRONT...FROM SRN MN INTO SW WI AND NRN IL. VIS IMAGERY SHOWED MID HIGH CLOUDS HAD THINNED OUT OVER THE NRN CWA WITH THE THICKER CLOUDS REMAINING NEAR THE WI BORDER. RADARS ALSO SHOWED RETURNS CREEPING FROM WI CLOSER TO THE BORDER BUT WITH SFC -RA REPORTS LAGGING FARTHER TO THE S DUE TO THE PRESENCE OF A SUBSTANTIAL 850-650 MB DRY LAYER PER 18Z KSAW TAMDAR SOUNDINGS AND EARLIER KRHI SOUNDING. WITH THE VERY DRY AIRMASS LINGERING TO THE NORTH AND CONFLUENT MID/UPPER LEVEL FLOW N OF THE AREA LEADING TO MAINLY E OR ESE SHIFT OF THE AFOREMENTIONED RAIN SUPPORTING DYNAMICS...ANY ADDITIONAL PROGRESS OF THE PCPN INTO UPPER MI FROM TONIGHT INTO EARLY SUN WILL BE MARGINAL. SO...LOWER END POPS WERE CONFINED TO MAINLY THE SRN HALF OF MENOMINEE COUNTY. ALTHOUGH THE MID/HIGH CLOUDS MAY REDUCE RADIATIONAL COOLING COMPARED TO LAST NIGHT...THEY SHOULD REMAIN THIN ENOUGH TO ALLOW INLAND TEMPS TO DROP INTO THE 40S. SIMILARLY...MAINLY THIN HIGH CLOUDS AGAIN SUNDAY AND DECENT SUNSHINE WITH 850 MB TEMPS AROUND 9C SUPPORTS MAX READINGS INTO THE LOWER 70S. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... STUBBORN PATTERN FINALLY BEGINS TO ERODE BY EARLY IN THE WORK WEEK...NEVERTHELESS SFC HIGH AND SOME MID LEVEL RIDGING WILL SHUNT THE BEST DYNAMICS SOUTH OF THE CWFA...SENDING THE PRECIP CHANCES SOUTH WITH IT THROUGH MONDAY. BROAD TROUGHING OVER THE WESTERN CONUS BEGINS TO SHIFT THE RIDGE EASTWARD...ALLOWING A SURFACE LOW OVER WEST CENTRAL CANADA TO DEEPEN WHILE REMAINING NEARLY STATIONARY FROM 00Z TUE TO 00Z WED. ENERGY WRAPPING AROUND THE LOW REACHES INTO THE NORTH CENTRAL PLAINS AND INTO THE UPPER GREAT LAKES. WARM FRONT IN CENTRAL WI BY TUE MORNING WARRANTS CONTINUED MENTION OF CHANCE POPS IN THE SOUTHERN CWFA OVERNIGHT MONDAY...ALTHOUGH ENERGY COULD AGAIN REMAIN MOSTLY SOUTH OF UPPER MI UNTIL TUESDAY AFTERNOON. WARM AND MOIST AIR ADVECTING INTO THE CWFA ON TUESDAY AHEAD OF THE TRAILING COLD FRONT ALSO LEND TO THE IDEA OF POSSIBLE SEVERE ACTIVITY WITH SOME OF DEVELOPING THUNDERSTORMS...ALTHOUGH THE BEST DYNAMICS AND MOST MOISTURE SUGGESTS THE GREATEST THREAT WOULD BE OVER THE EASTERN MN/WESTERN WI AREA. LOOKING AT SOME PARAMETERS MORE CLOSELY FOR THE TUESDAY AFTERNOON THROUGH EVENING TIMEFRAME SUGGESTS THAT SHOULD THUNDERSTORMS DEVELOP...SOME OF THE STORMS MAY BE SEVERE. BETWEEN 18Z TUE AND 06Z WED...0-6 BULK SHEAR OVER THE WESTERN COUNTIES AND LAKE SUPERIOR INCREASES FROM 30-35 KT TO THE 60S. AT THE SAME TIME...0-2 SHEAR TOPS OUT AROUND 30-40 KT WITH GOOD LOW LEVEL DIRECTIONAL SHEAR. KIMT HODOGRAPH SHOWS STRONG CLOCKWISE SPIN ALONG WITH AN LCL AROUND 1000 FT AT 21Z TUE. MUCAPES INCREASE DRAMATICALLY FROM WEST TO EAST ACROSS THE CWFA DURING THE DAY ON TUESDAY...PEAKING AROUND 2200 J/KG AT KIWD IN THE AFTERNOON. GIVEN THE UNCERTAINLY IN THE TIMING/CHANCE OF THUNDERSTORMS...NEVERMIND IF THEY COULD BE SEVERE OVER THE WEST/WEST CENTRAL...DID NOT INCREASE POPS THROUGH THE TIME PERIOD BUT MENTIONED IN HWO. MODELS SHOW MORE ZONAL FLOW BY THE DAY 6 TIMEFRAME...WITH SOME SHORTWAVES RIPPLING THROUGH...AND DIGGING UP A LOW FROM THE PLAINS AND EJECTING IT TOWARD THE UPPER GREAT LAKES...WITH RIDIGING OVER THE INTERMOUNTAIN WEST BY DAY 7. SO...GIVEN THE DECENT AGREEMENT...AT THIS POINT IT LOOKS LIKE THE OPEN HOUSE...SCHEDULED FOR SATURDAY...SHOULD BE GOOD TO GO...PROVIDED SHORTWAVES ROTATING AROUND THE BASE OF THE TROUGH REMAIN SOUTH OF THE CWFA. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... VFR CONDITIONS ARE EXPECTED TO PERSIST DUE TO LOW LEVEL DRY AIR HOLDING ON FROM HIGH PRESSURE JUST TO THE NE OF LAKE SUPERIOR. LOOK FOR A GENERAL EAST WIND...WITH INCREASING SPEED ON SUNDAY AS THE HIGH SHIFTS TO THE EAST AND A TROUGH DEVELOPS FROM NORTHERN IA INTO SRN WI. && .MARINE (FOR 4 PM LAKE SUPERIOR FCST ISSUANCE)... LIGHT SOUTHERLY WINDS WILL BACK TO THE E AND SE LATE THIS AFTERNOON AS THE HIGH DRIFTS TO THE E. AS LOW PRESSURE OVER THE NORTHERN HIGH PLAINS MOVES TOWARD THE REGION...EASTERLY WINDS WILL INCREASE OVER LAKE SUPERIOR LATE SUN AS HIGH PRES MOVES TOWARD JAMES BAY AND A LOW PRES TROUGH SPREADS INTO SRN MN AND SRN WI. WINDS INTO THE 15-25 KT RANGE ARE EXPECTED WITH THE HIGHEST WINDSPEED OVER THE FAR WRN LAKE FAVORED BY PRES UPSTREAM UPSTREAM PRES FALLS AND TERRAIN EFFECTS. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON WED AS LOW PRESSURE SYSTEM LIFTS NE OF LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...AJ SHORT TERM...JLB LONG TERM...JLL AVIATION...AJ MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1030 PM CDT MON AUG 20 2007 .UPDATE... ELEVATED LAPSE RATES HAVE WON OUT...AND POTENTIAL IS THERE FOR MORE THUNDERSTORM ACTIVITY ACROSS SRN AND CTRL MN. AS LATEST RUC MODEL RUNS COME IN...BETTER ELEVATED LIFTED INDICES COME IN FOR CONVECTION...WITH -6 TO -8 VALUES PROJECTED THROUGH 09Z OVER SOUTH CENTRAL MN. ALSO LOW TO MID-LEVEL FRONTOGENESIS PEGGED IN THAT AREA...SO TRAINING THUNDERSTORMS OVER SATURATED GROUND REMAINS A PRIMARY CONCERN. && .DISCUSSION... THE AREA HAS ONLY BEEN DEALING WITH VERY SCATTERED SHOWERS SINCE ABOUT MID MORNING...WHICH IS CERTAINLY A CHANGE FROM THE LAST FEW DAYS. FOG AND OVERCAST STRATUS DECK HAS BEEN THE MAJOR PROBLEM TODAY...KEEPING QUITE UNSEASONABLY COOL TEMPERATURES OVER THE AREA AGAIN TODAY. THE OVERCAST DECK HAS ALSO HELPED TO REDUCE SEVERE POSSIBILITIES TODAY...WITH SOUTHWESTERN AREAS...WHICH ARE STARTING TO SEE A DECREASE IN THE LOW DECK...SEEING THE ONLY POTENTIAL. OVERCAST SKIES SHOULD REMAIN THROUGH MUCH OF THE NIGHT...WITH A LITTLE LOW/MID LEVEL DRYING COMING IN FROM THE SOUTHWEST... SOMETHING THAT IS BECOMING APPARENT IN THE VISIBLE SATELLITE LOOP. HAVE KEPT A MENTION OF FOG IN THE GRIDS AFTER 06Z TONIGHT...AS CONTINUED SATURATION AND WARM ADVECTION ALOFT LEADS TO A CONTINUED THREAT OF REDUCED VISIBILITIES. THANKFULLY...IT DOES APPEAR THAT THE MAJOR FORCING FOR ADDITIONAL SHOWERS/THUNDERSTORMS WILL SHIFT TO THE NORTHERN AND CENTRAL PORTIONS OF THE AREA FOR TONIGHT...AS WELL AS SOUTH OF THE AREA ACROSS NORTHERN AND CENTRAL IOWA. WITH PWATS REMAINING HIGH ALONG THE IOWA BORDER...HOWEVER...ANY SHOWERS/STORMS THAT DEVELOP /AND THE CHANCES OF SHOWERS AND STORMS IN SOUTHERN MINNESOTA IS CERTAINLY NOT ZERO/ IN THIS AREA OVERNIGHT WILL BE CAPABLE OF HEAVY DOWNPOURS. LATE TOMORROW...ANOTHER TRAIN OF SHORTWAVES WILL MOVE ACROSS SOUTHERN MINNESOTA AND INTO WESTERN WISCONSIN...AS A BOUNDARY PARKS ITSELF...ONCE AGAIN...VERY NEAR THE IOWA/MINNESOTA BORDER. THIS WILL PLACE THE FLOODED AREAS IN THE PRIME REGION TO RECEIVE SOME HIGHER RAINFALL TOTALS DURING THIS TIME FRAME. FOR THE WEEKEND...WE MAY ACTUALLY HAVE A DRY SPELL...AS MODELS HAVE BEEN FAIRLY CONSISTENT IN DEPICTING A SURFACE HIGH SLIDING ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST DURING THIS PERIOD. MONDAY MAY FEATURE SOME WARM ADVECTION SHOWERS/STORMS AS WE GET RETURN FLOW ON THE BACKSIDE OF THE HIGH...BUT CONFIDENCE IN TIMING IS NOT ENOUGH TO INCLUDE AT THIS TIME. LATER SHIFTS WILL HAVE TO MONITOR THIS POTENTIAL. && .AVIATION.../FOR 00Z TAFS/ MAIN CONCERN CONTINUES TO BE CIGS AND VIS. NOT MUCH CHANGE IN THE PATTERN FROM PAST DAYS. AREA OF IFR AND LOWER CIGS WITH PERIODIC IFR VIS IN DRIZZLE CONTINUES TO PLAGUE CENTRAL MINNESOTA TAF SITES. WISCONSIN SITES ARE AT THE LOW END OF MVFR FOR NOW BUT EXPECT IFR TO RETURN LATE THIS EVENING. ALSO A CONCERN FOR SHOWERS AND THUNDERSTORMS THIS EVENING AS AN UPPER TROUGH SWINGS ACROSS THE AREA. CONFIDENCE IN COVER GAGE IS LOW BUT THE BEST CHANCE FOR SHOWERS WILL BE ACROSS KAXN AND KSTC AS WELL AS KRWF. EXPECT 2 DIFFERENT AREAS OF SHOWERS/STORMS TO DEVELOP. KMSP/KRNH/KEAU MAY FALL BETWEEN THESE AREAS BUT HAVE RETAINED TEMPO SHOWERS LATER THIS EVENING. WINDS WILL LIGHTEN UP LATE TONIGHT ALLOWING FOG TO DEVELOP. WITH THE PASSAGE OF THIS UPPER TROUGH THE SFC PATTERN WILL SHIFT A BIT AS WELL. HAVE CONTINUED TREND ...PERHAPS OPTIMISTICALLY...OF WINDS BECOMING WESTERLY STARTING TUESDAY MORNING. THIS WOULD LIKELY HELP DRIER AIR TO WORK IN...IF ONLY BRIEFLY...IMPROVING CIGS. HOWEVER...THERE IS STILL A CHANCE THAT WINDS WILL REMAIN LIGHT AND EASTERLY ACROSS CENTRAL MN AND WESTERN WI THROUGH THE AFTERNOON KEEPING LOW CIGS IN PLACE. WILL NEED TO WATCH CLOSELY. SHOWER AND THUNDER CHANCES WILL ALSO RETURN DURING THE AFTERNOON. ..MDB.. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...FLASH FLOOD WATCH UNTIL 4 AM CDT TUESDAY FOR BLUE EARTH-BROWN- FARIBAULT-FREEBORN-GOODHUE-LE SUEUR-MARTIN-NICOLLET-REDWOOD- RENVILLE-RICE-SIBLEY-STEELE-WASECA-WATONWAN COUNTY(IES). WI...NONE. && $$ KAT/MDB/MTF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 808 PM CDT MON AUG 20 2007 .DISCUSSION... THE REMNANTS OF WHAT WAS ONCE TROPICAL STORM ERIN CONTINUE TO MOVE OFF TO THE EAST. THE BULK OF THE RAINFALL HAS SHIFTED TO SOUTHEASTERN MISSOURI WITH JUST A FEW SHRA DEVELOPING SPORADICALLY IN ITS WAKE ACROSS CENTRAL MISSOURI. MID LEVEL NVA AND THE LOSS OF DAYTIME HEATING SHOULD SQUASH ANY LINGERING SHRA BY 9PM. WHILE THIS DISTURBANCE IS IN ITS SWAN SONG FOR OUR AREA...ATTENTION HAS NOW SHIFTED TO THE NORTHWEST ACROSS KS AND NEB...WHERE VIGOROUS CONVECTION CONTINUES TO BLOSSOM. THE AIRMASS ACROSS MUCH OF KANSAS AND NORTHWEST MISSOURI IS VERY UNSTABLE. 00Z LAPS DATA INDICATES SBCAPE AS HIGH AS 4000 J/KG WITH LIS AROUND -8C. WHILE INSTABILITY IS HIGH...THERE IS A DECENT CAP ACROSS MUCH OF KS AND NW MO. LAPS DATA INDICATES CIN BETWEEN 50 AND 100 J/KG AND THE 00Z KTOP SOUNDING SUPPORTS THESE VALUES. THUNDERSTORMS ERUPTED ALONG A PREFRONTAL TROUGH AND HAVE QUICKLY MOVED AWAY FROM THIS FEATURE SPLITTING INTO NO LESS THAN THREE DISTINCT COMPLEXES. THE COMPLEX OF INTEREST FOR OUR NECK OF THE WOODS TONIGHT IS CURRENTLY LOCATED JUST TO THE WEST OF MANHATTAN KS. TO THIS POINT...CONVECTIVE BEHAVIOR HAS BEEN REASONABLY FOLLOWING PROGGED CORFIDI VECTORS FROM THE NAM...GFS AND RUC. A SOUTHEAST MOTION SHOULD CONTINUE FOR THE NEXT FEW HOURS AS THE COMPLEX FEEDS ON HIGH SBCAPE. AS THE EVENING PROGRESSES...THIS COMPLEX WILL CONTINUE TO MOVE FARTHER AWAY FROM THE PREFRONTAL TROUGH AND INTO LESS FAVORABLE DEEP LAYER SHEAR. LITTLE CHANGE IN CIN IS EXPECTED AND INSTABILITY WILL LESSEN AS DAYTIME HEATING SUBSIDES. AT LEAST SOME DECREASE IN INTENSITY SHOULD RESULT. PRESENT INDICATIONS ARE THAT CONVECTION SHOULD MAINTAIN ITSELF FOR AT LEAST THE NEXT FEW HOURS. HEADING TOWARD MIDNIGHT...THE GFS... NAM AND RUC ALL CONTINUE TO SHOW A VEERING CORIFIDI VECTOR PROFILE. BY THIS TIME A NORTHEASTERLY COMPONENT IS EXPECTED...WITH A SOUTHWESTERLY LOW LEVEL JET OF 30-35KTS EXPECTED FROM OKLAHOMA INTO SOUTHERN KS. IT IS PLAUSIBLE THAT CONVECTION COULD TURN MORE TO THE SOUTH. THEREFORE...HAVE GONE AHEAD AND INCREASED RAIN CHANCE ACROSS EXTREME SE KS AND WESTERN MO AFTER MIDNIGHT. WILL REASSESS THE SITUATION WITH INCOMING 00Z RUC/NAM WRF OUTPUT AND ADJUST THE FORECAST AS NEEDED. GAGAN && .AVIATION... FOR THE 00Z TAF PACKAGE...PRIMARY CONCERNS REVOLVE AROUND FOG POTENTIAL FOR TONIGHT. PESKY CLUSTER OF STORMS THAT AFFECTED THE OZARKS MUCH OF TODAY NOW WELL EAST OF THE JLN AND SGF TERMINALS. SKIES ARE CLEARING AND JUST A FEW CIRRUS ARE EXPECTED FOR THE NEXT SEVERAL HOURS. MODEL OUTPUT CONTINUES TO INDICATE SUSTAINED WINDS AOA 7KTS ALL NIGHT TONIGHT...AND GIVEN CURRENT SFC PRESSURE GRADIENT I HAVE NO REASON TO ARGUE. NEVERTHELESS...IF TEMPERATURES DO APPROACH THEIR CROSSOVER VALUES IN THE LOWER 70S...PATCHY GROUND FOG IS NOT OUT OF THE QUESTION. HAVE CONTINUED TO MENTION 6SM BR OVERNIGHT AND WILL PERUSE THE 00Z SUITE OF MODELS TO ADJUST WITH 06Z TAF PACKAGE. WILL CONTINUE TO MONITOR BEHAVIOR OF BLOSSOMING CONVECTIVE COMPLEX OVER NEB/KS. AT THIS POINT AN INFLUX OF CIRRUS APPEARS TO THE BE MAIN SENSIBLE WX ISSUE FOR THE TAF SITES...BUT WILL MONITOR SAT AND RADAR TRENDS TO SEE IF DEVIANT MOVEMENT MANIFESTS ITSELF. GAGAN && .PREV DISCUSSION.../ISSUED 634 PM CDT MON AUG 20 2007/ DISCUSSION... MAIN FORECAST CONCERN TODAY IS THE AREA OF HEAVY RAIN SLOWLY TRAVERSING SOUTHWEST AND SOUTH CENTRAL MISSOURI. THE BACK SIDE OF THIS ACTIVITY IS QUITE SHARP WITH MODERATE SUBSIDENCE IN ITS WAKE...AND IT APPEARS IT SHOULD BE OUT OF THE CWA BY EARLY EVENING. ATTENTION THEN TURNS TO PRECIPITATION CHANCES AND THE ASSOCIATED TEMPERATURE RESPONSE TOWARD THE END OF THE WEEK. SHORT TERM (TODAY THROUGH WEDNESDAY) AS THE REMNANTS OF TROPICAL STORM ERIN EXIT TO THE EAST...SUBSIDENCE IS OVERTAKING THE AREA IN ITS WAKE AND GIVING A SHARP END TO THE PRECIPITATION. HAD TO KNOCK TEMPS DOWN QUITE A BIT IN THE RAINY SECTOR OF THE CWA BUT WE ARE WARMING UP NICELY BEHIND THIS ACTIVITY. A CUMULUS FIELD HAS BEEN ABLE TO MAINTAIN ITSELF WITH THE NEW FOUND SURFACE MOISTURE BUT LITTLE MORE IS EXPECTED TO DEVELOP THROUGH THE EVENING. THE PRESSURE GRADIENT SHOULD REMAIN STRONG ENOUGH TONIGHT TO KEEP THE LOW LEVELS MIXED...PREVENTING ANY MAJOR FOG FORMATION. HOWEVER...A SHARP DROP IN WIND SPEEDS TOWARD MORNING COULD LEAD TO SOME FOG DEVELOPMENT. WILL BE SOMETHING TO WATCH OVERNIGHT. TEMPERATURES TOMORROW SHOULD REBOUND NICELY INTO THE MID 90S IN THE ABSENCE OF ANY MAJOR CLOUD COVER. DEWPOINTS WILL REMAIN NEAR 70 IN THE WESTERN CWA WHICH SHOULD BRING HEAT INDICES INTO THE 100 PLUS DEGREE RANGE. HOWEVER IT DOES NOT APPEAR TO WARRANT ANY SORT OF HEAT ADVISORY AT THE MOMENT. LITTLE CHANGES WILL OCCUR BETWEEN TUESDAY AND WEDNESDAY WITH UPPER PATTERN REMAINING FAIRLY STAGNANT. LONG TERM (WEDNESDAY THROUGH SUNDAY) BY FRIDAY EVENING THE UPPER HIGH FLATTENS OUT AND SHIFTS SLIGHTLY SOUTHEAST. THIS SHOULD ALLOW THE TRAIN OF MID LEVEL WEAKNESSES CURRENTLY IMPACTING THE MID MISSOURI VALLEY TO SHIFT THEIR COLLECTIVE TRACKS FARTHER TO THE SOUTH. CURRENT INDICATIONS POINT TO CYCLOGENESIS ACROSS WESTERN KANSAS FRIDAY AFTERNOON. SOUTH WINDS WILL BRING A SLIGHT INCREASE TO SURFACE MOISTURE AND OVERALL INSTABILITY AS THE SYSTEM APPROACHES FRIDAY NIGHT INTO SATURDAY...BRINGING A CHANCE FOR THUNDERSTORMS INTO THE CWA. AT PRESENT...SHEAR APPEARS MODEST AT BEST BUT WILL BE MONITORED IN FUTURE SHIFTS FOR SEVERE POTENTIAL. EXACT TIMING OF PRECIPITATION AND CLOUDS WILL DICTATE TEMPERATURES. CURRENT FEELING IS THAT LOW 90S WILL PREVAIL AHEAD OF THE SYSTEM WITH UPPER 80S AFTER THE FRONTAL PASSAGE. 500 HEIGHTS BEGIN A SLOW RISE AGAIN AFTER THIS WAVE EXITS THE AREA AND IT SHOULD BE FAIRLY QUIET AFTER SATURDAY. BARJENBRUCH && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO SGF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1220 AM CDT MON AUG 20 2007 .DISCUSSION... UNSETTLED WEATHER EXPECTED ACROSS THE REGION TONIGHT. REMNANT WAVE OF WHAT WAS ONCE TS ERIN CONTINUES TO LIFT ENE INTO THE REGION. OVER THE PAST FEW HOURS...SFC OBS INDICATE THAT WE ARE LOSING A CLOSED CIRCULATION. ALOFT...HOWEVER...WAT VAP IMAGERY AND RUC INITIALIZATIONS OF WIND AND VORTICITY CONTINUE TO SUGGEST A WELL DEVELOPED CIRCULATION REMAINS IN PLACE NEAR OR JUST TO THE WEST OF THE MO/KS BORDER. EXTRAPOLATING RECENT TRENDS...THIS WAVE SHOULD CONTINUE TO MOVE TO THE ENE AND GRADUALLY OPEN AS ANOTHER POTENT SHORTWAVE DISTURBANCE SLIDES ACROSS THE UPPER MIDWEST. THE 00Z KSGF SOUNDING INDICATES THAT A MOIST AND MODESTLY UNSTABLE AIRMASS IS IN PLACE. AREA PROFILERS INDICATE 925/850MB WINDS OF 25-30KTS...WHICH SHOULD INCREASE OVER THE NEXT FEW HOURS. IN FACT BOTH THE NAM/WRF AND THE RUC INDICATE THAT A 40KT LLJ IS IMMINENT...RESULTING IN INCREASED MOISTURE TRANSPORT AND AN INFLUX OF HIGH THETA-E AIR. EXPECTATIONS ARE THAT BANDS OF SHRA AND A FEW EMBEDDED TSRA WILL CONTINUE TO EMANATE FROM THE CENTRAL CIRCULATION THIS EVENING...WITH THE BEST POTENTIAL FOR WIDESPREAD RAINFALL CENTERING OVER THE WESTERN HALF OF THE CWA OVERNIGHT. SEVERE WEATHER POTENTIAL IN THIS SITUATION IS MARGINAL AT BEST. THE BEST SFC BASED INSTABILITY WILL REMAIN CONFINED TO THE EASTERN CWA THIS EVENING AS MOST OF THIS AREA HAS BEEN ONLY SPORADICLY AFFECTED BY CONVECTION THUS FAR TODAY. OVER THE WESTERN HALF OF THE CWA...EARLIER RAINFALL HAS QUELLED TEMPERATURES AND REDUCED SFC BASED CAPE AND LI. HOWEVER...ELEVATED INSTABILITY WILL REMAIN IN PLACE AS THE CORE OF THE SYSTEM MOVES IN. GIVEN THAT THIS IS A WARM CORE SYSTEM...AND PWS ARE NEAR TWO INCHES...HEAVY RAINFALL WILL BE THE PRIMARY HAZARD TONIGHT. HAIL WILL BE NEARLY NON EXISTENT...WITH ONLY A MARGINAL RISK FOR A DAMAGING WIND GUST. HAVE GONE AHEAD AND REMOVED THE MENTION OF TORNADOES AS SFC BASED ACTIVITY WILL BE TOUGH TO COME BY TONIGHT. FLASH FLOOD WATCH LOOKS WELL POSITIONED AND WILL CONTINUE AS ADVERTISED. AN UPDATE TO HOURLY GRIDS IS FORTHCOMING...OTHERWISE THE FORECAST IS ON TRACK AT THIS TIME. GAGAN && .PREV DISCUSSION... /ISSUED 245 PM CDT SUN AUG 19 2007/ FORECAST CHALLENGE WITH THIS PACKAGE INCLUDES HEAVY RAIN AND SEVERE WEATHER POTENTIAL AS THE REMAINS OF TROPICAL STORM ERIN MOVE THROUGH SOUTHEAST KANSAS AND SOUTHERN MISSOURI TONIGHT. MODELS NOT HANDLING THE REMNANTS WELL AT ALL. CURRENTLY...LOW CENTERED OVER NORTH CENTRAL OKLAHOMA IN THE VICINITY OF PONCA CITY THIS AFTERNOON. MOISTURE FROM SATELLITE IMAGERY SHOWING AN EASTWARD MOVEMENT WHILE THE SURFACE LOW ITSELF SHOWING A MORE NORTHEAST MOVEMENT. THUNDERSTORMS MOVING THROUGH THE CENTRAL CWA THIS AFTERNOON ARE VERY EFFICIENT RAIN PRODUCERS. WE HAD ALMOST 6/10THS OF AN INCH OF RAINFALL IN TEN MINUTES FROM ONE OF THESE CELLS AS IT PASSED OVER THE OFFICE. RUC CAPES THIS AFTERNOON GENERALLY AROUND 1000 J/KG BASICALLY WHERE THE THUNDERSTORMS ARE FIRING UP. SHEAR VALUES REMAIN HIGH AS 850MB PROFILER WINDS SHOWING 25 TO 30 KNOTS OVER SOUTHWEST MISSOURI AND SOUTHEAST KANSAS. CLOUD COVERAGE KEEPING AFTERNOON TEMPERATURES DOWN. STARTING TO GET SOME SEVERE REPORTS WITH THESE THUNDERSTORMS AND WOULD EXPECT SEVERE THREAT TO CONTINUE THROUGH THE AFTERNOON. TONIGHT INTO MONDAY...SINCE BOTH MODELS HAVING A DIFFICULT TIME WITH REMNANTS OF ERIN...DECIDED TO FOLLOW HPC GUIDANCE. THIS BRINGS THE SURFACE LOW INTO SOUTHWEST MISSOURI SHORTLY AFTER 00Z AND TRACKS THE LOW INTO NORTHEASTERN MISSOURI OVERNIGHT. LOTS OF MOISTURE WITH THE LOW AS IT TRACKS THROUGH WITH 6 HOURLY QPF VALUES OVER AN INCH OVER WESTERN AND CENTRAL MISSOURI. PWATS REMAIN OVER 2 INCHES ON MODEL SOUNDINGS OVERNIGHT. WE HAVE BEEN DRY HERE FOR A LONG TIME AND THE RAIN IS A WELCOMED RELIEF...BUT GIVEN THE RAIN EFFICIENCY OF THESE STORMS...DECIDED TO ISSUE A FLASH FLOOD WATCH FOR THIS EVENING AND OVERNIGHT. WE KEEP A GOOD LOW LEVEL JET FROM THE SOUTHWEST AT 40KTS AROUND MIDNIGHT TONIGHT...SO SEVERE THREAT TO CONTINUE OVERNIGHT. LOW PUSHES OFF TO THE NORTHEAST BY LATE MORNING AND PRECIPITATION SHOULD BE ENDING FROM WEST TO EAST THROUGH THE DAY. TUESDAY ON...RIDGE OF HIGH PRESSURE TO BUILD BACK INTO THE CENTRAL U.S. TUESDAY INTO THE WEEK. GET SOME DISTURBANCES MOVING ALONG THE PERIPHERY OF THE RIDGE THAT MAY SET OFF SOME CONVECTION THROUGH THE WEEK. TEMPERATURES ARE EXPECTED TO CLIMB BACK INTO THE MID 90S THROUGH THE WEEK...THAT WILL GET OUR HEAT INDICES BACK UP TO AROUND OR SLIGHTLY ABOVE 100 DEGREES. GCC && .AVIATION... FOR THE 06Z TAF PACKAGE...BANDS OF SHRA CONTINUE TO DEVELOP ACROSS THE REGION. BETTER COVERAGE HAS DEVELOP DURING THE PAST HOUR NEAR THE MO/KS BORDER AND THIS TREND SHOULD CONTINUE OVER THE NEXT FEW HOURS. THE JLN AND SGF AERODROMES WILL EXPERIENCE OCCASIONAL BOUTS OF MODERATE TO HEAVY RAINFALL WITH ON AGAIN OFF AGAIN MVFR/IFR CIG AND VIS. THE UPPER WAVE RESPONSIBLE FOR THIS ACTIVITY WILL SLOWLY BUT DELIBERATELY SPREAD TO THE EAST AND CLEARING CONDITIONS ARE EXPECTED FROM MIDDAY ONWARD. OCCASIONALLY GUSTY WINDS ARE EXPECTED THROUGH THE MORNING HOURS. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH THROUGH MONDAY MORNING FOR MOZ055>058-068>070- 078>081-088>095-101>104. KS...NONE. && $$ WFO SGF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 642 PM CDT SUN AUG 19 2007 UPDATED AVIATION .DISCUSSION... FORECAST CHALLENGE WITH THIS PACKAGE INCLUDES HEAVY RAIN AND SEVERE WEATHER POTENTIAL AS THE REMAINS OF TROPICAL STORM ERIN MOVE THROUGH SOUTHEAST KANSAS AND SOUTHERN MISSOURI TONIGHT. MODELS NOT HANDLING THE REMNANTS WELL AT ALL. CURRENTLY...LOW CENTERED OVER NORTH CENTRAL OKLAHOMA IN THE VICINITY OF PONCA CITY THIS AFTERNOON. MOISTURE FROM SATELLITE IMAGERY SHOWING AN EASTWARD MOVEMENT WHILE THE SURFACE LOW ITSELF SHOWING A MORE NORTHEAST MOVEMENT. THUNDERSTORMS MOVING THROUGH THE CENTRAL CWA THIS AFTERNOON ARE VERY EFFICIENT RAIN PRODUCERS. WE HAD ALMOST 6/10THS OF AN INCH OF RAINFALL IN TEN MINUTES FROM ONE OF THESE CELLS AS IT PASSED OVER THE OFFICE. RUC CAPES THIS AFTERNOON GENERALLY AROUND 1000 J/KG BASICALLY WHERE THE THUNDERSTORMS ARE FIRING UP. SHEAR VALUES REMAIN HIGH AS 850MB PROFILER WINDS SHOWING 25 TO 30 KNOTS OVER SOUTHWEST MISSOURI AND SOUTHEAST KANSAS. CLOUD COVERAGE KEEPING AFTERNOON TEMPERATURES DOWN. STARTING TO GET SOME SEVERE REPORTS WITH THESE THUNDERSTORMS AND WOULD EXPECT SEVERE THREAT TO CONTINUE THROUGH THE AFTERNOON. TONIGHT INTO MONDAY...SINCE BOTH MODELS HAVING A DIFFICULT TIME WITH REMNANTS OF ERIN...DECIDED TO FOLLOW HPC GUIDANCE. THIS BRINGS THE SURFACE LOW INTO SOUTHWEST MISSOURI SHORTLY AFTER 00Z AND TRACKS THE LOW INTO NORTHEASTERN MISSOURI OVERNIGHT. LOTS OF MOISTURE WITH THE LOW AS IT TRACKS THROUGH WITH 6 HOURLY QPF VALUES OVER AN INCH OVER WESTERN AND CENTRAL MISSOURI. PWATS REMAIN OVER 2 INCHES ON MODEL SOUNDINGS OVERNIGHT. WE HAVE BEEN DRY HERE FOR A LONG TIME AND THE RAIN IS A WELCOMED RELIEF...BUT GIVEN THE RAIN EFFICIENCY OF THESE STORMS...DECIDED TO ISSUE A FLASH FLOOD WATCH FOR THIS EVENING AND OVERNIGHT. WE KEEP A GOOD LOW LEVEL JET FROM THE SOUTHWEST AT 40KTS AROUND MIDNIGHT TONIGHT...SO SEVERE THREAT TO CONTINUE OVERNIGHT. LOW PUSHES OFF TO THE NORTHEAST BY LATE MORNING AND PRECIPITATION SHOULD BE ENDING FROM WEST TO EAST THROUGH THE DAY. TUESDAY ON...RIDGE OF HIGH PRESSURE TO BUILD BACK INTO THE CENTRAL U.S. TUESDAY INTO THE WEEK. GET SOME DISTURBANCES MOVING ALONG THE PERIPHERY OF THE RIDGE THAT MAY SET OFF SOME CONVECTION THROUGH THE WEEK. TEMPERATURES ARE EXPECTED TO CLIMB BACK INTO THE MID 90S THROUGH THE WEEK...THAT WILL GET OUR HEAT INDICES BACK UP TO AROUND OR SLIGHTLY ABOVE 100 DEGREES. GCC && .AVIATION... FOR THE 00Z TAF PACKAGE...REMNANT OF WHAT WAS ONCE TROPICAL STORM ERIN CONTINUE TO LIFT INTO THE REGION. BAND OF LIGHT TO MODERATE SHRA CONTINUE TO DEVELOP ACROSS EASTERN KS/OK AS WELL AS SW MO AND NW ARK. THIS ON AGAIN...OFF AGAIN SHRA ACTIVITY WILL BE THE PRIMARY CONCERN FOR BOTH SGF AND JLN OVER THE NEXT 12 HOURS. THROUGH THE EVENING HOURS...OCCASIONAL BOUTS OF MVFR AND IFR WILL OCCUR AS THE BANDS OF SHRA DEVELOP AND MOVE TO THE NNE. DURING THE OVERNIGHT HOURS IT IS PLAUSIBLE THAT A LARGER BAND OF RAIN WILL DEVELOP NEAR SW MO TONIGHT...BRINGING THE POTENTIAL FOR IFR CONDITIONS. WILL AMEND THE TAFS AS NEEDED BASED ON RADAR TRENDS. OCCASIONAL GUSTY WINDS WILL OCCUR THROUGH THE NIGHT...PRIMARILY ASSOCIATED WITH THE BANDS OF SHRA. CLEARING FROM WEST TO EAST IS EXPECTED MONDAY AFTERNOON. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH FOR AREAS WEST OF A LINE FROM BRANSON TO OSAGE BEACH FROM 9 PM THROUGH 10 AM MONDAY. KS...NONE. && $$ WFO SGF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 245 PM CDT SUN AUG 19 2007 .DISCUSSION... FORECAST CHALLENGE WITH THIS PACKAGE INCLUDES HEAVY RAIN AND SEVERE WEATHER POTENTIAL AS THE REMAINS OF TROPICAL STORM ERIN MOVE THROUGH SOUTHEAST KANSAS AND SOUTHERN MISSOURI TONIGHT. MODELS NOT HANDLING THE REMNANTS WELL AT ALL. CURRENTLY...LOW CENTERED OVER NORTH CENTRAL OKLAHOMA IN THE VICINITY OF PONCA CITY THIS AFTERNOON. MOISTURE FROM SATELLITE IMAGERY SHOWING AN EASTWARD MOVEMENT WHILE THE SURFACE LOW ITSELF SHOWING A MORE NORTHEAST MOVEMENT. THUNDERSTORMS MOVING THROUGH THE CENTRAL CWA THIS AFTERNOON ARE VERY EFFICIENT RAIN PRODUCERS. WE HAD ALMOST 6/10THS OF AN INCH OF RAINFALL IN TEN MINUTES FROM ONE OF THESE CELLS AS IT PASSED OVER THE OFFICE. RUC CAPES THIS AFTERNOON GENERALLY AROUND 1000 J/KG BASICALLY WHERE THE THUNDERSTORMS ARE FIRING UP. SHEAR VALUES REMAIN HIGH AS 850MB PROFILER WINDS SHOWING 25 TO 30 KNOTS OVER SOUTHWEST MISSOURI AND SOUTHEAST KANSAS. CLOUD COVERAGE KEEPING AFTERNOON TEMPERATURES DOWN. STARTING TO GET SOME SEVERE REPORTS WITH THESE THUNDERSTORMS AND WOULD EXPECT SEVERE THREAT TO CONTINUE THROUGH THE AFTERNOON. TONIGHT INTO MONDAY...SINCE BOTH MODELS HAVING A DIFFICULT TIME WITH REMNANTS OF ERIN...DECIDED TO FOLLOW HPC GUIDANCE. THIS BRINGS THE SURFACE LOW INTO SOUTHWEST MISSOURI SHORTLY AFTER 00Z AND TRACKS THE LOW INTO NORTHEASTERN MISSOURI OVERNIGHT. LOTS OF MOISTURE WITH THE LOW AS IT TRACKS THROUGH WITH 6 HOURLY QPF VALUES OVER AN INCH OVER WESTERN AND CENTRAL MISSOURI. PWATS REMAIN OVER 2 INCHES ON MODEL SOUNDINGS OVERNIGHT. WE HAVE BEEN DRY HERE FOR A LONG TIME AND THE RAIN IS A WELCOMED RELIEF...BUT GIVEN THE RAIN EFFICIENCY OF THESE STORMS...DECIDED TO ISSUE A FLASH FLOOD WATCH FOR THIS EVENING AND OVERNIGHT. WE KEEP A GOOD LOW LEVEL JET FROM THE SOUTHWEST AT 40KTS AROUND MIDNIGHT TONIGHT...SO SEVERE THREAT TO CONTINUE OVERNIGHT. LOW PUSHES OFF TO THE NORTHEAST BY LATE MORNING AND PRECIPITATION SHOULD BE ENDING FROM WEST TO EAST THROUGH THE DAY. TUESDAY ON...RIDGE OF HIGH PRESSURE TO BUILD BACK INTO THE CENTRAL U.S. TUESDAY INTO THE WEEK. GET SOME DISTURBANCES MOVING ALONG THE PERIPHERY OF THE RIDGE THAT MAY SET OFF SOME CONVECTION THROUGH THE WEEK. TEMPERATURES ARE EXPECTED TO CLIMB BACK INTO THE MID 90S THROUGH THE WEEK...THAT WILL GET OUR HEAT INDICES BACK UP TO AROUND OR SLIGHTLY ABOVE 100 DEGREES. GCC && .AVIATION... AT 1715Z...SCATTERED SHOWERS WERE DEVELOPING AROUND THE SPRINGFIELD AIRPORT. KSGF WILL LIKELY EXPERIENCE A COUPLE BRIEF PERIODS OF MODERATE RAIN BEFORE THE AFTERNOON IS OVER. WILL ALSO MONITOR CONVECTION OVER OKLAHOMA AS IT SHIFTS INTO THE OZARKS THIS EVENING. THIS FEATURE IS THE REMNANT CIRCULATION OF TROPICAL STORM ERIN...AND COULD PRODUCE SOME VERY HEAVY RAINFALL ACROSS THE REGION. LOWERING CEILINGS AND VISIBILITIES WOULD BE EXPECTED IF THIS CIRCULATION TRACKS TOWARD THE SPRINGFIELD AIRPORT. THE JOPLIN SITE WILL ALSO NEED TO WATCH THIS AREA OF RAIN CLOSELY...HOWEVER...THIS CONVECTION COULD SHIFT SOUTH OF JOPLIN WITH TIME. PILOTS CAN ALSO EXPECT WIND SPEEDS TO INCREASE WITH TIME THIS EVENING. 15-20 KNOTS WITH HIGHER GUSTS IS NOT OUT OF THE QUESTION. CRAMER && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH FOR AREAS WEST OF A LINE FROM BRANSON TO OSAGE BEACH FROM 9 PM THROUGH 10 AM MONDAY. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 936 AM MDT MON AUG 20 2007 .SHORT TERM...VALID FOR TDY AND TUE... FORECAST IN VERY GOOD SHAPE...BUT HAVE MADE SOME TWEAKS TO FORECAST...MAINLY TO RELATIVE HUMIDITY FORECAST...BUT NO BIG CHANGES. FAST WESTERLY FLOW ALOFT OVER THE AREA TODAY. UPPER WAVE IS PUSHING OFF TO THE EAST IN DAKOTAS...BUT ANOTHER NICE WAVE IS CURRENTLY PUSHING ONTO PACIFIC NORTHWEST COAST. SOME CLOUDS ALREADY PUSHING INTO WESTERN ZONES AHEAD OF THE WAVE AND IN THE SOMEWHAT MOIST WESTERLY FLOW. BUF-KIT AND MODEL SOUNDING SHOWING GOOD LINKAGE AND MODERATELY STRONG WINDS IN LOW LEVELS TODAY SO WINDS OF 15 TO 30 MPH SHOULD BE COMMON ACROSS MOST OF THE AREA. RUC AND NAM SHOWING DEWPOINTS DROPPING INTO 20S IN WESTERN ZONES...30S WORKING FURTHER EAST INTO CENTRAL ZONES AND LOWER 40S FAR EAST. THIS WILL RESULT IN SLIGHTLY LOWER RELATIVE HUMIDITY VALUES THEN CURRENTLY FORECASTED. ONE PROBLEM COULD BE CLOUDS MOVING INTO AREA WHICH MAY KEEP TEMPERATURE DOWN A BIT...BUT CURRENT TEMPERATURES ALREADY AHEAD OF NAM FORECAST. DEWPOINTS ALSO LOWER THAN CURRENT NAM FORECAST. WITH THE WAVE THIS AFTERNOON AND EVENING...LIKE CURRENT LOW POPS IN WESTERN ZONES...AND HAVE LEFT ALONE EXCEPT TO EXPAND A BIT TO THE EAST THIS AFTERNOON. MAY ALSO SEE A PICK UP IN WINDS WITH THE WAVE IN WESTERN ZONES LATER THIS AFTERNOON. RASCH .LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN... MODELS CONTINUE TO BE IN FAIRLY GOOD AGREEMENT ONCE AGAIN FOR THE EXTENDED PERIOD. CURRENT FORECAST LOOKS GOOD AND DID NOT MAKE ANY MAJOR CHANGES. AGAIN...BELOW NORMAL TEMPERATURES LOOK TO CONTINUE FOR WEDNESDAY BEFORE TEMPERATURES WARM ABOVE NORMAL BY THE END OF THE WEEK. MAINLY ZONAL FLOW LOOKS TO BE THE NORM THROUGH THE PERIOD WITH AN OCCASIONAL DISTURBANCE MOVING OVERHEAD. MOISTURE STILL LOOKS TO BE LACKING BUT A WEAK COOL FRONT LOOKS TO MOVE ACROSS THE FORECAST AREA WEDNESDAY BRINGING A SLIGHT CHANCE FOR A SHOWER OR THUNDERSTORM WEDNESDAY AND AGAIN THURSDAY. DID MAKE A CHANGE IN REGARDS TO TEMPERATURES DUE TO THE FRONT AND LOWERED AFTERNOON HIGHS A FEW DEGREES WEDNESDAY AND THURSDAY. RIDGING BUILDS ACROSS THE STATE BY THE END OF THE WEEK ALLOWING FOR A RETURN TO ABOVE NORMAL TEMPERATURES BY NEXT WEEKEND. HOOLEY && .AVIATION... AREAS OF MVFR OR IFR VISIBILITIES IN SMOKE THIS MORNING... PARTICULARLY FROM SHR TO MLS...WILL IMPROVE TO VFR MOST AREAS BY MIDDAY AS THE AIRMASS BECOMES WELL MIXED. LOCAL MVFR IN SMOKE IS POSSIBLE AGAIN TONIGHT AFTER SUNSET. OTHERWISE VFR WILL PREVAIL OVER THE NEXT 24 HOURS. GUSTY WEST WINDS WILL DEVELOP TODAY...WITH GUSTS OF 25-35 KTS FROM 18-03Z. ISOLATED SHOWERS AND THUNDERSTORMS WILL FORM OVER THE HIGHER TERRAIN...AND LOCAL MVFR CIGS IS POSSIBLE IN THESE AREAS AS WELL. JKL && .PRELIMINARY POINT TEMP/POPS... TDY TUE WED THU FRI SAT SUN ------------------------------------------------------- BIL 079 055/080 052/079 053/079 053/081 055/088 058/088 0/N 20/B 02/T 22/T 20/U 00/U 00/U LVM 077 050/078 042/075 042/072 042/080 047/085 048/085 2/T 20/N 02/T 22/T 20/B 00/B 00/U HDN 082 056/083 055/084 057/082 055/086 056/092 058/092 0/N 20/B 02/T 22/T 20/U 00/U 00/U MLS 079 054/080 053/082 055/080 055/083 055/086 059/086 0/N 20/B 02/T 22/T 20/U 00/U 00/U 4BQ 082 054/082 052/084 057/080 056/082 055/088 060/088 0/N 20/B 02/T 22/T 20/B 00/U 00/U BHK 078 052/079 051/080 052/078 052/080 052/086 055/086 0/N 20/B 02/T 22/T 20/B 00/U 00/U SHR 081 050/081 049/083 052/082 050/082 050/090 053/090 1/K 20/B 02/T 22/T 20/U 00/U 00/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...RED FLAG WARNING IN EFFECT UNTIL 9 PM MDT THIS EVENING FOR ZONES 28>42-56>58-63>68. WY...NONE. && $$ WEATHER.GOV/BILLINGS mt AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HASTINGS NE 853 PM CDT SUN AUG 19 2007 .DISCUSSION...QUICK UPDATE TO FORECAST GRIDS TO REFLECT A DRY AND GENERALLY CLEAR TO MOSTLY CLEAR SKY FOR THE REMAINDER OF TONIGHT ACROSS NORTH CENTRAL KS INTO SOUTH CENTRAL NE. NO OTHER CHANGES MADE AT THIS TIME. && .PREV DISCUSSION... /ISSUED 634 PM CDT SUN AUG 19 2007/ AVIATION...FOR THE 00Z KGRI TAF A FAIRLY QUIET FIRST 12 HOURS IS ANTICIPATED AS AN UNLIMITED CEILING LOOKS LIKELY...ALTHOUGH SOME PATCHY FOG MAY DROP VISIBILITY DOWN TO 4 MILES LATE TONIGHT INTO EARLY MONDAY MORNING. A SMALL BUT POTENT UPPER DISTURBANCE WILL THEN PUSH A SURFACE TROUGH INTO THE TERMINAL EARLY TOMORROW AFTERNOON WITH WINDS EXPECTED TO SHIFT FROM THE SOUTH TO NORTH OR NORTHEAST BY LATE AFTERNOON. AHEAD OF THIS TROUGH AN ISOLATED CHANCE FOR SOME LATE MORNING SHOWERS OR THUNDERSTORMS MAY EXIST BUT FEEL COVERAGE WILL BE LOW ENOUGH TO KEEP OUT OF THE FORECAST. AN ADDITIONAL CHANCE MAY EXIST DURING THE LATE AFTERNOON AS WELL BUT EXPECT THE TROUGH TO BE FAR ENOUGH SOUTH THAT KGRI SHOULD REMAIN DRY. PREV DISCUSSION... /ISSUED 223 PM CDT SUN AUG 19 2007/ SHORT TERM...NOW THROUGH MONDAY NIGHT. BIGGEST CHALLENGE WILL BE CHANCES OF PRECIPITATION. SURFACE BOUNDARY NEAR THE NORTHERN CWA BORDER COULD BE THE FOCUS OF A FEW SHOWERS OR THUNDERSHOWERS IN NORTHERN CWA AND MAY SAG JUST SOUTH INTO THE EXTREME NORTHERN CWA. INCLUDED A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH EARLY EVENING. THIS BOUNDARY SHOULD EVENTUALLY MOVE NORTH TONIGHT AS A WARM FRONT. THE RUC DOES NOT SEEM TO BE DOING A VERY GOOD JOB IN THE FIRST 12 HOURS...WITH THE NAM BEING A BIT CLOSER TO REALITY AS FAR AS PRECIPITATION IS CONCERNED...BUT WITH SOME TIMING ISSUES. AFTER 12 HOURS HOWEVER...THE NAM LOSES MUCH OF ITS CREDIBILITY AND THE GFS LOOKS LIKE IT GENERALLY DOES A BETTER JOB. A QUICKLY MOVING SHORTWAVE TROUGH IS MOVING THROUGH THE NORTHWEST UNITED STATES TODAY AND THE EXTREME SOUTHERN FRINGE OF THIS TROUGH MAY AFFECT THE EXTREME NORTHERN PART OF THE CWA. MODELS GENERALLY SHOW THAT THIS ENERGY SHOULD BE TOO FAR NORTH TO SIGNIFICANTLY AFFECT US. ONE MINOR WORRY IS THAT THE FAR NORTH MAY BE IN THE VICINITY OF THE LEFT FRONT QUADRANT OF A MODEST AND WANING UPPER LEVEL JET. BUT WORKING AGAINST RAINFALL WILL ALSO BE A RELATIVELY DRY LAYER NEAR 850 MB WITH THE LOW LEVEL JET NOT PARTICULARLY STRONG IN THIS REGION. I WILL ULTIMATELY GO DRY FOR LATE TONIGHT AND MONDAY MORNING. THE LATEST RUN OF THE NAM PUTS QPF OVER THE CWA DURING THIS TIME PERIOD...BUT LOOKS STRANGE AS IF THERE ARE SOME CONVECTIVE FEEDBACK ISSUES. FOR MONDAY AFTERNOON AND EVENING THERE IS A CONCERN THAT STORMS MAY DEVELOP IN THE NORTHERN PLAINS IN ASSOCIATION WITH ANOTHER SHORTWAVE MOVING IN AND EVENTUALLY SPREAD SOUTH INTO OUR AREA AS A LOW LEVEL JET DEVELOPS DURING THE EVENING. THE CENTRAL/NORTHERN PART OF THE CWA LOOKS LIKE IT WILL MAINLY STAND THE BEST CHANCE FOR BEING NEAR THE NOSE OF THE LOW LEVEL JET. SEVERE WEATHER IS A POSSIBILITY WITH THIS AND WILL HAVE TO KEEP AN EYE ON IT. I WILL LEAN TOWARD KEEPING THE SLIGHT CHANCE OF PRECIPITATION THAT WE HAVE IN FOR THIS PERIOD ALREADY...BUT MAY BUMP UP CHANCES OF PRECIPITATION IN THE FAR EAST...CLOSER TO WHERE AN MCS IS MORE LIKELY TO DEVELOP. LONG TERM...TUESDAY THROUGH SUNDAY. FORECAST CONCERN DURING THIS TIME FRAME WILL CONTINUE TO BE CHANCE OF THUNDERSTORMS. OVERALL SCENARIO HAS NOT CHANGED MUCH AS WE END UP ON THE SOUTHERN END OF THE WESTERLIES WITH SURFACE BOUNDARY DROPPING SOUTH INTO OUR AREA AND THEN STALLING OUT...AS EAST/WEST FRONT LIES PARALLEL TO UPPER FLOW. ATTEMPTING TO PIN DOWN TIMING OF THE RAINS WILL CONTINUE TO BE DIFFICULT AS SURFACE FRONT LOCATION NOT COMPLETELY CLEAR CUT AND MAY BE INFLUENCED BY ANY CONVECTION THAT OCCURS THE PREVIOUS DAY. ALSO TOUGH TO TELL WHEN ANY EMBEDDED SHORT WAVE TROUGH WILL TRAVERSE THE PLAINS. DOES APPEAR THAT GFS SUFFERS FROM CONVECTIVE FEEDBACK ISSUES A COUPLE OF TIMES. PRECIPITABLE WATER VALUES AGAIN PRETTY HIGH BY MID WEEK SO HEAVY RAINS POSSIBLE ALONG THE FRONT. BY NEXT WEEKEND THE FRONT MAY PUSH FAR ENOUGH TO THE SOUTH...AS RIDGE TO THE WEST AMPLIFIES...TO KEEP IT DRY HERE AND WILL GO ALONG WITH SCENARIO FOR THE TIME BEING. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE HASTINGS NE 634 PM CDT SUN AUG 19 2007 .AVIATION...FOR THE 00Z KGRI TAF A FAIRLY QUIET FIRST 12 HOURS IS ANTICIPATED AS AN UNLIMITED CEILING LOOKS LIKELY...ALTHOUGH SOME PATCHY FOG MAY DROP VISIBILITY DOWN TO 4 MILES LATE TONIGHT INTO EARLY MONDAY MORNING. A SMALL BUT POTENT UPPER DISTURBANCE WILL THEN PUSH A SURFACE TROUGH INTO THE TERMINAL EARLY TOMORROW AFTERNOON WITH WINDS EXPECTED TO SHIFT FROM THE SOUTH TO NORTH OR NORTHEAST BY LATE AFTERNOON. AHEAD OF THIS TROUGH AN ISOLATED CHANCE FOR SOME LATE MORNING SHOWERS OR THUNDERSTORMS MAY EXIST BUT FEEL COVERAGE WILL BE LOW ENOUGH TO KEEP OUT OF THE FORECAST. AN ADDITIONAL CHANCE MAY EXIST DURING THE LATE AFTERNOON AS WELL BUT EXPECT THE TROUGH TO BE FAR ENOUGH SOUTH THAT KGRI SHOULD REMAIN DRY. && .PREV DISCUSSION... /ISSUED 223 PM CDT SUN AUG 19 2007/ SHORT TERM...NOW THROUGH MONDAY NIGHT. BIGGEST CHALLENGE WILL BE CHANCES OF PRECIPITATION. SURFACE BOUNDARY NEAR THE NORTHERN CWA BORDER COULD BE THE FOCUS OF A FEW SHOWERS OR THUNDERSHOWERS IN NORTHERN CWA AND MAY SAG JUST SOUTH INTO THE EXTREME NORTHERN CWA. INCLUDED A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH EARLY EVENING. THIS BOUNDARY SHOULD EVENTUALLY MOVE NORTH TONIGHT AS A WARM FRONT. THE RUC DOES NOT SEEM TO BE DOING A VERY GOOD JOB IN THE FIRST 12 HOURS...WITH THE NAM BEING A BIT CLOSER TO REALITY AS FAR AS PRECIPITATION IS CONCERNED...BUT WITH SOME TIMING ISSUES. AFTER 12 HOURS HOWEVER...THE NAM LOSES MUCH OF ITS CREDIBILITY AND THE GFS LOOKS LIKE IT GENERALLY DOES A BETTER JOB. A QUICKLY MOVING SHORTWAVE TROUGH IS MOVING THROUGH THE NORTHWEST UNITED STATES TODAY AND THE EXTREME SOUTHERN FRINGE OF THIS TROUGH MAY AFFECT THE EXTREME NORTHERN PART OF THE CWA. MODELS GENERALLY SHOW THAT THIS ENERGY SHOULD BE TOO FAR NORTH TO SIGNIFICANTLY AFFECT US. ONE MINOR WORRY IS THAT THE FAR NORTH MAY BE IN THE VICINITY OF THE LEFT FRONT QUADRANT OF A MODEST AND WANING UPPER LEVEL JET. BUT WORKING AGAINST RAINFALL WILL ALSO BE A RELATIVELY DRY LAYER NEAR 850 MB WITH THE LOW LEVEL JET NOT PARTICULARLY STRONG IN THIS REGION. I WILL ULTIMATELY GO DRY FOR LATE TONIGHT AND MONDAY MORNING. THE LATEST RUN OF THE NAM PUTS QPF OVER THE CWA DURING THIS TIME PERIOD...BUT LOOKS STRANGE AS IF THERE ARE SOME CONVECTIVE FEEDBACK ISSUES. FOR MONDAY AFTERNOON AND EVENING THERE IS A CONCERN THAT STORMS MAY DEVELOP IN THE NORTHERN PLAINS IN ASSOCIATION WITH ANOTHER SHORTWAVE MOVING IN AND EVENTUALLY SPREAD SOUTH INTO OUR AREA AS A LOW LEVEL JET DEVELOPS DURING THE EVENING. THE CENTRAL/NORTHERN PART OF THE CWA LOOKS LIKE IT WILL MAINLY STAND THE BEST CHANCE FOR BEING NEAR THE NOSE OF THE LOW LEVEL JET. SEVERE WEATHER IS A POSSIBILITY WITH THIS AND WILL HAVE TO KEEP AN EYE ON IT. I WILL LEAN TOWARD KEEPING THE SLIGHT CHANCE OF PRECIPITATION THAT WE HAVE IN FOR THIS PERIOD ALREADY...BUT MAY BUMP UP CHANCES OF PRECIPITATION IN THE FAR EAST...CLOSER TO WHERE AN MCS IS MORE LIKELY TO DEVELOP. LONG TERM...TUESDAY THROUGH SUNDAY. FORECAST CONCERN DURING THIS TIME FRAME WILL CONTINUE TO BE CHANCE OF THUNDERSTORMS. OVERALL SCENARIO HAS NOT CHANGED MUCH AS WE END UP ON THE SOUTHERN END OF THE WESTERLIES WITH SURFACE BOUNDARY DROPPING SOUTH INTO OUR AREA AND THEN STALLING OUT...AS EAST/WEST FRONT LIES PARALLEL TO UPPER FLOW. ATTEMPTING TO PIN DOWN TIMING OF THE RAINS WILL CONTINUE TO BE DIFFICULT AS SURFACE FRONT LOCATION NOT COMPLETELY CLEAR CUT AND MAY BE INFLUENCED BY ANY CONVECTION THAT OCCURS THE PREVIOUS DAY. ALSO TOUGH TO TELL WHEN ANY EMBEDDED SHORT WAVE TROUGH WILL TRAVERSE THE PLAINS. DOES APPEAR THAT GFS SUFFERS FROM CONVECTIVE FEEDBACK ISSUES A COUPLE OF TIMES. PRECIPITABLE WATER VALUES AGAIN PRETTY HIGH BY MID WEEK SO HEAVY RAINS POSSIBLE ALONG THE FRONT. BY NEXT WEEKEND THE FRONT MAY PUSH FAR ENOUGH TO THE SOUTH...AS RIDGE TO THE WEST AMPLIFIES...TO KEEP IT DRY HERE AND WILL GO ALONG WITH SCENARIO FOR THE TIME BEING. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 308 PM CDT SUN AUG 19 2007 .DISCUSSION... MAIN CONCERN FOR THE NEXT SEVERAL DAYS IS TIMING OF AND LOCATION OF CONVECTION. UPPER AIR CHARTS FROM THIS MORNING STILL SHOWED A GOOD AMOUNT OF MOISTURE IN THE LOWER AND MID LEVELS OF THE ATMOSPHERE FROM PART OF THE SWRN U.S. AND WEST TX UP INTO ERN NE...WRN IA... SD AND MN. SURFACE ANALYSIS EARLY THIS AFTN SHOWED A FRONT LOCATED FROM NERN IA NWWD BACK TO LOW PRESSURE OVER SWRN MN/NWRN IA THEN SEWD INTO NRN NE...THEN BACK NWWD INTO ERN MT. DEWPOINTS LOCALLY WERE IN THE UPPER 60S TO MID 70S AT MOST LOCATIONS. WATER VAPOR LOOP SHOWED MAIN CONVECTION ASSOCIATED WITH REMNANTS OF ERN ACROSS OK...A WEAK MID LEVEL LOW OVER NWRN MO MOVING NEWD AND A SHORTWAVE TROUGH RESPONSIBLE FOR STORMS OVER SWRN MN/NWRN IA/SERN SD/NERN NE MOVING EWD ACROSS SD AND NE. A MOIST PLUME WAS ALSO INCREASING IN COVERAGE AHEAD OF STRONG SYSTEM OVER THE PACIFIC NW PUSHING INTO THE ROCKIES. 20Z VISIBLE SATELLITE IMAGERY SHOWED SOME ENHANCEMENT TO CLOUDS ALONG FRONT OVER NERN NE. LITTLE OR NO CAP WAS INDICATED BY LATEST RUC MEAN LAYER CONVECTIVE INHIBITION. TONIGHT...EXPECT THAT MOST OF THE CONVECTION THIS AFTERNOON WILL PROBABLY DIE OUT THIS EVENING. WILL KEEP A SMALL CHANCE OF TSTMS GOING AFTER 06Z ACROSS WRN IA FOR CONTINUITY SAKE WITH BORDERING OFFICES. WILL HAVE TO KEEP AN EYE OUT FOR DEVELOPMENT OF LOW CLOUDS AND FOG...WHICH SEEM TO HAVE BEEN RELATIVELY COMMON THE PAST FEW WEEKS. EXPECT LOW TEMPS TO BE MAINLY IN THE LOWER 70S WITH SOME UPPER 60S NORTH. FOR NOW...WILL NOT MENTION A CHANCE OF PCPN LATE TONIGHT IN FAR WESTERN ZONES WITH DISTURBANCE NOW OUT OVER THE ROCKIES...BUT IT IS MOVING QUICKLY. MONDAY...IMPRESSIVE WAVE OVER THE WRN U.S. WILL TRACK NEWD TOWARD SRN ALTA BY 00Z TUESDAY...WITH MAIN PUNCH OF ENERGY MOVING ACROSS THE DKTS. THIS WILL HELP DRIVE A COLD FRONT EASTWARD. 12Z GFS SHOWED VERY WARM 700 MB TEMPS OVER OUR AREA DURING THE DAY (MAINLY 12C TO 15C) BUT ALSO A LOT OF 700 MB MOISTURE (WITH DEWPOINTS UP TO 12 BY LATE AFTN) SO SPC DAY 2 OUTLOOK SEEMED REASONABLE. BULK SHEAR IN THE 0-6 KM LAYER INCREASES TO 30-45 KTS...AND SURFACE BASED CAPE GET UP TO OVER 3000 J/KG. INCREASED POPS A LITTLE FOR THE DAYTIME PERIOD AND INTO THE EVENING. EXPECT HIGHS ABOUT 90 TO 95 CENTRAL AND SOUTH...BUT ONLY UPPER 80S FAR NORTH. CLOUD COVER WILL BE A BIG PLAYER AS TO HOW WARM IT GETS ON MONDAY. UNSETTLED PATTERN WILL CONTINUE MUCH OF THE WEEK WITH FAIRLY FAST FLOW ACROSS THE NRN U.S. AND A FRONTAL BOUNDARY OSCILLATING NORTH AND SOUTH THROUGH THE REGION. KEPT POPS IN THE SLIGHT CHANCE TO CHANCE RANGE. MIGHT BE ABLE TO FINE TUNE THINGS BETTER IN FUTURE FORECAST AS WE GET CLOSER. TIMING IS GOING TO BE PROBLEMATIC... BUT THE TUESDAY EVENING PERIOD AND WEDNESDAY NIGHT INTO THURSDAY NIGHT SEEM POTENTIALLY BUSY WITH HEAVY RAIN POTENTIAL. TUESDAYS HIGHS SHOULD BE 90 TO 95...WEDNESDAYS HIGHS IN THE MID 80S TO LOWER 90S AND THEN EXPECT MAINLY 80S THURSDAY THROUGH SATURDAY. LEFT NEXT WEEKEND DRY FOR NOW. && .AVIATION... FOR THE FOLLOWING TAF SITES...KOFK/KOMA/KLNK CONTINUED INTRUSION OF LOW AND MID LEVEL MOISTURE INTO THE CWA FROM LEFT OVER REMNANTS OF ERIN...WILL CONTINUE TO CAUSE WIDESPREAD CU FIELD ACROSS MUCH OF EASTERN NEBRASKA AND SOUTHWEST IOWA THROUGH THE AFTERNOON HOURS. FURTHER NORTH ALONG NE/SD BORDER... FAIRLY STATIONARY BOUNDARY IS THE FOCUS FOR THUNDERSTORM ACTIVITY... ESPECIALLY NORTH OF THE BOUNDARY INTO MN. VFR CONDITIONS SHOULD PREVAIL FOR MOST OF THE PERIOD UNTIL AROUND THE 09-12Z TIMEFRAME WHEN THE POTENTIAL FOR FOG FORMATION APPEARS TO BE LIKELY DUE TO LOW DEWPOINT DEPRESSIONS AND DECREASED WIND SPEEDS...WHICH COULD LOWER CEILINGS/ VISIBILITIES TO LIFR/LFR CONDITIONS FOR ALL TAF SITES. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ DISCUSSION...MILLER AVIATINO...REESE ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 223 PM CDT SUN AUG 19 2007 .SHORT TERM...NOW THROUGH MONDAY NIGHT. BIGGEST CHALLENGE WILL BE CHANCES OF PRECIPITATION. SURFACE BOUNDARY NEAR THE NORTHERN CWA BORDER COULD BE THE FOCUS OF A FEW SHOWERS OR THUNDERSHOWERS IN NORTHERN CWA AND MAY SAG JUST SOUTH INTO THE EXTREME NORTHERN CWA. INCLUDED A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH EARLY EVENING. THIS BOUNDARY SHOULD EVENTUALLY MOVE NORTH TONIGHT AS A WARM FRONT. THE RUC DOES NOT SEEM TO BE DOING A VERY GOOD JOB IN THE FIRST 12 HOURS...WITH THE NAM BEING A BIT CLOSER TO REALITY AS FAR AS PRECIPITATION IS CONCERNED...BUT WITH SOME TIMING ISSUES. AFTER 12 HOURS HOWEVER...THE NAM LOSES MUCH OF ITS CREDIBILITY AND THE GFS LOOKS LIKE IT GENERALLY DOES A BETTER JOB. A QUICKLY MOVING SHORTWAVE TROUGH IS MOVING THROUGH THE NORTHWEST UNITED STATES TODAY AND THE EXTREME SOUTHERN FRINGE OF THIS TROUGH MAY AFFECT THE EXTREME NORTHERN PART OF THE CWA. MODELS GENERALLY SHOW THAT THIS ENERGY SHOULD BE TOO FAR NORTH TO SIGNIFICANTLY AFFECT US. ONE MINOR WORRY IS THAT THE FAR NORTH MAY BE IN THE VICINITY OF THE LEFT FRONT QUADRANT OF A MODEST AND WANING UPPER LEVEL JET. BUT WORKING AGAINST RAINFALL WILL ALSO BE A RELATIVELY DRY LAYER NEAR 850 MB WITH THE LOW LEVEL JET NOT PARTICULARLY STRONG IN THIS REGION. I WILL ULTIMATELY GO DRY FOR LATE TONIGHT AND MONDAY MORNING. THE LATEST RUN OF THE NAM PUTS QPF OVER THE CWA DURING THIS TIME PERIOD...BUT LOOKS STRANGE AS IF THERE ARE SOME CONVECTIVE FEEDBACK ISSUES. FOR MONDAY AFTERNOON AND EVENING THERE IS A CONCERN THAT STORMS MAY DEVELOP IN THE NORTHERN PLAINS IN ASSOCIATION WITH ANOTHER SHORTWAVE MOVING IN AND EVENTUALLY SPREAD SOUTH INTO OUR AREA AS A LOW LEVEL JET DEVELOPS DURING THE EVENING. THE CENTRAL/NORTHERN PART OF THE CWA LOOKS LIKE IT WILL MAINLY STAND THE BEST CHANCE FOR BEING NEAR THE NOSE OF THE LOW LEVEL JET. SEVERE WEATHER IS A POSSIBILITY WITH THIS AND WILL HAVE TO KEEP AN EYE ON IT. I WILL LEAN TOWARD KEEPING THE SLIGHT CHANCE OF PRECIPITATION THAT WE HAVE IN FOR THIS PERIOD ALREADY...BUT MAY BUMP UP CHANCES OF PRECIPITATION IN THE FAR EAST...CLOSER TO WHERE AN MCS IS MORE LIKELY TO DEVELOP. .LONG TERM...TUESDAY THROUGH SUNDAY. FORECAST CONCERN DURING THIS TIME FRAME WILL CONTINUE TO BE CHANCE OF THUNDERSTORMS. OVERALL SCENARIO HAS NOT CHANGED MUCH AS WE END UP ON THE SOUTHERN END OF THE WESTERLIES WITH SURFACE BOUNDARY DROPPING SOUTH INTO OUR AREA AND THEN STALLING OUT...AS EAST/WEST FRONT LIES PARALLEL TO UPPER FLOW. ATTEMPTING TO PIN DOWN TIMING OF THE RAINS WILL CONTINUE TO BE DIFFICULT AS SURFACE FRONT LOCATION NOT COMPLETELY CLEAR CUT AND MAY BE INFLUENCED BY ANY CONVECTION THAT OCCURS THE PREVIOUS DAY. ALSO TOUGH TO TELL WHEN ANY EMBEDDED SHORT WAVE TROUGH WILL TRAVERSE THE PLAINS. DOES APPEAR THAT GFS SUFFERS FROM CONVECTIVE FEEDBACK ISSUES A COUPLE OF TIMES. PRECIPITABLE WATER VALUES AGAIN PRETTY HIGH BY MID WEEK SO HEAVY RAINS POSSIBLE ALONG THE FRONT. BY NEXT WEEKEND THE FRONT MAY PUSH FAR ENOUGH TO THE SOUTH...AS RIDGE TO THE WEST AMPLIFIES...TO KEEP IT DRY HERE AND WILL GO ALONG WITH SCENARIO FOR THE TIME BEING. && .PREV DISCUSSION... /ISSUED 124 PM CDT SUN AUG 19 2007/ AVIATION...18Z TAF. VFR CONDITIONS ARE EXPECTED THROUGHOUT THE FORECAST. ANY THUNDERSTORMS SHOULD BE TO THE NORTH ASSOCIATED WITH A BOUNDARY WHICH LIES WELL TO THE NORTH IN NORTH CENTRAL NEBRASKA. POSSIBLE MID-LEVEL BROKEN LAYER COMING IN OVERNIGHT. THE NAM SUGGESTS A DECREASE IN VISIBLITY...BUT DO NOT SEE A WHOLE LOT TO SUPPORT THIS AND THE NAM HAS RECENTLY BEEN OVERFORECASTING REDUCTION OF VISIBILITIES. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ HEINLEIN/EWALD ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 233 PM EDT SUN AUG 19 2007 .SYNOPSIS... WHILE HIGH PRESSURE WILL KEEP FAIR AND SEASONABLY COOL CONDITIONS ACROSS THE BULK OF THE FORECAST AREA THROUGH MONDAY...THERE WILL BE A SHARP GRADIENT OVER THE SOUTHERN TIER LEADING TO WIDESPREAD SHOWERS JUST SOUTH OF THE BORDER. TUESDAY WILL THEN SERVE AS A TRANSITION DAY AS WARMER AND MORE HUMID CONDITIONS WILL RETURN FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... SFC HIGH PRESSURE EXTENDING FROM HUDSON BAY TO THE CAROLIANS WILL CONTINUE TO KEEP FAIR BUT COOL WEATHER ACROSS THE BULK OF WESTERN AND NORTH CENTRAL NEW YORK TODAY AND TONIGHT...BUT A RIBBON OF MOISTURE JUST TO OUR SOUTH WILL RESULT IN WIDESPREAD SHOWERS FROM THE PENNSYLVANIA BORDER SOUTHWARDS. THE SHARP GRADIENT ON THE NRN EDGE OF THE PCPN WILL RESULT IN A LOWER FORECAST CONFIDENCE ACROSS THE IAG FRONTIER AND WRN SOUTHERN TIER...WHILE A HIGH CONFIDENCE FORECAST WILL BE FOUND EAST OF LK ONTARIO. LOOKING AT THE RADAR AND SATELLITE LOOPS AS OF 14Z WE HAVE DECIDED TO BRING THE LIKELY POPS FOR RAIN INTO THE SOUTHERN TIER A FEW HOURS EARLIER THAN THE EARLY MORNING PACKAGE. THIS AREA OF RAIN ON RADAR COINCIDES WELL WITH THE AREA OF LIFT THAT ONE WOULD EXPECT TO FIND UNDER THE ENTRANCE REGION OF A 130 KT H2 JET THAT IS ALIGNED FROM WESTERN ONTARIO AND THE UPPER GREAT LAKES TO NORTHERN NEW YORK AND COASTAL NEW ENGLAND. JET INDUCED LIFT FROM THE RR QUAD OF THE JET IS COMBINING WITH LOW LEVEL ISENTROPIC LIFT TO PRODUCE THIS SWATH OF RAIN. HOW ARE THE MODELS HANDLING THIS? THUS FAR THE NAM/WRF AND GFS ARE VERY SIMILAR IN THEIR SOLUTIONS ON THE NRN EDGE OF THE RAIN...BUT THE NAM/WRF APPEARS TO BE UNDERDONE AT THIS TIME AND DOES NOT HAVE A GOOD HANDLE ON THE EASTWARD EXTENT OF THE RAIN INTO PA. THE GFS DOES NOT HAVE THIS PROBLEM THROUGH ITS FIRST 6 HRS. THE SHORTER RANGE RUC IS GROSSLY UNDER DONE ON THE AREAL EXTENT OF THE RAIN AND APPEARS TO HAVE BIG PROBLEMS ALL THE WAY OUT THROUGH ITS 12 HR FORECAST. BOIL THIS ALL DOWN AND THE GFS SEEMS TO BE THE MODEL OF CHOICE...AS IT HAS BEEN WITH ITS SOLUTION FOR THE PAST SEVERAL DAYS. THE NAM/WRF IS JUST NOW COMING INTO LINE WITH IT. GIVEN THE IR AND COMPOSITE RADAR TRENDS...WILL CONTINUE TO RELY MORE ON THE GFS GUIDANCE WITH THIS RAIN EVENT. I WILL RAISE POPS EVER SO SLIGHTLY SOUTH OF BUFFALO SO THAT A CHANCE OF SPRINKLES WILL BE MENTIONED IN THE IAG FRONTIER TODAY WITH HIGH CHC POPS FOUND OVER THE SRN TIER. THE HIGH CHC POPS WILL BECOME LIKELY THIS EVENING FOR SITES NEAR THE BORDER. THIS FORECAST WILL BE A BIT MORE PESSIMISTIC THAN OUR SURROUNDING WFO`S...BUT MORE OPTIMISTIC THAN THE HYDROMETEOROLOGICAL PREDICTION CENTER (HPC) IN TERMS OF ACTUAL QPF. FOR TONIGHT...THE SHARP GRADIENT WILL REMAIN IN PLACE OVER NEW YORKS SOUTHERN TIER AND PA`S NRN TIER. HAVE RAISED POPS OVER PARTS OF THE IAG FRONTIER AND FINGER LAKES TO LOW CHC POPS TO ALLOW FOR A PASSING SHOWER...WHILE LIKELY POPS WILL BE FOUND OVER THE SRN TIER. AGAIN...OUR POPS WILL BE A LITTLE LOWER THAN SURROUNDING WFO`S BUT WILL BE MORE PESSIMISTIC IN TERMS OF THE HPC QPF. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... THE STRONG H2 JET THAT WILL BE PARTIALLY RESPONSIBLE FOR THE SWATH OF RAIN FROM SUNDAY WILL GRADUALLY PULL TO THE EAST AND SETTLE FURTHER SOUTH AS MONDAY AND MONDAY NIGHT PROGRESSES. THIS WILL HELP TO FURTHER SHUNT THE SWATH OF RAIN TO THE SOUTH...WITH ANY -SHRA OVER THE NEW YORKS SOUTHERN TIER ENDING BY MONDAY EVENING. MEANWHILE STRONG SFC HIGH PRESSURE ALONG THE ONTARIO/QUEBEC BORDER WILL PRODUCE PARTLY SUNNY SKIES ACROSS THE MAJORITY OF OUR FORECAST AREA. TEMPS MONDAY WILL REMAIN A LITTLE BELOW NORMAL WITH H8 TEMPS OF 8 TO 10 DEG C KEEPING MAX TEMPS FROM CLIMBING OUT OF THE 60S (SRN TIER) AND 70S. THE LOWER TEMPS OVER THE SRN TIER WILL BE LARGELY DUE TO THE CLOUDIER SKY CONDITIONS. FOR MONDAY NIGHT AND TUESDAY...THE SFC HIGH WILL DRIFT ACROSS NEW ENGLAND WHILE THE SUPPORTING UPPER RIDGE WILL CROSS THE LOWER GR LAKES. THIS WILL KEEP RAINFREE CONDITIONS ACROSS THE VAST MAJORITY OF THE FORECAST AREA...ALTHOUGH WE WILL CONTINUE TO MENTION LOW CHC POPS FOR A -SHRA OVER CHAUTAUQUA COUNTY WHERE THE RETURN FLOW AROUND THE HIGH COULD HELP TO USHER IN A SHOWER FROM THE SOUTH. THIS WILL ALSO HELP TO MESH BETTER WITH WFO CLE POPS TO OUR WEST. AS MENTIONED IN THE SYNOPSIS...THIS PERIOD WILL ALSO SERVE AS A TRANSITION BETWEEN MORE SUMMERY CONDITIONS THAT WILL BE LURKING JUST TO OUR SOUTH AND WEST. MUCH WARMER AND NOTICEABLY MORE HUMID CONDITIONS FOUND OVER WESTERN PA...OHIO AND MICHIGAN AT THAT TIME WILL BE POISED TO ADVANCE OUR WAY DURING THE REMAINDER OF THE WEEK. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... IN A NUTSHELL...THE EXTENDED PORTION OF THE FORECAST CONTINUES TO FEATURE VERY WARM AND HUMID CONDITIONS FOR THE MIDDLE AND LATTER PORTIONS OF THIS WEEK...FOLLOWED BY THE PASSAGE OF A FRONTAL SYSTEM NEXT WEEKEND...AND A RETURN TO COOLER AND DRIER WEATHER FOR NEXT SUNDAY. ON THE SYNOPTIC SCALE...A BROAD...FLAT RIDGE OVER THE EASTERN HALF OF THE NATION ON WEDNESDAY WILL GRADUALLY BUILD NORTHWARD THROUGH SATURDAY...WITH THE GENERAL LARGE-SCALE FLOW SHIFTING TO MORE OF A SOUTHWESTERLY ORIENTATION. THIS WILL ACT TO PUMP INCREASINGLY WARMER AND MORE HUMID AIR BACK INTO THE REGION...WITH 850 MB TEMPERATURES RISING FROM THE MID TEENS AT THE START OF THE PERIOD TO THE +17C TO +20C DEG C RANGE BY LATE IN THE WEEK. AT THE VERY LEAST...THIS SHOULD RESULT IN HIGH TEMPERATURES REACHING WELL INTO THE 80S...WITH EVEN SOME LOWER 90S POSSIBLE ACROSS PORTIONS OF THE AREA. AS OF RIGHT NOW...WILL CONTINUE TO PLAY THINGS A LITTLE CONSERVATIVE AND CALL FOR HIGHS REACHING THE MID TO UPPER 80S FOR THE THURSDAY THROUGH SATURDAY PERIOD...WHICH IS STILL A BIT ABOVE THE LATEST HPC AND MEX GUIDANCE. IN TERMS OF PRECIPITATION CHANCES LATER THIS WEEK...OUR AREA WILL BE SITUATED ON THE PERIPHERY OF THE LARGE SUBTROPICAL RIDGE THAT WILL BECOME ENTRENCHED FROM THE SOUTHEASTERN STATES TO THE WESTERN ATLANTIC...WITH A WEAK FRONTAL BOUNDARY LIKELY LYING JUST TO OUR NORTH. WITH THIS BOUNDARY IN SUCH CLOSE PROXIMITY...A NUMBER OF UPPER LEVEL WAVES/ASSOCIATED SURFACE REFLECTIONS EXPECTED TO WORK NORTHEAST ALONG IT...AND A VERY WARM AND HUMID AIRMASS ALREADY IN PLACE OVER THE AREA...I AM PRETTY MUCH FORCED TO RETAIN LOW CHANCE POPS FOR MUCH OF THIS PERIOD FROM CONTINUITY...EVEN THOUGH THE BULK OF THE TIME IS LIKELY TO BE DRY. THAT SAID...THE DRIEST PERIOD OF THE FORECAST IS MOST LIKELY TO BE FRIDAY NIGHT INTO SATURDAY MORNING...WHEN A MORE SIGNIFICANT WAVE IS EXPECTED TO RIPPLE ACROSS THE UPPER MIDWEST AND CENTRAL GREAT LAKES...FORCING THE AFOREMENTIONED FRONT A BIT FURTHER NORTHWARD...AND OUR AREA DEEPER INTO THE WARM SECTOR. HAVE THUS CUT POPS BACK BELOW THE CHANCE THRESHOLD FOR THIS PERIOD...WITH A GENERALLY DRY BUT HOT AND HUMID DAY ON SATURDAY...LIKELY THE MOST UNCOMFORTABLE OF THE WEEK. A COLD FRONT TRAILING FROM THE LOW WILL FOLLOW WITH ANOTHER THREAT OF SHOWERS AND THUNDERSTORMS FOR SATURDAY NIGHT...THEN DRIER AND SOMEWHAT COOLER CONDITIONS ARE EXPECTED TO RETURN ON SUNDAY. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... SEVERAL DISTURBANCES WILL PASS ALONG A STALLED OUT-FRONTAL BOUNDARY OVER OHIO AND WESTERN PENNSYLVANIA TONIGHT THROUGH MONDAY NIGHT...THOUGH MOST IF NOT ALL PRECIP WILL REMAIN TO THE SOUTH AND WEST OF OUR TERMINALS. THE ONE EXCEPTION TO THIS WILL BE AT KJHW AND ACROSS THE WESTERN SOUTHERN TIER...WHERE PERIODS OF LIGHT RAIN WILL BE POSSIBLE FROM TIME TO TIME. THERE WILL BE A SHARP GRADIENT IN CEILINGS ACROSS THE FORECAST AREA...GENERALLY RANGING FROM MVFR TO LOW VFR IN STRATUS/STRATOCU ACROSS FAR SOUTHWESTERN NY...TO VFR CIRRUS/UNLIMITED CEILINGS FROM KROC NORTHEAST ACROSS THE FINGER LAKES AND EASTERN LAKE ONTARIO REGION. AS FOR VSBYS...THOSE SHOULD GENERALLY BE VFR...WITH SOME OCCASIONAL RESTRICTIONS TO MVFR POSSIBLE ACROSS FAR SOUTHWESTERN NY. LOOKING FURTHER OUT...THE STALLED-OUT FRONTAL BOUNDARY TO OUR SOUTHWEST IS EXPECTED TO SLOWLY LIFT ACROSS WESTERN NEW YORK SOMETIME BETWEEN TUESDAY NIGHT AND WEDNESDAY NIGHT. WHILE THE EXACT TIMING OF THIS FRONTAL PASSAGE REMAINS IN QUESTION...IT WILL LIKELY BRING A MORE WIDESPREAD RISK OF SHOWERS AND THUNDERSTORMS TO THE AREA WHEN IT PASSES THROUGH...ALONG WITH THE CHANCE OF SOME MVFR-LEVEL RESTRICTIONS. && .MARINE... HIGH PRESSURE OVER ONTARIO WILL SHIFT TO WESTERN QUEBEC TONIGHT...WHILE A STATIONARY FRONT/LOW PRESSURE TROUGH REMAINS DRAPED FROM THE MIDWESTERN STATES EASTWARD ACROSS OHIO AND PENNSYLVANIA. AS THE HIGH TRACKS EAST TONIGHT...THE PRESSURE GRADIENT BETWEEN THESE TWO FEATURES WILL INCREASE...RESULTING IN INCREASING EAST TO NORTHEAST WINDS ACROSS THE LOWER LAKES. ON LAKE ONTARIO...WINDS WILL LIKELY INCREASE TO THE 15 TO 25 KNOT RANGE...RESULTING IN WAVES BUILDING TO 3 TO 6 FEET ALONG THE LAKESHORE BETWEEN THE NIAGARA RIVER AND IRONDEQUOIT BAY. WITH THESE CONDITIONS EXPECTED TO PERSIST THROUGH MUCH OF MONDAY BEFORE DIMINISHING AS THE PRESSURE GRADIENT RELAXES MONDAY EVENING...A SMALL CRAFT ADVISORY WILL BE IN EFFECT FOR THIS AREA FROM MIDNIGHT TONIGHT THROUGH MOST OF MONDAY EVENING. OTHERWISE...WINDS AND WAVES ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THROUGH TUESDAY. TUESDAY NIGHT INTO WEDNESDAY NIGHT...A WARM FRONT IS EXPECTED TO APPROACH AND CROSS THE AREA FROM SOUTHWEST TO NORTHEAST. THIS FEATURE WILL LIKELY BRING AN INCREASED RISK OF SHOWER AND THUNDERSTORM ACTIVITY TO THE AREA DURING THIS TIME FRAME. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 10 PM EDT MONDAY FOR LOZ043. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 11 PM EDT MONDAY FOR LOZ042. && $$ SYNOPSIS...RSH NEAR TERM...RSH/SAGE SHORT TERM...RSH LONG TERM...JJR AVIATION...JJR MARINE...JJR ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 125 PM EDT SUN AUG 19 2007 .SYNOPSIS... HIGH PRESSURE OFFSHORE WILL EXTEND WESTWARD ACROSS THE CAROLINAS THROUGH TUESDAY. WARM...HAZY AND HUMID CONDITIONS ARE EXPECTED MUCH OF THE WEEK. A WEAK COLD FRONT WILL ATTEMPT TO MOVE SOUTH FROM VIRGINIA INTO THE CAROLINAS BY THURSDAY...POSSIBLY PROVIDING TEMPORARY RELIEF. && .NEAR TERM /THROUGH TODAY/... EXTENSIVE CUMULUS FIELD NOW COVERING ALL MOST OF THE CWA WITH THE EXCEPTION OF THE FAR SOUTHERN COUNTIES. LATEST RUC AND GFS FOR THAT MATTER SHOW A LITTLE SEA BREEZE ACTIVITY THIS AFTERNOON. LATEST RADAR LOOPS DO SHOW A FEW RETURNS TRYING TO DEVELOP BUT VERY DRY MID LEVELS EVIDENT ON MORNING SOUNDINGS AND WATER VAPOR IMAGERY ARE INHIBITING ACTIVITY. OTHER THAN A TWEAK TO CLOUD COVER GRIDS...NO OTHER CHANGES. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... VERTICALLY STACKED HIGH PRESSURE FROM 700 MB UP THROUGH AT LEAST 200 MB WILL SIT OVER SOUTH CAROLINA THROUGH TUESDAY. THE HIGH WILL THEN SLOWLY RETROGRADE WEST WEDNESDAY. LARGE SCALE SUBSIDENCE AND SUBSEQUENT WARM DRY AIR ALOFT WILL ALSO KEEP CLOUDS AND PRECIPITATION AT A MINIMUM TONIGHT THROUGH TUESDAY. BELOW 850 MB...HIGH PRESSURE IS CENTERED OFFSHORE AND WILL KEEP A VERY CLIMATOLOGICAL SOUTH-SOUTHWESTERLY FLOW ACROSS THE CAROLINAS. AFTERNOON SEABREEZES WILL TRANSFER MOMENTUM INTO LOW LEVEL JETS EACH OF THE NEXT SEVERAL NIGHTS. THE ONLY EFFECT FROM THESE 20-30 KT LOW LEVEL JETS WILL BE WARM NIGHTS WITH 5-10 MPH SURFACE WINDS. BY WEDNESDAY...THE RETROGRESSION OF THE UPPER RIDGE WILL OPEN UP THE EASTERN CAROLINAS TO THE POSSIBILITY OF SLIGHT COOLING OF THE MID LEVELS WITH ANY UPPER LEVEL ENERGY ABLE TO DIVE SOUTH AROUND THE PERIPHERY OF THE RIDGE. WILL ONLY INTRODUCE 20 POPS AT THIS TIME ACROSS SOUTHEAST NC. THERE ARE SOME SUBTLE BUT SIGNIFICANT DIFFERENCES BETWEEN THE GFS AND NAM MODELS DEVELOPING LATE TUESDAY INTO WEDNESDAY. THE GFS IS MORE BULLISH PUSHING A RATHER STRONG VORT ACROSS NORTHERN NC WHICH DRIVES A SURFACE COLD FRONT INTO THE STATE. THE NAM IS MUCH WEAKER WITH THE VORT AND FARTHER NORTH WITH THE FRONT. AFTER COLLABORATION WITH WFO MHX...WE WILL FOLLOW THE NAM SOLUTION WHICH KEEPS THE FRONT TO THE NORTH. && .LONG TERM /THURSDAY THROUGH SATURDAY/... 595 DAM H5 RIDGE CENTERED NEAR SAV TO START THE PD. THIS FEATURE WILL SLOWLY RETROGRADE THROUGH THURSDAY AND THEN EXPAND SLIGHTLY BACK TO THE EAST WHILE REMAINING CENTERED OVER AL BY FRIDAY. THIS WILL MEAN A CONTINUATION OF ABV CLIMO TEMPS FOR MOST OF THE TIME. OPERATIONAL GFS BUILDS THE RIDGE MORE SHARPLY THAN MOST ENSEMBLE RUNS SO MEX STRINGS HAVE BEEN SLIGHTLY UNDERCUT. PRECIP CHANCES WILL BE MOST AFFECTED BY LOW LEVEL FEATURES GIVEN THE FAIRLY MINIMAL CHANGES IN THE UPPER PATTERN. PIEDMONT TROUGHINESS DEVELOPING SLOWLY ON WEDNESDAY WILL ACT TO IMPORT SOME LL AND MIDLVL MOISTURE BUT NOT ENOUGH TO WARRANT POPS EXCEPT FOR AT NIGHT. SLGT CHANCE POPS THEN SEEM TO BE PLAUSIBLE FOR THE REST OF THE WORK WEEK AS PW VALUES ARE AT OR SLIGHTLY ABV CLIMO BUT FORCING REMAINS QUITE WEAK. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... SOUTHEAST FLOW THIS AFTERNOON. CONVECTION TRYING TO FIRE WITH CUMULUS CONGESTUS FORMING AROUND THE AREA. THINK THUNDERSTORMS WILL BE ISOLATED ENOUGH TO LEAVE OUT OF THE TERMINALS FOR NOW. GOOD RADIATION AGAIN TONIGHT WILL BRING MVFR/IFR FOG AFTER 09Z. SEVERITY OF FOG WILL BE LEFT UP TO LATER TAFS. COULD ALSO SEE LIFR STRATUS AGAIN WITH THE WEAK ISENTROPIC LIFT. SOUTHWEST FLOW MONDAY MORNING...WITH A MVFR CEILING ALONG THE COAST POSSIBLE WITH GOOD LOW LEVEL MOISTURE. CONVECTION POSSIBLE TOWARD THE END OF THE FORECAST PERIOD. ISOLATED THUNDERSTORMS ON TUESDAY...SCATTERED WEDNESDAY AND THURSDAY. && .MARINE... NEAR TERM /THROUGH TODAY/... BUOY OBS SHOW ESE WINDS STILL A SOLID 15 KT...AS KLTX VWP INDICATES JETTING AROUND 20 KT AT 1000 FEET. SEAS RUNNING AROUND 3 FT...WITH A 17 SEC ESE SWELL STARTING TO SHOW UP. NOCTURNAL JETTING WILL WEAKEN AFTER DAYBREAK...ALLOWING WINDS TO VEER TO SE AS THE PATTERN BECOMES MORE SEABREEZE-DOMINATED. WILL KEEP CONDITIONS BELOW THRESHOLDS...CAPPING SPEEDS AT 15 KT AND SEAS AT 4 FT. SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... HIGH PRESSURE OFFSHORE WILL MAINTAIN A VERY CLIMATOLOGICAL SOUTH TO SOUTHWESTERLY WIND DIRECTION THROUGH THE PERIOD. WIND SPEEDS WILL INCREASE TO A SOLID 15 KNOTS EACH OF THE NEXT SEVERAL AFTERNOONS AND EVENINGS IN ASSOCIATION WITH THE SEABREEZE. STRONGEST WINDS ARE LIKELY TO BE LOCATED NEAR THE BEACHES BETWEEN THE HOURS OF 3 PM AND 9 PM. THE BIGGEST WEATHER IMPACT TO MARINERS OVER THE NEXT SEVERAL DAYS IS LIKELY TO BE SWELL FROM HURRICANE DEAN. THE WAVEWATCH MODEL WAS NEARLY PERFECT IN SHOWING THE 17-18 SECOND FORERUNNER SWELLS DEVELOPING YESTERDAY EVENING. IT NOW FORECASTS THE SWELL HEIGHT TO INCREASE TO 3-4 FT EVERY 10-12 SECONDS BY TUESDAY AND WEDNESDAY. THESE LONG PERIOD SWELLS WILL CARRY A LOT OF ENERGY AND WILL MAKE BAR AND INLET CONDITIONS QUITE ROUGH...PARTICULARLY AROUND LOW TIDE. SURFERS WILL ENJOY THE NICE SURF EXPECTED TUESDAY AND WEDNESDAY MORNINGS BEFORE THE SEABREEZE ADDS A WIND CHOP TO THE OCEAN. LONG TERM /THURSDAY THROUGH FRIDAY/... PRESSURE PATTERN QUITE TYPICAL OF AUGUST WITH HIGHEST VALUES IN THE WRN ATLANTIC AND A SWRLY FLOW LOCALLY. SERLY DEAN SWELL IS PROGGED TO BE ALL BUT GONE JUST BY THE START OF THE PD. GUIDANCE SHOWS A SECONDARY SWELL FRONT ARRIVE FROM THE EAST ON THURSDAY BUT THE GFS SEEMS TOO STRONG AND TOO FAR N WITH THE SFC WAVE/LOW AT THIS POINT. REGARDLESS...MOST OF THE PD WILL BE CHARACTERIZED BY SWRLY FLOW CAPPED AT 15 KT AND SEAS 2 TO 4 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...SHK NEAR TERM...SHK SHORT TERM...TRA LONG TERM...BACON AVIATION...HDL nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1220 PM EDT SUN AUG 19 2007 .SYNOPSIS... A WEAK FRONT ACROSS SOUTH CAROLINA WILL DISSIPATE THIS MORNING. HIGH PRESSURE OFFSHORE WILL EXTEND WESTWARD ACROSS THE CAROLINAS THROUGH TUESDAY. WARM...HAZY AND HUMID CONDITIONS ARE EXPECTED MUCH OF THE WEEK. A WEAK COLD FRONT WILL ATTEMPT TO MOVE SOUTH FROM VIRGINIA INTO THE CAROLINAS BY THURSDAY...POSSIBLY PROVIDING TEMPORARY RELIEF. && .NEAR TERM /THROUGH TODAY/... EXTENSIVE CUMULUS FIELD NOW COVERING ALL MOST OF THE CWA WITH THE EXCEPTION OF THE FAR SOUTHERN COUNTIES. LATEST RUC AND GFS FOR THAT MATTER SHOW A LITTLE SEA BREEZE ACTIVITY THIS AFTERNOON. LATEST RADAR LOOPS DO SHOW A FEW RETURNS TRYING TO DEVELOP BUT VERY DRY MID LEVELS EVIDENT ON MORNING SOUNDINGS AND WATER VAPOR IMAGERY ARE INHIBITING ACTIVITY. OTHER THAN A TWEAK TO CLOUD COVER GRIDS...NO OTHER CHANGES. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... VERTICALLY STACKED HIGH PRESSURE FROM 700 MB UP THROUGH AT LEAST 200 MB WILL SIT OVER SOUTH CAROLINA THROUGH TUESDAY. THE HIGH WILL THEN SLOWLY RETROGRADE WEST WEDNESDAY. LARGE SCALE SUBSIDENCE AND SUBSEQUENT WARM DRY AIR ALOFT WILL ALSO KEEP CLOUDS AND PRECIPITATION AT A MINIMUM TONIGHT THROUGH TUESDAY. BELOW 850 MB...HIGH PRESSURE IS CENTERED OFFSHORE AND WILL KEEP A VERY CLIMATOLOGICAL SOUTH-SOUTHWESTERLY FLOW ACROSS THE CAROLINAS. AFTERNOON SEABREEZES WILL TRANSFER MOMENTUM INTO LOW LEVEL JETS EACH OF THE NEXT SEVERAL NIGHTS. THE ONLY EFFECT FROM THESE 20-30 KT LOW LEVEL JETS WILL BE WARM NIGHTS WITH 5-10 MPH SURFACE WINDS. BY WEDNESDAY...THE RETROGRESSION OF THE UPPER RIDGE WILL OPEN UP THE EASTERN CAROLINAS TO THE POSSIBILITY OF SLIGHT COOLING OF THE MID LEVELS WITH ANY UPPER LEVEL ENERGY ABLE TO DIVE SOUTH AROUND THE PERIPHERY OF THE RIDGE. WILL ONLY INTRODUCE 20 POPS AT THIS TIME ACROSS SOUTHEAST NC. THERE ARE SOME SUBTLE BUT SIGNIFICANT DIFFERENCES BETWEEN THE GFS AND NAM MODELS DEVELOPING LATE TUESDAY INTO WEDNESDAY. THE GFS IS MORE BULLISH PUSHING A RATHER STRONG VORT ACROSS NORTHERN NC WHICH DRIVES A SURFACE COLD FRONT INTO THE STATE. THE NAM IS MUCH WEAKER WITH THE VORT AND FARTHER NORTH WITH THE FRONT. AFTER COLLABORATION WITH WFO MHX...WE WILL FOLLOW THE NAM SOLUTION WHICH KEEPS THE FRONT TO THE NORTH. && .LONG TERM /THURSDAY THROUGH SATURDAY/... 595 DAM H5 RIDGE CENTERED NEAR SAV TO START THE PD. THIS FEATURE WILL SLOWLY RETROGRADE THROUGH THURSDAY AND THEN EXPAND SLIGHTLY BACK TO THE EAST WHILE REMAINING CENTERED OVER AL BY FRIDAY. THIS WILL MEAN A CONTINUATION OF ABV CLIMO TEMPS FOR MOST OF THE TIME. OPERATIONAL GFS BUILDS THE RIDGE MORE SHARPLY THAN MOST ENSEMBLE RUNS SO MEX STRINGS HAVE BEEN SLIGHTLY UNDERCUT. PRECIP CHANCES WILL BE MOST AFFECTED BY LOW LEVEL FEATURES GIVEN THE FAIRLY MINIMAL CHANGES IN THE UPPER PATTERN. PIEDMONT TROUGHINESS DEVELOPING SLOWLY ON WEDNESDAY WILL ACT TO IMPORT SOME LL AND MIDLVL MOISTURE BUT NOT ENOUGH TO WARRANT POPS EXCEPT FOR AT NIGHT. SLGT CHANCE POPS THEN SEEM TO BE PLAUSIBLE FOR THE REST OF THE WORK WEEK AS PW VALUES ARE AT OR SLIGHTLY ABV CLIMO BUT FORCING REMAINS QUITE WEAK. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... SOUTHEAST FLOW WILL PREVAIL LATER TODAY...WITH VAD WIND PROFILE AND SKEW-T SHOWING MAINLY SOUTHEAST TO EAST FLOW AT MOST LEVELS BELOW 500 MPH. SOME ISOLATED SEA BREEZE ACTIVITY POSSIBLE AFTER 18Z...BUT NO TEMPO OR MENTION AT THIS TIME. MVFR OR POSSIBLE IFR FOG/STRATUS AGAIN TOWARD THE END OF THE FORECAST PERIOD. ISOLATED THUNDERSTORMS ON TUESDAY...SCATTERED WEDNESDAY AND THURSDAY. && .MARINE... NEAR TERM /THROUGH TODAY/... BUOY OBS SHOW ESE WINDS STILL A SOLID 15 KT...AS KLTX VWP INDICATES JETTING AROUND 20 KT AT 1000 FEET. SEAS RUNNING AROUND 3 FT...WITH A 17 SEC ESE SWELL STARTING TO SHOW UP. NOCTURNAL JETTING WILL WEAKEN AFTER DAYBREAK...ALLOWING WINDS TO VEER TO SE AS THE PATTERN BECOMES MORE SEABREEZE-DOMINATED. WILL KEEP CONDITIONS BELOW THRESHOLDS...CAPPING SPEEDS AT 15 KT AND SEAS AT 4 FT. SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... HIGH PRESSURE OFFSHORE WILL MAINTAIN A VERY CLIMATOLOGICAL SOUTH TO SOUTHWESTERLY WIND DIRECTION THROUGH THE PERIOD. WIND SPEEDS WILL INCREASE TO A SOLID 15 KNOTS EACH OF THE NEXT SEVERAL AFTERNOONS AND EVENINGS IN ASSOCIATION WITH THE SEABREEZE. STRONGEST WINDS ARE LIKELY TO BE LOCATED NEAR THE BEACHES BETWEEN THE HOURS OF 3 PM AND 9 PM. THE BIGGEST WEATHER IMPACT TO MARINERS OVER THE NEXT SEVERAL DAYS IS LIKELY TO BE SWELL FROM HURRICANE DEAN. THE WAVEWATCH MODEL WAS NEARLY PERFECT IN SHOWING THE 17-18 SECOND FORERUNNER SWELLS DEVELOPING YESTERDAY EVENING. IT NOW FORECASTS THE SWELL HEIGHT TO INCREASE TO 3-4 FT EVERY 10-12 SECONDS BY TUESDAY AND WEDNESDAY. THESE LONG PERIOD SWELLS WILL CARRY A LOT OF ENERGY AND WILL MAKE BAR AND INLET CONDITIONS QUITE ROUGH...PARTICULARLY AROUND LOW TIDE. SURFERS WILL ENJOY THE NICE SURF EXPECTED TUESDAY AND WEDNESDAY MORNINGS BEFORE THE SEABREEZE ADDS A WIND CHOP TO THE OCEAN. LONG TERM /THURSDAY THROUGH FRIDAY/... PRESSURE PATTERN QUITE TYPICAL OF AUGUST WITH HIGHEST VALUES IN THE WRN ATLANTIC AND A SWRLY FLOW LOCALLY. SERLY DEAN SWELL IS PROGGED TO BE ALL BUT GONE JUST BY THE START OF THE PD. GUIDANCE SHOWS A SECONDARY SWELL FRONT ARRIVE FROM THE EAST ON THURSDAY BUT THE GFS SEEMS TOO STRONG AND TOO FAR N WITH THE SFC WAVE/LOW AT THIS POINT. REGARDLESS...MOST OF THE PD WILL BE CHARACTERIZED BY SWRLY FLOW CAPPED AT 15 KT AND SEAS 2 TO 4 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...SHK SHORT TERM...TRA LONG TERM...BACON AVIATION...HDL nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 201 PM CDT MON AUG 20 2007 .SHORT TERM... PCPN CHANCES THE CONCERN TONIGHT-TUESDAY. FOR THE MOST PART OUR FCST AREA SPLIT IN-BETWEEN THE MAIN 500 MB LOW IN SASK AND THE REAL JUICY AND UNSTABLE AIR LOCATED FROM NEBRASKA INTO IOWA. THUS THINK MOST SIGHTS VALLEY AND EAST INTO MN WILL MEASURE RAINFALL TONIGHT (MAINLY THIS EVE) IT WILL NOT BE MUCH AND MORE SHOWERY VERSUS THUNDER AS INSTABILITY IS RATHER WEAK ALOFT (HOWEVER RUC DOES SHOW -2 SHOWWALTERS THIS EVE). AT 18Z SFC MAP SHOWS TROUGH LOCATED WEST OF MOT-BIS LINE AND MOVEMENT IS MORE ALONG THE LINE OF THE SLOWER NAM VERSUS THE FASTER GFS FROM 00Z AND 06Z RUNS EARLIER TODAY. WATER VAPOR SHOWS MAIN VORT NORTH OF THE BORDER WITH A VORT LOBE SOUTHEAST INTO NW/WCNTRL ND ATTM. WITH THE SLOWER TIMING CORRECT...STUCK WITH NAM TIMING TONIGHT WHICH WOULD BRING VORT LOBE INTO ERN ND 00Z THE VALLEY 00Z-02Z AND THEN BDE-BJI AREAS NR 06Z. TROUGH ITSELF IN THE PRESSURE FIELD WILL FOLLOW THIS TIME AS WELL...BUT NOT EXPECTING A BIG WIND SHIFT TONIGHT DUE TO LIGHT SFC WINDS AND LIMITED MIXING FROM 850 MB. WILL PROBABLY SEE SOUTHEAST WINDS GO LIGHT SOUTH BEHIND TROUGH...AND WITH DEW PTS HOLDING IN THE 50S OR AROUND 60 TONIGHT COULD WELL SEE AREAS OF FOG FORM. BEST BET WILL BE IN THE RED RIVER VALLEY AS CLEARING MAY OCCUR BRIEFLY OVERNIGHT AND DEW PTS REMAIN HIGH. FOG ALSO PSBL IN ERN CWA AS AIRMASS IS SATURATED AND THIS IS WHAT OCCURRED IN CNTRL MN MON AM. ON TUESDAY THE WINDS WILL TURN MORE WESTERLY AS WINDS MIX UP TO 850 MB. 500 MB UPPER LOW WILL BE OVER CNTRL MANITOBA...WITH -16C 500 MB TEMPS OVER NRN ND/NW MN. NAM SOUNDINGS WOULD SHOW CONVECTIVE TEMPS AROUND 80 AND THIS LIKELY TO BE REACHED...AND WITH ENOUGH LINGERING LOW LEVEL MOISTURE VALLEY EASTWARD INTO MN COULD SEE ISOLD AFTN TSTM ACTIVITY. INCLUDED SOME IN GRIDDS TO BLEND WITH FCSTS FROM DLH AND MPX. HIGH PRESSURE AND DRIER AIR WILL MOVE IN TUES OVERNIGHT AND WEDNESDAY. WITH 850 MB TEMPS SHOWING LITTLE COOLING TUESDAY OR WEDNESDAY WOULD EXPECT TEMPS TO REACH 80 OR SO. .LONG TERM (FRI-MON) A DRY/ZONAL FLOW WILL DOMINATE THE WEATHER PATTERN THROUGH THIS PERIOD. THERMAL FIELDS WILL REMAIN SLIGHTLY BELOW NORMAL INITIALLY...WITH SOME WARMING BY SUNDAY WITH SLIGHTLY BUILDING HEIGHTS OVER THE CENTRAL PLAINS. THE NEXT CHANCE AT SOME PRECIP MAY BE NEXT MONDAY AHEAD OF A FRONT...BUT CONFIDENCE IN TIMING/STRENGTH AND DEPTH OF MOISTURE THIS FAR OUT IS IN QUESTION. THEREFORE...WILL KEEP THE EXTENDED DRY WITH MOST SYSTEMS LATELY HAVING MOISTURE TAPPED FROM STORMS WELL TO THE SOUTH. && .AVIATION... A LARGE AREA OF IFR/LIFR CONDITIONS CONTINUES TO ADVECT NORTH THIS AFTERNOON. THERE WILL ALSO BE A BAND OF SHOWERS WITH EMBEDDED THUNDER MOVING FROM WEST TO EAST THROUGH THIS EVENING. HAVE KEPT TSRA MENTION OUT OF GFK...BUT THERE COULD BE A FEW RUMBLES CLOSE. FOG COULD BECOME AN ISSUE OVERNIGHT AT ALL TAF SITES NEAR THE SFC TROUGH ONCE WINDS BECOME LIGHT SOUTHERLY. IF CLEARING CAN DEVELOP NEAR THE TROUGH BEHIND THE LINE OF CONVECTION...THEN IFR/LIFR CONDITIONS WILL PERSIST INTO TUESDAY MORNING BEFORE DRIER SOUTHWEST SFC WINDS DEVELOP AROUND 15Z. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ RIDDLE/DK nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 137 PM EDT MON AUG 20 2007 .SYNOPSIS... A WARM FRONT WILL LIFT NORTHEAST INTO THE LOWER GREAT LAKES TODAY. WARM...MOIST AIR ACROSS THE REGION WILL RESULT IN SHOWERS AND THUNDERSTORMS. FOR TONIGHT...THE REMNANTS OF TROPICAL STORM ERIN WILL MOVE ACROSS THE AREA...BRINGING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... OPERATIONAL MODELS ARE IN FAIRLY DECENT AGREEMENT IN TERMS OF SYNOPTIC SCALE FEATURES. THUS...WILL USE A BLEND OF THESE...AND THE LATEST RUC40 MODEL FOR THE NEAR TERM. A WARM FRONT EXTENDED FROM THE MIDDLE MS RIVER VLY INTO THE LOWER OHIO VALLEY EARLY THIS MORNING. THIS FRONT IS FORECAST TO LIFT NE INTO THE LOWER GREAT LAKES BY THIS AFTN. MOSAIC RADAR CONTINUES TO INDICATE THAT THE BEST COVERAGE OF SHOWERS AND THUNDERSTORMS ARE NORTH OF THIS BOUNDARY ACRS NE IL...NRN IN...SRN LOWER MICHIGAN AND NRN OHIO. THIS IS WHERE THE BEST 925 MB-850 MB LOW LVL CONVERGENCE/FORCING IS OCCURRING. THIS FORCING IS EXPECTED TO LIFT SOME TO THE NE BY THIS AFTERNOON. THUS...WIDESPREAD SYNOPTIC SCALE PCPN IS NOT EXPECTED ACRS OUR REGION THIS MORNING. FOR THIS AFTN...MODELS CONTINUE TO DESTABILIZE THE ATMOSPHERE. THIS DESTABILIZATION...ALONG WITH THE APCH OF AN UPR LVL S/WV FROM THE WEST...WILL RESULT IN MAINLY SCATTERED CONVECTION. WITH HIGH PRECIPITABLE WATER VALUES NEAR 2 INCHES...ANY THUNDERSTORM WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL. SINCE THE MORE WIDESPREAD AND PROLONGED PERIOD OF PCPN IS EXPECTED OVERNIGHT WITH THE REMNANTS OF TROPICAL STORM ERIN...HAVE OPTED TO ISSUE FLOOD WATCH FOR THIS PERIOD. MORE ON THIS TOPIC WILL BE DISCUSSED IN THE SHORT TERM SECTION. AS FOR TEMPERATURES TODAY...IT SHOULD NOT TAKE MUCH SUNSHINE TO BOOST TEMPERATURES INTO THE 80S AND PERHAPS LOWER 90S. THUS...HAVE LEFT PREVIOUS FCSTERS HIGHS IN TACT. FINALLY...SPC HAS THE ENTIRE REGION UNDER A SLIGHT RISK FOR SEVERE THUNDERSTORMS TODAY INTO TONIGHT. THE PRIMARY THREAT WILL BE LARGE HAIL AND DAMAGING THUNDERSTORM WINDS. IF THIS TRANSPIRES...IT WILL LIKELY BE FROM MID AFTN INTO EARLY EVENING. NO UPDATE IS NEEDED LATE THIS MORNING. EXPECT CONVECTION TO BECOME MORE WIDESPREAD THIS AFTERNOON AS FORECAST. WILL MONITOR TEMPERATURES SINCE CVG HAS BEEN EASILY REACHING 90 SO WE MAY NEED TO BUMP UP THE FORECAST A COUPLE DEGREES IN A LATER UPDATE. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... THE REMNANTS OF TROPICAL STORM ERIN ARE EXPECTED TO PASS ACROSS THE REGION OVERNIGHT. THE BEST LOW LVL FORCING AND UPR DYNAMICS ARE EXPECTED MAINLY ALONG AND NORTH OF THE OHIO RIVER. HOWEVER...GIVEN THAT THERE IS STILL SOME UNCERTAINTY IN THE EXACT TRACK AND POSSIBLE MESOSCALE INTERACTIONS...HAVE OPTED FOR HIGH POPS EVEN SOUTH OF THE OHIO RIVER. THIS SYSTEM WILL BE ACCOMPANIED WITH HIGH PRECIPITABLE WATER VALUES IN EXCESS OF 2 INCHES. THUS...DESPITE THE REGION BEING IN A DROUGHT SITUATION...ANY HEAVY RAINFALL ON DRY...HARD SOILS CAN STILL LEAD TO POTENTIAL FLOODING PROBLEMS. HENCE...HAVE ISSUED A FLOOD WATCH FOR THE ENTIRE REGION. THE REMNANTS OF ERIN WILL MOVE EAST OF THE REGION ON TUESDAY. CHANCES OF SHOWERS AND THUNDERSTORMS WILL DECREASE RAPIDLY FROM WEST TO EAST BETWEEN THE 10Z AND 15Z TIME FRAME. HAVE LEFT A CHC FOR SHOWERS AND THUNDERSTORMS IN THE AFTN GIVEN THAT THE AIRMASS WILL DESTABILIZE ONCE AGAIN...AND THERE IS STILL THE POTENTIAL FOR WEAK IMPULSES IN THE FLOW ALOFT TO ACT AS A TRIGGERING MECHANISM. FOR TUESDAY NIGHT...SKIES WILL BECOME PARTLY CLOUDY. THERE WILL STILL BE A SMALL RISK OF A SHOWER OR THUNDERSTORM. LOWS TONIGHT WILL REMAIN WARM DUE TO THE HUMID AIRMASS...MAINLY IN THE UPPER 60S TO LOWER 70S. HIGHS ON TUESDAY WILL RANGE FROM THE LOWER 80S NE TO NEAR 90 ALONG AND SOUTH OF THE OHIO RIVER. LOWS TUESDAY NIGHT WILL AGAIN RANGE FROM THE UPPER 60S TO LOWER 70S. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... A FRONTAL BOUNDARY WILL REMAIN MAINLY TO THE NORTH OF OUR REGION THROUGH THE END OF THE WORK WEEK AS MID/UPPER LEVEL RIDGING BUILDS NORTHWARD FROM THE SOUTH. THIS WILL CONTINUE TO KEEP OUR FA ON THE EDGE OF BETTER CHANCE OF PCPN...AND WITH FA IN THE WARM SECTOR...WILL TRY TO LIMIT POPS TO 20 PERCENT OR LESS WEDNESDAY THROUGH FRIDAY. RIDGE WILL BREAK DOWN OVER THE WEEKEND WITH ASSOCIATED COLD FRONT MOVING ACROSS OUR AREA...LEADING TO A BETTER CHANCE OF THUNDERSTORMS FOR SATURDAY. GFS ENSEMBLE MEAN STILL NOT AS AGGRESSIVE AS THE OPERATIONAL GFS AND ECMWF BUILDING RIDGE UP INTO OUR SOUTHERN FA THROUGH LATE IN THE WEEK. AS A RESULT...WILL GO AHEAD AND TWEAK HIGH TEMPS UP A DEGREE OR TWO...PARTICULARLY FOR WEDNESDAY THROUGH FRIDAY. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... FIRST 2 HOURS OF FORECAST ARE VFR. CONDITIONS ARE DETERIORATING RAPIDLY WITH SCATTERED CONVECTION BEGINNING ALREADY NEAR DAY AND ILN. CMH AND LCK CAN ANTICIPATE SCATTERED CONVECTION WITH TEMPORARY MVFR VISIBILITIES STARTING AT 20Z. CVG AND LUK CAN EXPECT SCATTERED CONVECTION WITH TEMPORARY MVFR VISIBILITIES STARTING BY 23Z. WIDESPREAD CONVECTION WILL BRING VISIBILITIES AS LOW AS IFR AND MVFR CEILINGS TO ALL TAF SITES TONIGHT ESPECIALLY BETWEEN 04Z AND 10Z. THOUGH DAY ILN CMH AND LCK WILL RETAIN MVFR CEILINGS...SOME IMPROVEMENT WILL OCCUR AFTER 12Z WITH VFR FORECAST AT CVG AND LUK OUTLOOK...TSTMS POSSIBLE TUESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...FLOOD WATCH FROM 6 PM EDT THIS EVENING THROUGH LATE TONIGHT FOR OHZ026-034-035-042>046-051>056-060>065-070>074- 077>082-088. KY...FLOOD WATCH FROM 6 PM EDT THIS EVENING THROUGH LATE TONIGHT FOR KYZ089>100. IN...FLOOD WATCH FROM 6 PM EDT THIS EVENING THROUGH LATE TONIGHT FOR INZ050-058-059-066-073>075-080. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION... oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 648 AM EDT SUN AUG 19 2007 .SYNOPSIS... A WARM FRONT WILL LIFT NORTHEAST FROM THE LOWER OHIO VALLEY INTO THE LOWER GREAT LAKES TODAY. THIS FRONT WILL REMAIN ACROSS THE REGION INTO THE FIRST PART OF THE WEEK...ACTING AS A FOCUS FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A WARM FRONT ACRS THE MID MS AND LOWER OHIO RIVER VLY WILL LIFT SLOWLY NE TOWARD THE LOWER GREAT LAKES TODAY. WARM...MOIST ASCENT WAS OCCURRING WELL NORTH OF THIS BOUNDARY INTO THE UPR MIDWEST AND LOWER GREAT LAKES REGION THIS MORNING. MOSAIC RADAR WAS SHOWING A BAND OF PCPN FROM SRN MN SE INTO NRN OHIO. WILL USE A BLEND OF THE OPERATIONAL NAM-WRF AND LATEST RUC40 MODELS FOR THE NEAR TERM FCST AS THEY ARE CAPTURING THE CURRENT PCPN BAND THE BEST. STILL LOOKS LIKE THE MAJORITY OF THE PCPN...ELEVATED IN NATURE...WILL JUST SKIM OUR FAR NORTH THIS MORNING. BY THIS AFTN...WEAK EMBEDDED S/WVS IN THE WNW FLOW ALOFT MAY TRIGGER SOME MORE SHOWERS AND THUNDERSTORMS ACRS THE NORTH. THE REMAINDER OF THE REGION SHOULD REMAIN MAINLY DRY THROUGH LATE AFTN EXCEPT THE SW WHERE A SMALL CHC OF SHOWERS AND THUNDERSTORMS HAVE BEEN PLACED IN THE FCST DUE TO AN APCHING S/WV AND INCREASING INSTABILITY. TEMPERATURES WILL BE CLOUD AND PCPN DEPENDENT...AND WILL REQUIRE SOME SHORT TERM ADJUSTMENTS. FOR NOW...HAVE TAILORED HIGHS FROM THE UPPER 70S NORTH TO THE UPPER 80S SOUTH. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... A VERY COMPLEX WEATHER PATTERN WILL BE SETTING UP ACRS THE REGION THROUGH TUESDAY. AFOREMENTIONED WARM FRONT WILL STALL OUT AS A STATIONARY BOUNDARY LATE TONIGHT INTO MONDAY NIGHT. EMBEDDED S/WV IMPULSES WILL RIPPLE WITHIN THE WNW FLOW ALOFT ACRS THIS BOUNDARY. TO ADD INSULT TO INJURY...LATEST OPERATIONAL MODELS ARE NOW BRINGING THE REMNANTS OF TROPICAL STORM ERIN INTO THE OHIO VALLEY REGION LATE MONDAY NIGHT INTO TUESDAY. DEEP MOISTURE FROM ERIN IS FCST TO GET DRAWN NE INTO OUR AREA ON MONDAY...AND WILL BE ENTRENCHED ACRS THE REGION MONDAY NIGHT INTO TUESDAY. THE COMBINATION OF DEEP MOISTURE EMBEDDED S/WVS...AND LOW LVL CONVERGENCE IN THE VCNTY OF FRONTAL BOUNDARY WILL BRING A HIGH LIKELIHOOD FOR SHOWERS AND THUNDERSTORMS THROUGH THE SHORT TERM PERIOD. THE BEST CHC IS EXPECTED TO OCCUR ACRS THE NRN TWO THIRDS OF THE CWFA ON MONDAY IN CLOSER PROXIMITY TO THE FRONTAL BOUNDARY. HAVE INCREASED POPS TO THE LIKELY CATEGORY FOR THE ENTIRE REGION MONDAY NIGHT AS THE REMNANTS OF ERIN MOVES SLOWLY INTO THE REGION. HAVE INCREASED POPS TO HIGH CHANCE ON TUESDAY AS THE REMNANTS OF ERIN SLOWLY EXIT THE REGION. GIVEN THE PROSPECT OF HEAVY RAIN...HAVE PLACED THIS WORDING IN THE FCST. OUR AREA CONTINUES TO BE UNDER A MODERATE TO SEVERE DROUGHT...SO WILL NOT BE ISSUING ANY HEADLINES IN TERMS OF FLASH FLOOD/FLOOD WATCHES ATTM. HOWEVER...IF WIDESPREAD PCPN MATERIALIZES ON MONDAY...THIS MAY HAVE TO BE RECONSIDERED FOR MONDAY NIGHT INTO TUESDAY AS 1 AND 3 HOUR FLASH FLOOD GUIDANCE VALUES POTENTIALLY DECREASE FROM HEAVY RAIN ON MONDAY. TEMPERATURES WILL BE QUITE DIFFICULT GIVEN THE AMOUNT OF CLOUDS AND PCPN. MAV MOS GUIDANCE CONTINUES TO BE MUCH COOLER THAN THE MET MOS. HAVE LEANED MORE TOWARD THE COOLER MAV MOS. AGAIN...SHORT TERM TEMPERATURE ADJUSTMENTS WILL LIKELY BE NEEDED THROUGH THE PERIOD...PARTICULARLY FOR THE DAYLIGHT HOURS. AS A FINAL NOTE...SPC HAS THE SWRN PART OF OUR FCST AREA IN A SLIGHT RISK FOR SEVERE STORMS ON MONDAY. THIS WILL BE HIGHLY DEPENDENT ON HOW UNSTABLE THE ATMOSPHERE CAN GET AMIDST CLOUD COVER. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... MID/UPPER LEVEL RIDGE OVER THE SOUTHERN UNITED STATES WILL SLOWLY BUILD NORTHWARD THROUGH THE END OF THE WORK WEEK. THIS WILL TEND TO KEEP OUR FA ON THE SOUTHERN FRINGE OF THE MORE ACTIVE WESTERLY FLOW AFFECTING THE GREAT LAKES. AS A RESULT...WILL GENERALLY KEEP POPS IN THE 20 PERCENT RANGE THROUGH FRIDAY...WITH THE BEST CHANCE ACROSS OUR NORTHERN FA. MODELS INDICATING THAT THE RIDGE WILL BEGIN TO BREAK DOWN TOWARD NEXT WEEKEND...BRINGING A BETTER CHANCE OF PCPN BY SATURDAY. AS HIGH BUILDS SLOWLY NORTH ACROSS OUR AREA...WE SHOULD ALSO SEE A GRADUAL WARM UP IN TEMPERATURES THROUGH FRIDAY. 06Z AND 12Z OPERATIONAL GFS ARE STRONGER WITH THE RIDGE AND THUS WARMER THAN THE 00Z GFS ENSEMBLE WEDNESDAY THROUGH FRIDAY. WILL THEREFORE TREND TEMPS A TAD COOLER THAN MOS THROUGH FRIDAY. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... LARGE AREA OF -SHRA/TSRA NORTH OF A WARM FRNTL BNDRY EXTNDG FROM UPR MISSISSIPPI VLY SE INTO CNTRL/LOWER GRT LKS. WITH WELL DEFINED 850 LLJ BACK ACRS IOWA/MINNESOTA HELPING TO INITIATE NEW CONVECTIVE DVLPMNT IN THESE AREAS...CONVECTION WILL CONTINUE TO PROPAGATE SE ALONG WARM FRONT INTO LWR MICHIGAN/NRN PORTIONS OF INDIANA AND OHIO TODAY. THIS MAIN AREA OF PCPN SHOULD REMAIN FOCUSED NORTH OF THE TERMINALS ACRS NRN OHIO IN CLOSER PROXIMITY TO THE FRNTL BNDRY ALL DAY. MODEL SOUNDINGS CONTINUE TO SHOW DRIER AIR WITHIN THE BNDRY LYR HANGING INTO THE AFTN HOURS. WHILE THERE WILL BE SOME SUNSHINE...ESPECIALLY AT KCVG AND KLUK...EXPECT MSTLY CLDY SKIES FOR MUCH OF THE DAY WITH PREDOMINANT AC DECK BTWN 10-15KFT. AS DEEPER MOISTURE BEINGS TO SLOWLY ADVECT INTO THE REGION FROM THE SOUTHWEST DURING THE AFTN/EVNG HOURS AND WEAK MID LVL S/WV PASS THRU REGION...EXPECT WDLY SCT -SHRA/TSRA WILL DVLP. BULK OF THE PCPN WILL AGAIN REMAIN LARGELY NORTH OF THE TERMINALS TONIGHT....FOCUSED NORTH OF THE WARM FRONT DRAPED ACRS REGION. HAVE BROUGHT SOME SCT SC/CU AFT 00Z BUT WITH PCPN COVERAGE REMAINING WDLY SCT AT BEST UNTIL LAST SVRL HOURS OF FCST...WILL KEEP ANY PCPN MENTION OUT OF KDAY/KCMH/KLCK ATTM. OUTLOOK...TSTMS POSSIBLE MONDAY AND TUESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...LOTT AVIATION...RYAN oh AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 1104 AM CDT MON AUG 20 2007 .DISCUSSION... STORMS STRENGTHENED A BIT THIS MORNING WITH SOME ISOLATED WIND DAMAGE OVER PARTS OF NORTHWEST IOWA BETWEEN ABOUT 900 AM CDT AND 1030 AM CDT. THIS WAS ON TOP OF WIDESPREAD HEAVY RAIN AND FLASH FLOODING OVER PARTS OF SW MN AND NW IA. FOR THIS AFTERNOON...BIG QUESTION ON HOW MUCH WE CAN RECOVER BEHIND ONGOING MCS. NGH PROFILER WINDS AT 15Z IN 925-850MB LAYER RUNNING ABOUT 240-260 DEGREES WHILE 12Z NAM ABOUT 190 DEGREES AND 12Z RUC ABOUT 200 DEGREES. SO...INCOMING STRONG WAVE WILL NEED TO DO SOME WORK TO BACK THE LOW LEVEL WIND FIELD TO THE VERY SUPPORTIVE SEVERE ENVIRONMENT THAT BOTH MODELS INDICATE. WITH THIS IN MIND...BELIEVE THAT THE BULK OF THE SEVERE POTENTIAL WILL BE ALONG THE FAR SOUTHERN CWA INTO NORTHWEST IOWA...WHICH IS WHERE THE EXPECTED LOCATION OF THE NEAR SFC BOUNDARY SHOULD BE. WILL ALSO HAVE SOME ISSUES WITH THE CAP...BUT WITH A STRONG WAVE COMING IN...BELIEVE THAT THIS WILL BE OVERCOME. AND WITH 4000 J/KG CAPE VIA A STRONG DRY PUNCH IN THE MID LEVELS AND DECENT SHEAR...SEVERE STORMS ARE LIKELY. AND WITH LOW LCL`S...WOULD EXPECT TORNADOES TO BE AN ISSUE AS WELL. WILL SLOW HEATING IN THE EAST A LITTLE. 08 && .AVIATION... SCATTERED IFR AND MVFR CONDITIONS DEVELOPING BEHIND MCS. WILL ALSO SEE POTENTIAL FOR SEVERE THUNDERSTORMS...ESPECIALLY NEAR KSUX...LATE THIS AFTERNOON AND EARLY THIS EVENING. && .PREV DISCUSSION... ANOTHER UPR IMPULSE PUSHING ACRS THE DKTS THIS MORNING...AND SFC BNDRY REALLY NOT IN A PLACE ALL THAT DIFFERENT FROM YDA AT THIS TIME. SAME OLD SOPPY ATMOSPHERE AS WELL. NICE COMPLEX OF STORMS CONTINUES TO EAST...INEXPLICABLY IN WELL IN WAKE OF EXITING WAVE AND BENEATH STRONG DRYING PUSH ALFT. LKLY THAT THIS HELPED TO DESTABILIZE AREA OF TRAILING BNDRY...AND WITH NLG PROFILER/FSD VWP CONTINUING TO SHOW A CLASSIC WAA PATTERN...REGENERATION HAS CONTINUED UNTIL EFFECT OF UPSTREAM WAVE CLOSING IN. MAIN CONCERNS AGAIN SURROUND CONVECTIVE NATURE NEXT SEVERAL DAYS...SPECIFICALLY HEAVY RAINFALL THREAT... AND THEN AN INCREASING THREAT FOR SEVERE STORMS AS MID LVL WNDS STRENGTHEN WITH APPROACHING UPR TROUGH. ELEVATED STORMS ALSO WL PUSH FROM CNTRL INTO ERN SD THIS MORNING... FAIRLY WELL TIMED WITH 750ISH THETA E ADVECTION. SHUD SEE ACTIVITY BE FAIRLY PERSISTENT MOVING EWRD AS NO SIGNS THAT THETA E ADVECTION WL CEASE...ESPLY THRU NRN CWA...BUT SOME DECREASING INTENSITY WITH PROGRESS. LKLY TO LINK UP WITH FORMER MENTIONED I90 CONVECTION. HOWEVER...ITS WAVE SEEN OVER YELLOWSTONE VCNTY THAT WL BE THE BIG PLAYER FOR AFTN CONVECTIVE THREAT. PLUME OF STEEP MID LVL LAPSE RATES FOLLOWING MORNING WAVE...WHICH SHUD SLOW UP CONVECTION FOR A TIME BEHIND FEATURE. INSTABILITY WL BECOME QUITE FORMIDIBLE... ESTIMATED 3-4KJ/KG CAPE WITH DEEP AND DISTRIBUTED SHEAR OF ARND 50 KTS. CONCERN AREA IS SPECIFIALLY FAR SERN SD...NERN NEBRASKA...AND MOST OF NW IA AND I90 AREA OF SW MN...WITH GREATEST THREAT TOWARD KSUX AREA. SHEAR/THERMO PARAMETERS INDICATE THAT IN ADDITION TO VERY LARGE HAIL AND DAMAGING WIND THREAT WITH DISCRETE SUPERCELLS... WL ALSO HAVE TO GIVE SERIOUS WATCH TO TORNADIC THREAT NR BOUNDARIES WITH SFC WAVE IN NERN NEBRASKA ENHANCING THREAT LOCALLY. FFG HAS BEEN PUMMELLED BY REPEATED HEAVY RAINS ACRS AREAS OF SW MN AND NW IA LAST COUPLE DAYS...LOW ENOUGH THAT EVEN A MODEST WARM CLOUD STORM COULD EASILY FORCE THE ISSUE. WENT AHEAD AND ISSUED FFA FOR MUCH OF SW MN AND ERN PORTIONS OF NW IA FOR AFTN/TONIGHT. THIS DOES NOT MEAN THRAT DOES NOT EXIST THIS MORNING FOR MORE LOCALIZED AREA...AND THAT WOULD BE THE REGENERATIVE AREA ALONG THE I90 CORRIDOR IN SW MN. PCPN SHUD VASTLY TAPER OFF AFTER MIDNIGHT... LAST IN FAR ERN AREAS...AS CONDITIONS STABILIZE FOR THE MOMENT. HERCULEAN TASK TO TRY AND PIN DOWN ANYTHING AFTER TONIGHT...AS GUIDANCE DIVERGING TO A POINT THAT BOUNDARY LOCATION AND WAVE TIMING DOES NOT MATCH RUN TO RUN AND MODEL TO MODEL IN THE LEAST BIT. FOR THE MOST PART...DID NOT OFFER UP A GREAT DEAL OF CHANGE TO THE GRAND SENSE OF THE FCST BEYOND THIS POINT. ANOTHER STRONG IMPULSE LOOKS TO SWING THRU CYCLONIC UPR FLOW ON TUE AFTN/EVNG...AND DEPENDING IF MAIN BNDRY IS WELL TO NW AT 00Z WED PER EC/NAM...WELL S PER UK/GFS...OR BISECTING CWA PER CANADIAN...WL VASTLY DETERMINE DISTRIBUTION OF CONVECTION AS WELL AS SVR THREAT. FOR THE TIME... KEPT THE MINORITY BUT MIDDLE OF THE ROAD APPROACH...WHICH WOULD AGAIN BRING HEAVY RAINFALL THREAT FOR MUCH OF SERN 1/3 OF CWA... AS WELL AS A STRONG SEVERE WEATHER THREAT FOR MAINLY EVNG...AS CAPPING AHEAD OF NEXT WK SHUD KEEP DAMPER ON ACTION UNTIL WAVE APPROACHES LATE IN DAY. WL HAVE TO WATCH FOR HEAVY RAIN THREAT AGAIN WED NIGHT THRU SRN AREAS...WITH STALLING BNDRY JUST TO S...SETTING UP A GOOD JET ENTRANCE DYNAMICAL SITUATION. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...FLASH FLOOD WATCH FROM 1 PM CDT THIS AFTERNOON THROUGH LATE TONIGHT FOR IAZ002-003-013-014-022. MN...FLASH FLOOD WATCH FROM 1 PM CDT THIS AFTERNOON THROUGH LATE TONIGHT FOR MNZ071-072-080-081-089-090. NE...NONE. SD...NONE. && $$ CHAPMAN sd AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD...CORRECTED 1145 PM CDT SUN AUG 19 2007 .DISCUSSION... THUNDERSTORMS HANGING ON NW IA THIS EVENING NEAR A STALLED OUT BNDRY. THIS ACTIVITY SHOULD SLOWLY WANE THROUGH THE EVENING HOURS. ALTHOUGH THESE STORMS ARE IN AN AREA OF RECENTLY HEAVY RAINS...NOT OVERLY CONCERNED WITH FLASH FLOODING THE REMAINDER OF THE EVENING...AS CONVECTION IS WEAK AND STORM COVERAGE IS RATHER SMALL...BUT SOMETHING TO WATCH. AT LEAST SMALL CHANCES FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE NIGHT AS BROAD ISENTROPIC ASCENT WILL PERSIST IN SW MN AND NW IA. THUNDERSTORMS HAVE ONCE AGAIN FORMED OVER THE NRN ROCKIES THIS EVENING AHEAD OF A STRONGER SHORT WAVE MOVE THROUGH THE PAC NW. MOST OF THIS WAVE WILL LIFT N INTO CANADA...HOWEVER SOME ENERGY WILL SPILL E...BREAKING DOWN SW RIDGE OVER THE CNTRL PLNS. ATTM STORMS ABOUT TO CROSS INTO SD FROM WY. THESE ACTIVITY WILL LIKELY CONTINUE EWRD MOVEMENT OVERNIGHT. BEST GUESS AT TIMING WOULD BRING THUNDER INTO THE JAMES RIVER VALLEY SOMETIME AROUND 3 AM. NO SEVERE STORMS EXPECTED...JUST THE POTENTIAL FOR SOME HEAVY RAIN. FLOOD THREAT IS MINIMAL AS STORM SHOULD MOVE EAST A FAST ENOUGH CLIP...THAT HEAVY RAIN WOULD MAINLY BE SHOT LIVED. BETTER POTENTIAL FOR FLOODING RAINS INTO ERN AREAS TOMORROW EVENING. THE OTHER THING TO WATCH TONIGHT IS THE FOG. MANY AREAS NORTH OF THE SFC FRONT ALREADY REPORTING FOG THIS EVENING. SOME PLACES IN SW MN AOB 1/4 SM...ALTHOUGH THIS IS MAINLY LOCALIZE ALONG UPSLOPE/ERN SIDE OF BUFFALO RIDGE. WILL MONITOR FOR A DENSE FOG ADVISORY...BUT AFTER LOOKING AT MODEL PROGGED SOUNDING...WOULD LIKE TO SEE LESS MOISTURE ABOVE INVERSION LAYER TO PRODUCE WIDESPREAD DENSE FOG. ALSO...ANY STORMS LATER TONIGHT SHOULD SHAKE UP THE BNDRY LAYER. && .AVIATION... IFR CONDITIONS EXPECTED NORTH OF I90 FOR THE REMAINDER OF THE NIGHT. EXPECT THESE LOW CLOUDS TO MOVE INTO FSD AND DROP CIGS BLO 1000 FT THIS EVENING. CIGS ARE EXPECTED TO REMAIN ABOVE 3000 FT IN KSUX EARLY TONIGHT...HOWEVER AS WINDS LIGHT AND WITH AMPLE MOISTURE...AM CONCERNED ABOUT FOG FORMATION. EXPECTATION ALL TAF SITES WILL HAVE VSBYS FALL BLO 5 SM. AT KFSD...NEAR THE SURFACE BNDY AND IN THE WARM SECTOR AT KSUX...VSBYS MAY DROP BLO 1SM FOR A PERIOD LATE TONIGHT. CONVECTION DEVELOPING OVER WY AT THIS TIME IS EXPECTED TO REACH ERN SD BY 12Z AND IS EXPECTED TO REMAIN N OF KSUX. A STRONG WAVE AND FRONT WILL APPROACH DURING THE AFTERNOON. WHILE EFFECTS OF MORNING CONVECTION IS EXPECTED TO KEEP PRECIP NORTH OF KHON...HAVE ADDED CHC OF TSRA AT KSUX AND KFSD AFTER 20Z. && .PREV DISCUSSION... MORE HEAVY RAIN FOR THE NORTHEAST PORTION OF THE FSD CWA TODAY... WITH RADAR ESTIMATES THE HIGHEST ACROSS NORTHERN COTTONWOOD AND NORTHERN MURRAY COUNTIES. MUCH OF SW MINNESOTA AND NW IOWA NOW SATURATED FROM RECENT RAINS...SO ISSUED A FLASH FLOOD WATCH EARLIER TODAY FOR THIS AREA...AND WILL CONTINUE THE WATCH THRU MID EVENING...AS CONVECTION CONTINUES THAT AREA. THIS CONVECTION SHOULD WIND DOWN BY MID/LATE EVENING AS THE UPPER SUPPORT SHIFTS EAST. NORTHWEST IOWA AND ADJOINING COUNTIES OF SOUTHWEST MINNESOTA... SOUTHEAST SOUTH DAKOTA AND EXTREME NORTHEAST NEBRASKA HAS HEATED OUT TODAY...AND IS THE MOST UNSTABLE WITH VERY JUICY LOW LEVEL SOUTH TO SOUTHWEST FLOW. THIS AREA HAS THE HIGHEST RISK OF LATE AFTERNOON AND EVENING SEVERE WEATHER...ESPECIALLY IF THE BOUNDARY LAYER WINDS VEER TO MORE SOUTHERLY OR SOUTHEASTLY PER THE LATEST RUC. SOME RISK OF AN ISOLATED TORNADO THRU EARLY EVENING...ESPECIALLY NEAR THE NORTHWEST IOWA AND SOUTHWEST MINNESOTA BORDER COUNTIES...WHERE THE SHEER WILL BE THE BEST. THE REST OF THE FA WILL BE RAIN FREE MOST OF THE NIGHT...AFTER A FEW ISOLATED EARLY EVENING SHOWERS...BUT FOG... REDUCING VSBYS TO LESS THAN A MILE IN SOME AREAS..WILL BE COMMON LATE TONIGHT THROUGH EARLY MONDAY MORNING. THE CHANCE FOR THUNDERSTORMS WILL INCREASE AGAIN ACROSS THE WEST TOWARD MORNING AS THE NEXT UPPER LEVEL DISTURBANCE APPROACHES...WITH MORE HEAVY RAIN BECOMING LIKELY ACROSS THE CENTRAL AND EASTERN PORTIONS OF THE FA DURING THE DAY MONDAY. TEMPERATURES TONIGHT WILL BE COOLEST ACROSS THE NORTH WHERE LITTLE HEATING OCCURRED TODAY. QUITE THE ADVENTUROUS FCST THIS WEEK WITH CONTINUED STREAM OF SHORT WAVES INTERACTING WITH E/W BOUNDARIES AND SLY LOW LVL INFLOW OF GULF MOISTURE. MODELS AGREE FAIRLY WELL THAT MAIN WAVES AND ASSCD TSTMS WILL DVLP ESEWD OVR AREA FM LATE MON MRNG THRU THE AFTN...AGAIN TUE AFTN AND EVE...AND ENEWD OVR AREA LATE WED INTO THU. ANY ONE OF THESE WAVES WILL HAVE GREAT POTENTIAL FOR HEAVY RAIN WITH LESSER CHCS OF SVR DUE TO LACK OF GREAT INSTABILITY. FNTL BOUNDARY WAVERING OVER AREA WILL CONTINUE TO CAUSE ISSUES WITH TEMP FCSTG WITH POTENTIALLY GREAT CONTRAST FM NORTH TO SOUTH IN CWA...BUT TREND IS FOR MODERATION OF AIR MASS TO THE NORTH...SO HOPEFULLY NO MORE 30 DEGREE TEMP VARIATIONS FM N TO S IN CWA. MAIN ISSUE WILL BE RAIN COOLED AIR. KEPT OUT CHCS PRECIP FOR FRI NGT INTO NEXT WEEKEND FOR NOW AS DYNAMICS WEAKEN QUITE A BIT. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$ LIEBL/SCHUMACHER/RYRHOLM sd AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD...CORRECTED 430 PM CDT SUN AUG 19 2007 .DISCUSSION... MORE HEAVY RAIN FOR THE NORTHEAST PORTION OF THE FSD CWA TODAY... WITH RADAR ESTIMATES THE HIGHEST ACROSS NORTHERN COTTONWOOD AND NORTHERN MURRAY COUNTIES. MUCH OF SW MINNESOTA AND NW IOWA NOW SATURATED FROM RECENT RAINS...SO ISSUED A FLASH FLOOD WATCH EARLIER TODAY FOR THIS AREA...AND WILL CONTINUE THE WATCH THRU MID EVENING...AS CONVECTION CONTINUES THAT AREA. THIS CONVECTION SHOULD WIND DOWN BY MID/LATE EVENING AS THE UPPER SUPPORT SHIFTS EAST. NORTHWEST IOWA AND ADJOINING COUNTIES OF SOUTHWEST MINNESOTA... SOUTHEAST SOUTH DAKOTA AND EXTREME NORTHEAST NEBRASKA HAS HEATED OUT TODAY...AND IS THE MOST UNSTABLE WITH VERY JUICY LOW LEVEL SOUTH TO SOUTHWEST FLOW. THIS AREA HAS THE HIGHEST RISK OF LATE AFTERNOON AND EVENING SEVERE WEATHER...ESPECIALLY IF THE BOUNDARY LAYER WINDS VEER TO MORE SOUTHERLY OR SOUTHEASTLY PER THE LATEST RUC. SOME RISK OF AN ISOLATED TORNADO THRU EARLY EVENING...ESPECIALLY NEAR THE NORTHWEST IOWA AND SOUTHWEST MINNESOTA BORDER COUNTIES...WHERE THE SHEER WILL BE THE BEST. THE REST OF THE FA WILL BE RAIN FREE MOST OF THE NIGHT...AFTER A FEW ISOLATED EARLY EVENING SHOWERS...BUT FOG... REDUCING VSBYS TO LESS THAN A MILE IN SOME AREAS..WILL BE COMMON LATE TONIGHT THROUGH EARLY MONDAY MORNING. THE CHANCE FOR THUNDERSTORMS WILL INCREASE AGAIN ACROSS THE WEST TOWARD MORNING AS THE NEXT UPPER LEVEL DISTURBANCE APPROACHES...WITH MORE HEAVY RAIN BECOMING LIKELY ACROSS THE CENTRAL AND EASTERN PORTIONS OF THE FA DURING THE DAY MONDAY. TEMPERATURES TONIGHT WILL BE COOLEST ACROSS THE NORTH WHERE LITTLE HEATING OCCURRED TODAY. QUITE THE ADVENTUROUS FCST THIS WEEK WITH CONTINUED STREAM OF SHORT WAVES INTERACTING WITH E/W BOUNDARIES AND SLY LOW LVL INFLOW OF GULF MOISTURE. MODELS AGREE FAIRLY WELL THAT MAIN WAVES AND ASSCD TSTMS WILL DVLP ESEWD OVR AREA FM LATE MON MRNG THRU THE AFTN...AGAIN TUE AFTN AND EVE...AND ENEWD OVR AREA LATE WED INTO THU. ANY ONE OF THESE WAVES WILL HAVE GREAT POTENTIAL FOR HEAVY RAIN WITH LESSER CHCS OF SVR DUE TO LACK OF GREAT INSTABILITY. FNTL BOUNDARY WAVERING OVER AREA WILL CONTINUE TO CAUSE ISSUES WITH TEMP FCSTG WITH POTENTIALLY GREAT CONTRAST FM NORTH TO SOUTH IN CWA...BUT TREND IS FOR MODERATION OF AIR MASS TO THE NORTH...SO HOPEFULLY NO MORE 30 DEGREE TEMP VARIATIONS FM N TO S IN CWA. MAIN ISSUE WILL BE RAIN COOLED AIR. KEPT OUT CHCS PRECIP FOR FRI NGT INTO NEXT WEEKEND FOR NOW AS DYNAMICS WEAKEN QUITE A BIT. && .AVIATION... IFR CONDITIONS WILL CONTINUE THRU MID MORNING MONDAY ACROSS MOST OF SOUTHEAST SD AND MUCH OF SW MINNESOTA. VFR CIGS ACROSS NW IOWA THIS EVENING...BUT A RISK OF SEVERE THUNDERSTORMS THRU MID EVENING...THEN EXPECT KSUX TO GO DOWN IN IFR FOG AFTER 20/05Z...THRU MID MORNING MONDAY. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...FLASH FLOOD WATCH UNTIL 9 PM CDT THIS EVENING FOR IAZ003-014. MN...FLASH FLOOD WATCH UNTIL 9 PM CDT THIS EVENING FOR MNZ081-090. NE...NONE. SD...NONE. && $$ RYRHOLM/HARMON sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN 938 AM CDT SUN AUG 19 2007 .DISCUSSION... QUIET MORNING ACROSS THE FORECAST AREA WITH MOSTLY SUNNY SKIES AND TEMPERATURES MAINLY IN THE 80S. REMNANTS OF TROPICAL STORM ERIN SEEM TO BE MOVING MORE DUE EAST AT THE MOMENT. LATEST RUC MODEL CONTINUES SHOWING THE REMNANTS MOVING NORTHEAST. WILL KEEP AN EYE ON THE MOVEMENT AND MAY UPDATE POPS LATER IF CONDITIONS WARRANT. WILL SEND AN UPDATE TO REMOVE MORNING WORDING BUT AT THIS POINT NO OTHER CHANGES ARE NEEDED. && .PREV DISCUSSION... /ISSUED 305 AM CDT SUN AUG 19 2007/ DISCUSSION... SKIES WERE MOSTLY CLEAR THIS MORNING WITH SOME STATIONS REPORTING SOME LIGHT FOG/HAZE...MAINLY WHERE IT RAINED YESTERDAY. TEMPERATURES RANGED FROM THE LOWER 70S TO NEAR 80S DEGREES AND DEW POINTS RANGED FROM THE UPPER 60S TO MID 70S. VERY LITTLE CHANGE EXPECTED TODAY...WITH DEADLY HEAT STILL THE MAIN FOCUS. MAX TEMPERATURES TODAY WILL REACH NEAR 100 DEGREES WITH HEAT INDICES AROUND 105 OR GREATER. PERHAPS WHERE IT RAINED...TEMPS MAY BE HARD PRESSED TO REACH 100 BUT HUMIDITY LEVELS WILL COUNTERACT THAT AND MAKE IT FEEL MUCH WARMER THAN THE AMBIENT TEMPERATURE. EXPECT A FEW THUNDERSTORMS AGAIN THIS AFTERNOON NEAR PEAK HEATING. SOME OF THESE STORMS WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS IN EXCESS OF 50 MPH AND SMALL HAIL. THE LARGE COMPLEX OF THUNDERSTORMS THAT EXPLODED OVER WEST/CENTRAL OKLAHOMA YESTERDAY EVENING WILL TRANSLATE ALONG THE W/NW FRINGE OF THE UPPER HIGH AND CLIP A SMALL PORTION OF THE NORTHWEST FORECAST AREA MONDAY. THUS THE ASSOCIATED CLOUD COVER WILL INHIBIT DAYTIME TEMPERATURES FROM MAKING IT INTO THE TRIPLE DIGITS. GUIDANCE NUMBERS ARE MUCH COOLER FOR MONDAY...AND BASED ON PERSISTENCE HAVE OPTED TO FORECAST ABOUT FOUR DEGREES WARMER THAN GUIDANCE. THIS HINGES ON A COUPLE OF GIVENS...SUCH AS NO RAINFALL AND MINIMAL CLOUD COVER. SOMETHING TO MONITOR FOR THE NEXT FORECAST. SOME AREAS ACROSS THE FORECAST AREA WILL REACH HEAT ADVISORY CRITERIA ON MONDAY. ANTICIPATE THE UPPER HIGH TO BUILD WEST OVER THE MID SOUTH TUESDAY BRINGING TRIPLE DIGIT TEMPERATURES BACK INTO THE FORECAST AND A HEAT ADVISORY TUESDAY THROUGH THURSDAY. THE UPPER HIGH BREAKS DOWN AND WEAKENS A LITTLE BY NEXT WEEKEND WHICH SHOULD DROP TEMPERATURES INTO THE MID 90S. && .PRELIMINARY POINT TEMPS/POPS... MEM 100 77 97 77 / 20 20 20 20 MKL 99 73 98 72 / 20 20 20 20 JBR 98 74 94 73 / 20 20 20 20 TUP 98 74 97 72 / 10 20 20 20 && .MEG WATCHES/WARNINGS/ADVISORIES... AR...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR CLAY-CRAIGHEAD- CRITTENDEN-CROSS-GREENE-LAWRENCE-LEE AR-MISSISSIPPI- PHILLIPS-POINSETT-RANDOLPH-ST. FRANCIS. MO...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR DUNKLIN-PEMISCOT. MS...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR ALCORN-BENTON MS- CALHOUN-CHICKASAW-COAHOMA-DESOTO-ITAWAMBA-LAFAYETTE-LEE MS- MARSHALL-MONROE-PANOLA-PONTOTOC-PRENTISS-QUITMAN- TALLAHATCHIE-TATE-TIPPAH-TISHOMINGO-TUNICA-UNION-YALOBUSHA. TN...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR CHESTER-CROCKETT- DECATUR-DYER-FAYETTE-HARDEMAN-HARDIN-HAYWOOD-HENDERSON- LAUDERDALE-MADISON-MCNAIRY-SHELBY-TIPTON. HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 8 PM CDT THIS EVENING FOR CARROLL-GIBSON-HENRY-LAKE-OBION-WEAKLEY. && $$ tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 906 PM CDT SUN AUG 19 2007 .UPDATE...WATER VAPOUR IMAGERY...AND RUC/NAM/GFS STREAMLINES NEAR 600MB...DEPICT AN UPPER LOW. THE DETERMINISTIC SOLNS PROG A WWD MOVEMENT OVERNIGHT...WITH THE MSA/CWFA UNDER THE SUBSIDENT SIDE OF THIS SYSTEM OVERNIGHT/EARLY MONDAY. THUS CONFIDENCE LEVEL IS LOW FOR CONVECTION OVERNIGHT...YET WL RETAIN VERY LOW POPS OVR THE WATERS. WL NOT INTRODUCE ACTIVITY OVR LAND. PATCHY FOG REMAINS A POSSIBILITY OWING TO NEAR SFC MSTR/INCREASING DRYING ALOFT/LGT SFC WIND. SFC PRESSURE GRADIENT WL REMAIN CONSISTENT WITH COASTAL WIND NO GREATER THAN 15KT SUSTAINED OVERNIGHT. && .AVIATION...MVFR VSBYS ARE EXPECTED TO DEVELOP OVER TAF SITES ALONG AND EAST OF US281 BETWEEN 08Z-09Z. VSBYS SHOULD IMPROVE TO VFR BETWEEN 13Z-14Z WITH ISOLATED -SHRA ACTIVITY (AND ASSOCIATED TEMPO MVFR CIGS) APPROACHING FROM THE GULF. CONVECTIVE ACTIVITY SHOULD ONLY AFFECT THE KCRP-KVCT SITES BETWEEN 14Z-17Z. KVCT COULD ALSO SEE ISOLATED TSTM ACTIVITY BETWEEN 17Z-19Z. WILL HANDLE THE AFOREMENTIONED ACTIVITY WITH VCSH/VCTS IN THE KCRP AND KVCT TAFS SINCE CONVECTION IS ONLY EXPECTED TO BE ISOLATED IN NATURE. OTHERWISE...VFR CONDITIONS WILL PREVAIL AREAWIDE AFTER 14Z THROUGH MONDAY NIGHT. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 77 93 76 92 77 / 10 10 10 30 20 VICTORIA 76 92 75 92 76 / 10 10 10 30 20 LAREDO 79 102 79 100 79 / 10 10 10 20 10 ALICE 76 95 75 94 76 / 10 10 10 30 20 ROCKPORT 81 92 80 92 81 / 10 10 20 30 20 COTULLA 74 97 74 96 75 / 10 10 10 20 10 KINGSVILLE 77 94 76 93 78 / 10 10 10 30 20 NAVY CORPUS 81 91 81 91 81 / 10 10 20 30 20 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ WC/87...UPDATE TM/95...AVIATION tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 859 PM EDT MON AUG 20 2007 .SYNOPSIS... A WEAK FRONTAL BOUNDARY WILL CONTINUE TO MEANDER ACROSS PARTS OF THE AREA THROUGH MID WEEK BEFORE DISSIPATING. STRONG HIGH PRESSURE SHOULD BUILD BACK IN FROM THE SOUTHWEST BY WEEKS END KEEPING HOT AND HUMID WEATHER GOING INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... SURFACE FRONTAL BOUNDARY HAS RETREATED BACK ALMOST TO THE BLUE RIDGE THIS EVENING AS REFLECTED BY NE FLOW AT LYH/FVX. HOWEVER CONVECTION HAS BEEN ISOLATED AT BEST GIVEN BEST LIFT/SUPPORT TO THE NORTH AND DECENT BUT SHALLOW CONVERGENCE ALONG THE BOUNDARY. ALSO APPEARS THAT DEEP WESTERLY FLOW/MIXING AS SEEN VIA 00Z RAOBS...AND SHOT OF LOWER DEWPTS OVER SW VA PER MSAS HAVE PUT A LID ON TSRA SO FAR. LATEST SHORT TERM MODELS INCLUDING THE RUC/WRF WHICH HAVE BEEN TOO MOIST OF LATE ALSO SHOWING MOST SHRA JUST NORTH OVERNIGHT AS LOSS OF HEATING SHOULD LIMIT COVERAGE ESPCLY AFTER MIDNIGHT. STILL APPEARS BEST SHOT AT ORGANIZED COVERAGE WILL BE IN THE FAR NORTH CLOSER TO PASSING DYNAMICS AND UNDER SOMEWHAT DEEPER RH CLOSER TO THE OLD FRONT. SINCE COULD ALSO SEE SHRA STILL BACK BUILD FROM BANDS OFF TO THE NE PLAN TO LEAVE AT LEAST LOW CHANCES GOING NORTHERN THIRD EARLY ON AND DIMINISH SOME LATE. OTRW THINK MAINLY DRY ACROSS THE SOUTH WHERE SHOULD STAY MAINLY CLEAR OUTSIDE DEBRIS CLOUDS WHILE PC/MOSTLY CLOUDY PERSISTS UP NORTH. CLOUDS AND LOW LEVEL MIXING WILL KEEP TEMPS UP IN THE NORTH WHILE LOWS CLOSER TO LAV MOS LIKELY ELSEWHERE GIVEN CLEAR SKIES AND LIGHTER WINDS OVERNIGHT. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... SHORTWAVE ENERGY OVER THE MID-MISSISSIPPI VALLEY WILL RIDE UP OVER THE RIDGE TONIGHT AND PUSH INTO THE SOUTHERN APPALACHIANS BY MORNING. THIS WILL LIKELY PULL MID-ATLANTIC CONVECTION SOUTH AND INTO THE NORTHERN PART OF THE CWA BY MORNING. THIS CONVECTION MAY SINK SOUTH DURING THE DAY TMRW...BUT WILL MOST LIKELY AFFECT VA AND WV COUNTIES...WITH ONLY ISOLATED STORMS OVER NC. REMAINS OF THIS MCS PUSH OFF TO THE NORTHEAST LEAVING SOME POSSIBLE BOUNDARIES AROUND ON WEDNESDAY FOR SCATTERED CONVECTION. DO NOT EXPECT ANY ORGANIZED CONVECTION WED BUT LEFT 20/30 POPS MAINLY IN THE MOUNTAINS. HIGHS WILL REBOUND EASILY TO THE MID 90S OVER THE EAST AND UPPER 80S/LOW 90S IN THE MOUNTAINS. && .LONG TERM /THURSDAY THROUGH MONDAY/... SAME STORY DIFFERENT DAY. GFS WARMS 850 MB TO 22-23C ON FRIDAY WHICH WOULD LIKELY PRODUCE THE WARMEST DAY OF THE WEEK. GUIDANCE HAS MID-90S EVEN IN THE NRV AND NEAR 90 GREENBRIER VALLEY. COULD DEFINITELY BE THREATENING RECORDS HIGHS AGAIN...WITH DEPARTURES FROM CLIMO APPROACHING PLUS 10 TO 15 DEGREES. THROUGH MOST OF THE LATE WEEK AND INTO THE WEEKEND NO REAL FRONTAL BOUNDARIES TO SPEAK OF OTHER THAN WHAT OUTFLOWS MAY DEVELOP FROM ANY THUNDERSTORMS. WITH SURFACE DEWPOINTS IN THE 60S AND LOW 70S THERE WILL BE PLENTY OF LOW-LEVEL MOISTURE BUT NOT MUCH IN THE WAY OF UPPER LEVEL SUPPORT. THE SOUTHEASTERN U.S. RIDGE REMAINS DOMINANT IN THE EXTENDED ALTHOUGH HEIGHTS RISE OFF THE SOUTHEAST COAST BY MONDAY AS SOME NORTHERN STREAM ENERGY TRIES TO FLATTEN OUT THE RIDGE BY EARLY NEXT WEEK. THE SURFACE REFLECTION IS A FRONTAL PASSAGE BY MONDAY WHICH MAY HELP DROP 850 TEMPS BACK INTO THE UPPER TEENS AND SURFACE TEMPERATURES CLOSER TO NORMAL BUT STILL LIKELY A FEW DEGREES ABOVE. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... BACKDOOR COLD FRONT CURRENTLY IS POSITIONED JUST TO THE SOUTH OF KLYH AS NOTED BY A NE WIND THERE. CONCERN IN THIS AREA THROUGH THE NIGHT WILL BE FOR THE NEAR SURFACE WINDS TO DECOUPLE WITH RESIDUAL MOISTURE UNDER THE RESULTANT INVERSION DEVELOPING INTO ANOTHER IFR OR LOWER STRATUS LAYER AND ACCOMPANYING IFR VISIBILITIES DUE TO LIGHT FOG. KDAN MAY JUST BE ON THE FRINGE OF SIMILAR CONDITIONS FORMING THERE AS WELL. LINE OF SHRA/TSRA CURRENTLY HEADING EAST OUT OF WV INTO NORTHERN VA. THERE HAS BEEN A LITTLE FORMATION OF ADDITIONAL SHRA/TSRA ON THE SOUTHERN END OF THIS LINE. MAY SEE AN ISOLATD SHRA/TSRA NEAR KLYH THROUGH ABOUT 02Z BECAUSE OF THIS. THE KLWB...KBLF..AND KROA TAF SITES WILL BE CHARACTERIZED BY SW WINDS AT THE SURFACE LESS THAN 10 KTS...ALSO WITH AN ACCOMPANYING INVERSION AND PATCHY MVFR LIGHT FOG FORMING. ABOVE THE INVERSION SOUTHWEST TO WEST WINDS WILL BE INCREASING INTO THE 25 TO 35 KT RANGE BY MORNING. HAVE INCLUDED LOW LEVEL WIND SHEAR AT MOST LOCATIONS BY SUNRISE TO ACCOUNT FOR THIS. AFTER SUNRISE...THE INVERSION WILL BREAK AND WE WILL START TO GET SOME STRONGER GUSTS TO REACH THE SURFACE. KLYH SHOULD SEE THIS HAPPEN LAST UNTIL THE SURFACE BACKDOOR FRONT HAS A CHANCE TO HEAD BACK NORTH. WILL ALSO KEEP THE LOWER CLOUDS THERE THROUGH THE MID TO LATE MORNING. BY THE AFTERNOON A WAVE MOVING THROUGH THE NOW PREDOMINANT WESTERLY FLOW WILL ALLOW FOR SHRA/TSRA DEVELOPMENT MAINLY IN THE NORTH AND IN THE MOUNTAINS. SOUTHSIDE VA AND NEIGHBORING NC MAY EXPERIENCE TOO STRONG OF A DOWNSLOPE INFLUENCE FOR CONVECTION TO FIRE. THE ACTIVITY MAY JUMP THAT AREA INTO EASTERN PARTS OF VA AND NC. FOR THE REMAINDER OF THE WEEK...SUMMER TIME PULSE CONVECTION IS POSSIBLE EACH AFTERNOON AND EVENING. && .CLIMATE... ROANOKE...BLUEFIELD...AND BLACKSBURG ALREADY AHEAD OF A PACE TO BREAK MONTHLY AVERAGE AUGUST HEAT RECORDS LOOKING AT DATA THROUGH AUGUST 20. ROANOKE OVER 2 DEGREES AHEAD OF THE PREVIOUS RECORD PACE FOR THE FIRST 20 DAYS BACK IN THE DROUGHT YEAR OF 1988. THE NEXT 7 DAYS WILL DO NOTHING BUT PAD THOSE NUMBERS. DANVILLE ON PACE FOR 2ND HIGHEST...WHILE LYNCHBURG WITH A LONGER PERIOD OF RECORD AND SOMEWHAT LESS EXTREME HEAT IS NOT IN THE TOP 10 YET. RAINFALL NUMBERS ARE NOT MUCH BETTER AND SEVERAL STATIONS COULD STILL SET ALL-TIME DRIEST AUGUST...BLACKSBURG HAS ONLY 0.12 INCHES THIS MONTH. WITH THE HEAT/DRY COMBINATION THE DROUGHT CONDITIONS ARE LIKELY TO WORSEN ACROSS THE AREA. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/PC NEAR TERM...JH/JS SHORT TERM...JS/PC LONG TERM...PC AVIATION...DS/JS CLIMATE... va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 329 PM EDT SUN AUG 19 2007 .SYNOPSIS... HOT AND HUMID WEATHER WILL PREVAIL NEXT FEW DAYS AS FRONTAL BOUNDARY TO OUR NORTH WILL PUSH SLOWLY INTO THE AREA AND STALL DURING THE DAY MONDAY BUT BRING ONLY A SLIGHT INCREASE IN RAINFALL CHANCES. && .NEAR TERM /THROUGH MONDAY/... SOUTHWEST FLOW INTO THE REGION HAS INCREASED DEWPOINTS DRAMATICALLY OVER YESTERDAY AT THIS TIME. A SFC BOUNDARY/DEVELOPING WARM FRONT REMAINS JUST NORTH OF THE CWA. RADAR SHOWS ISOLD SHOWERS/STORMS DEVELOPING ACROSS THE GREENBRIER VALLEY AREA IN THE AREA OF BEST LOW LEVEL CONVERGENCE. THESE STORMS SHOULD MOVE EASTWARD INTO THE VA MTNS/SHEN VALLEY AND POSSIBLY PIEDMONT THIS EVENING. UNTIL SUNSET...OTHER ISOLD STORMS MAY STILL DEVELOP IN THE MTNS AS WELL. I HAVE KEPT THE SLIGHT CHC TSTMS THRU 800 PM ALL MTNS AND FOOTHILLS... AND THEN HAVE JUST A SLIGHT CHC IN THE WEST CEN VA FOOTHILLS PIEDMONT. LATE TONIGHT...WEAKENING CONVECTION THAT DEVELOPS IN THE OHIO VALLEY MAY BE MOVING INTO WESTERN SLOPES AREAS OF SE WV...SO I KEPT THE LOW CHC POPS OUT THAT WAY. STAYED AT OR ABOVE MOS FOR LOWS TONIGHT- SHOULD BE A WARM AND MUGGY NIGHT WITH THE INCREASED DEWPOINTS. KEY TO MONDAY FORECAST IS POSITION OF THE BOUNDARY/WARM FRONT. IS ANY ORGANIZED CONVECTION FROM THE OHIO VALLEY MOVES ALONG IT OVERNIGHT...IT MAY GET PUSHED SOUTHWARD INTO THE CWA. BOTH THE NAM AND GFS BRING IT NEAR NORTHERN SECTIONS. FOR NOW...I FELT THE BEST COURSE WAS TO RAISE THE POPS AROUND 10 PCT TO THE NORTH...AND KEEP THE SLIGHT CHC OR LESS ACROSS SOUTHERN SECTIONS OF THE CWA. SOUTHERN SECTIONS WILL BE HOT AND HUMID MONDAY...BUT WILL HAVE HEAT INDICES OF AROUND 100 WHICH IS BELOW ADVISORY LEVELS OF 105. LOOKS LIKE RECORD HIGH TEMPS FOR MONDAY WIL BE OUT OF REACH AS WELL. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... MAIN QUESTION IS THE POSSIBLE EFFECTS FROM THE REMAINS OF TD ERIN AND IT DOES NOT LOOK ESPECIALLY PROMISING AT THIS POINT. 12Z RUNS OF GFS/NAM HAVE NOW BACKED OFF SOMEWHAT ON THE PRECIP COVERAGE ACROSS THE CWA AND KEEP BULK THE ENERGY ASSOCIATED WITH ERIN TO THE NORTH. PWATS INCREASE TO AROUND 2 INCHES BY EARLY WED. BUT MAIN FORCING REMAINS NORTH OF THE MASON-DIXON LINE. SCATTERED SHOWERS STILL POSSIBLE WHICH COULD PRODUCE LOCALLY HEAVY RAINFALL BUT WIDESPREAD SOAKING POSSIBILITY REMAINS SLIM. 12Z CANADIAN MODEL ALSO CAME IN WITH QPF BULLSEYE CONSIDERABLY FURTHER NORTH THAN ITS 00Z RUN...MAINLY ACROSS MD AND SOUTHERN PA LATE TUESDAY INTO WEDNESDAY. TEMPERATURES WILL CONTINUE TO RUN 4 TO 6 ABOVE CLIMO DURING THE PERIOD. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... 596 DM RIDGE OVER THE SOUTHEASTERN US VERY HARD TO DISLODGE DURING THE EXTENDED PERIOD. THE SURFACE BOUNDARY ACROSS THE EASTERN CWA WILL WASH OUT BY LATE THURSDAY LEAVING WEAK HIGH PRESSURE ACROSS THE MID-ATLANTIC AND VERY WARM TEMPERATURES FOR THE LATE WEEK AND INTO THE WEEKEND. POPS IN THE 20/30 RANGE OFFER LITTLE LIKELIHOOD OF DROUGHT RELIEF. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... LAPS AND MSAS SHOWING THE AREA BECOMING UNSTABLE THIS AFTERNOON WITH THE SOUTHWEST FLOW BRINGING HIGHER SFC DEWPOINTS. THERE IS LITTLE IN THE WAY OF FORCING FOR CONVECTION LATE THIS AFTERNOON OTHER THAN DIFF HEATING AND WEAK CONVERGENCE IN THE MTNS WEST OF THE BLUE RIDGE. RUC MODEL SHOWS PRECIP IN THE NEW RIVER AND ROA VALLEYS 21 TO 00Z...AND THEN MOVING EAST INTO THE PIEDMONT. 12Z NAM INITIATES A LITTLE FURTHER EAST...BUT HINTS AT THE SAME. FOR THIS REASON...I HAVE KEPT IN THE VICINITY TSTM THAT WE ALREADY HAD GOING FOR ROA...LYH AND DAN. I REMOVED IT FROM BLF AND LWB. I ALSO NARROWED THE WINDOW OF VICINITY TSTMS DOWN TO 3 HOUR PERIODS. OTHER THAN A CHANCE FOR IFR OR MVFR WITH A PASSING TSTM...I LOOK FOR MAINLY VFR CONDITIONS THRU THE NEXT 24 HOURS. LYH MAY HAVE A PERIOD OF MVFR FOG TOWARD MORNING. I KEPT IN THE LIGHT SHOWERS FOR LWB AS MODELS STILL SHOW SOME WEAKENING CONVECTION MAKING IT INTO SE WV OVERNIGHT. SOUTHWEST TO WEST WINDS WILL PICK UP AGAIN ON MONDAY TO AROUND 10 KNOTS ALL TAF SITES. MONDAY AFTERNOON THROUGH WEDNESDAY...WILL SEE AN INCREASE IN THUNDERSTORM ACTIVITY AS WAVES TRACK ALONG A STATIONARY BOUNDARY IN THE OHIO VALLEY AND ALONG THE MASON-DIXON LINE. GREATEST CHANCE FOR ACTIVITY WILL BE IN THE GREENBRIER VALLEY (LWB) AND LESS CHANCE TOWARD SOUTHSIDE VA (DAN). && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PC NEAR TERM...JJ SHORT TERM...PC LONG TERM...PC AVIATION...JJ va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 142 PM EDT SUN AUG 19 2007 .SYNOPSIS... HIGH PRESSURE WILL SLIDE OFF THE MID ATLANTIC COAST TODAY. PRECIPITATION CHANCES WILL START TO INCREASE HEADING INTO NEXT WEEK AS THE FRONT MOVES NORTH AGAIN AS A WARM FRONT INTO THE OHIO VALLEY. TEMPERATURES WILL ONCE AGAIN BE ABOVE NORMAL. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WITH A SOLID OVERCAST OF STRATO-CUMULUS OVER THE PIEDMONTS OF NW NC AND WEST CENTRAL VA...I HAVE UPDATED THE GRIDS FOR MORE SKY COVER THIS MORNING. WITH HEATING...THIS OVC SHOULD SCATTER OUT AROUND NOON OR SHORTLY AFTER. BECAUSE OF THE SKY COVER...I LOWERED HIGH TEMPS A DEGREE OR TWO IN THE PIEDMONT. I RAISED THE HIGH TEMPS A DEGREE OR TWO IN THE WEST WITH PLENTY OF SUN...A WARM START AND WEAK WARM ADVECTION THIS AFTERNOON. BLF MAY HIT 90 DEGREES...WHICH IS THEIR RECORD FOR TODAY- 90 DEGREES SET IN 1988. NO OTHER RECORD HIGHS SHOULD BE THREATENED. OTHER CHANGE TO THE FCST WAS TO RAISE THE DEWPOINTS IN THE PIEDMONT WITH UPPER 60S TO 70 DEGREE DEWPOINTS SURGING NORTHEAST ACROSS NC. FINALLY...I RAISED POPS IN THE MTNS ENOUGH TO HAVE ISOLD TSTMS ALL AREAS. LOOKS LIKE PIEDMONT AREAS WILL BE THE MOST UNSTABLE WITH THOSE HIGH DEWPOINTS...BUT NO BOUNDARY OR UPPER LEVEL FORCING TO GENERATE STORMS...SO WOULD PROBABLY NEED STORMS TO DEVELOP IN THE MTNS AND THEN MOVE EASTWARD INTO THE FOOTHILLS AND PIEDMONT. BETTER CHC FOR STORMS WOULD THEN BE EARLY EVENING IN THE PIEDMONT. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... MODELS HAVE BE SHOWING STATIONARY BOUNDARY DEVELOPING FROM THE GREAT LAKES THROUGH THE OHIO VALLEY AND ALONG THE MASON-DIXON LINE. 07Z SUN SATELLITE DATA IS VERIFYING THIS BOUNDARY. THE FORECAST THROUGH TUESDAY DEPENDS ON THE LOCATION OF THIS BOUNDARY AND WAVES DEVELOPING ON IT AND RIDING AROUND UPPER LEVEL RIDGE IN SOUTHEASTERN US. WAVES THAT MAKE IT INTO THE OHIO VALLEY WILL ALLOW THIS BOUNDARY TO SINK TO THE SOUTH. WITH MOISTURE IN THE AREA AND ENERGY FROM THESE WAVES WILL BRING A GOOD CHANCE OF STORMS TO NORTHERN CWA. WITH MORE INFLUENCE OF THE UPPER LEVEL RIDGE TO THE SOUTH...ISOLATED DIURNAL CONVECTION IS POSSIBLE BUT THE FOCUS WILL BE ACROSS THE GREENBRIER VALLEY AND THE VA HIGHLANDS. ONCE ONE WAVE EXITS THE OHIO VALLEY...ANOTHER ONE WILL DEVELOP UPSTREAM ALLOWING THE BOUNDARY TO DRIFT BACK TO THE NORTH. CONVECTION MAY LINGER DEEPER INTO MONDAY NIGHT AS A LEE TROF BECOMES A LITTLE STRONGER. TUESDAY LOOKS LIKE A REPEAT OF MONDAY BUT 00Z GFS BRINGS ONE OF THE WAVES/MCS INTO CENTRAL WV-VA. THIS WILL BRING A BETTER CHANCE FOR STORMS NORTH OF 460. AREA WILL REMAIN ON THE WARM SIDE OF THE FRONT AND WITH UPPER LEVEL RIDGE TO THE SOUTH...TEMPERATURES WILL RUN ABOVE NORMAL INTO TUESDAY. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... THIS TIME PERIOD WILL BE CHARACTERIZED BY A TRANSITION BACK TO A MORE DIURNAL POTENTIAL FOR SHOWERS AND STORMS MAINLY IN WESTERN PARTS OF THE AREA. WHILE ADDITIONAL SHOWERS/STORMS WILL BE POSSIBLE MAINLY IN THE NORTH WITH THE AFOREMENTIONED FRONT STILL IN THE PROXIMITY OF THE AREA TUESDAY NIGHT INTO WEDNESDAY...AN APPROACHING TROUGH IN THE CENTRAL PART OF THE U.S. WILL HELP LIFT THIS FRONT NORTH INTO NEW ENGLAND. AS THIS HAPPENS...THE UPPER RIDGE WILL BUILD BACK NORTH OVER OUR AREA. THIS WILL PLACE US IN A REGIME WITH LIMITED...IF ANY...DYNAMICS ALOFT...BUT WE STILL WILL HAVE PLENTY OF LOW LEVEL MOISTURE AND AFTERNOON INSTABILITY FOR ISOLATED TO SCATTERED SHOWERS AND STORMS MAINLY IN THE MOUNTAINS. THE RIDGE AGAIN WILL GET SHUNTED SOUTH HEADING INTO THE WEEKEND AS ANOTHER COLD FRONT TRIES TO PUSH INTO THE AREA. A BETTER CHANCE OF ORGANIZED PRECIPITATION WILL RETURN TO THE AREA BECAUSE OF THIS. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... LAPS AND MSAS SHOWING THE AREA BECOMING UNSTABLE THIS AFTERNOON WITH THE SOUTHWEST FLOW BRINGING HIGHER SFC DEWPOINTS. THERE IS LITTLE IN THE WAY OF FORCING FOR CONVECTION LATE THIS AFTERNOON OTHER THAN DIFF HEATING AND WEAK CONVERGENCE IN THE MTNS WEST OF THE BLUE RIDGE. RUC MODEL SHOWS PRECIP IN THE NEW RIVER AND ROA VALLEYS 21 TO 00Z...AND THEN MOVING EAST INTO THE PIEDMONT. 12Z NAM INITIATES A LITTLE FURTHER EAST...BUT HINTS AT THE SAME. FOR THIS REASON...I HAVE KEPT IN THE VICINITY TSTM THAT WE ALREADY HAD GOING FOR ROA...LYH AND DAN. I REMOVED IT FROM BLF AND LWB. I ALSO NARROWED THE WINDOW OF VICINITY TSTMS DOWN TO 3 HOUR PERIODS. OTHER THAN A CHANCE FOR IFR OR MVFR WITH A PASSING TSTM...I LOOK FOR MAINLY VFR CONDITIONS THRU THE NEXT 24 HOURS. LYH MAY HAVE A PERIOD OF MVFR FOG TOWARD MORNING. I KEPT IN THE LIGHT SHOWERS FOR LWB AS MODELS STILL SHOW SOME WEAKENING CONVECTION MAKING IT INTO SE WV OVERNIGHT. SOUTHWEST TO WEST WINDS WILL PICK UP AGAIN ON MONDAY TO AROUND 10 KNOTS ALL TAF SITES. MONDAY AFTERNOON THROUGH WEDNESDAY...WILL SEE AN INCREASE IN THUNDERSTORM ACTIVITY AS WAVES TRACK ALONG A STATIONARY BOUNDARY IN THE OHIO VALLEY AND ALONG THE MASON-DIXON LINE. GREATEST CHANCE FOR ACTIVITY WILL BE IN THE GREENBRIER VALLEY (LWB) AND LESS CHANCE TOWARD SOUTHSIDE VA (DAN). && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...RCS NEAR TERM...JJ SHORT TERM...RCS LONG TERM...DS AVIATION...JJ/RCS va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SEATTLE WA 330 AM PDT SUN AUG 19 2007 .SYNOPSIS...AN UPPER LEVEL TROUGH WILL SWING THROUGH THE AREA TODAY WITH SHOWERS PERSISTING THROUGH THE EVENING HOURS THEN DIMINISHING AFTER MIDNIGHT. ANOTHER ROUND OF SHOWERS ARE EXPECTED ON MONDAY AS ANOTHER UPPER LEVEL SYSTEM PASSES THROUGH THE STATE. DRY WEATHER WITH WARMER TEMPERATURES ARE EXPECTED FROM TUESDAY ON THROUGH THE WEEKEND AS AN UPPER LEVEL RIDGE DEVELOPS OVER THE PACIFIC AND WESTERN U.S. && .SHORT TERM...WATER VAPOR IMAGERY AND RUC ANALYSIS THIS MORNING SHOWS THE UPPER LEVEL TROUGH AXIS JUST OFF THE WA/OR COAST WITH WESTERN WASHINGTON UNDER THE DIFFLUENT ZONE. RADAR SHOWING LIGHT BUT STEADY PRECIP ACROSS THE AREA WITH MOST LOCALES REPORTING A FEW HUNDREDTHS OF AN INCH PER HOUR. LIGHT RAIN WILL SWITCH OVER TO SHOWERS THIS AFTERNOON AS THE TROUGH PASSES THROUGH THE AREA. MODELS SHOW THE AXIS SHIFTING EAST AND RIGHT OVER THE CASCADES BY 18Z. MM5 GFS ALSO HINTING AT WEAK CONVERGENCE AROUND NORTHERN KING AND SNOHOMISH COUNTIES. THIS SYSTEM HAS HAD A HISTORY OF PRODUCING A FEW ISOLATED THUNDERSTORMS NEAR THE COLD CORE...BUT MODEL SOUNDINGS APPEAR TOO STABLE FOR ANY ACTIVITY TODAY. TEMPERATURES TODAY WILL BE FAIRLY MILD WITH ONLY MID TO UPPER 60S EXPECTED. A MODEST 66 AT SEATAC IS 10 DEGREES BELOW AVERAGE FOR THIS TIME OF YEAR. THE TROUGH WILL MOVE INTO E WA AND IDAHO THIS EVENING WITH SHOWERS TAPERING OFF AND LIMITED TO MOSTLY THE CASCADES. SHOWERS WILL RETURN THE THE COAST EARLY MONDAY WITH PRECIP SPREADING INLAND THROUGH THE MORNING AND AFTERNOON AS ANOTHER POTENT AND FAST MOVING SHORTWAVE TROUGH PASSES THROUGH. BY TUESDAY...WEAK UPPER LEVEL RIDGING AND NW FLOW ALOFT WILL RESULT IN DRIER AND SLIGHTLY WARMER TEMPERATURES ACROSS THE AREA. .LONG TERM...IT LOOKS LIKE THE REMAINDER OF THE WORK WEEK WILL BE DRY AS THE BROAD UPPER LEVEL RIDGE BUILDS ACROSS THE CENTRAL PACIFIC...WITH HEIGHTS RISING ACROSS THE PACNW. TEMPERATURES WILL SLOWLY WARM EACH DAY WITH POSSIBLE 80S RETURNING TO THE INTERIOR BY FRIDAY AND SATURDAY AS H5 582 HEIGHTS REACH UP INTO THE AREA. A PLEASANT RETURN TO SUMMER INDEED. FOR THE WEEKEND...MODELS TRYING TO BRING CLOSED LOW DOWN FROM GULF OF AK WITH A FRONT SLIDING DOWN THE BC COAST TOWARD WA. TOO FAR OUT TO EVEN WORRY ABOUT IT YET SO NO BIG CHANGES MADE. 33 && .AVIATION...MOISTURE CONTINUES TO STREAM IN FROM THE SOUTHWEST AS UPPER TROF APPROACHES COAST. EXPECT CONDITIONS TO CONTINUE TO DETERIORATE THRU 15Z AS PRECIP CONTINUES TO FALL INTO MOIST BOUNDARY LAYER. ONCE TROF AXIS PASSES INLAND IN THE NEXT FEW HOURS FLOW WILL VEER AROUND TO BECOME MORE WESTERLY. MESO MODELS INDICATE THIS WILL GENERATE A PERIOD OF CONVERGENCE WITH CONTINUED LOW CONDITIONS NORTH SOUND BUT WITH IMPROVING CONDITIONS ELSEWHERE. GENERALLY MVFR...BUT WITH SOME LOCAL IFR...WILL CONTINUE THROUGH AT LEAST 15Z. KSEA WINDS WILL REMAIN LIGHT AND SLY. COLMAN && .SEW WATCHES/WARNINGS/ADVISORIES...NONE. $$ WEATHER.GOV/SEATTLE wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 600 AM CDT MON AUG 20 2007 .UPDATE...RAPID WARMING OF TOPS AND DECREASE IN COVERAGE AND INTENSITY OF 88-D RETURNS HAS LED TO THE CANCELLATION OF THE FFA. && 10 .PREV DISCUSSION... /ISSUED 355 AM CDT MON AUG 20 2007/ DISCUSSION...FCST FOCUS IS ON WET AND UNSETTLED PATTERN THROUGH FRIDAY. NEXT WEEKEND WE WILL HOPEFULLY DRY OUT...BUT UNTIL THEN LOOKS LIKE SEVERAL ROUNDS OF THUNDERSTORMS AND POTENTIAL FOR MORE HEAVY RAIN AND SVR WX AT TIMES. OVERALL ROUGH GO OF IT FOR MUCH OF THE WEEK. HOPING FOR A BIT OF A LULL HERE TODAY BUT APPEARS WE WILL STILL BE A STILL UNDER THE GUN THIS MORNING. WATER VAPOR/RUC SHOWS SHORT WAVE FROM CNTRL WI EXTENDING SW INTO IA. DRYING NOTED ON WATER VAPOR EXTENDING FROM SW MN BACK INTO THE ERN DAKOTAS. 30 KT H8 LLJ STILL IMPINGING UPON BAROCLINIC ZONE LAID OUT ACRS THE CWA. SOME WEAKENING AND VEERING NOTED ON BLR PROFILER. MOISTURE GRADIENT NOT NEARLY AS TIGHT AS LAST NIGHT AS MOISTURE HAS BECOME FAIRLY UNIFORM ACRS SRN WI. WILL NEED TO HAVE HIGHER POPS IN THE SOUTH ESP THIS MORNING AS LLJ STILL DOING ITS THING PER RADAR TRENDS UPSTREAM. HAVE BEEN MULLING OVER WHAT TO DO WITH FFA...HAVE DECIDED TO EXTEND IT TO 18Z MAINLY TO ACCOUNT FOR COMPLEX ACRS ERN IA. TOPS STILL COOLING A BIT AND NOTICING A MORE EWD DRIFT RATHER THAN ESE...SO WILL BUMP THE POPS IN THE SOUTH. H8 PROGS INDICATE SOME RIDGING WILL EVOLVE TODAY WITH H8 JET SHIFTING TO THE EAST LEAVING LITTLE IN THE WAY OF CONVERGENCE. 00Z ECMWF AMONG OTHER MODELS SHOWING A RELATIVE MIN IN FRONTOGENETICAL FORCING WHILE THETAE ADVECTION ALSO TRAILS OFF AFT THE MRNG HRS. WHILE CANNOT RULE OUT PCPN DEVELOPING THIS AFTN THE BRIEF SUBSIDENCE IN WAKE OF WAVE AND THE LESS FAVORABLE H8 FORCING IN PLACE WOULD SEEM TO IMPLY LESS COVERAGE TO THE PCPN. ALSO GUID POPS ARE MAXED OUT AT 12Z THIS MORNING THEN TREND DOWN. WILL CERTAINLY HAVE HIGHER POPS THIS MORNING AND THEN TRAIL THEM OFF. A GOOD DEAL OF LOW CLOUD COVER WILL LINGER TODAY SO ANOTHER COOLISH DAY IN STORE. RELATIVE LULL INTO TONIGHT WITH LLJ PROGS REFOCUSING TO OUR WEST AHEAD OF ANOTHER SHORT WAVE. SPEED AND STRENGTH OF WAVE ON MODELS VARIES HOWEVER BEST TIME FRAME FOR PCPN ASSOC WITH IT WILL BE TUESDAY. SFC PROGS SHOWING THE WARM FRONT THAT HAS BEEN SITUATED TO OUR SOUTH FOR THESE BOUTS OF HEAVY RAIN WILL HEAD BACK NORTH. GETTING SOME AMAZING DEW POINTS FROM THE MET MOS...77 AND 78 AT THE DELLS FOR TUE AND WED. A LITTLE ON THE HIGH SIDE...WILL STEER LOWER TOWARDS MAV MOS. BUFKIT SHOWS CAPES GETTING OVER 1K FOR TUE. OVERALL UPPER FLOW PATTERN FROM TUE NIGHT RIGHT INTO FRI WILL BE FAVORABLE FOR SEVERAL PERIODS OF TSTORMS. BOUNDARY WILL BE MEANDERING WITH UPPER FLOW FAVORABLE FOR BRINGING WAVES OF UPPER SUPPORT ACROSS TO INTERACT WITH FRONTAL BOUNDARY AND INSTAB. APPEARS STRONGEST SIGNALS ARE COMING FOR TUE NGT...WED NGT AND THU...SO HAVE OPTED TO BOOST TO LIKELY THOSE PERIODS. MODELS VARY ON THE LAST WAVE FOR FRIDAY WITH GFS MOST AGGRESSIVE. ECMWF AND CANADIAN NOT AS EXCITED. WILL STILL HAVE A CHC THOUGH FOR FRIDAY. WILL BE ISSUING AN ESF TO LAY OUT POTENTIAL FOR MORE FLOODING THIS WEEK DUE TO SATURATED GROUNDS AND THESE ADDITIONAL BOUTS OF CONVECTION. AT THIS POINT NEXT WEEKEND SHAPING UP TO BE QUIETER. 10 AVIATION...XPCT WDSPRD IFR CIGS/VSBYY IN -RA/-TSRA/BR THRU 00Z TUE WITH SATURATED BOUNDARY LAYER. EAST WINDS ALSO PICKING UP MOISTURE FROM LAKE MICHIGAN. IMPROVEMENT EXPECTED TO MVFR CIGS/VSBYS AFT 18Z AFTER SHORT WAVE ENERGY MOVES OUT OF AREA. STNRY FNT ACRS IA AND NRN IL THRU PD. MKX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 1 PM CDT THIS AFTERNOON FOR WIZ056>058- 062>072. && .MKX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 355 AM CDT MON AUG 20 2007 .DISCUSSION...FCST FOCUS IS ON WET AND UNSETTLED PATTERN THROUGH FRIDAY. NEXT WEEKEND WE WILL HOPEFULLY DRY OUT...BUT UNTIL THEN LOOKS LIKE SEVERAL ROUNDS OF THUNDERSTORMS AND POTENTIAL FOR MORE HEAVY RAIN AND SVR WX AT TIMES. OVERALL ROUGH GO OF IT FOR MUCH OF THE WEEK. HOPING FOR A BIT OF A LULL HERE TODAY BUT APPEARS WE WILL STILL BE A STILL UNDER THE GUN THIS MORNING. WATER VAPOR/RUC SHOWS SHORT WAVE FROM CNTRL WI EXTENDING SW INTO IA. DRYING NOTED ON WATER VAPOR EXTENDING FROM SW MN BACK INTO THE ERN DAKOTAS. 30 KT H8 LLJ STILL IMPINGING UPON BAROCLINIC ZONE LAID OUT ACRS THE CWA. SOME WEAKENING AND VEERING NOTED ON BLR PROFILER. MOISTURE GRADIENT NOT NEARLY AS TIGHT AS LAST NIGHT AS MOISTURE HAS BECOME FAIRLY UNIFORM ACRS SRN WI. WILL NEED TO HAVE HIGHER POPS IN THE SOUTH ESP THIS MORNING AS LLJ STILL DOING ITS THING PER RADAR TRENDS UPSTREAM. HAVE BEEN MULLING OVER WHAT TO DO WITH FFA...HAVE DECIDED TO EXTEND IT TO 18Z MAINLY TO ACCOUNT FOR COMPLEX ACRS ERN IA. TOPS STILL COOLING A BIT AND NOTICING A MORE EWD DRIFT RATHER THAN ESE...SO WILL BUMP THE POPS IN THE SOUTH. H8 PROGS INDICATE SOME RIDGING WILL EVOLVE TODAY WITH H8 JET SHIFTING TO THE EAST LEAVING LITTLE IN THE WAY OF CONVERGENCE. 00Z ECMWF AMONG OTHER MODELS SHOWING A RELATIVE MIN IN FRONTOGENETICAL FORCING WHILE THETAE ADVECTION ALSO TRAILS OFF AFT THE MRNG HRS. WHILE CANNOT RULE OUT PCPN DEVELOPING THIS AFTN THE BRIEF SUBSIDENCE IN WAKE OF WAVE AND THE LESS FAVORABLE H8 FORCING IN PLACE WOULD SEEM TO IMPLY LESS COVERAGE TO THE PCPN. ALSO GUID POPS ARE MAXED OUT AT 12Z THIS MORNING THEN TREND DOWN. WILL CERTAINLY HAVE HIGHER POPS THIS MORNING AND THEN TRAIL THEM OFF. A GOOD DEAL OF LOW CLOUD COVER WILL LINGER TODAY SO ANOTHER COOLISH DAY IN STORE. RELATIVE LULL INTO TONIGHT WITH LLJ PROGS REFOCUSING TO OUR WEST AHEAD OF ANOTHER SHORT WAVE. SPEED AND STRENGTH OF WAVE ON MODELS VARIES HOWEVER BEST TIME FRAME FOR PCPN ASSOC WITH IT WILL BE TUESDAY. SFC PROGS SHOWING THE WARM FRONT THAT HAS BEEN SITUATED TO OUR SOUTH FOR THESE BOUTS OF HEAVY RAIN WILL HEAD BACK NORTH. GETTING SOME AMAZING DEW POINTS FROM THE MET MOS...77 AND 78 AT THE DELLS FOR TUE AND WED. A LITTLE ON THE HIGH SIDE...WILL STEER LOWER TOWARDS MAV MOS. BUFKIT SHOWS CAPES GETTING OVER 1K FOR TUE. OVERALL UPPER FLOW PATTERN FROM TUE NIGHT RIGHT INTO FRI WILL BE FAVORABLE FOR SEVERAL PERIODS OF TSTORMS. BOUNDARY WILL BE MEANDERING WITH UPPER FLOW FAVORABLE FOR BRINGING WAVES OF UPPER SUPPORT ACROSS TO INTERACT WITH FRONTAL BOUNDARY AND INSTAB. APPEARS STRONGEST SIGNALS ARE COMING FOR TUE NGT...WED NGT AND THU...SO HAVE OPTED TO BOOST TO LIKELY THOSE PERIODS. MODELS VARY ON THE LAST WAVE FOR FRIDAY WITH GFS MOST AGGRESSIVE. ECMWF AND CANADIAN NOT AS EXCITED. WILL STILL HAVE A CHC THOUGH FOR FRIDAY. WILL BE ISSUING AN ESF TO LAY OUT POTENTIAL FOR MORE FLOODING THIS WEEK DUE TO SATURATED GROUNDS AND THESE ADDITIONAL BOUTS OF CONVECTION. AT THIS POINT NEXT WEEKEND SHAPING UP TO BE QUIETER. && 10 .AVIATION...XPCT WDSPRD IFR CIGS/VSBYY IN -RA/-TSRA/BR THRU 00Z TUE WITH SATURATED BOUNDARY LAYER. EAST WINDS ALSO PICKING UP MOISTURE FROM LAKE MICHIGAN. IMPROVEMENT EXPECTED TO MVFR CIGS/VSBYS AFT 18Z AFTER SHORT WAVE ENERGY MOVES OUT OF AREA. STNRY FNT ACRS IA AND NRN IL THRU PD. && .MKX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 1 PM CDT THIS AFTERNOON FOR WIZ056>058- 062>072. && $$ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 341 AM CDT MON AUG 20 2007 .SHORT TERM...TODAY THROUGH WEDNESDAY MAIN FORECAST CONCERNS WILL TIMING OF SHORTWAVE TROUGHS AND PLACEMENT OF SURFACE FRONT THROUGH FORECAST PERIOD. LATEST WATER VAPOR SATELLITE IMAGERY INDICATING A SHORTWAVE RIDGE OVER THE UPPER MIDWEST AND GREAT LAKES REGION. UPPER LEVEL TROUGH OVER THE NORTHERN ROCKIES FLATTENING SHORTWAVE RIDGE. LATEST 06Z SURFACE ANALYSIS INDICATING SURFACE FRONT EXTENDING FROM EASTERN NEBRASKA INTO NORTHERN ILLINOIS. LATEST MOSAIC RADAR INDICATED SHOWERS AND THUNDERSTORMS ALONG AND NORTH OF THE FRONT. THIS IS IN ASSOCIATION OF DECENT MOISTURE TRANSPORT AT 850MB PER LATEST RUC ANALYSIS. THE 00Z MONDAY GFS AND NAM INITIALIZED THE UPPER LEVEL PATTERN WELL PER LATEST WATER VAPOR IMAGERY. BOTH MODELS ARE IN GOOD AGREEMENT IN IN DEVELOPING FAST WEST TO EAST ZONAL FLOW ACROSS THE NORTHERN TIER THROUGH PERIOD. THOUGH...BIG DIFFERENCES BEGIN TO SHOW UP AFTER 12Z TUESDAY WITH TIMING AND PLACEMENT OF SURFACE FEATURES AND SHORTWAVE TROUGHS ALOFT. CONFIDENCE IN FORECAST THROUGH 12Z TUESDAY IS MODERATE WITH NEXT SHORTWAVE TROUGH OVER THE WESTERN DAKOTA MOVING INTO FORECAST LATE THIS AFTERNOON INTO THIS EVENING. CONFIDENCE IS LOW AFTER 12Z TUESDAY...BASED ON THE INCONSISTENCIES IN THE TIMING AND PLACEMENT OF SURFACE FRONT/UPPER LEVEL SHORTWAVE TROUGHS. TODAY INTO TONIGHT...CURRENT WEAK SHORTWAVE TROUGH OVER SOUTHEAST MINNESOTA AND NORTHERN IOWA MOVES EAST FORECAST AREA BY 15Z MONDAY. BOTH THE 00Z MONDAY GFS AND NAM INDICATE WEAK SUBSIDENCE BEHIND SHORTWAVE TROUGH PER TIME HEIGHT CROSS SECTIONS. THIS WILL ALLOW FOR A SMALL BREAK OF PRECIPITATION CHANCES ACROSS THE FORECAST AREA DURING THE MID DAY TODAY. NEXT SHORTWAVE TROUGH OVER THE DAKOTAS MOVES EAST INTO CENTRAL MINNESOTA BY 00Z TUESDAY. 00Z MONDAY GFS MUCH STRONGER WITH MOISTURE CONVERGENCE AND TRANSPORT ASSOCIATED WITH SHORTWAVE TROUGH THAN NAM. BOTH THE 00Z GFS ENSEMBLES AND 21Z SREF DOES INDICATE OVER 60 PERCENT PROBABILITY OF MEASURABLE PRECIPITATION OVER FORECAST LATE THIS AFTERNOON INTO TONIGHT. THOUGH...BOTH THE 00Z MONDAY MODELS INDICATE BEST LIFT AND MOISTURE CONVERGENCE NORTHWEST OF FORECAST AREA. HAVE ADJUSTED PRECIPITATION CHANCES DURING THE DAY FOR EXPECTED SUBSIDENCE IN WAKE OF FIRST SHORTWAVE TROUGH. DIFFERENCES IN MODELS ON PLACEMENT AND TIMING OF SURFACE FRONT AND ASSOCIATED SHORTWAVE TROUGHS...ALLOWS FOR VERY LOW CONFIDENCE IN FORECAST TUESDAY INTO WEDNESDAY. 00Z MONDAY GFS MUCH FASTER WITH SURFACE LOW THAN NAM. THOUGH...BOTH MODELS CONTINUE TO INDICATE STRONG MOISTURE TRANSPORT AND THETA E CONVERGENCE ASSOCIATED WITH SHORTWAVE TROUGH TUESDAY NIGHT. WILL INCREASE CHANCES OF PRECIPITATION TUESDAY NIGHT ACROSS SOUTHERN FORECAST AREA. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY MAIN FORECAST CONCERNS IS PLACEMENT OF SURFACE FRONT OVER THE CENTRAL PLAINS THROUGH PERIOD. LATEST 00Z MONDAY GFS AND ECMWF INDICATE SURFACE FRONT REMAINS NEARLY STATIONARY OVER CENTRAL ILLINOIS AND NORTHERN MISSOURI THROUGH PERIOD. CONFIDENCE IN TIMING OF SHORTWAVE TROUGHS MOVING ALONG SURFACE IS LOW. PREVIOUS FORECAST HAS GOOD HANDLE ON PRECIPITATION TRENDS AND WILL MAKE NO CHANGES AT THIS TIME. .AVIATION... BETTER FORCING...MOISTURE TRANSPORT/LIFT FOR SHRA/TSRA MOVES OFF TO THE SOUTH/EAST OF THE TAF SITES FOR TODAY/TONIGHT. HOWEVER...SCT SHRA/TSRA STILL POSSIBLE WITH SOME WEAK MOISTURE TRANSPORT/LIFT OVER THE AREA. OF GREATER CONCERN IS ABUNDANT MOISTURE TRAPPED BELOW THE SFC-850MB WARM FRONTAL INVERSION OVER THE AREA. EAST/SOUTHEAST SFC WINDS AND PLENTY OF SHRA/TSRA TO THE EAST/SOUTH OF THE AREA WILL ALLOW FOR LITTLE SCOURING OF THE LOW LEVEL MOISTURE...LOW CLOUDS AND FOG. APPEARS MVFR/IFR CIGS AND VFR TO IFR VSBYS /DEPENDING ON LOCAL ELEVATION/ WILL BE THE RULE THRU MUCH TODAY/TONIGHT. SOME SMALL IMPROVEMENT OF CIGS/VSBYS DURING THE LATE MORNING TO EARLY EVENING HOURS DUE TO WEAK DIURNAL WARMING. .HYDROLOGY... CURRENT RADAR INDICATES SCATTERED SHOWERS AND THUNDERSTORMS ALONG AND SOUTH OF THE MINNESOTA/IOWA BORDER. WILL ALLOW FLASH FLOOD WATCH TO EXPIRE AT 09Z MONDAY BASED ON PRECIPITATION AMOUNTS WILL RANGE FROM AROUND A TENTH TO TWO TENTHS OF AN INCH FROM ONGOING PRECIPITATION. SOME RIVERS ARE ABOVE FLOOD STAGE ACROSS THE SOUTHERN HALF OF THE HSA AT THIS TIME. WITH A FRONT NEARLY STATIONARY ACROSS SOUTHERN IOWA THE NEXT COUPLE OF DAYS. A SERIES OF SHORTWAVE TROUGHS ALONG AND NORTH OF THE FRONT WILL PROVIDE THE CHANCES OF SHOWERS AND THUNDERSTORMS. ANY ADDITIONAL RAINFALL WILL ALLOW FOR THE POSSIBILITY OF ADDITIONAL RISES ALONG RIVERS AND STREAMS. SEE FLOOD WARNINGS FOR ALL THE DETAILS ON THE RIVERS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ .SHORT TERM AND LONG TERM...DTJ .AVIATION...RRS wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 824 PM CDT SUN AUG 19 2007 .UPDATE...WILL CONTINUE FLASH FLOOD WATCH FOR TONIGHT ALTHOUGH CURRENT SYNOPTIC PATTERN YIELDING MIXED SIGNALS. CONVECTIVE COMPLEX OVER IOWA WITH VERY COLD CLOUD TOPS MOVING SOUTHEAST INTO VERY RICH MOIST AND UNSTABLE AIRMASS. HOWEVER 500 MILLIBAR RUC ANALYSIS SHOWING 17 UNIT VORTICITY CENTER OVER WEST CENTRAL WISCONSIN MOVING EAST. ASSOCIATED 500 MILLIBAR DIVERGENCE WITH THIS VORTICITY MAX SHOULD PROVIDE CONTINUED UPPER AIR SUPPORT TO BROAD RAIN AREA AND EMBEDDED CONVECTION APPROACHING WESTERN CWA FROM MISSISSIPPI RIVER. IN ADDITION 850 MILLIBAR FLOW FROM BOTH RUC PROG AND NEARBY PROFILERS FEEDING A 25 KNOT LOW LEVEL JET INTO CWA FROM EASTERN IOWA AND WESTERN ILLINOIS OVER BAROCLINIC ZONE ACROSS CWA. FINALLY VERY LOW FLASH FLOOD GUIDANCE VALUES OVER WATCH AREA DICTATE THAT EVEN A PERIOD OF MODERATE RAIN WOULD BE A CONCERN FOR EITHER RIVER OF FLASH FLOODING. && .PREV DISCUSSION... /ISSUED 328 PM CDT SUN AUG 19 2007/ DISCUSSION...FCST FOCUS ON NEXT ROUND OF HEAVY RAINFALL TONIGHT AND ACTIVE WX PATTERN FOR MUCH OF THIS WEEK. CWA RELATIVELY RAIN-FREE WITH RGNL PROFILERS AND 88-D VAD WINDS SHOWING 850 MB WINDS HAVE VEERED TO THE WEST...WITH BEST LIFT FOCUSED ON NRN IL CLOSER TO SFC WRM FRONT. RESPITE WILL BE SHORT-LIVED AS 2 FEATURES APPROACH CWA. CONVECTION IN SW/ SCNRTL MN AHEAD OF SHORT WAVE TROUGH THAT WATER VAPOR IMAGERY PLACES IN FAR SE S DAKOTA...SECOND FEATURE IS APPARENT MCV EJECTING NEWD FROM REMAINS OF ERIN WITH ASSOCIATED MOISTURE SURGING NWD THRU NRN MO/SE IA AND INTERACTING WITH SFC FNT DRAPED ACROSS NRN IL. TSTMS ARE FORMING IN NERN IA AHEAD OF THIS MCV. SPC MESOANALYSIS HAS 2 GROWING AREAS OF 2 INCH PWS WITH THESE FEATURES THAT MODEL FCSTS MOVE INTO CWA AFTER 00Z. SFC-850 AND 850-700MB 2D FRONTOGENTIC FCSTS SHOW INCREASING FORCING AS 850 MB WINDS BACK TO THE SW AHEAD OF THE SHRT WV TROUGH OVER LINGERING BAROCLINIC ZONE...THO WINDS WILL BE LOWER THAN LAST NIGHT...IN THE 20-30 KT RANGE. SFC FRONT LIFTS CLOSER TO SRN WI AS WELL. MIXED LAYER THETA-E ADVECTION INCREASES OVER CWA BETWEEN 06Z AND 12Z...WITH GFS BUFKIT SNDGS INDICATING ELEVATED CAPE FOR MSN INCREASING FROM AROUND 650 J/KG AT 03Z...TO AROUND 1000 J/KG BY 09Z. CRAS INFRARED FCSTS ALSO INDICATE INCREASING CONVECTIVE POTENTIAL OVER SRN WI AS THE TWO AREAS PHASE OVER NE IA/SW WI WITH CRAS SHOWING COLDEST CLOUD TOPS MOVING FROM SE MN/NE IA AT 00Z SPREADING OVER THE CWA BETWEEN 03Z AND 06Z. WITH SATURATED GROUND AND ONGOING FLOOD PROBLEMS IN WRN CWA...AND LOW COUNTY FLASH FLOOD GUIDANCE VALUES...WILL ISSUE A FLASH FLOOD WATCH FROM 23Z TODAY THRU 12Z MONDAY FOR COUNTIES CURRENTLY IN THE FLOOD WARNING. WILL KEEP THE CURRENT FLOOD WARNING GOING UNTIL 7 PM FOR S CNTRL WI COUNTIES WHERE THERE IS ONGOING FLOODING PROBLEMS...BUT CANCEL FOR SE WI COUNTIES. BEST FORCING FINALLY MOVES SOUTH OF CWA DURING THE LATE DAY MONDAY...BUT SFC BNDRY...850MB BAROCLINIC ZONE AND SERIES OF SHRT WAVES EJECTING FROM NW U.S. TROF AND TRACKING ACROSS NRN U.S IN ZONAL FLOW WILL KEEP CHC PCPN IN FCST UNTIL LATE IN THE WEEK. EXTENDED...A BLEND OF GFS ENSEMBLES AND ECMWF PREFERRED FOR EXTENDED. THIS SOLUTION...FOLLOWING FRONTAL PASSAGE WEDNESDAY...DROPS THE SFC BNDRY TO THE WI/IL BRDER AND STALLS THERE FOR THURSDAY. 850 MB FLOW BACKS TO THE SW AHEAD OF APPROACHING WAVE FROM THE PLAINS AND PROVIDES LIFT ACROSS BNDRY TO KEEP CHC FOR SHOWERS AND STORMS IN FCST...ESPECIALLY THURSDAY AFTERNOON AND EVENING. THIS LAST WAVE IN A SERIES TRACKS ACROSS WRN GREAT LAKES FRIDAY...FOLLOWED BY A NEEDED BREAK IN THE ACTIVE WEATHER AS DRY COOL CANADIAN HIGH PRESSURE BUILDS IN SATURDAY BEHIND DEPARTING SFC LOW AND HOLDS OVER REGION THRU THE WEEKEND. AVIATION...XPCT WDSPRD MVFR CONDS IN -RA/-TSRA/BR THRU 00Z MON. AREAS OF IFR CIGS/VSBYS EXPCTD IN PDS OF HVY RA/TSRA INTO 18Z MON. STNRY FNT ACRS IA AND NRN IL THRU PD WITH MSTR LIFTING OVR FNT INTO SRN WI. MKX WATCHES/WARNINGS/ADVISORIES... FLOOD WARNING UNTIL 7 PM FOR WIZ056>058-062>064-067>069. FLASH FLOOD WATCH FROM 6 PM CDT THIS EVENING UNTIL 7 AM CDT MONDAY FOR WIZ056>058-062>072. $$ && .MKX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 7 AM CDT MONDAY FOR WIZ056>058-062>072. && $$ ZAJDEL wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 149 AM EDT TUE AUG 21 2007 .AVIATION... FOCUS NEXT 6 HOURS WILL LIE WITH DEPARTING SHOWERS MOVING ACROSS FWA AND THEN STALLED BOUNDARY ACROSS THE AREA. BULK OF PRECIP HAS SHIFTED SE OF KFWA...BUT NEW DEVELOPMENT TRYING TO GET GOING TO THE WEST. EXPECT THIS TREND TO CONTINUE A FEW MORE HOURS BEFORE RISE IN PRESSURE TO THE WEST SHOULD PASS OVERHEAD AND BRING A TEMP END TO PRECIP. MSTR RICH ATMOSPHERE FROM COMBINATION OF RAINFALL AND TROPICAL AIRMASS WILL ALLOW FOG/LOW CLOUDS TO PERSIST INTO TUES AM...SO HAVE KEPT IFR CIGS GOING INTO THE MORNING. AT KSBN ONLY LOW CLOUDS/FOG TO DEAL WITH FOR NOW. THEN MAIN FOCUS TURNS TO LARGE COMPLEX IN EASTERN IOWA WORKING EAST. TRAJECTORIES AND LOW LEVEL FLOW WOULD SUGGEST THIS SHOULD KEEP TRACKING EAST AND ARRIVE SOMETIME IN THE MORNING OR EARLY AFTERNOON. POSSIBLY BASED ON LLJ SIGNALS THAT NEW DEVELOPMENT COULD OCCUR ON LEADING EDGE AND ALLOW FOR SOONER ARRIVAL. FOR NOW WILL LEAVE BEYOND 12Z ALONE IN TAFS AND LOOK AT THINGS CLOSE AS THE EVENT DRAWS NEAR. && .SHORT TERM... TONIGHT THROUGH TUESDAY AFTERNOON... OVERALL SYNOPSIS ACROSS THE CONUS SHOWS STRONG RIDGING CENTERED OVER THE SOUTHEASTERN CONUS AND DESERT SOUTHWEST WITH NEARLY ZONAL FLOW ACROSS THE NORTHERN STATES...SMALL AMPLIFIED RIDGE FROM THE EXTREME NORTHWESTERN GREAT LAKES INTO HUDSON BAY. LAST BITS OF ERIN REMAIN ACROSS THE OZARKS. SURFACE FRONT REMAINS SITUATED FROM THE MOD VALLEY TO NEAR CHICAGO ACROSS NORTHERN INDIANA INTO CENTRAL OHIO. CURRENT RUC ANALYSIS SHOWS DECENT 30 TO 40 KT LOW LEVEL JET STILL DRIVING INTO THE BOUNDARY...THOUGH THE WINDS SEEM TO HAVE VEERED SOME TO THE WEST...POSSIBLY THE REASONING FOR THE LESSER AMOUNTS ACROSS THE NORTHERN PORTIONS OF THE FORECAST AREA TODAY. FLOODING CONCERNS ARE LESSENING QUICKLY ACROSS THE REGION. TONIGHT THE BEST FORCING APPEARS TO BE DRIFTING EAST OF THE REGION AS MODELS AND LATEST RUC ANALYSIS EACH SHOWS THE BETTER FRONTOGENETICAL FORCING ACROSS NORTHERN OHIO AND PARTS EAST. COMBINED WITH THE MOISTURE ROBBING EFFECTS OF CONVECTION ACROSS CENTRAL INDIANA THE RAINFALL AMOUNTS SHOULD BE LOWER THAN PREVIOUS THINKING. BECAUSE OF THESE FACTORS WILL BE DROPPING THE FLOOD WATCH ACROSS THE ENTIRE REGION. RIVER FLOODING WILL BE THE MAIN CONCERN THE NEXT FEW DAYS. MORE SOUTHERLY FLOW ACROSS THE REGION AT THE SURFACE HAS BROUGHT DEWPOINTS UP INTO THE MID TO UPPER 60S ACROSS MUCH OF THE REGION...LOW TEMPS WILL NOT DROP MUCH BELOW THE UPPER 60S FOR MUCH OF THE AREA...OUTSIDE OF THE FAR NW COUNTIES NEAR HILLSDALE MI WHERE MID TO LOWER 60S WILL BE POSSIBLE. TUESDAY THE FRONT SHOULD LIFT SLIGHTLY NORTH FURTHER INTO THE GREAT LAKES...WITH WARMER AND MOIST AIR MOVING INTO THE REGION. ALL DAY PRECIP LOOKS UNLIKELY...BUT MORE SCATTERED ACTIVITY DOES. AFTERNOON HEATING WILL DROP LI`S TO AROUND -5 OR -6 WITH SURFACE BASED CAPES NEARING 2000 TO 2500 J/KG BY MID AFTERNOON. SCATTERED AFTERNOON THUNDERSTORMS WILL DEVELOP...WITH VERY LOCALIZED HEAVY RAINFALL POSSIBLE. WITH THE COVERAGE OF STORMS NOT NEARLY AS GREAT...SOME NUISANCE FLOODING AND QUICK FLASH FLOODING MAY OCCUR BUT A NEED FOR A FLOOD WATCH IS UNWARRANTED AT THIS TIME FOR THIS ACTIVITY. HIGHS WILL REBOUND TO MORE SEASONAL LEVELS...ONLY LIMITED BY THE CLOUD COVER AS H850 TEMPS JUMP TO NEAR 20C ACROSS THE AREA. HIGHS WILL PUSH INTO THE 80S WITH SOME UPPER 80S POSSIBLE ACROSS THE SOUTHERN COUNTIES. && .LONG TERM... BEGINNING OF FCST PERIOD SHOULD FEATURE DIMINISHING CHANCES OF PRECIP AS FRONTAL BOUNDARY LIFTS NORTH OF THE AREA AND WHATS LEFT OF ERIN SHIFTS EASTWARD. HAVE TRENDED GRIDS TUE NITE THROUGH WED MORNING ACCORDINGLY WITH DRY FCST OVER ALL BUT NORTHERN CWA BY 12Z WED. THIS WILL HAVE OUR CWA IN WARM SECTOR...WARM HUMID AND VERY UNSTABLE AIRMASS COMBINED WITH AMPLE LOW LEVEL MOISTURE FROM RECENT RAINS SHOULD BE SUFFICIENT TO TRIGGER SCT TSRA BY THE AFTERNOON HOURS ON WED DESPITE THE LACK OF ANY APPARENT LARGER SCALE FOCUS AND FORCING. MODELS INDICATING PREVAILING SW FLOW WITH OUR AREA IN WARM SECTOR THROUGH THURSDAY...SUGGESTING THE POTENTIAL FOR A MORE SUSTAINED 1 TO 2 DAY PERIOD OF DRY WEATHER DEVELOPING IN THIS TIME FRAME...BUT FOR NOW WILL KEEP SMALL CHANCE POPS FROM CURRENT FCST AND SEE IF MODELS CONTINUE THIS TREND. NO MAJOR CHANGES IN REMAINDER OF EXTENDED AS MEDIUM RANGE MODELS INDICATE COLD FRONT TO MOVE THROUGH ON SAT BRINGING DRY FCST TO THE AREA DAYS 6 AND 7. WARMING TREND EXPECTED MID WEEK AS FRONTAL BOUNDARY LIFTS NORTH ALLOWING TEMPS TO REACH NEAR 90...WITH LOWER 90S POSSIBLE WED AND THUR IF ANY APPRECIABLE AMOUNT OF SUN. WITH DEWPOINTS AROUND 70F HEAT INDICES COULD APPROACH 100 WED AND THU AFTN IF L90S ARE REALIZED. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SCHOTT/LASHLEY LONG TERM....LOGSDON AVIATION...FISHER in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 259 AM EDT TUE AUG 21 2007 .SHORT TERM (TODAY AND TONIGHT):... PCPN POTENTIAL AND TEMPS THE MAIN FORECAST PROBLEM FOR THE SHORT TERM. REMNANTS OF ERIN WILL ACCELERATE EAST TO EAST SOUTHEAST ACROSS FA TODAY. TRW/RW WILL ENTER NWRN PTNS OF FA ABOUT THE TIME THIS FCST IS ISSUED AND THEN AS ERIN STARTS TO ACCELERATE EASTWARD...THE PCPN THREAT WILL GREATLY DIMINISH WEST TO EAST ACROSS FA BY LATE MORNING INTO THE EARLY AFTERNOON HOURS. WILL GO WI 50 PCT POPS FOR A TIME WEST TO EAST ACROSS FA THIS MORNING INTO EARLY AFTN IN THE EAST. NO MENTION OF PCPN TONIGHT AS PER CURRENT FCST. WITH SUNSHINE INCREASING DURING THE AFTERNOON HOURS...EXPECT VERY WARM HIGH TEMPS MOSTLY IN THE LOWER TO MIDDLE 90S TODAY. THIS AGREES WELL WITH OUR CURRENT FCST AND THE PREFERRED MAV FCST TRENDS. --21 LONG TERM (WEDNESDAY THROUGH MONDAY)... WEDNESDAY THROUGH THURSDAY... THE UPPER AIR PATTERN FOR WEDNESDAY AND THURSDAY WILL FEATURE A FAST ZONAL FLOW WITH THE JET STREAK ALONG THE US/CANADIAN BORDER. ONE LOW AMPLITUDE TROUGH WILL EXIT NEW ENGLAND WEDNESDAY WHILE A JET STREAK ACROSS THE UPPER MIDWEST WILL ACCOMPANY AN UPPER LOW ACROSS THE CANADIAN PROVINCES. OF MORE DIRECT IMPORTANCE TO OUR AREA IS THE VERY STRONG UPPER RIDGE EXPECTED ACROSS THE SOUTHERN STATES. THE 00Z THURS FORECAST 500MB HEIGHTS OF UP TO 597DM ACROSS THE GULF STATES BY THE GFS ENSEMBLES IS 2 STANDARD DEVIATIONS ABOVE NORMAL. THE CENTER OF HIGH PRESSURE NEAR THE SURFACE WILL ALSO CENTER OVER THE GULF STATES. THIS WILL BRING SOUTHWEST FLOW TO THE LOWER OHIO VALLEY WITH ONLY MODEST MOISTURE AVAILABLE. WITH 925MB TEMPERATURES APPROACHING 30 ON THURSDAY...TEMPERATURES WILL EASILY MOVE BACK INTO THE UPPER 90S BY THURSDAY AFTERNOON. EXPECT LITTLE CHANCE OF RAIN THESE TWO DAYS. THE AXIS OF HIGHER MOISTURE WILL LIE TO OUR NORTHWEST...STRETCHING FROM THE CENTRAL PLAINS TO THE WESTERN GREAT LAKES. FRIDAY THROUGH MONDAY... RIDGING WILL REMAIN STRONG ACROSS THE SOUTHEASTERN STATES. THE STORM TRACK ON FRIDAY WILL REMAIN ALONG A NEARLY STATIONARY FRONT FROM KANSAS THROUGH THE WESTERN GREAT LAKES. LOW PRESSURE MOVING ACROSS THE GREAT LAKES LATE FRIDAY WILL ALLOW THIS BOUNDARY TO SAG SOUTH AS A COLD FRONT. EVENTUALLY THIS WEAKENING FRONT WILL APPROACH KENTUCKY BY SATURDAY. MOISTURE WILL INCREASE AHEAD OF THIS BOUNDARY AND SO WILL CONTINUE PRECIPITATION CHANCES FOR THE WEEKEND TIME FRAME. THE LATEST GFS SLOWS DOWN THE PROGRESS OF THE FRONT...WHICH MAY STALL NEAR KENTUCKY SUNDAY. HAVE ADDED POPS FOR SUNDAY. JSD && .AVIATION (06Z TAFS):... THE REMNANTS OF ERIN TO MOVE ACROSS NORTHERN POTIONS OF FA DURING THE LATE NIGHT AND MORNING TIME FRAME. WILL GO WI MTN OF VCTS IN TAFS...SDF FOR LATER TONIGHT AND DURING MORNING FOR LEX. THE REMNANTS ACCELERATE OFF TO THE EAST SOUTHEAST DURING THE MORNING. LATEST RUC40 INDICATES SAME. GENERALLY VFR CONDS THROUGH THIS TAF PERIOD. ENOUGH CLOUDS AND SFC GRADIENT TO ELIMINATE ANY REAL THREAT OF MVFR CONDS WITH LATE NIGHT FOG. PRESSURE GRADIENT RELAXES SOME DURING THE AFTERNOON AND EVE ON WED AND WILL LIKEWISE REDUCE THE WIND SPEEDS IN TAFS. ALSO...THE LOW LEVEL WIND FIELDS NOT AS ROBUST AS THE EARLIER INDICATED IN PREVIOUS MODEL RUNS SO OPTED NOT TO MENTION LLWS OVERNIGHT. --21 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 159 AM CDT TUE AUG 21 2007 .DISCUSSION... ONGOING CONVECTION FROM DECAY OF EXTRA TROPICAL ERIN REMNANTS BEST IDENTIFIED BY RUC/NAM...W/SENSIBLE WEATHER REALIZATION PERHAPS BEST REFLECTED BY NOT ONLY MEASURABLE PCPN BUT ALSO 5-15 MPH MID AUGUST BREEZE. IT LIFTS THE NOW MCV AND OPENS THE WAVE TODAY WHILE LINGERING A POP ESP NERN PTNS FA...ANOTHER REASON WE PREFER NAM LEAN GIVEN DRY GFS SOLUTION. AFTER TODAY THOUGH THE INCREASING PREDOMINANT WEATHER FACTOR/INFLUENCE WILL BE THE BUILDING 597DM+ H5 HIGH PRESSURE DOME ACROSS THE SOUTH. IT WILL ARC ITS RIDGELINE UP THE MS VALLEY AND RESULT IN A RETURN OF HEAT/HUMIDITY THAT WILL ALLOW HEAT INDICES TO HIT/EXCEED 100 AND MAY APPROACH 105 WED-FRI. ALL OF THIS IS FAIRLY WELL REPRESENTED IN THE CURRENT FORECAST SO ONLY MINOR ADJUSTMENTS FOR 00Z DATA INCORPORATION AND COLLABORATION WERE NEEDED. THEN AFTER THAT THE HIGH BREAKS DOWN...THE FLOW GOES MORE ZONAL...AND NRN STREAM STEERING ALLOWS A FRONTAL BOUNDARY TO LAY OUT ACROSS THE OH VALLEY...RESULTING IN CHC POPS OVER THE WEEKEND. THE LATEST GFS FLIRTS WITH EXTENDING THIS CHANCE INTO EARLY NEXT WEEK BUT THE OVERALL TREND IS WELL REPRESENTED IN THE EXISTING PACKAGE SO WE`LL AWAIT MORE MODEL INGEST BEFORE ALTERING LONG RANGE PTN OF FORECAST. A NAM BIAS RESULTS IN A LEAN TOWARD ITS MET BASED MOS...WHICH MEANS MAINLY SLIGHTLY COOLER (BUT STILL HOT) HIGHS TODAY...AFTER THAT ALL THE MOS IS PRETTY CLOSE. && .AVIATION... SCT-BKN CEILINGS IN MOST LOCATIONS OVERNIGHT...BUT SHOULD SEE SOME LOWER CEILINGS NEAR KEVV AND KPAH DUE TO SCT SHRA/TSRA ACTIVITY APPROACHING. COULD SEE SOME MVFR FOG EARLY THIS MORNING AND ALSO WITH ANY PRECIP. PRECIPITATION SHOULD START TO CURTAIL TOWARD SUNRISE AS UPPER LEVEL SYSTEM MOVES OFF TO THE EAST. HOWEVER...ANOTHER SYSTEM ON ITS HEELS COULD PRODUCE ADDITIONAL SHRA/TSRA DURING THE DAY TODAY ALONG WITH SCT 4000 FT CUMULUS. FOR NOW HAVE JUST VICINITY THUNDERSTORM AS SUBSEQUENT SETS OF TAFS SHOULD BE BETTER ABLE TO NAIL DOWN TIMING. WINDS WILL BE GUSTY AGAIN TODAY BY MID MORNING OUT OF THE SOUTHWEST BUT SHOULD TAPER OFF BY SUNSET. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 140 AM EDT TUE AUG 21 2007 .AVIATION (06Z TAFS):... THE REMNANTS OF ERIN TO MOVE ACROSS NORTHERN POTIONS OF FA DURING THE LATE NIGHT AND MORNING TIME FRAME. WILL GO WI MTN OF VCTS IN TAFS...SDF FOR LATER TONIGHT AND DURING MORNING FOR LEX. THE REMNANTS ACCELERATE OFF TO THE EAST SOUTHEAST DURING THE MORNING. LATEST RUC40 INDICATES SAME. GENERALLY VFR CONDS THROUGH THIS TAF PERIOD. ENOUGH CLOUDS AND SFC GRADIENT TO ELIMINATE ANY REAL THREAT OF MVFR CONDS WITH LATE NIGHT FOG. PRESSURE GRADIENT RELAXES SOME DURING THE AFTERNOON AND EVE ON WED AND WILL LIKEWISE REDUCE THE WIND SPEEDS IN TAFS. ALSO...THE LOW LEVEL WIND FIELDS NOT AS ROBUST AS THE EARLIER INDICATED IN PREVIOUS MODEL RUNS SO OPTED NOT TO MENTION LLWS OVERNIGHT. --21 && .EVENING UPDATE... LOWERED PRECIP OVERNIGHT GIVEN CURRENT RADAR TRENDS. SHORTWAVE NEAR ST. LOUIS IS CURRENTLY GENERATING NEW CONVECTION OVER SERN MO. THIS SHOULD MOVE EAST TOWARD THE CWA. THIS COMBINED WITH OUTFLOW BOUNDARIES FROM STORMS ACROSS IN/OH AND SYNOPTIC BOUNDARY ACROSS CENTRAL IL/IN (ALSO GENERATING NEW CONVECTION NOW) SHOULD CONTINUE THE THREAT OF SHOWERS AND STORMS OVERNIGHT...MAINLY NW OF A LINE FROM BOWLING GREEN TO FRANKFORT OVERNIGHT...WITH THE BEST CHANCE ACROSS THE FAR WRN AND NRN CWA. SINCE I LOWERED LIKELY POPS TO CHC (SIMILAR TO SREF VALUES)...ALSO TOOK OUT THE MENTION OF HVY RAIN THOUGH ANY STORMS THAT DO FORM WILL IN FACT CONTAIN HEAVY RAINFALL. GIVEN THE LOW-LEVEL WINDS IN PLACE...COULD ALSO HAVE GUSTY WINDS WITH THE STRONGER CELLS. BECAUSE OF THIS...MENTIONED LLWS IN THE TAFS AS WELL. LOWERED CLOUD COVER BASED ON CURRENT CONDITIONS...AND BUMPED UP OVERNIGHT LOWS A DEGREE OR TWO WITH INCREASED CLOUD COVER EXPECTED TOWARD MORNING. AL && .PREV DISCUSSION... SHORT TERM (TONIGHT AND TUESDAY)... A MOIST SOUTHWEST FLOW CONTINUES ACROSS THE OHIO VALLEY WHICH PRODUCED TEMPERATURES IN THE MIDDLE 90S OVER CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA. WITH THIS BEING THE 22ND DAY WITH THE TEMPERATURE AT 90 OR ABOVE IN LOUISVILLE THAT RECORD PREVIOUSLY SET IN 1936 HAS NOW BEEN BROKEN. A SHORTWAVE LOCATED OVER MISSOURI THIS AFTERNOON WILL MOVE ACROSS SOUTH CENTRAL INDIANA OVERNIGHT AND WILL ENHANCE THE CHANCE OF PRECIPITATION GENERALLY NORTH OF THE WESTERN KENTUCKY AND BLUEGRASS PARKWAYS. PW VALUES WILL INCREASE TO GREATER THAN 2 INCHES SO HEAVY RAINFALL WILL BE A CONCERN. LOW LEVEL WINDS WILL CONTINUE AT 20 TO 30KTS SO GUSTY WINDS MAY BE AN ISSUE AS WELL. PRECIPITATION CHANGES WILL DECREASE TUESDAY AS THE S/W MOVES EAST OF THE AREA. A WESTERLY FLOW WILL KEEP WARM AIR ADVECTING INTO THE REGION SO TEMPERATURES WILL AGAIN RISE ABOVE 90 ACROSS THE FORECAST AREA. SLD/JA LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... HIGH PRESSURE FROM THE SURFACE INTO THE MID LEVELS OF THE ATMOSPHERE WILL KEEP DRY BUT HOT WEATHER OVER CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA THROUGH MUCH OF THE REST OF THE WORK WEEK. HOWEVER WITH DEW POINTS STILL AROUND 70...HEAT INDICES WILL BE NEAR OR ABOVE 100 THROUGH FRIDAY. TUESDAY NIGHT THROUGH FRIDAY... THE MAIN PROBLEM FOR THE FIRST PART OF THE LONGER TERM WILL BE HOW HIGH THE TEMPERATURES WILL BE AND THE HEAT INDICES. THE NAM IS SEVERAL DEGREES COOLER THAN THE GFS ON HIGH TEMPERATURES AND WITHOUT A SIGNIFICANT FRONTAL PASSAGE TEMPERATURES CLOSER TO THE GFS MOS GUIDANCE SEEMS MORE REASONABLE. WEAK SOUTHWEST WINDS WILL PERSIST AND THIS WILL KEEP THE WARMER AIR OVER OUR REGION. THIS PATTER WILL HOLD THROUGH FRIDAY...BEFORE AN UPPER LEVEL TROUGH MOVING ACROSS SOUTHERN CANADA ALLOWS A FRONT TO DROP SOUTHEAST TOWARD THE OHIO VALLEY. FRIDAY NIGHT THROUGH MONDAY... AS THE UPPER LEVEL TROUGH MENTIONED ABOVE MOVES EAST ACROSS SOUTHERN CANADA...A COLD FRONT WILL DROP SOUTHEAST TOWARD THE LOWER OHIO VALLEY. WITH HIGH PRESSURE ANCHORED ALONG THE SOUTHEAST COAST...THE SLOWER GFS AND ECMWF ARE PREFERRED FOR THE FRONTAL MOVEMENT. THE LATTER MODEL RUNS ARE SLOWING DOWN THE FRONTAL PASSAGE WHICH ADDS SUPPORT TO THIS REASONING. WILL KEEP A SMALL CHANCE OF THUNDERSTORMS FOR FRIDAY NIGHT ACROSS THE NORTH WITH THE CHANCE OF STORMS SPREADING ACROSS THE FORECAST AREA ON SATURDAY THEN END FROM THE WEST SATURDAY NIGHT AS THE FRONT EXITS THE AREA. HIGH PRESSURE MOVING EAST ACROSS THE GREAT LAKES WILL BRING COOLER AIR INTO CENTRAL KENTUCKY AND SOUTH CENTRAL INDIANA ON SUNDAY AND MONDAY. SCHOLZ && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 431 AM EDT TUE AUG 21 2007 .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED TROUGHING COVERING MUCH OF WESTERN CANADA AND FROM WASHINGTON INTO NORTH DAKOTA...WHILE RIDGING WAS PRESENT DOWNSTREAM FROM ONTARIO SOUTHWARD THROUGH THE GREAT LAKES. THREE SHRTWVS OF NOTE INCLUDE ONE OVER NORTHEAST WI...ANOTHER IN NW MN/FAR WRN ONTARIO AND A THIRD IN SW MN. DPVA FROM THE NORTHEAST WI SHRTWV HELPED TO PRODUCE A FEW SHOWERS AND THUNDERSTORMS ACROSS THE EAST HALF OF WI LAST EVENING. HOWEVER...AS THEY TRIED TO PUSH INTO THE DRIER AIRMASS OVER THE CWA AS EVIDENCED BY A 01Z TAMDAR SOUNDING FROM SAW...THEY HAVE BEEN FALLING APART. ANOTHER REPRESENTATION OF THE DRY AIR IS WITH THE SURFACE DEWPOINTS...WITH READINGS IN THE UPPER 40S F INLAND OVER THE EASTERN U.P. AND NORTHERN LOWER MI. SE WINDS AROUND HIGH PRESSURE SITUATED OVER FAR WESTERN QUEBEC IS WHAT APPEARS TO BE HOLDING DRY AIR INTO THE CWA. THE SECOND SHRTWV OVER NW MN/FAR WRN ONTARIO IS HELPING TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS ACROSS FAR NORTHERN MN INTO WESTERN ONTARIO. TO THE SW...STRONGER CONVECTION STRETCHES FROM EAST CENTRAL MN THROUGH SW WI...EASTERN IOWA AND NE MO...AIDED BY THE SW MN SHRTWV AND STRONG 850 THETA-E ADVECTION ALONG AND JUST NORTH OF A SURFACE STATIONARY FRONTAL BOUNDARY ALONG I-80. && .DISCUSSION... MAIN FORECAST CONCERN REMAINS RAIN CHANCES THROUGH THE WEEK TO ALLEVIATE THE CURRENT DROUGHT. TODAY...UPPER RIDGE OVER THE CWA WILL PUSH EAST TODAY DUE TO THE SHRTWVS OVER MINNESOTA AND FAR WESTERN ONTARIO LIFTING NORTHEAST. SHRTWV OF MOST INTEREST TO BRING POSSIBLE PCPN TO THE CWA IS THE ONE OVER SW MN. THE REGIONAL CANADIAN...13 KM RUC AND LOCAL WRF-ARW RUNS SEEM TO HAVE THE BEST HANDLE ON THIS SHRTWV AND ITS ASSOCIATED PCPN...BRINGING IT ACROSS WESTERN LAKE SUPERIOR AND THE WEST HALF OF UPPER MICHIGAN TODAY. THIS SEEMS REASONABLE TOO SINCE THE 850MB MOISTURE TRANSPORT VECTORS ARE PROGGED TO VEER FROM THE CURRENT SE TOWARDS THE SW...ALLOWING THE AIR TO MOISTEN. REMOVED THE LIKELY WORDING BECAUSE OF CONCERN OF LINGERING DRY AIR...BUT 50 POPS FOR WESTERN LAKE SUPERIOR AND THE FAR WESTERN U.P. WILL REMAIN. HOWEVER...A DIFFERENT SCENARIO EXISTS FOR THE EASTERN U.P. AS THE 850MB MOISTURE TRANSPORT VECTORS REMAIN SE THROUGH THE DAY... HOLDING DRY AIR IN. THUS HAVE NO PCPN FORECAST EAST OF MARQUETTE AND ESCANABA. THE TEMPERATURE FORECAST IS QUITE TRICKY AS IT DEPENDS ON BOTH HOW FAR EASTWARD THE CURRENT MVFR DECK ACROSS MN AND WI MAKES IT...ALONG WITH ANY CONVECTION SPREADING MID/HIGH CLOUDS EASTWARD. WITH THE 850MB MOISTURE TRANSPORT VECTORS VEERING OVER THE WEST HALF OF THE CWA...WOULD IMAGINE THAT THE MVFR DECK SHOULD MOVE IN...WITH CEILINGS RISING IN THE AFTERNOON WITH DIURNAL HEATING. SE WINDS HOLDING OVER THE EAST HALF SUGGESTS THAT ONLY INCREASING HIGH CLOUDS IN THE AFTERNOON SHOULD BE OF CONCERN...THUS WARMEST READINGS EXPECTED THERE (MID 70S). TONIGHT...SW MN SHRTWV SHOULD BE OVER THE WESTERN CWA AT 00Z WED. WITH THE UPPER FLOW PROGGED TO REMAIN SW...THIS SHRTWV SHOULD RAPIDLY HEAD UP INTO ONTARIO. DPVA ASSOCIATED WITH THE WAVE MAY CONTINUE SOME SHOWERS AND THUNDERSTORMS...WITH THE GREATEST PROBABILITY OVER THE KEWEENAW AND EASTERN LAKE SUPERIOR. BY 06Z...MUCH OF THE PCPN SHOULD BE FINISHED. HOWEVER...MODELS SHOW THE CURRENT FRONTAL BOUNDARY TO THE SOUTH NEAR I-80 BEING LIFTED NORTHWARD...AND ESPECIALLY SO IN THE 00Z GFS CASE WHERE CONVECTIVE FEEDBACK IS PRESENT. SHOWERS AND THUNDERSTORMS DEVELOPING ALONG THE FRONTAL BOUNDARY MAY END UP BRUSHING THE LAKE MICHIGAN ZONES AFTER 06Z. THUS HAVE A SLIGHT CHANCE PRESENT IN THAT AREA. WITH PLENTY OF LOW CLOUDS OVER THE AREA AND HIGHER DEWPOINTS...NOT EXPECTING LOWS TO DROP TOO MUCH. PREVIOUS FORECAST LOWS SEEMED REASONABLE. WEDNESDAY...UPPER LEVEL FLOW PROGGED TO TURN A LITTLE MORE WESTERLY...COMBINED WITH OUTFLOW BOUNDARIES FROM THE OVERNIGHT CONVECTION SHOULD HELP PUSH THE MAIN FRONTAL BOUNDARY BACK SOUTH AGAIN TOWARDS MKE AND DTX. THUS...ANY PCPN ALONG LAKE MICHIGAN SHOULD END IN THE MORNING. DURING THE AFTERNOON...MOST OF THE MODELS SHOW A LINGERING NORTH TO SOUTH TROUGH OVER THE CENTRAL U.P.. THIS TROUGH AXIS SHOULD ALLOW FOR LAKE BREEZES TO DEVELOP...ESPECIALLY WITH THE INLAND AREAS WARMING UP INTO THE UPPER 70S/LOW 80S WITH 850MB TEMPS BETWEEN 14-16C. CONVERGENCE ALONG THE LAKE BREEZES AND SURFACE TROUGH...COMBINED WITH LINGERING LOW LEVEL MOISTURE...MAY INITIATE SOME SHOWERS AND THUNDERSTORMS AS SHOWN BY THE REGIONAL CANADIAN AND LOCAL WRF-ARW RUN. GIVEN THAT THESE STORMS ARE DIURNALLY DRIVEN...THEY SHOULD END BY 00Z. WED NIGHT INTO THU...MODELS SEEM TO BE COMING TOGETHER ON A SCENARIO FOR SOME DECENT RAINS FOR THE CWA...PARTICULARLY ON THU. UPPER LEVEL FLOW IS PROGGED TO BACK TO THE SW IN RESPONSE TO A TROUGH DIGGING INTO WYOMING AND SOUTH DAKOTA DURING THIS PERIOD. IN ADDITION... MODELS SHOW A PIECE OF THE CURRENT UPPER LEVEL LOW IN DEEP SOUTH TX GETTING PICKED UP AHEAD OF THIS TROUGH AND LIFTING TOWARDS THE AREA. IF THE GFS/UKMET/CANADIAN ARE CORRECT...THE BACKING UPPER LEVEL FLOW SHOULD ALLOW THE FRONTAL BOUNDARY NEAR MKE AND DTX TO LIFT BACK NORTH TOWARDS NORTHERN LOWER MICHIGAN. THE PIECE OF THE UPPER LEVEL LOW WILL DEVELOP A SURFACE LOW ALONG THE FRONTAL BOUNDARY...WHICH THEN MOVES TOWARDS NORTHERN LAKE MICHIGAN ON THU. HIGH PRECIPITABLE WATER VALUES ASSOCIATED WITH THE SHRTWV (1.5 TO 2 INCHES) COMBINED WITH DPVA AND UPPER LEVEL JET FORCING (90-110 KT JET MAX OVER NE ONTARIO PROVIDING UPPER LEVEL DIVERGENCE OVER THE AREA) WOULD SUGGEST THE POSSIBILITY FOR A HEAVY RAIN EVENT. BOTH THE GFS AND UKMET PRODUCE A LOT OF CONVECTIVE QPF. THE NAM DOES TOO...BUT JUST FURTHER SOUTH. FOR NOW...ON THU HAVE INCLUDED POPS ACROSS ALL OF THE CWA...AND RAISED THEM TO 40 FOR THE CENTRAL AND EAST. IF FUTURE RUNS CONTINUE TO SHOW THE SAME SCENARIO...RAISING TO LIKELY ALONG WITH INCREASING QPF AMOUNTS WILL BE REQUIRED. PREVIOUS FORECAST TEMPS FOR BOTH WED NIGHT AND THU SEEM REASONABLE. BEYOND THU...WILL MAINTAIN SOME CHANCE POPS FOR THE SOUTH CENTRAL AND EAST THU NIGHT INTO FRI FOR TIMING UNCERTAINTIES WITH THE DEPARTURE OF THE SURFACE LOW AND SHRTWV. HOWEVER...IT SEEMS LIKE POPS MAY BE ABLE TO BE DROPPED AT SOME POINT FOR FRI IF CURRENT TRENDS FROM THE 00Z GFS/ECMWF CONTINUE. HIGH PRESSURE THEN BUILDS IN FOR THE WEEKEND...PROVIDING FOR ANOTHER STRETCH OF DRY WEATHER. LOWS MAY GET CHILLY SAT NIGHT WITH A PRECIPITABLE WATER MINIMUM COMING ACROSS AND LIGHT WINDS. COOP GUIDANCE SHOWS A LOW OF 43 FOR CHAMPION. ABOVE NORMAL CONDITIONS EXPECTED INTO EARLY NEXT WEEK AFTER SAT NIGHT AS SOUTHERLY FLOW KICKS UP ON THE BACK SIDE OF THE HIGH. && .FIRE WEATHER... ANOTHER NOT SO GOOD DAY FOR THE SLEEPER LAKE FIRE IS PLANNED TODAY. GIVEN TEMPERATURES RISING INTO THE MID 70S...DEWPOINTS WILL DROP AT LEAST INTO THE LOW 50S...RESULTING IN MIN RHS BETWEEN 40-45 PERCENT. THESE ARE 10 PERCENT HIGHER THAN YESTERDAY...BUT 10-METER ESE WINDS OF 15 KT WITH GUSTS PERHAPS AS HIGH AS 25 KT AS INDICATED BY THE 13 KM RUC WILL PUSH THE FIRE TOWARDS COUNTY ROAD 407. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... ONCE AGAIN...MAIN FCST CHALLENGE IS DETERMINING WHEN MVFR CLOUD DECK WILL ADVANCE E TO KCMX/KSAW. SO FAR TONIGHT...DRY LOW-LEVEL SE FLOW HAS REMAINED VERY EFFECTIVE AT PREVENTING MVFR CIGS OVER FAR WRN UPPER MI AND NW WI FROM EDGING E. HAVE THUS AGAIN OPTED TO DELAY MVFR CLOUD ARRIVAL FROM PREVIOUS FCST GIVEN RECENT TRENDS AND PERSISTENT DRY FLOW FROM THE SE (MVFR CLOUDS SHOULD ARRIVE DURING THE MID TO LATE MORNING TUE). PLENTY OF LOW END MVFR AND IFR CIGS DOMINATE LARGE PORTIONS OF WI AND MN. HOWEVER...LATEST GUIDANCE SUGGESTS SFC TROF THAT WAS EXPECTED TO REACH UPPER MI TUE MAY DISSIPATE...AND THIS WOULD ALLOW AN INFLUX OF SOMEWHAT DRIER AIR FROM THE SE TO CONTINUE. SO...CONFIDENCE IN -SHRA OCCURRING HAS ALSO DECREASED. WHILE SOME -SHRA ARE STILL POSSIBLE...CONFIDENCE IN -SHRA OCCURRING AT EITHER SITE IS LOW ENOUGH TO DROP MENTION FROM FCST. STILL BELIEVE SOME OF THE LWR MVFR CIGS WILL MAKE AN APPEARANCE. IF DECENT COVERAGE OF SHRA DOES OCCUR AT SOME POINT TUE...IFR CIGS WOULD LIKELY DEVELOP LATE IN THE AFTN WITH POSSIBLE MVFR/IFR VSBY IN FOG TAKING SHAPE TUE EVENING. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER JAMES BAY AND A TROUGH MOVING EASTWARD FROM THE WESTERN DAKOTAS WILL MAINTAIN A SE WIND OF 15 TO 25 KT ON LAKE SUPERIOR THROUGH TODAY. WINDS WILL DIMINISH BELOW 20 KT TONIGHT WHEN A TROUGH APPROACHES. LOOK FOR WINDS TO REMAIN BELOW 20 KT ACROSS LAKE SUPERIOR THROUGH THE REST OF THE PERIOD AS A WEAK PRESSURE GRADIENT EXISTS...ESPECIALLY WITH HIGH PRESSURE BUILDING IN TEMPORARILY ON FRIDAY. NO GALES FORESEEN. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION/FIRE WEATHER...AJ AVIATION...ROLFSON MARINE...MICHELS mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 115 AM EDT TUE AUG 21 2007 .UPDATE (ISSUED AT 1037 PM EDT)... MAIN FCST ISSUE IS POTENTIAL OF SHRA OVER THE W AND SW OVERNIGHT. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A COUPLE OF SHORTWAVES OF NOTE UPSTREAM. FIRST IS OVER WRN WI AND THE SECOND EXTENDS FROM SRN SASKATCHEWAN TO ERN ND. SHORTWAVE OVER WRN WI HAS TRIGGERED SCT SHRA/TSRA IN WI WITH THUNDER AS CLOSE AS ABOUT 35 MILES S OF KIWD. HOWEVER...PCPN HAS YET TO ACTUALLY REACH UPPER MI...AND RADAR TRENDS THIS EVENING SUGGEST A TENDENCY FOR PCPN TO DEVELOP MORE TO THE S WITH TIME WHILE THE NRN PORTION DISSIPATES. NET RESULT IS A SE MOTION. GUESS THAT`S NO SURPRISE GIVEN THE DROUGHT PATTERN THAT DOMINATES THE FCST AREA. SINCE WI SHORTWAVE IS INDICATED TO WEAKEN BY ALL GUIDANCE... INCLUDING 00Z RUC...AS IT HEADS E AND SINCE A PERSISTENT E TO SE FLOW WILL MAINTAIN A FEED OF DRY AIR...DOUBT THAT PCPN WILL MAKE MUCH PROGRESS INTO FCST AREA OVERNIGHT. AREAS ALONG THE WI BORDER APPEAR TO HAVE THE BEST OPPORTUNITY TO SEE SOME PCPN GIVEN BETTER MOISTURE DEPTH INDICATED BY 00Z KGRB SOUNDING. EVENING RADAR TRENDS ALSO SUPPORT THIS THINKING. TAIL END OF SHORTWAVE FROM SASKATCHEWAN TO ERN ND MAY SUPPORT SOME SHRA OVER WRN LAKE SUPERIOR...MAINLY LATE IN THE NIGHT. SO...FOR THE UPDATE...WILL INCLUDE LOW POPS ALONG THE WI BORDER AREAS AND OVER WRN LAKE SUPERIOR. WILL KEEP THE REST OF THE FCST AREA DRY FOR THE OVERNIGHT. SINCE THERE IS A LACK OF INSTABILITY IN UPPER MI AND SHORTWAVE WILL BE WEAKENING...WILL REMOVE MENTION OF THUNDER. && .PREV DISCUSSION (ISSUED AT 421 PM EDT)... SHORT TERM (TONIGHT AND TUE)... PLENTY OF LOW CLOUDS HAVE REMAINED ACROSS THE SOUTHWESTERN PORTIONS OF THE CWA...MAINLY TO THE SOUTH AND WEST OF THE CMX TO SAW SITES. UNDER THE DENSE LOWER CLOUDS...MORNING DRIZZLE WAS NOTICED ON THE RADAR ACROSS PORTIONS OF SOUTH CENTRAL UPPER MICHIGAN. THIS PRECIPITATION WAS ABLE TO DRY UP QUICKLY LATE THIS MORNING AND EARLY THIS AFTERNOON. AM CONTINUING TO WATCH THE PROGRESSION OF OUR NEXT WEATHER MAKER...IN THE FORM OF A SURFACE LOW OVER WESTERN SASKATCHEWAN...SLOWLY PROGRESSING NORTHEASTWARD AND INTO WESTERN MANITOBA BY THE END OF THE PERIOD. CONFIDENCE IN THIS FORECAST PERIOD HAS INCREASED SLIGHTLY SINCE THE OVERNIGHT HOURS AS THE NEAR TERM MODELS HAVE COME INTO A LITTLE BETTER AGREEMENT WITH THE ONSET OF SHOWERS AND THUNDERSTORM ACTIVITY FOR TUESDAY. THE 12Z NAM HAS SLOWED DOWN THE INCOMING TROUGH/COLD FRONT. FOLLOWING SUIT THE 12Z GFS HAS DONE SOMETHING SIMILAR...BUT STILL NOT QUITE AS SLOW AS THE NAM. BOTH HAVE LINED UP CLOSER TO MY INITIAL THINKING...WHICH WAS A CONTINUATION OF THE EXISTING SETUP...DROUGHT EQUALS DROUGHT. THEREFORE...WAS THINKING THAT THE WESTERN CWA WOULD ONCE AGAIN RECEIVE THE GREATEST CHANCE OF SIGNIFICANT PRECIPITATION...WHILE THE EAST WILL BE LUCKY TO GET MORE THAN A TENTH OF AN INCH OUT OF THIS SYSTEM. SIMILAR TO PREVIOUS SYSTEMS...A SPLITTING OF THE PRECIPITATION IS EXPECTED. HAVE ADDED LIKELY POPS TO THE WESTERN PORTIONS OF THE AREA...MAINLY JUST WESTERN LAKE SUPERIOR. LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... FOR TUE NIGHT...TRIMMED BACK POPS WITH PWATS DROPPING AFTER 00Z WED...AND INCREASED STABILITY WITH THE LOSS OF DIURNAL HEATING. LOCALLY RUN WRF-ARW HAS ONLY THE SINGLE BAND OF PRECIP STRETCHING ACROSS THE UPPER PENINSULA...AND HAS THINGS CLEARING OUR OF THE CENTRAL BY 00Z WED AND OUT OF THE FAR EAST BY 06Z. 12Z NAM/GFS BOTH TRY TO BRING UP A SECOND PRECIP LOBE AFTER 06Z...H85 THETA E RIDGE CONTINUES TO SET UP JUST TO THE SOUTH OF THE CWFA AND OVER SOUTHERN WI WITH ENERGY FROM FIRST SHORTWAVE TRACKING JUST TO THE NORTH OF THE CWFA AND THE SECOND RIPPLING THROUGH THE KGRB AREA AROUND 12Z WED. MUCH LIKE THINGS HAVE BEEN GOING OVER THE LAST SEVERAL WEEKS...THE BULK OF THE PRECIP MISSES UPPER MI. ON WED AND WED NIGHT...DIRTY LITTLE SHORTWWAVE PUSHES ACROSS CWFA AND KEEPS THE PICTURE MUDDLED FOR PRECIP CHANCES. Q-VECTOR CONVERGENCE AGAIN LOOKS TO THE NORTH AND SOUTH OF THE CWFA AND THE JET DYNAMICS HIT BEST OVER ONTARIO. BY THU...BEST MID LEVEL ENERGY AGAIN BECOMES FOCUSED TO OUR SOUTH WITH DRIER AIR AND SUBSIDENCE OVER THE WESTERN LAKE AND INTO THE NORTHWESTERN COUNTIES. THE CURRENT WX GRID DEPICTS THIS SCENARIO WELL...SO WILL ESSENTIALLY LEAVE THIS UNTOUCHED. ON FRI...LOLLYGAGGING FRONT TO THE SE OF THE CWFA...AND THEN ADVANCING SYSTEM MOVING IN FROM THE SOUTHWEST. WILL KEEP THE CHANCE POPS IN THE SE CWFA FOR THE TIMEFRAME...BUT KEEP THE NORTHERN PORTIONS DRY. FOR SAT...IF YOU BELIEVE THE 00Z GEFS...THINGS LOOK GOOD FOR THE OPEN HOUSE WITH FRONTAL PASSAGE MORE PROGRESSIVE THAN PRIOR SOLUTIONS WITH COLD FRONT SOUTH OF THE CWFA BY 00Z FRI. DRIER AIR MOVING IN BEHIND THE FRONT SHOULD LIMIT PRECIP CHANCES IN THE NORTH...SAVE FOR LAKE EFFECT CLOUDS WITH A NORTHERLY WIND. A SECOND SYSTEM EXTENDING UP FROM THE PLAINS MAY BRING SOME PRECIP CHANCES TO THE SOUTHERN PORTION OF THE CWFA ON SAT...DEBATED WHETHER TO ADD POPS...BUT KEPT FORECAST DRY ATTM GIVEN UNCERTAINTY IN HOW FAR SOUTH SYSTEM WILL BE. FOR SUN AND MON...MORE UNCERTAINLY CURRENTLY EXISTS WITH MODELS DIVERGING BETWEEN TROUGHINESS AND RIDGINESS OVER THE EASTERN PORTION OF THE CONUS...WITH ENSEMBLE SOLUTIONS POINTING TOWARD A FAIRLY ZONAL FLOW OVER THE EATERN CONUS AND A SURFACE HIGH BUILDING INTO THE GREAT LAKES REGION. ATTM...WILL KEEP THE EXTENDED FORECAST DRY WITH NEAR CLIMO TEMPS. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... ONCE AGAIN...MAIN FCST CHALLENGE IS DETERMINING WHEN MVFR CLOUD DECK WILL ADVANCE E TO KCMX/KSAW. SO FAR TONIGHT...DRY LOW-LEVEL SE FLOW HAS REMAINED VERY EFFECTIVE AT PREVENTING MVFR CIGS OVER FAR WRN UPPER MI AND NW WI FROM EDGING E. HAVE THUS AGAIN OPTED TO DELAY MVFR CLOUD ARRIVAL FROM PREVIOUS FCST GIVEN RECENT TRENDS AND PERSISTENT DRY FLOW FROM THE SE (MVFR CLOUDS SHOULD ARRIVE DURING THE MID TO LATE MORNING TUE). PLENTY OF LOW END MVFR AND IFR CIGS DOMINATE LARGE PORTIONS OF WI AND MN. HOWEVER...LATEST GUIDANCE SUGGESTS SFC TROF THAT WAS EXPECTED TO REACH UPPER MI TUE MAY DISSIPATE...AND THIS WOULD ALLOW AN INFLUX OF SOMEWHAT DRIER AIR FROM THE SE TO CONTINUE. SO...CONFIDENCE IN -SHRA OCCURRING HAS ALSO DECREASED. WHILE SOME -SHRA ARE STILL POSSIBLE...CONFIDENCE IN -SHRA OCCURRING AT EITHER SITE IS LOW ENOUGH TO DROP MENTION FROM FCST. STILL BELIEVE SOME OF THE LWR MVFR CIGS WILL MAKE AN APPEARANCE. IF DECENT COVERAGE OF SHRA DOES OCCUR AT SOME POINT TUE...IFR CIGS WOULD LIKELY DEVELOP LATE IN THE AFTN WITH POSSIBLE MVFR/IFR VSBY IN FOG TAKING SHAPE TUE EVENING. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER JAMES BAY AND A TROUGH MOVING EASTWARD FROM THE WESTERN DAKOTAS WILL MAINTAIN AN EAST TO SOUTHEASTERLY WIND OF 15 TO 25 KT ON LAKE SUPERIOR THROUGH TONIGHT. WINDS WILL DIMINISH BELOW 20 KT ON WESTERN LAKE SUPERIOR TUE...BUT REMAIN AS HIGH AS 25 KT ON EASTERN LAKE SUPERIOR UNTIL LATE TUE AFTERNOON WHEN THE TROUGH APPROACHES THE CENTRAL PORTION OF THE LAKE. LOOK FOR WINDS TO REMAIN BELOW 20 KT ACROSS LAKE SUPERIOR THROUGH THE REST OF THE PERIOD AS A WEAK PRESSURE GRADIENT EXISTS...ESPECIALLY WITH HIGH PRESSURE BUILDING IN ON TEMPORARILY ON FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SHORT TERM...KF LONG TERM...JLL AVIATION...ROLFSON MARINE...KF/KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 315 AM EDT TUE AUG 21 2007 .SYNOPSIS...A LARGE AND STRONG AREA OF HIGH PRESSURE WILL PERSIST OVER THE SOUTHEAST STATES... RESULTING IN CONTINUED HOT AND DRY CONDITIONS OVER THE REGION THROUGH LATE WEEK. && .NEAR TERM /THROUGH TONIGHT/... THE FIRST POINT OF CONCERN FOR TODAY IS THE LOW STRATUS... THE RESIDUAL STABLE POOL PRODUCED BY EARLIER VA CONVECTION... WHICH HAS BEEN SLOWLY BUT STEADILY SURGING SOUTHWARD TOWARD THE NC/VA BORDER OVER THE LAST SEVERAL HOURS. SATELLITE IMAGERY INDICATES THAT THIS PROGRESSION HAS SLOWED IN THE LAST HOUR... AND THE LATEST RUC AND SREF TAKE THIS BOUNDARY JUST NORTH OF RDU BEFORE MIXING OUT THE LOW CLOUDS IN THE MORNING. THIS EVOLUTION LOOKS REASONABLE AND WILL GO WITH INITIAL HIGH CLOUD COVER IN THE BORDER COUNTIES FOLLOWED BY QUICKLY INCREASING SUNSHINE. THE SECOND POINT OF CONCERN ARE TODAY`S HIGHS AND HEAT INDEX VALUES. WITH EXPECTATIONS OF A NEARLY DRY ADIABATIC LOW LEVEL LAPSE RATE AS WE SAW YESTERDAY AND WITH SIMILAR THICKNESSES AND MINIMAL TEMPERATURE ADVECTION IN THE LOW LEVELS... HIGHS TODAY SHOULD BE CLOSE TO YESTERDAY`S... 98-102... CLOSE TO THE RECORDS (SEE CLIMATE SECTION BELOW). WE SHOULD ALSO SEE AN AFTERNOON PLUNGE OF THE DEWPOINTS... ESPECIALLY WEST OF I-95. THE 00Z UPPER AIR DATA INDICATES NO ADVECTION OF MOISTURE UP THROUGH 925-850 MB... AND TAKING CURRENT DEWPOINTS ALOFT DOWN THE MIXING RATIO YIELDS VALUES FROM THE UPPER 50S TO MID 60S BY MID AFTERNOON. THIS KEEPS HEAT INDEX VALUES JUST BELOW ADVISORY CRITERIA. HOWEVER... SINCE THIS IS THE SECOND STRAIGHT DAY OF VERY HOT TEMPERATURES AND WE`RE NOT DROPPING MUCH AT ALL AT NIGHT... WILL MENTION THE THREAT POSED BY THE HEAT IN THE HAZARDOUS WEATHER OUTLOOK. AND LAST BUT NOT LEAST... THE CHANCES FOR A FEW THUNDERSTORMS VERY LATE THIS AFTERNOON THROUGH THE MIDNIGHT HOUR TONIGHT LOOK TO BE IMPROVING. IF THE MORNING STRATUS TAKES LONGER THAN EXPECTED TO BURN OFF... IT MAY SET OFF A DIFFERENTIAL HEATING BOUNDARY ALONG WHICH A MESOSCALE CONVECTIVE VORTEX... CURRENTLY OVER THE KY/IN BORDER ACCORDING TO WATER VAPOR IMAGERY... COULD TRACK. THE NAM AND GFS DROP THIS WAVE SOUTHEAST THROUGH NC THIS EVENING... AND THERE SHOULD BE ENOUGH EVENING DEWPOINT RECOVERY OVER THE COASTAL PLAIN FOR MODERATE INSTABILITY WITH A GOOD SHOT AT BETTER THAN 1500 J/KG OF CAPE. GFS FORECAST TOTAL TOTALS IN THIS AREA EXCEED 50... THE K-INDEX EXCEEDS 40... AND N-CAPE CLIMBS ABOVE 0.15. DEEP LAYER SHEAR ISN`T TOO SHABBY EITHER... AROUND 20-25 KTS. WILL GO WITH 20-28% STORM CHANCES VERY LATE THIS AFTERNOON THROUGH 06Z... BEST OVER THE NORTHEAST AND EASTERN COUNTIES OF CENTRAL NC... TRAILING OFF WELL BEFORE DAYBREAK. LOWS 72-77. -GIH && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... BOTH THE NAM AND GFS DROP A SURFACE BOUNDARY INTO CENTRAL NC WEDNESDAY MORNING BEHIND THE MID LEVEL WAVE PASSAGE... HOWEVER THE NAM IS MUCH MORE EMPHATIC ABOUT HOLDING THE STABLE POOL OVER THE NORTHEAST CWA FOR MUCH OF THE DAY. AT FIRST GLANCE THIS LOOKS IMPLAUSIBLE CONSIDERING THE TIME OF YEAR... HOWEVER THIS AIR MASS IS INDEED PRODUCING IFR/LIFR CLOUDS OVER THE GREAT LAKES... AND IN LOOKING AT THE TENACITY OF THE CURRENT VA STRATUS... AND WITH THE FACT THAT THE NAM HAS SHOWN THIS STABLE NOSE LATE WEDNESDAY INTO THURSDAY FOR THREE STRAIGHT RUNS... IT MAY BE ONTO SOMETHING. HAVE TRIMMED BACK HIGHS ON WEDNESDAY ACROSS THE NORTHEAST TO THE LOWER 90S... RANGING TO THE UPPER 90S IN THE SOUTH. WILL CONTINUE TO LEAVE OUT POPS FOR NOW WITH THE LACK OF A TRIGGER FOR LARGE SCALE LIFT AND THE MARGINAL INSTABILITY. LOWS WEDNESDAY NIGHT 68 NORTHEAST TO 75 SOUTH... AND WILL INTRODUCE HIGHER SKY COVER THROUGH THURSDAY MORNING. HIGHS THURSDAY 94-99... ALTHOUGH IF THE NAM PERSISTS IN SHOWING NEAR TO BELOW NORMAL THICKNESSES... NEARLY 1400 M... IN THE FAR NORTHEAST CWA THURSDAY... WILL NEED TO CUT BACK THESE HIGHS FURTHER. -GIH && .LONG TERM /FRIDAY THROUGH MONDAY/... THE MID LEVEL RIDGE HOLDS FIRM OVER NC FRIDAY... AND CONTINUED HOT AND DRY LOOKS REASONABLE WITH WARM MID LEVEL TEMPS. THE LATEST GFS LOOKS TO HAVE SOME CONVECTIVE FEEDBACK OVER NC FRIDAY... AND HAVE DISCOUNTED THIS PRECIP. A POSITIVELY TILTED SHORTWAVE TROUGH TRACKS THROUGH THE GREAT LAKES FRIDAY NIGHT THROUGH SATURDAY... ALTHOUGH THE MID LEVEL FLOW OVER NC REMAINS FLAT TO ANTICYCLONIC INTO SUNDAY. MINOR PERTURBATIONS IN THE WESTERLIES APPEAR VERY SPURIOUS AND CANNOT BE TRUSTED... SO EVEN WITH THE APPROACH OF THIS BROAD AND WEAK SHORTWAVE TROUGH (WEAKER ON THE 00Z/21 GFS AND 12Z/20 ECMWF AS COMPARED TO THE 18Z/20 GFS) AND ITS ATTENDANT COLD FRONT... PINPOINTING ANY PARTICULAR FORCING FEATURE IS NEARLY IMPOSSIBLE. WILL HOLD ONTO ISOLATED LATE DAY POPS IN THE LATTER PART OF THE MEDIUM RANGE... WHICH IS BELOW CLIMATOLOGY BUT WITHIN THE REALM OF POSSIBILITY GIVEN THE ABOVE-NORMAL PRECIPITABLE WATER FROM SATURDAY THROUGH MONDAY. LITTLE TO NO CHANGES ARE NEEDED TO TEMPERATURES... AS THICKNESSES SUGGEST THEY SHOULD HOLD ABOUT 2-3 CATEGORIES ABOVE NORMAL. -GIH && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. SATELLITE IMAGERY DEPICTS SOUTHWARD SURGE OF STRATUS ASSOCIATED WITH STATIONARY SURFACE BOUNDARY OVER VIRGINIA APPEARS TO HAVE FINALLY SLOWED DOWN TO NEARLY A HALT ACROSS THE EXTREME NORTHERN SECTIONS OF THE FORECAST. HENDERSON IS REPORTING A BROKEN CEILING AT 800 FT...BUT OTHERWISE A STEADY SW WIND FLOW OF 4 TO 7 KTS SHOULD KEEP THE LOW CLOUDS AT BAY ACROSS CENTRAL AND SOUTHERN PORTIONS OF VIRGINIA. A STRONG VORT MAX WILL MOVE ACROSS THE AREA IN THE WESTERLY FLOW ALOFT TOMORROW AFTERNOON AND EVENING. THIS WILL BRING A PERIOD OF BROKEN MID AND HIGH CLOUDS BY 21Z IN THE WEST...SPREADING SOUTHEAST THROUGH THE EVENING. ISOLATED CONVECTION WILL ALSO BE POSSIBLE AS TRIPLE DIGIT TEMPERATURES WILL BE SUFFICE FOR UPDRAFT SUPPORT...BUT WILL NOT BE INCLUDED DUE TO ISOLATED NATURE. SW WINDS WILL INCREASE SOME DURING THE DAY TOMORROW AS DEEP MIXING OCCURS. WINDS IN THE MIXED LAYER WILL BE ANYWHERE FROM 15-25KTS...SO GUSTS OF UP TO 20KTS ARE CERTAINLY POSSIBLE. THROUGH THE REMAINDER OF THE WEEK...PREDOMINANTLY VFR CONDITIONS ARE EXPECTED AS THE FORECAST AREA REMAINS UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE. THE EXCEPTION LOOKS TO BE WITH PREDAWN STRATUS/FOG AS SURFACE BOUNDARY SETTLES OVER THE AREA. CHANCES FOR DIURNAL CONVECTION DURING THIS TIME WILL BE BELOW NORMAL. -CBL && .CLIMATE... HERE ARE THE RECORD HIGHS FOR TODAY THROUGH FRIDAY: RDU- AUG 21: 101 IN 1983 AUG 22: 101 IN 1983 AUG 23: 103 IN 2002 AUG 24: 100 IN 2002 GSO- AUG 21: 100 IN 1983 AUG 22: 100 IN 1983 AUG 23: 99 IN 1983 AUG 24: 98 IN 1968 THE MODERATE AND SEVERE DROUGHT CONDITIONS ACROSS CENTRAL ARE NOT NOT EXPECTED TO SEE ANY SIGNIFICANT IMPROVEMENT THROUGH THE 7 DAY FORECAST AS THERE REMAINS NO APPARENT WEATHER FEATURE TO SUPPORT WIDESPREAD RAINFALL. AS OF AUGUST 20TH...THE MONTH TO DATE RAINFALL AT GSO AND RDU IS 0.34" AND 0.26" RESPECTIVELY. THIS WILL RESULT IN SIGNIFICANT AUGUST RAINFALL DEFICITS LEADING INTO THE LAST WEEK OF AUGUST AND A STRONG LIKELIHOOD OF BEING ONE OF THE DRIEST AUGUSTS ON RECORD. LISTED BELOW IS THE DRIEST AUGUST AT GSO AND RDU ON RECORD. TOP 5 DRIEST AUGUSTS ON RECORD. GSO RDU (SINCE 1928) (SINCE 1944) 1) 0.71/1972 0.81/1950 2) 1.13/1979 1.01/1997 3) 1.19/1962 1.13/1984 4) 1.40/1932 1.31/1956 5) 1.44/1983 1.52/1976 HOT AND DRY CONDITIONS HAVE LED TO RECORD WARMTH THIS MONTH ACROSS CENTRAL NORTH CAROLINA. IN FACT... IF WE EXPERIENCE NORMAL TEMPERATURES FOR THE REMAINDER OF THE MONTH RDU WOULD BREAK THE RECORD FOR THE WARMEST AUGUST ON RECORD... AND GSO WOULD FALL A TENTH OF A DEGREE SHORT OF THE WARMEST AUGUST ON RECORD. HOWEVER... TEMPERATURES THROUGH THE END OF AUGUST LOOK TO BE AT OR ABOVE NORMAL. THUS... THE RECORDS LISTED BELOW ARE LIKELY TO FALL. THE CURRENT MEAN AVERAGE TEMPERATURE AT RDU AND GSO AS OF AUGUST 20TH IS 84.4F AND 83.6F RESPECTIVELY. TOP 5 WARMEST AVERAGE TEMPERATURES FOR AUGUST ON RECORD. GSO RDU (SINCE 1929) (SINCE 1944) 1) 80.0/1975 80.6/1995 2) 79.7/1988 80.5/2006 3) 79.4/2006 80.3/1988 4) 79.4/1995 80.2/2005 5) 79.3/2005 80.0/1999 && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...CBL CLIMATE...CBL nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 420 AM EDT TUE AUG 21 2007 .SYNOPSIS... A NEARLY STATIONARY FRONTAL BOUNDARY WILL REMAIN ACROSS NORTHERN OHIO TODAY...WHILE THE REMNANTS OF TROPICAL STORM ERIN MOVE ACROSS THE OHIO VALLEY THIS MORNING. THE PROXIMITY OF BOTH OF THESE FEATURES WILL KEEP SCATTERED THUNDERSTORMS ACROSS THE REGION TODAY. INCREASINGLY HOT AND HUMID CONDITIONS CAN BE EXPECTED FOR THE SECOND HALF OF THE WEEK AS AN UPPER LEVEL RIDGE BUILDS INTO THE OHIO VALLEY. && .NEAR TERM /THROUGH TONIGHT/... MOST OF THE FCST AREA HAS BEEN IN A RELATIVE PCPN LULL FOR LAST SVRL HOURS AS FRNTL BNDRY HAS RETURNED BACK TO THE NORTH. PERSISTENT AND HEAVY RAINFALL CONTINUING INVOF BNDRY FROM NEAR KFWA EAST THRU KAOH AND KMFD. WITHIN THIS BAND OF HEAVY RAIN...1-3 INCHES HAS FALLEN SINCE LATE LAST EVNG. UNDER MSTLY CLDY SKIES...TEMPS WERE AROUND 70 DEG ERLY THIS MRNG. WILL BE DROPPING FLOOD WATCH WITH ZONE FCST ISSUANCE. MUCH OF THE CONVECTION ASSOCD WITH THE SFC WAVE MOVING ALONG BNDRY SHOULD REMAIN ALONG OR JUST NORTH OF FCST AREA IN NORTH CNTRL OH THIS MRNG. REMNANTS OF ERIN CONTINUE TO SLOWLY MOVE EAST OVER LWR OH VLY. CONVECTION HAS INCREASED ACRS SRN INDIANA AND WRN KY IN THE LAST FEW HOURS WITH 40-45KT 850 LLJ FEEDING DVLPMNT. 06Z RUC INDCG LLJ WILL SHIFT EAST ACRS SRN 1/2 FCST AREA THIS MRNG WITH LO LVL FORCING BECOMG LESS FAVORABLE AS ERIN REMNANTS SHIFT EAST. HAVE EMPLOYED 50 POPS FOR MOST OF THE MRNG AS ACTIVITY LKLY TO REMAIN SCATTERED IN NATURE. PWATS REMAIN BTWN 2 AND 2.25 INCHES WITH TORRENTIAL RAINFALL EXPECTED AS ERIN REMNANTS PASS. SUBSIDENCE DVLPS ACRS MUCH OF FCST AREA THIS AFTN IN WAKE OF REMNANTS OF ERIN AND AFOREMENTIONED SFC WAVE ALONG FRNTL BNDRY IN NRN IN/OH. THIS SHOULD HELP TO SCOUR OUT CLOUDS ACRS MUCH OF THE FCST AREA. DESPITE MLCAPES CLIMBING TO BTWN 1000-2000 J/KG...LACK OF SIGNIFICANT FORCING SHOULD KEEP ANY CONVECTIVE DVLPMNT ISOLD TO WDLY SCT IN NATURE. ONE QUESTION MARK SURROUNDS THE MID LVL S/WV CURRENTLY SITTING OVER IOWA AIDING LARGE (BUT WEAKENING) TSTM COMPLEX. NONE OF THE 00Z MODELS HANDLED THIS FEATURE PARTICULARLY WELL. IT SEEMS REASONABLE THAT THIS S/WV WILL RIDE ALONG BNDRY TODAY AND BE LOCATED ACRS NRN IN/OH BY LATE THIS AFTN. THIS COULD POTENTIALLY FUEL ADDL TSTM DVLPMNT FOR THE LATE AFTN AND EVNG ACRS FAR NRN SECTIONS OF FCST AREA. THIS WILL NEED TO BE MONITORED THROUGHOUT THE DAY. HAVE MAINTAINED CHANCE POPS INTO THE OVERNIGHT ACRS NRN 1/3 FCST AREA. FURTHER SOUTH...SUPPRESSED MID LVL RIDGE WILL BEGIN EXPANDING BACK NORTH INTO OH VLY WITH MID LVL HGT RISES. EXPECT DRY CONDITIONS AS A RESULT WITH NO APPRECIABLE FORCING AND DISTANCE FROM FRNTL BNDRY IN NRN IN/OH. TEMPS...TEMPS ARE A BIT TRICKY TODAY DUE TO UNCERTAINTY WITH PCPN AND HOW EXTENSIVE CLOUDS WILL BE THIS MRNG AND INTO THE ERLY AFTN. HAVE KEPT TEMPS NEAR MAV GUID IN NRN FCST AREA...WITH MANY LOCATIONS HOLDING IN THE L/M80S. FURTHER SOUTH...HAVE GONE ABV TEMP GUID WITH L90S EXPECTED. EVEN WITH SCT TSTMS THIS MRNG ASSOCD WITH ERIN REMNANTS...MANY LOCATIONS (KCVG INCLUDED) SHOULD HAVE NO PROBLEM REACHING 90 DEG YET AGAIN. TRENDED TOWARDS WARMER MET GUID FOR LOWS TONIGHT. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... THE SHORT TERM CAN BE SUMMED UP IN ONE WORD...HOT. MID LVL HGT RISES WILL PERSIST FOR WED AND THURS WITH THE RIDGE RETURNING INTO THE OH VLY. THE FRNTL BNDRY WILL REMAIN DISPLACED TO THE NORTH OF THE FCST AREA. INCREASING AMOUNTS OF DRIER AIR WITHIN THE MID LVLS WILL HELP REINTRODUCE A MID LVL CAP AND WITH NOT MUCH IN WAY OF ANY MID/UPR LVL FORCING. AVAIL INSTABILITY DURING THE AFTN AND EVNG WILL BE MAIN CATALYST FOR ISOLD TSTMS WED AND THURS. ISOLD TSTMS WILL BE POSSIBLE BOTH WED AND THU...PARTICULARLY ACRS NRN 1/2 FCST AREA. RIDGE SHOULD GAIN AN EVEN GREATER FOOTHOLD THURS AS FRNTL BNDRY SHIFTS FURTHER NORTH INTO LWR MICHIGAN. WITH DEWPTS REMAINING IN THE M/U60S TO AROUND 70 THROUGHOUT THE PERIOD...OPPRESSIVE CONDITIONS ARE EXPECTED. FCST HEAT INDICES WILL BE AT OR JUST ABV 100 DEG ACRS SRN 1/2 FCST AREA WED AND THURS. TAKING THIS INTO ACCOUNT...WILL BE ISSUING AN EXCESSIVE HEAT WATCH FOR HAMILTON CO AND THE CINCY METRO BEGINNING WED AND CONTINUING THRU FRI. IN ALL LIKELIHOOD...THIS WILL NEED TO BE UPGRADED TO A HEAT WARNING. 100+ HEAT INDICES OVER REMAINDER OF SRN FCST AREA WOULD BE SUFFICIENT FOR A HEAT ADV. AS THE INITIAL EFFECTS WILL NOT BE EXPERIENCED UNTIL WED AFTN (PERIOD 3)...WILL HOLD OFF ON ADV HEADLINES ATTM. MAY EVENTUALLY NEED TO CONSIDER HEAT HEADLINES FOR DAY METRO AS WELL. TEMPS...HAVE TRENDED NEAR OR ABV MAV GUID FOR HIGHS BOTH WED AND THURS. CVG METRO SAW VIRTUALLY NO RAIN MON/MON EVNG...AND WILL LKLY ONLY SEE SPOTTY RAIN THIS MRNG AS REMNANTS OF ERIN PASS TO SOUTH ACRS CNTRL KY. CONSIDERING HOW EASILY KCVG HAS BEEN ABLE TO SURPASS GUID ON HIGHS OVER LAST FEW WEEKS...EXPECT IT WILL DO SO AGAIN. TAKING THAT INTO ACCOUNT AS WELL AS FCST OF 850 TEMPS AT 22-23C BY THURS...HAVE BUMPED UP HIGHS A FEW DEG FROM PREV FCST. WILL CLIMB INTO M/U90S BY THURS AND MAY VERY WELL FLIRT WITH 100 DEG AGAIN THURS AFTN. KCVG CONTINUES TO WORK ON ITS WARMEST AUG ON RECORD. && .LONG TERM /FRIDAY THROUGH MONDAY/... RIDGE WILL REMAIN ACRS REGION FRI...WITH 850 TEMPS MAXING AT 23-24C. UNDER MSTLY SUNNY SKIES...THAT WOULD SUGGEST HIGHS FRI AFTN IN THE U90S TO POTENTIALLY NEAR 100 DEG. RIDGE WILL BEGIN TO BREAK DOWN LATE IN THE WEEK WITH SOME SHORT WAVE ENERGY AND ITS ASSOCIATED FRONT MOVING THROUGH SATURDAY INTO SUNDAY. THIS WILL LEAD TO A BETTER CHANCE FOR THUNDERSTORMS OVER THE WEEKEND. MODELS HAVE TRENDED A LITTLE SLOWER WITH THIS SO WILL GO AHEAD AND LINGER SOME LOW POPS THROUGH SUNDAY. NAM-WRF NOT AS AGGRESSIVE AS THE GFS BUILDING RIDGE UP INTO OUR AREA AND AS A RESULT IS CONSIDERABLY COOLER WITH ITS THERMAL FIELDS/GUIDANCE TEMPS. WILL GO AHEAD AND LEAN TOWARD THE WARMER GFS BASED ON THE WARMER BIAS OVER THE LAST SEVERAL WEEKS AND TO MAINTAIN CONSISTENCY WITH OUR ONGOING FORECAST. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... MAIN FCST PROBLEM THIS MORNING IS THE DEVELOPING LIFR CIGS AT KDAY...KILN...KCMH AND KLCK. RECENT RAINFALL AT THESE LOCATIONS HAVE SATURATED THE AIRMASS. WITH WEAK WAA OVERNIGHT...THESE SITES SHOULD CONTINUE TO SEE LIFR CIGS WITH MAINLY MVFR VSBYS WITH MIST. AS FOR KCVG AND KLUK...THEY BARELY RECEIVED ANY PCPN AND THUS THEIR CIGS SHOULD REMAIN IN THE VFR CATEGORY. THEY WILL EXPERIENCE...HOWEVER...SOME MINOR MVFR CONDITIONS WITH MIST. CIGS WILL BE SLOW TO RISE DURING THE MORNING HOURS. ALL AFFECTED AFOREMENTIONED SITES SHOULD BREAK OUT INTO VFR CIGS BY 18Z. THEREAFTER...WEAK MID LVL RIDGING WILL KEEP ANY POP UP SHOWER/THUNDERSTORMS AT A MINIMUM DURING THE PEAK HEATING OF THE DAY. THUS...WILL NOT MENTION AT TAFS. FOR THE PERIOD BETWEEN 00Z AND 06Z WEDNESDAY...AN APCHING S/WV MAY RESULT IN MORE SCATTERED SHOWER/THUNDERSTORM ACTIVITY ACRS THE WRN PART OF THE FCST AREA. CHC/S ARE STILL AT 30 PERCENT AND THUS WILL LEAVE OUT OF THE TAFS. OUTLOOK...BETTER CHANCE OF THUNDERSTORMS EXPECTED ON SATURDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...EXCESSIVE HEAT WATCH FROM WEDNESDAY AFTERNOON THROUGH LATE FRIDAY NIGHT FOR OHZ077. KY...NONE. IN...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM...RYAN/LOTT AVIATION...HICKMAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 415 AM EDT TUE AUG 21 2007 .SYNOPSIS... A STATIONARY FRONT...LOCATED JUST SOUTH OF PENNSYLVANIA TODAY...WILL LIFT NORTH OF THE REGION AS A WARM FRONT BY LATE THIS WEEK. A COLD FRONT WILL SWEEP THROUGH THE STATE OVER THE WEEKEND...FOLLOWED BY A HIGH PRESSURE SYSTEM BY EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... QUASI-STATIONARY SFC FNTL BNDRY DRAPED FROM THE MID MS VLY EWD TO THE CNTRL APPALACHIANS WILL REMAIN THE FOCUS FOR LOCALLY HVY RAINFALL OVR PARTS OF CENTRAL PA THRU EARLY AFTN. PW VALUES SOME 2-3 STD ABV NORMAL ASSOCIATED WITH THE REMNANTS OF TROPICAL STORM ERIN WILL OVERRUN THIS BOUNDARY...PRODUCING POTENTIALLY FLOODING RAINS ACROSS THE SOUTHERN HALF OF THE STATE. LATEST RADAR DATA SHOWS A BAND OF MODERATE TO HVY RAIN FALLING FROM NORTHERN OHIO INTO WESTERN PA...ASSOCIATED WITH STRONG 850MB THETA-E ADVECTION ON THE NOSE OF 40KT WSWLY LOW LVL JET. RAIN SHOULD TAPER TO DRIZZLE BY LATE TDY...AS UPPER LVL SHORTWAVE TRACKING ACROSS THE EASTERN LAKES WILL PUSH REMNANTS OF ERIN EAST OF THE REGION BY LATE AFTN. OPERATIONAL GFS/NAM NOT VERIFYING WELL IN THE FIRST 6HRS...PLACING HEAVIEST RAIN TOO FAR NORTH. RADAR TRENDS AND LATEST RUC GUIDANCE SUGGEST HEAVIEST RAIN WILL BE CLOSER TO LOW LVL BAROCLINIC ZONE ACROSS THE SOUTHERN HALF OF PA. MULTISENSOR PRECIP ESTIMATES SHOWS UP TO 2.5 INCHES HAVE ALREADY FALLEN ACROSS PORTIONS OF THE LAUREL HIGHLANDS/SC MTNS. THESE AMOUNTS HAVE ONLY PRODUCED MINOR FLOODING SO FAR. HOWEVER...AN ADDITIONAL 1-2 INCHES OVER THIS REGION COULD PRODUCE MORE SIGNIFICANT FLOODING LATER TDY. WILL EXTEND THE CURRENT FLOOD WATCH THRU THE AFTN TO BETTER CORRELATE WITH THE EXPECTED END OF SIG RAIN AND ALSO TO COLLABORATE WITH NEIGHBORING OFFICES. LITTLE IF ANY DIURNAL TEMP TREND WILL TAKE PLACE TDY UNDER SOLID BLANKET OF LLVL SC. LLVL ELY FLOW WILL CONTINUE TO BANK COOL...MOIST AIR EAST OF THE ALLEGHENY PLATEAU...RESULTING IN HIGHS WELL BLW SEASONAL NORMS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... PLENTY OF LOW LEVEL MOISTURE WILL REMAIN TRAPPED BENEATH THE MID LEVEL WESTERLIES TONIGHT AND WED...KEEPING CENTRAL PA CLOUDY AND COOL. BEST CHC FOR AFTN BREAKS IN THE STRATOCU...ALONG WITH SCT PM TSRA...WILL BE ACROSS THE ALLEGHENIES. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... DARKER AND GLOOMIER WEATHER GRADUALLY COMES TO AN END BY LATE WEEK AS WE RETURN TO MORE OF A SUMMER LIKE DIURNAL PATTERN. WARM AND HUMID RIDGE BUILDS TO OUR SOUTH...BUT PROXIMITY TO SOUTHERN EDGE OF JET WILL KEEP MENTION OF DAILY SHOWERS/TSTORMS IN MUCH OF THE EXTENDED FORECAST - ESPECIALLY THU INTO FRI. WESTERLY FLOW AND LACK OF A STRONG STORM SYSTEM WILL KEEP WARMER AND MORE MOIST AIR IN PLACE FOR A WHILE. && .AVIATION /07Z TUESDAY THROUGH SATURDAY/... WIDESPREAD IFR CIGS WITH AREAS OF IFR VSBYS AND LIFR CIGS WILL CONTINUE THROUGH THE TAF FCST PERIOD. ON AND OFF SHOWERS ALONG WITH AREAS OF FOG AND SOME DRIZZLE WILL CONTINUE OVERNIGHT. THE HEAVIEST RAIN OVER CENTRAL PA DURING THE NEXT 2 TO 3 HOURS WILL BE MAINLY NEAR AND ALONG THE PA/MARYLAND BORDER. SOME IMPROVEMENT TO VFR VSBYS WITH MVFR CIGS MAY OCCUR LATER IN THE DAY TUESDAY AS A WEAK RIDGE OF HIGH PRESSURE ALOFT BUILDS ACROSS THE REGION AND DECREASES THE COVERAGE OF SHOWERS AND THUNDERSTORMS. SOME LOW LEVEL WIND SHEAR...CAUSED BY A LIGHT EAST TO SOUTHEAST SFC WIND TOPPED BY A SOUTHWESTERLY WIND OF 30-40 KTS AT 2 KFT AGL WILL OCCUR OVERNIGHT. WARMER AND MORE HUMID AIR SHOULD MOVE INTO THE REGION FOR WEDNESDAY THROUGH FRIDAY AS THE SFC WARM FRONT LIFTS JUST NORTH OF PA. THIS WILL BRING MAINLY VFR FLYING CONDITIONS WITH PERIODS OF IFR/MVFR CIGS AND VSBYS IN MORE CONVECTIVE PRECIP /SHRA AND TSRA/. && .HYDROLOGY... FLOODING IS NOT ANTICIPATED ALONG THE LARGER STREAMS AND RIVERS OF CENTRAL PA. HOWEVER...RISES TO 3/4 BANKFULL ARE EXPECTED ACROSS THE FRANKSTOWN BRANCH OF THE JUNIATA RIVER...AS WELL AS THE YOUGHIOGHENY RIVER. && .CTP WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 4 PM EDT TODAY FOR PAZ017>019-024>028- 033>036-049-050-052-056>059-063>066. && $$ SYNOPSIS...FITZGERALD NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD/RXR LONG TERM...RXR AVIATION...LAMBERT/GARTNER HYDROLOGY...FITZGERALD pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 930 AM EDT TUE AUG 21 2007 .SYNOPSIS... A COOL AIR MASS WILL IMPACT EASTERN NEW YORK AND WESTERN NEW ENGLAND THROUGH WEDNESDAY. A WARM FRONT WILL REMAIN OVER THE MID ATLANTIC REGION THROUGH TODAY WITH WEAK WAVES OF LOW PRESSURE MOVING ALONG IT. SOME LIGHT BATCHES OF RAINFALL WILL OCCUR SOUTH OF THE CAPITAL REGION TODAY. HIGH PRESSURE WILL MOVE OFF THE NOVA SCOTIA COAST TONIGHT INTO WEDNESDAY WITH MAINLY DRY WEATHER. THE WARM FRONT WILL FINALLY MOVE THROUGH THE REGION WEDNESDAY NIGHT INTO THURSDAY MORNING WITH A CHANCE OF SHOWERS AND THUNDERSTORMS AND MORE HUMID WEATHER. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... FOG WITHIN THE CAPITAL DISTRICT IS SLOWLY LIFTING INTO A BROKEN STRATUS DECK. HOWEVER...UPSTREAM MID AND HIGH LEVEL MOISTURE CONTINUES TO MOVE EAST WHICH WILL KEEP THE CLOUDS IN THE FORECAST FOR THE REST OF TODAY. THERE WILL BE A SHARP CUT OFF TO THE PRECIP AND CLOUD SHIELD FROM A BROKEN CI/CS DECK ACROSS THE NORTHERN PORTIONS OF THE CWA TO A SOLID OVERCAST FROM THE CAPITAL DISTRICT AND POINTS SOUTHWARD. UPSTREAM RADARS SHOW AN EXPANDING AREA OF SHOWERS WHICH IS CORRESPONDING TO MID LEVEL INCREASING FGEN (CENTERED AROUND 850MB). NUMERICAL FORECASTS FROM 06Z AND LATEST RUN OF THE RUC POINTS TOWARD THE PREVIOUS FORECAST IDEA OF THE RAIN FLIRTING WITH THE CAPITAL DISTRICT TODAY. WILL ADJUST THE PRECIP SLIGHTLY FURTHER NORTH AND WILL MONITOR UPSTREAM TRENDS BEFORE EXPANDING THE RAINFALL. TEMPERATURES WITH THE CLOUD COVER WILL STILL REMAIN QUITE COOL FOR AUGUST STANDARDS WITH MAINLY 60S EXPECTED (NORMAL HIGH AROUND 80F). && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... BOUNDARY LAYER THERMAL GRADIENT ASSOCIATED WITH THE OLD FRONTAL BOUNDARY WILL GRADUALLY TRACK NORTHEAST. LOW LEVEL FORCING WILL WEAKEN AS UPPER ENERGY EXITS AND THERMAL GRADIENT LOOSENS A BIT. ANY LIGHT RAIN IN SOUTHERN AREAS WILL END DURING THE EVENING. MOSTLY CLOUDY SKY WILL PREVAIL TONIGHT AND WEDNESDAY AS LOW LEVEL FLOW GRADUALLY TURNS FROM SOUTHEAST TO SOUTH. TEMPERATURES WEDNESDAY NUDGING INTO THE LOWER 70S IN WARMER AREAS. CONSIDERABLE CONFLICTS IN GUIDANCE FOR WEDNESDAY NIGHT AND THURSDAY. FORECASTED UPPER JET STRUCTURE DOES NOT SUPPORT ANY ORGANIZED SYSTEM TO AFFECT THE REGION...BUT INCREASINGLY WARM AND HUMID AIR MASS WILL BUILD INTO THE REGION...PERHAPS INCREASING CHANCES FOR DIURNAL TYPE PRECIPITATION. NOT TOUCHING MUCH BEYOND WEDNESDAY DUE TO THE UNCERTAINTY. AS CURRENT FORECAST STANDS...CHANCES FOR SHOWERS LATER WEDNESDAY AND WEDNESDAY NIGHT...MOVING OUT EARLY THURSDAY. THURSDAY IS WHEN THE NOTICEABLE WARMING IS EXPECTED TO TAKE PLACE...WITH MORE SUN AND TEMPERATURES REACHING 80 OR BETTER. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... UPPER RIDGING BUILDS INTO THE REGION FOR FRIDAY AND SATURDAY...ALONG WITH BOUNDARY LAYER TEMPERATURES WARMING. WEST TO SOUTHWEST LOW LEVEL FLOW SETS UP...AND TEMPERATURES SHOULD REACH WELL INTO THE 80S. STILL A DECENT CONSENSUS FOR A FRONTAL SYSTEM LATER SATURDAY AND SATURDAY NIGHT WITH CHANCES FOR SHOWERS AND STORMS. AT THIS TIME...LOOKS LIKE JUST A LITTLE BIT OF COOLING AS UPPER FLOW REMAINS RATHER FLAT LATER IN THE WEEKEND AND THE BEGINNING OF NEXT WEEK. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... OCCASIONAL LIGHT RAIN IS EXPECTED AT KPOU THROUGH AT LEAST LATE THIS AFTERNOON. OTHERWISE...EXPECT DRY CONDITIONS TODAY. NEARLY CALM WINDS SHOULD BECOME E/SE...AND INCREASE TO 5-10 KT THIS AFTERNOON...AND THEN BECOME LIGHT/VARIABLE TONIGHT. TERMINAL SPECIFICS ARE LISTED BELOW. KGFL...AREAS OF IFR SHOULD QUICKLY IMPROVE TO VFR BETWEEN 12Z-14Z/TUE...WITH VFR CLOUDS EXPECTED THEREAFTER. ADDITIONAL MVFR/IFR VSBYS COULD REDEVELOP AFTER 06Z/WED...BUT INCREASING MID LEVEL CLOUDS MAY THWART FOG DEVELOPMENT. KALB...AREAS OF LIFR/VLIFR WILL GRADUALLY IMPROVE TO MVFR...AND THEN VFR BETWEEN 14Z-16Z/TUE...THEN EXPECT VFR CONDITIONS THROUGH THE DAY AND INTO AT LEAST THE FIRST HALF OF TONIGHT. INCREASING LOW/MID LEVEL CLOUDS SHOULD PREVENT FOG DEVELOPMENT TONIGHT/EARLY WED AM. KPOU...OCCASIONAL BOUTS OF MAINLY LIGHT RAIN ARE EXPECTED TO PERSIST THROUGH THE DAY. THUS...HAVE INDICATED MVFR CONDITIONS...ALTHOUGH A FEW PERIODS OF IFR ARE POSSIBLE...MAINLY FOR CIGS...DURING ANY PERIODS OF STEADIER RAINFALL. WED...VFR/MVFR...CHANCE OF SHOWERS/TSTMS. THUR...VFR/MVFR...CHANCE OF SHOWERS/TSTMS. FRI...VFR/MVFR...CHANCE OF SHOWERS/TSTMS. SAT...VFR/MVFR...CHANCE OF SHOWERS/TSTMS. && .HYDROLOGY... NO HYDRO PROBLEMS EXPECTED THROUGH AT LEAST TUESDAY. RIVER FLOWS REMAIN AT OR BELOW NORMAL LEVELS. RAINFALL ACROSS SOUTHERN PORTIONS OF THE HUDSON VALLEY...CATSKILLS AND LITCHFIELD COUNTY THROUGH EARLY THIS EVENING WILL HAVE NO EFFECT ON AREA RIVERS AND STREAMS. RIVER LEVELS WILL REMAIN STEADY OR SLOWLY FALL OVER THE NEXT FEW DAYS...EXCEPT WHERE AFFECTED BY RESERVOIR RELEASES AND/OR POWER GENERATION. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ NEAR TERM...BGM AVIATION...KL/BGM WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 935 AM EDT TUE AUG 21 2007 RIDGE OF HIGH PRESSURE SURFACE AND ALOFT IS NOTED OVER THE AREA. WATER VAPOR IMAGERY SHOWS FAIRLY STRONG SUBSIDENCE/DRY AIR OVER THE FORECAST AREA WITH A MEAN LAYER RIDGE 1000-500 MB FROM NRN LA TO ERN GA AND OFFSHORE INTO THE ATLANTIC PER RUC ANALYSIS. DRY AIR SHOWS UP WELL IN MODEL CROSS SECTIONS WITH LOW LEVEL MOISTURE CONFINED BELOW ABOUT 750 MB. JAX SOUNDING INDICATED PWAT OF 1.3 INCHES AND WARMING BELOW 800 MB FROM 24 HRS AGO INDICATING A HOTTER DAY IN STORE THAN MONDAY. LITTLE ADJUSTMENT MADE TO TEMPS WITH MID TO UPPER 90S EXPECTED AND HEAT INDEX VALUES PROBABLY TOPPING OUT AROUND 106 TO 109. A RECORD HIGH (MOSTLY LIKELY A TIE) IS POSSIBLE TODAY AT SITES BELOW. ACCORDING TO MODEL LOW LEVEL MOISTURE...CU FIELD WILL BE MOSTLY IN THE FEW-SCT RANGE SO MOSTLY SUNNY CONDS SHOULD SUFFICE. RECORD HIGH TEMPERATURES 8/21 8/22 ALMA 100 IN 1968 100 IN 1968 ST. SIMONS 98 IN 1983 97 IN 1966 GAINESVILLE 98 IN 1954 96 IN 1966 JACKSONVILLE 101 IN 1901 100 IN 1900 && .AVIATION...VFR TO PREVAIL TODAY. PER NAM GUIDANCE A BRIEF CIG NEAR 3 KFT POSSIBLE S OF GNV 18Z-00Z. && .MARINE...A S-SE FLOW AROUND 10 KT AT THIS TIME. SEAS ARE IN SOLID 3-4 FT RANGE PER BUOYS. SWELLS OF ABOUT 2.5 TO 3 FT WITH PERIODS OF ABOUT 10 SECONDS ARE DOMINATING THE SEA STATE. WITH SEA BREEZE KICKING IN WINDS WILL INCREASE TO ABOUT 10-15 KT DURING THE DAY. RIP CURRENT RISK EXPECTED TO CONTINUE TO BE MODERATE THROUGH THE WEEK DUE TO LONG PERIOD SWELLS. && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ SHASHY fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1108 AM EDT TUE AUG 21 2007 .UPDATE... MAIN ISSUES COVERED WITH THE MORNING UPDATE WAS TO LOWER TEMPERATURES THIS AFTERNOON FOR THE NORTHERN TWO THIRDS OF THE FORECAST AREA. CLOUD COVER HAS LIMITED HEATING THIS MORNING...AND IT APPEARS THAT IT WILL TAKE SOME TIME TO ERODE THROUGH ENOUGH FOR SIGNIFICANT JUMPS IN TEMPS TO OCCUR. ALSO HAVE LOWERED PRECIP CHANCES THIS AFTERNOON SOME...SHORT RANGE MODELS SUCH AS THE RUC SHOW SOME DEVELOPMENT THIS AFTERNOON...BUT SOME UNCERTAINTY THERE AS THE THE AMOUNT OF HEATING FOR SOLID CONVECTION TO FIRE...MAY END UP BEING MORE SHOWERS. BOUNDARY STILL SITS ACROSS THE FORECAST AREA SO PRECIP IS STILL A CONCERN BUT WITH LITTLE FRONTOGENTICAL FORCING...MORE SO WELL TO THE EAST AND WEAKENED LOW LEVEL JET WHICH IS MOVING NEARLY PARALLEL TO THE FRONT BELIEVE THAT THE LOWERING OF POP IS JUSTIFIED. PWATS ARE STILL VERY HIGH...SO MENTIONED HEAVY RAINFALL WITH ANY THUNDERSTORMS THAT DO DEVELOP...BUT THE EFFECTS WOULD BE VERY LOCALIZED. && .PREV DISCUSSION... /ISSUED 701 AM EDT TUE AUG 21 2007/ SHORT TERM...TODAY AND TONIGHT. VERY COMPLEX SETUP NEXT 24 HOURS. STATIONARY BOUNDARY DRAPED ACROSS THE SOUTHERN PART OF THE CWA HAS REMAINED ACTIVE ALL NIGHT...MAINLY IN A NARROW BAND FROM MIAMI/WABASH COUNTY EAST INTO PART OF NW OHIO. SOME AREAS JUST TONIGHT HAVE PICKED UP ANOTHER 2 TO 4 INCHES OF RAINFALL ON TOP OF WHAT HAS ALREADY FALLEN. SEE RECENT SPENES FOR FLOODING TRENDS IN THIS AREA. CURRENTLY HAVE THINGS HANDLED WITH AREAL FLOOD WARNING IN THE MORNING HOURS. ALSO IN TERMS OF GRIDS/ZONES WILL COVER WITH PRE-1ST PERIOD WORDING. ACTIVITY SHOULD CALM AROUND 12Z AS FOCUS THEN TURNS TO COMPLEX WORKING ACROSS EASTERN IA/WESTERN ILLINOIS. OVERALL COMPLEX WAS MORE IMPRESSIVE A FEW HOURS AGO WITH A NICE LINE OF CONVECTION ON THE LEADING EDGE. HOWEVER AS THE COLD POOL HAS LOST ITS PUNCH CONVECTION HAD DIMINISHED BUT STRATIFORM AREA STILL HOLDING ON. TRAJECTORIES WOULD BRING THIS AREA IN THIS MORNING WORKING EAST WITH TIME INTO THIS AFTERNOON. NAM/GFS OF NO USE AS THEY ARE NOT EVEN PICKING UP ON THESE FEATURES. 4 KM WRF HAS SOME SIGNALS WITH CONVECTION IN IOWA AROUND 6Z BUT A BIT TOO SLOW/FAR WEST. THEN JUST STALLS THE COMPLEX OUT BY 12Z WHICH IS NOT EVEN CLOSE TO OCCURRING. THINK AT LEAST SOME RAIN/SHOWERS SHOULD MAKE IN THIS AM SO HAVE INCREASED POPS TO LIKELY IN THE WEST THIS AM. AND THEN SCT WEST/LIKELY EAST THIS AFTERNOON. SEVERAL THINGS TO WATCH THROUGH THE DAY WARRANT HOLDING OFF ON TOO MANY MORE CHANGES. WITH PWATS AROUND 2" AND SLOWER OVERALL FLOW...VERY HEAVY RAIN STILL A THREAT. MENTIONED HEAVY RAIN IN GRIDS/ZONES. IN TERMS OF HEADLINES...WITH WIDESPREAD HYDRO CONCERNS IN PLACE NOW FOR A FEW DAYS...REISSUING FLOOD WATCH WILL LIKELY SERVE MUCH OVERALL PURPOSE...SO WILL CONTINUE WITH NO WATCH AND USE WARNINGS AS NEEDED. TONIGHT...MODELS TRY TO TAKE BOUNDARY NORTH INTO MI THROUGH THE NIGHT. SOME CONCERN THAT WITH ONGOING CONVECTION TODAY THAT BOUNDARY MAY STRUGGLE TO WORK NORTH. 4KM WRF REDEVELOPS CONVECTION DURING THE EVENING HOURS MUCH LIKE HAS OCCURRED PAST FEW NIGHTS. AM INCLINED TO GIVE IT A NOD...AND WOULD LIKE TO MAKE CHANGES BUT SINCE ENOUGH ISSUES WITH 1ST PERIOD LET ALONE 2ND PERIOD WILL LEAVE TNGT FORECAST INTACT. TEMPS WILL HAVE A MASSIVE BUST POTENTIAL TODAY WITH TIGHT GRADIENT POSSIBLE N TO S. HAVE LOWERED TEMPS INTO THE LOWER 70S N TO LOW 80S SOUTH. ANY SUNSHINE WILL QUICKLY ALLOW THEM TO CLIMB AND ALSO CREATE ADDITIONAL ISSUES IN TERMS OF CONVECTION AND INCREASING HEAT INDICES. LONG TERM... WEDNESDAY THROUGH MONDAY. UNSETTLED AND STORMY PATTN TO CONT UNTIL SAT. LTL CHG IN OVERALL FLAT WESTERLY FLW ALOFT W/STATIONARY FNTL BNDRY STRETCHED OUT ACRS THE MIDWEST. SFC WAVE OVR KS WILL CONT TO LIFT NEWD TWD LK HURON BY WED EVENING AND ALLOW SFC BNDRY TO MIX WELL NWD AND PLACE CWA SQUARELY WITHIN WHAT SHLD BE A VRY UNSTABLE WARM SECTOR WED AFTN. 00Z MODEL SOLUTIONS CERTAINLY FLOUNDERING W/MESOSCALE DETAILS...MOST NOTABLY THE FAILURE OF CAPTURING MCS OVR ERN IA/NE MO THIS MORNING. SUSPICION AT THIS POINT IS RENEWED MCS/MCV GENERATION UPSTREAM ACRS THE PLAINS WILL OCCUR TONIGHT ACRS IA AND PROGRESS EWD INTO THE AREA BY AFTN. HWVR GIVEN ABUNDANT MSTR HERE AND CONTD LL WAA IN PLACE...CERTAINLY COULD SEE OTHER STORMS POP IN DIFFERENTIAL HEATING. LTL CHG XPCD THU/THU NIGHT OTHER THEN A MORE DEFINED LARGE SCALE TRIGGER AS SECONDARY STRONGER FNTL WAVE KICKS NEWD INTO THE WRN LAKES BY AFTN W/VRY UNSTABLE AIRMASS IN PLACE ONCE AGAIN. HOWEVER GFS MOS TEMPS ARE RIDICULOUS AND DISCARDED IN FVR OF MORE PALATABLE MET NUMBERS AND SAME FOR FRI. THIRD AND FINAL SFC WAVE TO KICK OUT SOMETIME FRI ALTHOUGH MED RANGE MODEL SOLUTIONS QUITE LARGE AND UNCERTAIN. CONSENSUS WOULD BRING CDFNT THROUGH CWA SOMETIME FRI NIGHT W/SFC RIDGING BLDG THROUGH THE WEEKEND AND A NEEDED DRYING OUT. WILL MAKE FEW CHGS TO GOING GRIDS WHICH HAVE A GOOD HANDLE ON THINGS. AVIATION... WIDESPREAD LIFR/IFR CONDS THIS MORNING WILL SLOWLY IMPROVE W/VFR XPCD TWD 18Z. PRIMARY ISSUE FOR THIS MORNING IS WHETHER OR NOT CONVN REDVLPS AHD OF MCV OVR WRN IL ALG OUTFLW BNDRY APCHG WRN INDIANA BORDER. BTR SPRT ACRS THE SOUTH EARLY ON ESP W/SMALL CONVECTIVE CLUSTER WEST OF KIKK WHICH MAY SURVIVE THE TRIP EASTWARD AND AFFECT THE KFWA TERMINAL TWD 16Z IF IT HOLDS. OTHER ISSUE IS IF/WHEN/WHERE CONVN DVLPS THIS AFTN. DOUBT STATIONARY FNTL BNDRY WILL MAKE MUCH PROGRESS NORTHWARD ESP GIVEN MERGER OF OUTFLW BNDRY COMING OUT OF IL. SFC WAVE EJECTING OUT OF KS AND RENEWED LL MASS FLUX THIS AFTN SHLD REFIRE STORMS AND WILL AT THIS POINT CARRY A CB MENTION IN THE LEAST. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE.......SCHOTT SHORT TERM/AVIATION...HOLSTEN LONG TERM....FISHER in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1030 AM EDT TUE AUG 21 2007 LATE MORNING FORECAST UPDATED TO REFLECT WIDESPREAD RAINFALL. HAVE ALSO ADJUSTED TEMPERATURES DOWN ACROSS THE NORTHERN PORTION OF THE FORECAST AREA BECAUSE OF THE RAIN AND CLOUD COVER. STILL FEEL MUCH OF THE AREA WILL SEE SOME SUNSHINE THIS AFTERNOON AND AT LEAST THE SOUTH SHOULD SEE TEMPERATURES WELL INTO THE MID AND UPPER 90S. FORECAST ALREADY OUT. --JA PREVIOUS DISCUSSION BELOW... SHORT TERM (TODAY AND TONIGHT):... PCPN POTENTIAL AND TEMPS THE MAIN FORECAST PROBLEM FOR THE SHORT TERM. REMNANTS OF ERIN WILL ACCELERATE EAST TO EAST SOUTHEAST ACROSS FA TODAY. TRW/RW WILL ENTER NWRN PTNS OF FA ABOUT THE TIME THIS FCST IS ISSUED AND THEN AS ERIN STARTS TO ACCELERATE EASTWARD...THE PCPN THREAT WILL GREATLY DIMINISH WEST TO EAST ACROSS FA BY LATE MORNING INTO THE EARLY AFTERNOON HOURS. WILL GO WI 50 PCT POPS FOR A TIME WEST TO EAST ACROSS FA THIS MORNING INTO EARLY AFTN IN THE EAST. NO MENTION OF PCPN TONIGHT AS PER CURRENT FCST. WITH SUNSHINE INCREASING DURING THE AFTERNOON HOURS...EXPECT VERY WARM HIGH TEMPS MOSTLY IN THE LOWER TO MIDDLE 90S TODAY. THIS AGREES WELL WITH OUR CURRENT FCST AND THE PREFERRED MAV FCST TRENDS. --21 LONG TERM (WEDNESDAY THROUGH MONDAY)... WEDNESDAY THROUGH THURSDAY... THE UPPER AIR PATTERN FOR WEDNESDAY AND THURSDAY WILL FEATURE A FAST ZONAL FLOW WITH THE JET STREAK ALONG THE US/CANADIAN BORDER. ONE LOW AMPLITUDE TROUGH WILL EXIT NEW ENGLAND WEDNESDAY WHILE A JET STREAK ACROSS THE UPPER MIDWEST WILL ACCOMPANY AN UPPER LOW ACROSS THE CANADIAN PROVINCES. OF MORE DIRECT IMPORTANCE TO OUR AREA IS THE VERY STRONG UPPER RIDGE EXPECTED ACROSS THE SOUTHERN STATES. THE 00Z THURS FORECAST 500MB HEIGHTS OF UP TO 597DM ACROSS THE GULF STATES BY THE GFS ENSEMBLES IS 2 STANDARD DEVIATIONS ABOVE NORMAL. THE CENTER OF HIGH PRESSURE NEAR THE SURFACE WILL ALSO CENTER OVER THE GULF STATES. THIS WILL BRING SOUTHWEST FLOW TO THE LOWER OHIO VALLEY WITH ONLY MODEST MOISTURE AVAILABLE. WITH 925MB TEMPERATURES APPROACHING 30 ON THURSDAY...TEMPERATURES WILL EASILY MOVE BACK INTO THE UPPER 90S BY THURSDAY AFTERNOON. EXPECT LITTLE CHANCE OF RAIN THESE TWO DAYS. THE AXIS OF HIGHER MOISTURE WILL LIE TO OUR NORTHWEST...STRETCHING FROM THE CENTRAL PLAINS TO THE WESTERN GREAT LAKES. FRIDAY THROUGH MONDAY... RIDGING WILL REMAIN STRONG ACROSS THE SOUTHEASTERN STATES. THE STORM TRACK ON FRIDAY WILL REMAIN ALONG A NEARLY STATIONARY FRONT FROM KANSAS THROUGH THE WESTERN GREAT LAKES. LOW PRESSURE MOVING ACROSS THE GREAT LAKES LATE FRIDAY WILL ALLOW THIS BOUNDARY TO SAG SOUTH AS A COLD FRONT. EVENTUALLY THIS WEAKENING FRONT WILL APPROACH KENTUCKY BY SATURDAY. MOISTURE WILL INCREASE AHEAD OF THIS BOUNDARY AND SO WILL CONTINUE PRECIPITATION CHANCES FOR THE WEEKEND TIME FRAME. THE LATEST GFS SLOWS DOWN THE PROGRESS OF THE FRONT...WHICH MAY STALL NEAR KENTUCKY SUNDAY. HAVE ADDED POPS FOR SUNDAY. JSD && .AVIATION (12Z TAFS):... THE REMNANTS OF ERIN CONT TO MOVE ACROSS THE VERY NORTH AND WESTERN PORTIONS OF FA...OVERALL THE PCPN INTENSITY HAS DIMINISHED AS WELL AS THE LIGHTNING. OUR EXPERIMENTAL WRF AND THE LATEST RUC 40 STILL SHOW THE SYSTEM ACCELERATING OFF TO THE EAST TO EAST SOUTHEAST TODAY. WILL KEEP TEMPO GROUP FOR MVFR CONDS WITH TRW- EARLY FOR SDF AND FOR LEX A BIT LATER THIS MORNING. ONCE THIS DISTURBANCE CLEARS OUR REGION...THE SFC PRESS GRAD WEAKENS EVEN MORE SO WITH THE LATEST 06Z MODEL RUNS. SO WE WILL WILL BACK OFF A BIT ON THE GUSTY WINDS FOR THIS AFTERNOON. EXCEPT FOR SOME MVFR PCPN TEMPO GROUPS GNRLY VFR CONDS FOR THE BULK OF THE TAF PERIOD. --21 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 644 AM EDT TUE AUG 21 2007 .AVIATION (12Z TAFS):... THE REMNANTS OF ERIN CONT TO MOVE ACROSS THE VERY NORTH AND WESTERN PORTIONS OF FA...OVERALL THE PCPN INTENSITY HAS DIMINISHED AS WELL AS THE LIGHTNING. OUR EXPERIMENTAL WRF AND THE LATEST RUC 40 STILL SHOW THE SYSTEM ACCELERATING OFF TO THE EAST TO EAST SOUTHEAST TODAY. WILL KEEP TEMPO GROUP FOR MVFR CONDS WITH TRW- EARLY FOR SDF AND FOR LEX A BIT LATER THIS MORNING. ONCE THIS DISTURBANCE CLEARS OUR REGION...THE SFC PRESS GRAD WEAKENS EVEN MORE SO WITH THE LATEST 06Z MODEL RUNS. SO WE WILL WILL BACK OFF A BIT ON THE GUSTY WINDS FOR THIS AFTERNOON. EXCEPT FOR SOME MVFR PCPN TEMPO GROUPS GNRLY VFR CONDS FOR THE BULK OF THE TAF PERIOD. --21 && .SHORT TERM (TODAY AND TONIGHT):... PCPN POTENTIAL AND TEMPS THE MAIN FORECAST PROBLEM FOR THE SHORT TERM. REMNANTS OF ERIN WILL ACCELERATE EAST TO EAST SOUTHEAST ACROSS FA TODAY. TRW/RW WILL ENTER NWRN PTNS OF FA ABOUT THE TIME THIS FCST IS ISSUED AND THEN AS ERIN STARTS TO ACCELERATE EASTWARD...THE PCPN THREAT WILL GREATLY DIMINISH WEST TO EAST ACROSS FA BY LATE MORNING INTO THE EARLY AFTERNOON HOURS. WILL GO WI 50 PCT POPS FOR A TIME WEST TO EAST ACROSS FA THIS MORNING INTO EARLY AFTN IN THE EAST. NO MENTION OF PCPN TONIGHT AS PER CURRENT FCST. WITH SUNSHINE INCREASING DURING THE AFTERNOON HOURS...EXPECT VERY WARM HIGH TEMPS MOSTLY IN THE LOWER TO MIDDLE 90S TODAY. THIS AGREES WELL WITH OUR CURRENT FCST AND THE PREFERRED MAV FCST TRENDS. --21 LONG TERM (WEDNESDAY THROUGH MONDAY)... WEDNESDAY THROUGH THURSDAY... THE UPPER AIR PATTERN FOR WEDNESDAY AND THURSDAY WILL FEATURE A FAST ZONAL FLOW WITH THE JET STREAK ALONG THE US/CANADIAN BORDER. ONE LOW AMPLITUDE TROUGH WILL EXIT NEW ENGLAND WEDNESDAY WHILE A JET STREAK ACROSS THE UPPER MIDWEST WILL ACCOMPANY AN UPPER LOW ACROSS THE CANADIAN PROVINCES. OF MORE DIRECT IMPORTANCE TO OUR AREA IS THE VERY STRONG UPPER RIDGE EXPECTED ACROSS THE SOUTHERN STATES. THE 00Z THURS FORECAST 500MB HEIGHTS OF UP TO 597DM ACROSS THE GULF STATES BY THE GFS ENSEMBLES IS 2 STANDARD DEVIATIONS ABOVE NORMAL. THE CENTER OF HIGH PRESSURE NEAR THE SURFACE WILL ALSO CENTER OVER THE GULF STATES. THIS WILL BRING SOUTHWEST FLOW TO THE LOWER OHIO VALLEY WITH ONLY MODEST MOISTURE AVAILABLE. WITH 925MB TEMPERATURES APPROACHING 30 ON THURSDAY...TEMPERATURES WILL EASILY MOVE BACK INTO THE UPPER 90S BY THURSDAY AFTERNOON. EXPECT LITTLE CHANCE OF RAIN THESE TWO DAYS. THE AXIS OF HIGHER MOISTURE WILL LIE TO OUR NORTHWEST...STRETCHING FROM THE CENTRAL PLAINS TO THE WESTERN GREAT LAKES. FRIDAY THROUGH MONDAY... RIDGING WILL REMAIN STRONG ACROSS THE SOUTHEASTERN STATES. THE STORM TRACK ON FRIDAY WILL REMAIN ALONG A NEARLY STATIONARY FRONT FROM KANSAS THROUGH THE WESTERN GREAT LAKES. LOW PRESSURE MOVING ACROSS THE GREAT LAKES LATE FRIDAY WILL ALLOW THIS BOUNDARY TO SAG SOUTH AS A COLD FRONT. EVENTUALLY THIS WEAKENING FRONT WILL APPROACH KENTUCKY BY SATURDAY. MOISTURE WILL INCREASE AHEAD OF THIS BOUNDARY AND SO WILL CONTINUE PRECIPITATION CHANCES FOR THE WEEKEND TIME FRAME. THE LATEST GFS SLOWS DOWN THE PROGRESS OF THE FRONT...WHICH MAY STALL NEAR KENTUCKY SUNDAY. HAVE ADDED POPS FOR SUNDAY. JSD && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1150 AM EDT TUE AUG 21 2007 .SYNOPSIS...A WEAK AREA OF LOW PRESSURE WILL DEVELOP ALONG A STALLED FRONT NEAR THE VIRGINIA BORDER AND PRODUCE A FEW SHOWERS AND THUNDERSTORMS OVER OUR AREA THIS AFTERNOON... THEN MOVE OFF THE TIDEWATER VA COAST TONIGHT. MEANWHILE... RIDGING ALOFT WILL EXPAND ACROSS THE SOUTHEASTERN QUARTER OF THE NATION AND RESULT IN CONTINUED HOT AND DRY CONDITIONS OVER THE REGION THROUGH THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... SFC ANALYSIS THIS MORNING SHOW A THERMAL BOUNDARY NEAR AND ALONG THE NC/VA STATE LINE. TEMPS SOUTH OF THE BOUNDARY IN CENTRAL NC WERE IN THE LOWER 90S...WHILE TEMPS NORTH OF THE BOUNDARY IN CENTRAL VA WERE IN THE LOWER 70S. THIS THERMAL BOUNDARY IS PRIMARILY THE RESULT OF DIFFERENTIAL HEATING ASSOC/W THICK LOW STRATUS OVER CENTRAL VA. A SFC TROUGH AXIS WAS LOCATED ACROSS THE PORTIONS OF NC/VA... STRETCHING WEST SOUTHWEST ROUGHLY FROM NORFOLK VA TO HICKORY NC. DEWPOINTS ACROSS NORTH CAROLINA WERE IN THE UPPER 60S TO LOWER 70S. ALOFT...A SHORTWAVE/VORTMAX ASSOC/W THE REMNANTS OF TS ERIN WAS LOCATED OVER CENTRAL/WESTERN KENTUCKY THIS MORNING. THIS FEATURE SHOWS UP ON RAOB ANALYSIS...RUC H5 HEIGHT/VORT FIELDS...AND IN WV IMAGERY WHICH CAN BE USED TO CLEARLY TRACE THIS FEATURE BACK OVER OK/MO AS ERIN`S REMNANTS. WELL...THE SLIGHT CHANCE POP YESTERDAY AFT/EVE IN AREAS ADJACENT TO THE NC/VA DID NOT WORK OUT. CONVECTION ACTUALLY DEVELOPED IN AND/OR ADVECTED INTO THE WEDGE OF COOL AIR IN CENTRAL/NORTHERN VA YESTERDAY AFT/EVE...WHILE NOTHING FORMED FURTHER SOUTH ALONG THE NC/VA BORDER WHERE THE BEST SFC CONVERGENCE AND WARMER SFC TEMPS WERE. THE BEST EXPLANATION FOR THIS SEEMS TO BE THAT STRONG DIURNAL HEATING/MIXING DROPPED SFC DEWPOINTS LOW ENOUGH (UPPER 50S TO LOWER 60S) THAT THE AMOUNT OF AVAILABLE INSTABILITY WAS SEVERELY LIMITED...AND SUFFICIENT UPPER LEVEL SUPPORT WAS ABSENT. FOR THIS AFTERNOON...A FEW THINGS HAVE CHANGED COMPARED TO YESTERDAY. THE MOST NOTICEABLE CHANGE IS THAT WE SHOULD HAVE SOME GOOD UPPER LEVEL SUPPORT IN THE FORM OF A SHORTWAVE ASSOC/W THE REMNANTS OF TS ERIN CROSSING INTO THE AREA LATER THIS EVENING. THIS UPPER LEVEL FEATURE IS CURRENTLY FORCING SHOWERS/STORMS OVER MUCH OF KENTUCKY...AND THE 13Z RUC MODEL RUN SHOWS THE SHORTWAVE AND ASSOC 20-25/S VORT ADVECTING INTO W/SW VIRGINIA AND NORTHWEST NC BY 00Z THIS EVENING. GFS/NAM BUFR AND RUC40 FCST SOUNDINGS ALL SEEM TO SHOW AN AIRMASS THAT IS MORE UNSTABLE THAN YESTERDAY...WITH AFTERNOON PWAT VALUES IN THE 1.50-2.00" RANGE. IN FACT...THE 12Z GSO SOUNDING THIS MORNING HAD A 33F DEWPOINT AT 700MB...IN CONTRAST TO A 14F DEWPOINT AT 700MB 12Z YESTERDAY. ALTHOUGH SFC DEWPOINTS ARE EXPECTED TO CRASH AGAIN THIS AFTERNOON INTO THE UPPER 50S TO LOWER 60S...SOME PORTIONS OF THE COASTAL PLAIN WILL LIKELY SEE DEWPOINTS REMAIN IN THE UPPER 60S TO NEAR 70F...AND IT IS DIFFICULT TO PINPOINT EXACTLY WHERE THIS CUTOFF LINE OR GRADIENT WILL BE. EVEN WITH DEWPOINTS IN THE LOWER 60S...ALL THE FCST MODELS MENTIONED SHOW AFTERNOON SFC BASED CAPE VALUES AROUND 1500 J/KG WITH STEEP DRY ADIABATIC LAPSE RATES UP TO 750-700 MB. OBVIOUSLY IF DEWPOINTS ARE HIGHER...THIS VALUE GOES UP AND IF DEWPOINTS ARE LOWER...THIS VALUE GOES DOWN. THEREFORE...IT SEEMS THERE WILL BE A BETTER POTENTIAL FOR CONVECTION TODAY VERSUS YESTERDAY FOR THE FOLLOWING REASONS: 1)THE APPROACH OF TS ERIN`S REMNANTS INTO WESTERN NC/VA BY 00Z. 2)A WEST-EAST SFC TROUGH OVER VA/NC PROVIDING AND A STALLED THERMAL BOUNDARY IN SOUTHERN VA PROVIDING SFC CONVERGENCE 3)MORE MOISTURE ALOFT (AFTERNOON PWAT VALUES BETWEEN 1.50-2.00") 4)FCST SOUNDINGS SHOWING SFC BASED CAPE VALUES AROUND 1500 J/KG EVEN WITH SFC DEWPOINTS IN THE LOWER 60S. MITIGATING FACTORS FOR CONVECTIVE DEVELOPMENT THIS AFTERNOON INCLUDE VERY DRY LOW-LEVELS (SFC TO ~800MB) AND 30 KT WESTERLY MID-LEVEL FLOW WHICH COULD AID IN FURTHER DOWNSLOPE DRYING IN THE LOWER LEVELS. BEST CHANCE FOR CONVECTION THIS EVENING WILL LIKELY BE IN NORTHERN PORTIONS OF THE CWA AFTER 21Z...CLOSER TO THE TRACK OF THE UPPER LEVEL SHORTWAVE/VORT WHICH WILL CROSS THROUGH CENTRAL NC AFTER 00Z THIS EVENING. CONVECTION WILL MOST LIKELY FIRE ALONG THE FOOTHILLS/MOUNTAINS THIS AFTERNOON AND ADVECT EASTWARD TOWARD THE VA/NC PIEDMONT VIA 30KT MID-LEVEL WESTERLY FLOW. CURRENT POPS LOOK MORE OR LESS OK WITH THE BETTER CHANCES IN THE NORTH AND LOWER CHANCES IN THE SOUTH...PRIMARILY AFTER 21Z...AND CONTINUING AFTER SUNSET AS THE UPPER LEVEL WAVE SWINGS THROUGH. THE SPC CURRENTLY HAS PORTIONS OF NORTH CENTRAL AND NORTHEAST NC IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS THIS EVENING. WITH STEEP LOW-LEVEL LAPSE RATES FROM THE SFC THROUGH 750MB...INVERTED-V SOUNDING PROFILES... AND 30KT MID LEVEL FLOW...DAMAGING WINDS APPEAR TO BE THE PRIMARY THREAT WITH ANY CONVECTION THAT DEVELOPS THIS EVENING. CURRENT FORECAST HIGH TEMPS THIS EVENING APPEAR ON TRACK...WITH HEAT INDICES IN THE 100-104F RANGE GIVEN THAT DEWPOINTS ARE EXPECTED TO DROP INTO THE UPPER 50S AND LOWER 60S IN MOST LOCATIONS. ISOLATED AREAS IN THE FAR EASTERN COASTAL PLAIN WHERE DEWPOINTS WILL BE HIGHER COULD POSSIBLY SEE HEAT INDICES ABOVE 105F FOR A BRIEF TIME THIS AFTERNOON... ALTHOUGH THE DURATION AND AREAL EXTENT OF THESE HIGHER INDICES ARE SUCH THAT A HEAT ADVISORY WOULD NOT BE WARRANTED. -VINCENT && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... BOTH THE NAM AND GFS DROP A SURFACE BOUNDARY INTO CENTRAL NC WEDNESDAY MORNING BEHIND THE MID LEVEL WAVE PASSAGE... HOWEVER THE NAM IS MUCH MORE EMPHATIC ABOUT HOLDING THE STABLE POOL OVER THE NORTHEAST CWA FOR MUCH OF THE DAY. AT FIRST GLANCE THIS LOOKS IMPLAUSIBLE CONSIDERING THE TIME OF YEAR... HOWEVER THIS AIR MASS IS INDEED PRODUCING IFR/LIFR CLOUDS OVER THE GREAT LAKES... AND IN LOOKING AT THE TENACITY OF THE CURRENT VA STRATUS... AND WITH THE FACT THAT THE NAM HAS SHOWN THIS STABLE NOSE LATE WEDNESDAY INTO THURSDAY FOR THREE STRAIGHT RUNS... IT MAY BE ONTO SOMETHING. HAVE TRIMMED BACK HIGHS ON WEDNESDAY ACROSS THE NORTHEAST TO THE LOWER 90S... RANGING TO THE UPPER 90S IN THE SOUTH. WILL CONTINUE TO LEAVE OUT POPS FOR NOW WITH THE LACK OF A TRIGGER FOR LARGE SCALE LIFT AND THE MARGINAL INSTABILITY. LOWS WEDNESDAY NIGHT 68 NORTHEAST TO 75 SOUTH... AND WILL INTRODUCE HIGHER SKY COVER THROUGH THURSDAY MORNING. HIGHS THURSDAY 94-99... ALTHOUGH IF THE NAM PERSISTS IN SHOWING NEAR TO BELOW NORMAL THICKNESSES... NEARLY 1400 M... IN THE FAR NORTHEAST CWA THURSDAY... WILL NEED TO CUT BACK THESE HIGHS FURTHER. -GIH && .LONG TERM /FRIDAY THROUGH MONDAY/... THE MID LEVEL RIDGE HOLDS FIRM OVER NC FRIDAY... AND CONTINUED HOT AND DRY LOOKS REASONABLE WITH WARM MID LEVEL TEMPS. THE LATEST GFS LOOKS TO HAVE SOME CONVECTIVE FEEDBACK OVER NC FRIDAY... AND HAVE DISCOUNTED THIS PRECIP. A POSITIVELY TILTED SHORTWAVE TROUGH TRACKS THROUGH THE GREAT LAKES FRIDAY NIGHT THROUGH SATURDAY... ALTHOUGH THE MID LEVEL FLOW OVER NC REMAINS FLAT TO ANTICYCLONIC INTO SUNDAY. MINOR PERTURBATIONS IN THE WESTERLIES APPEAR VERY SPURIOUS AND CANNOT BE TRUSTED... SO EVEN WITH THE APPROACH OF THIS BROAD AND WEAK SHORTWAVE TROUGH (WEAKER ON THE 00Z/21 GFS AND 12Z/20 ECMWF AS COMPARED TO THE 18Z/20 GFS) AND ITS ATTENDANT COLD FRONT... PINPOINTING ANY PARTICULAR FORCING FEATURE IS NEARLY IMPOSSIBLE. WILL HOLD ONTO ISOLATED LATE DAY POPS IN THE LATTER PART OF THE MEDIUM RANGE... WHICH IS BELOW CLIMATOLOGY BUT WITHIN THE REALM OF POSSIBILITY GIVEN THE ABOVE-NORMAL PRECIPITABLE WATER FROM SATURDAY THROUGH MONDAY. LITTLE TO NO CHANGES ARE NEEDED TO TEMPERATURES... AS THICKNESSES SUGGEST THEY SHOULD HOLD ABOUT 2-3 CATEGORIES ABOVE NORMAL. -GIH && .AVIATION /16Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. SATELLITE IMAGERY DEPICTS SOUTHWARD SURGE OF STRATUS ASSOCIATED WITH STATIONARY SURFACE BOUNDARY OVER VIRGINIA APPEARS TO HAVE FINALLY SLOWED DOWN TO NEARLY A HALT ACROSS THE EXTREME NORTHERN SECTIONS OF THE FORECAST. HENDERSON IS REPORTING A BROKEN CEILING AT 800 FT...BUT OTHERWISE A STEADY SW WIND FLOW OF 4 TO 7 KTS SHOULD KEEP THE LOW CLOUDS AT BAY ACROSS CENTRAL AND SOUTHERN PORTIONS OF VIRGINIA. A STRONG VORT MAX WILL MOVE ACROSS THE AREA IN THE WESTERLY FLOW ALOFT TOMORROW AFTERNOON AND EVENING. THIS WILL BRING A PERIOD OF BROKEN MID AND HIGH CLOUDS BY 21Z IN THE WEST...SPREADING SOUTHEAST THROUGH THE EVENING. ISOLATED CONVECTION WILL ALSO BE POSSIBLE AS TRIPLE DIGIT TEMPERATURES WILL BE SUFFICE FOR UPDRAFT SUPPORT...BUT WILL NOT BE INCLUDED DUE TO ISOLATED NATURE. SW WINDS WILL INCREASE SOME DURING THE DAY TOMORROW AS DEEP MIXING OCCURS. WINDS IN THE MIXED LAYER WILL BE ANYWHERE FROM 15-25KTS...SO GUSTS OF UP TO 20KTS ARE CERTAINLY POSSIBLE. THROUGH THE REMAINDER OF THE WEEK...PREDOMINANTLY VFR CONDITIONS ARE EXPECTED AS THE FORECAST AREA REMAINS UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE. THE EXCEPTION LOOKS TO BE WITH PREDAWN STRATUS/FOG AS SURFACE BOUNDARY SETTLES OVER THE AREA. CHANCES FOR DIURNAL CONVECTION DURING THIS TIME WILL BE BELOW NORMAL. -CBL && .CLIMATE... HERE ARE THE RECORD HIGHS FOR TODAY THROUGH FRIDAY: RDU- AUG 21: 101 IN 1983 AUG 22: 101 IN 1983 AUG 23: 103 IN 2002 AUG 24: 100 IN 2002 GSO- AUG 21: 100 IN 1983 AUG 22: 100 IN 1983 AUG 23: 99 IN 1983 AUG 24: 98 IN 1968 THE MODERATE AND SEVERE DROUGHT CONDITIONS ACROSS CENTRAL ARE NOT NOT EXPECTED TO SEE ANY SIGNIFICANT IMPROVEMENT THROUGH THE 7 DAY FORECAST AS THERE REMAINS NO APPARENT WEATHER FEATURE TO SUPPORT WIDESPREAD RAINFALL. AS OF AUGUST 20TH...THE MONTH TO DATE RAINFALL AT GSO AND RDU IS 0.34" AND 0.26" RESPECTIVELY. THIS WILL RESULT IN SIGNIFICANT AUGUST RAINFALL DEFICITS LEADING INTO THE LAST WEEK OF AUGUST AND A STRONG LIKELIHOOD OF BEING ONE OF THE DRIEST AUGUSTS ON RECORD. LISTED BELOW IS THE DRIEST AUGUST AT GSO AND RDU ON RECORD. TOP 5 DRIEST AUGUSTS ON RECORD. GSO RDU (SINCE 1928) (SINCE 1944) 1) 0.71/1972 0.81/1950 2) 1.13/1979 1.01/1997 3) 1.19/1962 1.13/1984 4) 1.40/1932 1.31/1956 5) 1.44/1983 1.52/1976 HOT AND DRY CONDITIONS HAVE LED TO RECORD WARMTH THIS MONTH ACROSS CENTRAL NORTH CAROLINA. IN FACT... IF WE EXPERIENCE NORMAL TEMPERATURES FOR THE REMAINDER OF THE MONTH RDU WOULD BREAK THE RECORD FOR THE WARMEST AUGUST ON RECORD... AND GSO WOULD FALL A TENTH OF A DEGREE SHORT OF THE WARMEST AUGUST ON RECORD. HOWEVER... TEMPERATURES THROUGH THE END OF AUGUST LOOK TO BE AT OR ABOVE NORMAL. THUS... THE RECORDS LISTED BELOW ARE LIKELY TO FALL. THE CURRENT MEAN AVERAGE TEMPERATURE AT RDU AND GSO AS OF AUGUST 20TH IS 84.4F AND 83.6F RESPECTIVELY. TOP 5 WARMEST AVERAGE TEMPERATURES FOR AUGUST ON RECORD. GSO RDU (SINCE 1929) (SINCE 1944) 1) 80.0/1975 80.6/1995 2) 79.7/1988 80.5/2006 3) 79.4/2006 80.3/1988 4) 79.4/1995 80.2/2005 5) 79.3/2005 80.0/1999 && .RAH WATCHES/WARNINGS/ADVISORIES... && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...CBL CLIMATE...CBL nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 1005 AM EDT TUE AUG 21 2007 .SYNOPSIS... PERSISTENT...STRONG HIGH PRESSURE ALOFT WILL RESULT IN HOT TEMPERATURES ACROSS NC THIS WEEK. A STATIONARY BOUNDARY ACROSS VIRGINIA THIS MORNING WILL BEGIN TO DRIFT SOUTH ACROSS EASTERN NC ON WEDNESDAY. A WEAK DISTURBANCE ALOFT WILL COMBINE WITH THE WEAK FRONT TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS MAINLY WEST AND NORTH OF OUR AREA TONIGHT. && .NEAR TERM /THROUGH TONIGHT/... NO UPDATE PLANNED. HOT TEMPERATURES EXPECTED AGAIN TODAY ACROSS EASTERN NORTH CAROLINA. READINGS LIKELY TO BE ABOUT 3 DEGREES COOLER THAN MAV BUT WE STILL ARE EXPECTING WIDESPREAD HIGHS IN THE MIDDLE AND UPPER 90S. HEAT INDEX VALUES WILL QUICKLY APPROACH ADVISORY LEVELS OF AROUND 105 DEGREES EARLY THIS AFTERNOON...HOWEVER...DEEP WESTERLY FLOW WILL PRODUCE DEEP MIXING DURING MAX HEATING ALLOWING DEWPOINTS TO DROP. USING THE TOP OF THE MIXING LAYER SUPPORTS DEWPOINTS DROPPING INTO THE MIDDLE 60S DEEP INLAND AND AROUND 70 IN THE HIGHWAY 17 CORRIDOR. THUS HEAT INDEX VALUES SHOULD REMAIN JUST BELOW THE 105 DEGREE THRESHOLD. ALONG THE COAST THE SEA BREEZE SHOULD KEEP THE AREA "COOLED" DOWN TO AROUND 90 DEGREES BUT DEWPOINTS SHOULD REMAIN IN THE 70S WITH MAX HEAT INDEX VALES IN THE LOW 100S. WHILE THE NAM/RUC MODELS LOOK OVERDONE ACROSS EASTERN NC WITH PRECIPITATION AMOUNTS OVERNIGHT...IT NOW LOOKS LIKE A WEAKENING AREA OF SHOWERS AND STORMS WILL TRY TO MOVE ACROSS EASTERN NC LATE TONIGHT. EVEN THE WETTER NAM KEEPS THE LOW LEVELS VERY DRY SO I AM NOT EXPECTING MUCH RELIEF FROM OUR DRY CONDITIONS BUT I WILL HAVE TO CONSIDER ADDING A SMALL POP IN THE FORECAST AFTER THE NEXT MODEL RUN. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY/... THE GFS CONTINUES TO BE THE FAVORED MODEL AS THE NAM LOOKS TOO AMPLIFIED IN ITS SOLUTION ACROSS THE SOUTHEAST. HIGH PRESSURE WILL EXTEND INTO THE SOUTHEAST STATES FROM THE WESTERN ATLANTIC. THE FRONTAL BOUNDARY TO OUR NORTH NEVER MAKES IT INTO THE FORECAST AREA. A WEAK TROF PASSES THROUGH TONIGHT AND THE GFS CRANKS OUT SOME LIGHT QPF. HOWEVER...FORECAST SOUNDINGS IN THE BOUNDARY LAYER ARE EXTREMELY DRY SO NO PRECIP IN THE SHORT TERM. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... NO CHANGES FROM PREVIOUS FCST. LITTLE FORCING TO SUPPORT PRECIP FRI AND SAT WITH UPR RDG CONT. LATE IN THE WEEKEND AND EARLY NEXT WEEK FRONTAL BNDRY WILL BE A BIT CLOSER TO THE NW AND MAY SEE A BIT BETTER CHANCE OF SOME CONVECTION. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS ARE EXPECTED THROUGHOUT DAY AS THE ATMOSPHERE APPEARS TOO DRY FOR DIURNAL DEEP CONVECTION. THE ATMOSPHERE IS EXPECTED TO WELL MIXED OVERNIGHT LIMITING THE POTENTIAL FOR FOG OR STRATUS. DEBRIS CLOUDS FROM UPSTREAM CONVECTION WILL STREAM EAST INTO THE AREA OVERNIGHT BUT WE ARE EXPECTING THE BASES OF THESE CLOUDS TO TO BE MAINLY ABOVE 3000 FEET. VFR THROUGH THE REST OF THE PERIOD OUTSIDE OF POSSIBLE MVFR FOG IN THE PREDAWN HOURS EACH DAY. && .MARINE... NO UPDATE PLANNED THIS MORNING. THE SCA WILL REMAIN IN EFFECT FOR THE CENTRAL WATERS. THERE WILL LIKELY BE A BRIEF DECREASE IN WINDS THIS AFTERNOON ACROSS THE WATERS NORTH OF HATTERAS...BUT LOW PRESSURE IS EXPECTED TO MOVE EAST ALONG THE STALLED FRONT LOCATED JUST TO THE NORTH OF THE WATERS TONIGHT. THIS WILL PINCH THE GRADIENT WITH WINDS AGAIN REACHING SUSTAINED 20 KT KEEPING SEAS AROUND 6 FEET IN THE ADVSIORY AREA. THE BOUNDARY IS EXPECTED TO DRIFT SOUTH ACROSS THE AREA WED WITH A MUCH WEAKER GRADIENT AND WIND SPEEDS EXPECTED. THE FRONT WILL GRADUALLY DISSIPATE LATER IN THE WEEK WITH WEAK HIGH PRES OFFSHORE PRODUCING S/SW WINDS. WENT CLOSE TO WAVEWATCH FOR SEAS FOR THE NEAR TERM. NOT SURE ABOUT THE 5 TO 6 FT SEAS WAVEWATCH IS SHOWING LATER THU AND THU NIGHT WITH SE SWELL ENERGY...WENT ABOUT A FOOT BELOW GUIDANCE WITH SEAS 3 TO 5 FT MOST AREAS LATE IN THE WEEK. RIP CURRENT...WL CONT HIGH RISK TODAY FOR S/SE FACING BEACHES FROM HAT S. WILL CONT TO SEE A 3 FT SE SWELL TODAY AND COMBINED WITH S/SW WINDS WILL PRODUCE DECENT WAVE ENERGY S OF HAT. WITH OFFSHORE WINDS AND MORE PARALLEL SWELL ENERGY KEPT LOW THREAT ACROSS NRN BEACHES. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM EDT WEDNESDAY FOR AMZ152-154. && $$ SYNOPSIS...JME NEAR TERM...JME SHORT TERM...HSA LONG TERM...HSA AVIATION...JME MARINE...JME nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 339 PM EDT TUE AUG 21 2007 .SYNOPSIS... STATIONARY FRONT TO OUR SOUTH WITH HIGH PRESSURE ANCHORED OVER THE NORTHEAST WILL MAINTAIN AN EAST FLOW TONIGHT INTO WEDNESDAY. AS LOW PRESSURE MOVES OFF THE COAST WEDNESDAY MORNING, HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH WEDNESDAY NIGHT. ANOTHER FRONTAL SYSTEM WILL APPROACH LATE WEDNESDAY AND SETTLE OVER THE REGION INTO FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... THE FLASH FLOOD WATCH HAS BEEN CANCELLED. THERE WILL BE SOME SPOTTY HEAVY RAIN BUT NOT ENOUGH TO CAUSE ANY PROBLEMS. ANY FLOODING POTENTIAL WILL BE HANDLED BY LOCALIZED WARNINGS. YOU WOULD HAVE TO GO WEST TO THE WEST VIRGINIA PANHANDLE TO GET BACK TO AUGUST TEMPERATURES. WHILE THEY ARE BASKING IN 80 + DEGREES AND DEW POINTS APPROACHING 70, OUR CWA IS EXPERIENCING SOME VERY CHILLY AUGUST TEMPERATURES. WOULD YOU BELIEVE IT`S ONLY IN THE 50S(MT. POCONO 52). IF THE WATER TEMPERATURES HAVE NOT BEEN AS WARM AS THEY HAVE BEEN, WITH THE NORTHEAST WIND WE MAY EVEN EVEN COOLER! ANYWAY, THE OVERRUNNING COOL RAINS HAVE MOVED EAST EXCEPT FOR SOME TEXAS -LIKE DRIZZLE CONTINUING. HIGH PRESSURE TO THE NORTHEAST IS GOING TO INFLUENCE THE WEATHER RIGHT INTO TUESDAY MAINTAINING A EAST TO NORTHEAST WIND. THE HIGH PRESSURE RIDGE WEDGES DOWN TO THE APPALACHIANS THROUGH WEDNESDAY. OVERNIGHT LOW TEMPERATURES TONIGHT WILL HOLD STEADY IN MOST PLACES. KEEPING AN EYE ON THE AREA WHERE SPC HAS RECENTLY ISSUED THE SVR THUNDERSTORM WATCH. THE NAM HAS BEEN ADVERTISING A HEAVY RAIN EVENT FOR MARYLANDS EASTERN SHORE/DE AND ALMOST INTO SOUTHERN NEW JERSEY. WITH THE REMNANTS OF TS ERIN MOVING INTO THE MID ATLANTIC STATES. EXPECT TO SEE THE PRECIPITATION CONTINUE EAST AFTER MIDNIGHT AND THE SURFACE LOW EXITS DELMARVA PENINSULA WEDNESDAY MORNING. A HEFTY 1.5 INCHES COULD FALL SOMEWHERE IN OUR EXTREME SOUTHERN ZONES SO I`M GOING TO INSERT THE MENTION OF HEAVY RAIN FOR SOUTHERN AREAS. WE CONTINUE TO BE IN THE RIGHT ENTRANCE REGION OF A SAGGING 300MB JET AND THERE IS SIGNIFICANT MOISTURE CONVERGENCE OVER WERN PA/WVA/NORTHERN VA WITH THE RUC IS SHOWING SOME HEAVY PCPN OVER THE SOUTHERN ZONES BEGINNING LATE THIS EVENING. THE VWP FROM DIX 88D SHOWS THE EAST WIND EXTENDING UP THROUGH 3,000 FT AT 20 TO 25 KTS. THEN WARM ADVECTION ABOVE, CAPPING OFF AT 13,000 FT. SOME CIRRUS IS ALSO STREAKING IN OVERHEAD. && .SHORT TERM /WEDNESDAY/... STARTED BY LOWERING THE HIGH FOR WEDNESDAY AS WE CONTINUE IN A NORTHEAST FLOW. THE INTERVAL BETWEEN THE PRECIPITATION NOW AND THE NEXT EVENT IS NOT GOING TO BE THAT LONG. PERHAPS WEDNESDAY AFTERNOON WILL BE JUST CLOUDY AND THE TEMPERATURES INTO THE 70S. THE UPPER RIDGE BEGINS TO BUILD NORTHEAST FROM THE MISSISSIPPI VALLEY ON WEDNESDAY. WITH THE WARM AIR ADVECTION WILL COME THE CHANCE OF MORE SHOWERS BY NIGHTFALL. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... FAST FLOW ALOFT WEDNESDAY NIGHT BRING A SURFACE FRONT TO THE SOUTHERN GREAT LAKES. AHEAD OF THE FRONT, THE AIR WILL BE VERY HUMID WITH DEW POINTS APPROACHING 70 AND 80H TEMPERATURES OF 18C. THE SOUTHERLY FLOW WILL ADVECT THE UNSTABLE AIR NORTHEAST, EAST OF THE APPALACHIANS WITH THE CHANCE OF SHOWERS AND THUNDERSTORMS DEVELOPING DURING THE DAY THURSDAY. HIGHS WILL PUNCH INTO THE MID 80S(A COUPLE DEGREES ABOVE NORMAL) AND IT WILL BE VERY MUGGY WITH SOME MID LEVEL CLOUDS OVERHEAD. HIGH PRESSURE ALOFT WILL STRETCH FROM TEXAS TO THE MID ATLANTIC, WHILE A LAZY SURFACE FRONT MOVES VERY SLOWLY TO THE SOUTH. THE GENERAL LOCATION WILL BE FROM OKLAHOMA TO THE SOUTHERN GREAT LAKES. SOME VERY HEAVY RAIN WILL FALL ALONG THAT AXIS INTO SUNDAY WITH A CLASSIC DIFFLUENT THICKNESS PATTERN WITH WAVES MOVING ALONG THE FRONT. HOWEVER, WE REMAIN ON THE WEAK UPPER RIDGE SIDE OF THE SET UP UNTIL SUNDAY AFTERNOON WHEN THE FRONT FINALLY MOVES SOUTH OF OUR CWA. THIS WILL NOT SIGNAL THE ALL CLEAR SIGN FOR NICE WEATHER AS A COUPLE WAVES WILL MOVE NORTHEAST ALONG THE FRONT AND KEEP THE MENTION OF SHOWERS INTO TUESDAY, ESPECIALLY OVER THE SOUTHERN HALF OF THE CWA. TEMPERATURES IN THE SOUTHERN POCONOS THROUGH THE PERIOD WILL BE A FEW DEGREES EITHER SIDE OF 80S DEGREES UNTIL SUNDAY THEN DROP BACK INTO THE 70S. THE SOUTHERN AREAS WILL SEE VERY WARM AND HUMID CONDITIONS. && .AVIATION /18Z TODAY THROUGH SUNDAY/... THE PROLONGED PERIOD OF POOR FLYING WEATHER WITH WIDESPREAD IFR OR LOW MVFR CONDITIONS CONTINUES ACROSS THE AREA THIS AFTERNOON. ALTHOUGH THE BACK EDGE OF THE (MOST RECENT) STEADIER RAIN IS PULLING AWAY THIS AFTERNOON...MORE SCATTERED SHOWERS AND AREAS OF DRIZZLE WILL LINGER ACROSS THE TAFS SITES TONIGHT AND INTO THE EARLY PART OF WEDNESDAY. ITS POSSIBLE THAT BETTER CONDITIONS MAY ARRIVE BY THE WEDNESDAY MORNING RUSH...BUT ITS STILL TOO EARLY TO BE THAT OPTIMISTIC. I WILL GO ALONG WITH THE GUIDANCE NUMBERS FOR NOW. FURTHER OUT...BETTER CONDITIONS WILL ARRIVE LATER DURING THE DAY WEDNESDAY AS UPPER RIDGING BEGINS...AND THE EASTERLY FLOW WILL DIMINISH SOMEWHAT. THERE WILL STILL BE PERIODS OF MVFR IN SCATTERED SHOWERS DURING THE LATE PART OF THE WEEK AND DURING THE WEEKEND. && .MARINE... MODELS IN GOOD AGREEMENT REGARDING THE SHORT TERM WINDS ON THE WATERS. A MODERATE EASTERLY FLOW AROUND 20 KTS WILL BE OVER THE OCEAN WATERS TONIGHT AND THE FIRST PART OF WEDNESDAY AS LOW PRESSURE PASSES TO THE SOUTH AND A HIGH REMAINS OVER NEW ENGLAND. THE WRF-NAM MODEL HOLDS THE WINDS IN LONGER WED AS THE LOW REMAINS IN PLACE... BUT THE GFS SLOWLY WEAKENS THE WIND FIELDS WED. WE WILL KEEP THE SCA FLAG GOING AS SEAS HAVE BUILT NICELY INTO THE 9 FT RANGE AT 44025 AND THESE SEAS SHOULD PUSH TOWARDS OUR NORTHERN WATERS...BUT ARRIVE NOT QUITE THAT HIGH HERE. GUIDANCE SHOWS THAT AT LEAST 5 FT SEAS CAN BE EXPECTED THE REST OF THE WEEK AT THE SOUTHERN BUOY...SO I WILL EXTEND THE SCA FLAG ANOTHER 12 HOURS INTO THU FOR NOW. && .CLIMATE... UNLESS WE SEE A THINNING OF THE CLOUDS THE NEXT TWO HOURS, WE WILL ENTER THE RECORD BOOKS FOR THE LOWEST MAX FOR THIS DATE. THE RECORD WAS SET 81 YEARS AGO, 1926 WITH A LOW MAX OF 66 DEGREES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 PM EDT THURSDAY FOR ANZ450>455. && $$ SYNOPSIS/NEAR-SHORT-LONG TERM/CLIMATE...EBERWINE AVIATION/MARINE...O`HARA de AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 320 PM CDT TUE AUG 21 2007 .DISCUSSION FOR AFTERNOON ZONES/GRIDS... 320 PM CDT PRECIP AND HYDROLOGIC IMPACTS REMAIN THE MAIN FORECAST CONCERN THROUGH THE WEEK. AN UPPER LEVEL SHORT WAVE WHICH BROUGHT SHOWERS AND ISOLD STORMS TO AREAS MAINLY SOUTH OF INTERSTATE 80 THIS MORNING HAS MOVED OFF TO THE EAST WITH SOME PARTIAL CLEARING ACROSS NORTHEAST ILLINOIS IN THE WAKE OF THIS SHORT WAVE. LOW CLOUDS HAVE FILLED BACK IN RAPIDLY HOWEVER...ESPECIALLY FROM DUBUQUE TO AURORA IN ASSOCIATION WITH FRONTAL BOUNDARY LIFTING BACK TO THE NORTH THIS AFTERNOON. WATER VAPOR IMAGERY THIS AFTERNOON INDICATING A WELL DEFINED UPPER LEVEL SHORT WAVE MOVING THROUGH NORTH DAKOTA. THIS SHORT WAVE IS EXPECTED TO GET INGESTED INTO THE UPPER LEVEL CYCLONIC CIRCULATION ASSOCIATED WITH THE UPPER LOW CENTERED ACROSS WEST CENTRAL MANITOBA. ANOTHER WEAKER SHORT WAVE ACROSS NORTHERN MISSOURI IS EXPECTED TO TRACK INTO CENTRAL ILLINOIS THIS EVENING. WITH THE PARTIAL CLEARING THAT HAS OCCURRED ACROSS SOUTHERN PORTIONS OF THE CWA TEMPERATURES HAVE RISEN INTO THE MID 80S WITH DEW PTS IN THE MID 70S. SPC RUC ANALYSIS MESOANALYSIS GRAPHICS INDICATE AN AXIS OF MLCAPES ON THE ORDER OF 2-3 J/KG ACROSS EXTREME SOUTHERN PORTIONS OF THE CWA. AS THE NORTHERN MISSOURI SHORT WAVE TRACK EASTWARD THIS EVENING...CANNOT RULE OUT POSSIBILITY OF ISOLD-SCT THUNDERSTORMS DEVELOPING SOUTH OF I-80 EARLY THIS EVENING. IT STILL APPEARS AS THOUGH A BETTER CHANCE OF PRECIP WILL OCCUR LATE TONIGHT...ESPECIALLY ACROSS EXTREME NORTHERN PORTIONS OF THE FORECAST AREA. CONVECTION IS EXPECTED TO DEVELOP ACROSS WESTERN IOWA DURING THE EVENING AS LOW LEVEL JET STRENGTHENS...AND AS UPPER LEVEL SHORT WAVE ACROSS THE DAKOTAS TRACKS INTO MINNESOTA. GIVEN FAIRLY STEADY NORTHWARD PROGRESS OF THE LOW LEVEL WARM FRONT TODAY...BAND OF HEAVIEST PRECIP SHOULD REMAIN TO THE WEST AND NORTH OF THE AREA. UPPER LEVEL FORCING/JET DYNAMICS ALSO APPEAR TO BE MORE FAVORABLE FURTHER NORTH DURING THE OVERNIGHT HOURS. WILL HOLD OFF ON THE ISSUANCE OF ANY HYDROLOGY HEADLINES AT THIS TIME...BUT EVENING SHIFT WILL HAVE TO MONITOR CONVECTIVE TRENDS. LOW LEVEL FRONT SHOULD GET SUPRESSED BACK TO THE SOUTH ON THURSDAY WITH PASSAGE OF NORTHERN STREAM SHORT WAVE...AND DUE TO ANY OUTFLOWS DROPPING INTO THE AREA FROM OVERNIGHT CONVECTION. GIVEN LOW LEVEL BOUNDARY IN THE AREA TOMORROW AND PERSISTENT LOW LEVEL SRY FLOW OVER THIS BOUNDARY WILL MAINTAIN HIGH END CHANCE POPS THROUGH THE DAY TOMORROW. SEVERE THREAT WILL BE DEPENDENT ON THE DEGREE OF DESTABILIZATION THAT CAN OCCUR TOMORROW AFTERNOON. FORECAST SOUNDINGS INDICATING SOME SUGGESTION OF THE POSSIBILITY OF BEING CAPPED TO SFC BASED CONVECTION. BUT EVEN IF PARCELS ARE NOT SURFACE BASED...ELEVATED INSTABILITY LOOKS QUITE IMPRESSIVE IN FORECAST SOUNDINGS. SHORT WAVE PATTERN ACROSS THE AREA WILL BECOME MORE ACTIVE WEDNESDAY NIGHT THROUGH FRIDAY AS SHORT WAVES EJECT OUT EASTWARD THROUGH THE ROCKIES FROM A LONGWAVE TROUGH AXIS MOVING INTO THE WESTERN CONUS ALLOWING FOR CONTINUED WAVERING OF FRONTAL BOUNDARY ACROSS THE SOUTHERN GREAT LAKES. HYDRO SITUATION WILL NEED TO BE MONITORED THROUGH THE END OF THE WEEK WITH THURSDAY NIGHT/FRIDAY PERIOD POSSIBLY SHAPING UP AS A PERIOD OF CONCERN FOR RAINFALL AS FRONT MOVES THROUGH THE AREA. STRONGER MID/UPPER LEVEL FORCING ALSO EXPECTED BY FRIDAY AS AS MAIN UPPER LEVEL TROUGH FROM THE WESTERN CONUS MOVES THROUGH THE AREA. THIS SHOULD RESULT IN PROGRESSIVE COLD FRONTAL BOUNDARY THROUGH THE AREA BY EARLY SATURDAY BRINGING AN END TO THE PRECIP CHANCES...ALONG WITH COOLER AND LESS HUMID CONDITIONS FOR THE WEEKEND. UPPER RIDGING WILL BUILD BACK INTO THE WESTERN GREAT LAKES REGION SUNDAY NIGHT INTO MONDAY IN ADVANCE OF BROAD UPPER LOW ACROSS SOUTHWEST CANADA. TEMPERATURES WILL MODERATE BACK INTO THE MID 80S TOWARD THE END OF THE PERIOD. STILL SOME QUESTION IN REGARDS TO PROGRESSION OF THIS SOUTHWEST CANADIAN SHORT WAVE SO WILL HOLD OFF ON ANY TUES POPS AT THIS TIME. MARSILI && .AVIATION DISCUSSION REGARDING 18Z TAFS... 100 PM CDT SFC ANALYSIS AND SATLT IMAGERY SHOWS WARM FRONTAL BOUNDARY AT 17Z EXTENDING FROM NR DBQ-JOT-VPZ. THIS BOUNDARY WILL CONTINUE LIFTING NORTHWARD ACROSS ENTR AREA THIS AFTN...MARKED MOST NOTABLY BY RETREAT/EROSION OF IFR CLOUD DECK. MOST AREAS HAVE ALSREADY SEEN LWR DECK SCT OUT REVEALING BKN VFR LYR ABV. EXPECT THIS TREND TO CONTINUE ERLY THIS AFTN. HOWEVER...GIVE HIGH DEW POINT AIR POOLED ALG/JUST S OF WARM FRONT AND ENUF SUNSHINE TO ALLOW TEMPS TO JUMP INTO LOW-MID 80S DURG COURSE OF AFTN...FCST SOUNDINGS RESULT IN SIG DESTABILIZATION. BASED ON THIS WILL HAVE TEMPO MVFR CIGS AS CU FIELD DVLPS. AMS TO BCM QUITE UNSTABLE BY 00Z WITH FCST LI/S AOB -5 AND CAPES APCHG 3500 J/KG. EXPECT THERE WILL BE SOME TSTMS DVLP OUT OF THIS BUT WITHOUT ANY APPARENT MID/UPR LVL FEATURE TO FOCUS ON ATTM...WILL FCST ISOLD COVG AND NOT PUT MENTION IN TAFS. MORE SIG COVG OF SHWRS/TSTMS EXPECTED LATE TNGT INTO ERLY WED MRNG AS WEAK SHRT WAVE NOW MOVG EWD FROM CNTRL NEB/SD ACTS ON UNSTABLE AMS TO TRIGGER TSTM CLUSTER TO W OF RGN THIS EVENING. BEST LLVL FORCING FOR STMS FCT TO BE MAINLY N OF IL/WI STA LN...BUT AT THIS POINT...INCREASED PROBABILITY OF STMS FURTHER S ACRS NRN IL/NWRN IND WARRANTS AT LEAST A MENTION OF SHWRS WITH CUMULONIMBI DURG THIS TIME. WITH DEW POINTS IN LWR 70S...EXPECT VIS WILL ALSO LWR IN FOG/HAZE TO MVFR RANGE AFT SUNSET DUE TO LGT WIND REGIME...BUT WITH WARM FRONT N OF AREA...WOULD BE SURPRISED TO SEE ANYTHING CLOSE TO CONDS PAST 12 HRS. WINDS IN PROCESS OF BCMG SSWLY ACROSS RGN AS WARM FRONT MOVED NWD. SPEEDS TO PMN QUITE LGT...GENLY BLO 10 KTS...WITH SOME BACKING TO SSE DURG NIGHTTIME HRS. MERZLOCK && .MARINE DISCUSSION... 100 PM CDT A HIGH PRESSURE CENTER OVER CENTRAL QUEBEC WILL MOVE EAST THROUGH THE MARITIMES BY WEDNESDAY MORNING. MEANWHILE...A LOW OVER SASKATCHEWAN WILL MOVE NORTHEAST TO HUDSON BAY BY THURSDAY MORNING. BY FRIDAY MORNING A COLD FRONT TRAILING SOUTHWESTWARD FROM THIS LOW WILL PUSH SOUTH ACROSS THE UPPER GREAT LAKES...CLEARING LAKE MICHIGAN FRIDAY NIGHT AND SATURDAY. WINDS WILL REMAIN LIGHT SELY-SLY THRU TNGT AND BCM MORE S-SSWLY LATER TNGT AND ESPECIALLY WED AS WARM FRONT SHIFTS NWD A BIT AND FLOW VEERS AHD OF APCHG CANADIAN WX SYS/COLD FRONT. SPEEDS TO RMN QUITE LGT WITH 10 TO 15 KT RNGE PREVAILING. SHWRS/TSTMS EXPECTED TO INCRS IN COVERAGE TNGT...AND CONTINUE FROM TIME TO TIME THRU THU NGT-FRI. GREATEST LIKELIHOOD OF STMS WILL BE OVR SRN 1/2 OF LAKE LATE TNGT-ERLY WED...THEN AGAIN THUR NGT...AND FINALLY ON FRIDAY ALG/AHD OF COLD FRONT. MERZLOCK && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 319 PM EDT TUE AUG 21 2007 .SHORT TERM... TONIGHT THROUGH WEDNESDAY AFTERNOON... MAIN PLAYER ACROSS THE REGION IS THE NEARLY STATIONARY BOUNDARY WHICH HAS BEEN DRAPED ACROSS THE REGION FOR THE LAST FEW DAYS. FINALLY SHOWING SIGNS OF A SLOW RETREAT TO THE NORTH THIS EVENING. CLOUD COVER LIMITED HEATING ACROSS THE REGION DIMINISHING CONVECTIVE DEVELOPMENT...AND LITTLE OTHER SOURCE OF FORCING EXISTS ACROSS THE AREA AS CROSS FRONTAL FLOW FROM THE LOW LEVEL JET ENDED AND LITTLE FRONTOGENETICAL FORCING EXISTS PER LATEST RUC DATA. WILL LEAN TOWARDS THE RUC AND NAM/SREF THIS PERIOD. FRONT STILL HOLDING ACROSS THE REGION THIS AFTERNOON...SMALL SURFACE LOW PULLING EAST ALONG THE BOUNDARY INTO THIS EVENING. LATEST RUC WIND DATA AT LAYERS H925-850 AND H850-700 SHOWING WINDS BECOMING MORE SOUTHERLY AND THEREFORE SHOULD START TO PUSH THE FRONT NORTH MORE INTO THE GREAT LAKES REGION...AS THE SMALL LOW MOVES FURTHER INTO THE UPPER OHIO VALLEY TONIGHT. A FEW SHOWERS AND AN ISOLATED T-STORM WILL BE POSSIBLE...BUT COVERAGE ACROSS THE REGION LOOKS TO BE MINIMAL. SOME LOW CEILINGS EXPECTED OVERNIGHT...POSSIBLY MIXING OUT SOME IF THE SOUTHERLY FLOW INCREASES MORE THAN CURRENT THINKING. DEWPOINTS HAVE CONTINUED SLOW CLIMB TODAY...NEARING THE UPPER 60S AND LOWER 70S AREAWIDE. WARM OVERNIGHT LOWS NEAR 70 ACROSS THE FORECAST AREA. WITH THE FRONT PUSHING NORTH ACROSS THE REGION DURING THE MORNING WINDS WILL BECOME MORE SOUTHERLY OR SOUTHWESTERLY. ANY LOWER VSBY AND CEILINGS WILL LIFT FAIRLY QUICKLY DURING THE MORNING. THIS WILL ALLOW FOR DECENT HEATING DURING THE DAY AND WITH H850 TEMPS NEAR 20C AFTERNOON TEMPERATURES WILL REACH THE MIDDLE AND UPPER 80S. HAVE WENT SLIGHTLY UNDER THE MOS BLEND AS SOME ISSUES WITH CLOUD COVER MAY LIMIT HEATING SOME...AND PLENTY OF MOISTURE IN THE GROUND WHICH WILL TAKE SOME OF THE HEATING ENERGY FOR EVAPORATION. WITH DEWPOINTS IN THE LOWER 70S...HEAT INDICES APPROACHING THE LOWER TO MIDDLE 90S WILL BE POSSIBLE. ANOTHER SIDE RESULT WITH THE AFTERNOON HEATING WILL BE THE DEVELOPMENT OF SOME SCATTERED SHOWERS AND THUNDERSTORMS. FORECAST SOUNDING INDICATE THAT A FEW STORMS MAY BE STRONG TO SEVERE WITH STRONG GUSTY DOWNBURST WINDS...AS WINDEX VALUES HAVE APPROACHED VALUES OF 1.2 OR 1.3. INSTABILITY INDICES ARE SHOWING LI`S NEARING -5 TO -7 WITH SURFACE BASED CAPES AROUND 2500-3000 J/KG. PWATS REMAIN SOMEWHAT HIGH CLOSE TO 1.7 OR 1.8 INCHES...ALLOWING FOR LOCALIZED HEAVY RAINFALL AMOUNTS. NOT EVERYONE WILL SEE RAINFALL...SO ADDITIONAL WIDESPREAD FLOODING CONCERNS ARE LOW...BUT ISOLATED FLASH FLOODING COULD OCCUR...ESPECIALLY IN NORTHEAST INDIANA AND NORTHWESTERN OHIO WHERE EXTREME RAINFALL TOTALS THE LAST 48 HOURS HAVE OCCURRED. && .LONG TERM... BEGINNING OF FCST PERIOD HINGES ON EVENTUAL POSITION OF SFC BOUNDARY...WHICH MODELS CONTINUE TO PROG PUSHING NORTH OF OUR CWA ALBEIT NOT TOO MUCH NORTH. MAIN PLAYER THU NITE APPEARS TO BE MCS DEVELOPMENT TO OUR WEST AND ITS EVENTUAL EASTWARD TRACK. LLJ OVER KS/OK WILL NOSE UP INTO SOUTHERN IA AND COINCIDE WITH LOW LEVEL THETAE RIDGE AND MOISTURE CONVERGENCE AND SERVE AS CONVECTIVE INITIATION AREA. 00Z THU HAS E/W ORIENTATION OF 850-300MB THICKNESS PATTERN OVER OUR AREA WITH RIDGE BUILDING UP INTO KS/NE. THICKNESS RIDGE BUILDS WITH TIME AND MOVES THROUGH IA AND UP INTO SW WI BY 12Z THU. IF THIS SCENARIO PLAYS OUT EXPECT MCS TO RIDE THE RIDGE AND TRACK PRIMARILY NORTH OF OUR CWA...WITH NORTHWESTERN PORTION MAIN THREAT FOR ANY CONVECTION. THAT SAID THIS IS BY NO MEANS A SURE BET AS ANY SLIGHT DEVIATION IN PLACEMENT OF SFC BOUNDARY AND ANY RESIDUAL EFFECTS FROM CONVECTION DEVELOPING TUES NITE AND WED WILL CERTAINLY PLAY A ROLE. WILL CONTINUE WITH PRECIP CHANCES OVER ENTIRE CWA IN CHANCE RANGE WITH HIGHER VALUES FOCUSED IN NORTHWEST CWA...AS CURRENT GRIDS HAVE GOOD HANDLE ON THIS. AREA REMAINS IN WARM SECTOR THURSDAY WITH PLENTY OF MOISTURE AND INSTABILITY TO WORK WITH EXPECT POTENTIAL FOR AFTN CONVECTION. SFC WAVE WILL BE MOVING ALONG FRONTAL BOUNDARY UP INTO NORTHERN GREAT LAKES REGION AND DRAG TRAILING COLD FRONT TOWARD OUR AREA AND PROVIDE FOCUS FOR ADDITIONAL PRECIP CHANCES FRIDAY AND SATURDAY. FRONT TO PASS THROUGH THE AREA ON SAT BRINGING COOLER DRIER AIRMASS INTO THE REGION AND WILL STAY WITH DRY FORECAST REMAINDER OF EXTENDED. NAM AND GFS BOTH HAVE 850MB TEMPS REACHING 22C BY THU AFTN...SUGGESTING L90S WITH ANY APPRECIABLE AMOUNT OF SUN...BUT AMOUNT OF SENSIBLE HEATING REALIZED MAY BE HAMPERED BY AMPLE LOW LEVEL MOISTURE ALONG WITH EVAPOTRANSPIRATION FROM RECENT RAINS. STILL...WILL GO TOWARD L90S IN SOUTHERN CWA AND TAPER TO U80S IN NORTH WHERE BETTER CHANCE FOR EXTENSIVE CLOUD COVER EXISTS. TEMPS TO DROP BACK TO NEAR NORMAL DAYS 5-7. && .AVIATION...18Z TAFS MAIN CONCERNS FOR THE TAF PERIODS ACROSS THE REGION WILL BE MVFR OR IFR CONDITIONS DUE TO LOW CIGS AND VSBY. AREAS ACROSS NORTHWEST OHIO AND NORTHEAST INDIANA WILL CONTINUE TO SEE LOW CIGS IN THE IFR RANGE THROUGH THE AFTERNOON BEFORE RISING SLIGHTLY BEFORE EVENING. VFR CONDITIONS ELSEWHERE THROUGH THE EVENING...WITH A FEW SCATTERED SHOWERS POSSIBLE...ESPECIALLY WEST OF A LINE FROM SBN TO GUS. CIGS WILL LOWER TONIGHT TO NEAR IFR LEVELS...WITH VSBYS DROPPING TO 2 TO 3 SM. SOME LIFTING OF THE CIGS EXPECTED DURING THE LATE MORNING...WITH SCATTERED SHOWERS DEVELOPING BY AFTERNOON. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SCHOTT LONG TERM....LOGSDON AVIATION...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 137 PM EDT TUE AUG 21 2007 .AVIATION (18Z TAFS)... MAIN CONCERNS FOR THE TAF PERIODS ACROSS THE REGION WILL BE MVFR OR IFR CONDITIONS DUE TO LOW CIGS AND VSBY. AREAS ACROSS NORTHWEST OHIO AND NORTHEAST INDIANA WILL CONTINUE TO SEE LOW CIGS IN THE IFR RANGE THROUGH THE AFTERNOON BEFORE RISING SLIGHTLY BEFORE EVENING. VFR CONDITIONS ELSEWHERE THROUGH THE EVENING...WITH A FEW SCATTERED SHOWERS POSSIBLE...ESPECIALLY WEST OF A LINE FROM SBN TO GUS. CIGS WILL LOWER TONIGHT TO NEAR IFR LEVELS...WITH VSBYS DROPPING TO 2 TO 3 SM. SOME LIFTING OF THE CIGS EXPECTED DURING THE LATE MORNING...WITH SCATTERED SHOWERS DEVELOPING BY AFTERNOON. && .PREV DISCUSSION... /ISSUED 1108 AM EDT TUE AUG 21 2007/ UPDATE... MAIN ISSUES COVERED WITH THE MORNING UPDATE WAS TO LOWER TEMPERATURES THIS AFTERNOON FOR THE NORTHERN TWO THIRDS OF THE FORECAST AREA. CLOUD COVER HAS LIMITED HEATING THIS MORNING...AND IT APPEARS THAT IT WILL TAKE SOME TIME TO ERODE THROUGH ENOUGH FOR SIGNIFICANT JUMPS IN TEMPS TO OCCUR. ALSO HAVE LOWERED PRECIP CHANCES THIS AFTERNOON SOME...SHORT RANGE MODELS SUCH AS THE RUC SHOW SOME DEVELOPMENT THIS AFTERNOON...BUT SOME UNCERTAINTY THERE AS THE THE AMOUNT OF HEATING FOR SOLID CONVECTION TO FIRE...MAY END UP BEING MORE SHOWERS. BOUNDARY STILL SITS ACROSS THE FORECAST AREA SO PRECIP IS STILL A CONCERN BUT WITH LITTLE FRONTOGENTICAL FORCING...MORE SO WELL TO THE EAST AND WEAKENED LOW LEVEL JET WHICH IS MOVING NEARLY PARALLEL TO THE FRONT BELIEVE THAT THE LOWERING OF POP IS JUSTIFIED. PWATS ARE STILL VERY HIGH...SO MENTIONED HEAVY RAINFALL WITH ANY THUNDERSTORMS THAT DO DEVELOP...BUT THE EFFECTS WOULD BE VERY LOCALIZED. PREV DISCUSSION... /ISSUED 701 AM EDT TUE AUG 21 2007/ SHORT TERM...TODAY AND TONIGHT. VERY COMPLEX SETUP NEXT 24 HOURS. STATIONARY BOUNDARY DRAPED ACROSS THE SOUTHERN PART OF THE CWA HAS REMAINED ACTIVE ALL NIGHT...MAINLY IN A NARROW BAND FROM MIAMI/WABASH COUNTY EAST INTO PART OF NW OHIO. SOME AREAS JUST TONIGHT HAVE PICKED UP ANOTHER 2 TO 4 INCHES OF RAINFALL ON TOP OF WHAT HAS ALREADY FALLEN. SEE RECENT SPENES FOR FLOODING TRENDS IN THIS AREA. CURRENTLY HAVE THINGS HANDLED WITH AREAL FLOOD WARNING IN THE MORNING HOURS. ALSO IN TERMS OF GRIDS/ZONES WILL COVER WITH PRE-1ST PERIOD WORDING. ACTIVITY SHOULD CALM AROUND 12Z AS FOCUS THEN TURNS TO COMPLEX WORKING ACROSS EASTERN IA/WESTERN ILLINOIS. OVERALL COMPLEX WAS MORE IMPRESSIVE A FEW HOURS AGO WITH A NICE LINE OF CONVECTION ON THE LEADING EDGE. HOWEVER AS THE COLD POOL HAS LOST ITS PUNCH CONVECTION HAD DIMINISHED BUT STRATIFORM AREA STILL HOLDING ON. TRAJECTORIES WOULD BRING THIS AREA IN THIS MORNING WORKING EAST WITH TIME INTO THIS AFTERNOON. NAM/GFS OF NO USE AS THEY ARE NOT EVEN PICKING UP ON THESE FEATURES. 4 KM WRF HAS SOME SIGNALS WITH CONVECTION IN IOWA AROUND 6Z BUT A BIT TOO SLOW/FAR WEST. THEN JUST STALLS THE COMPLEX OUT BY 12Z WHICH IS NOT EVEN CLOSE TO OCCURRING. THINK AT LEAST SOME RAIN/SHOWERS SHOULD MAKE IN THIS AM SO HAVE INCREASED POPS TO LIKELY IN THE WEST THIS AM. AND THEN SCT WEST/LIKELY EAST THIS AFTERNOON. SEVERAL THINGS TO WATCH THROUGH THE DAY WARRANT HOLDING OFF ON TOO MANY MORE CHANGES. WITH PWATS AROUND 2" AND SLOWER OVERALL FLOW...VERY HEAVY RAIN STILL A THREAT. MENTIONED HEAVY RAIN IN GRIDS/ZONES. IN TERMS OF HEADLINES...WITH WIDESPREAD HYDRO CONCERNS IN PLACE NOW FOR A FEW DAYS...REISSUING FLOOD WATCH WILL LIKELY SERVE MUCH OVERALL PURPOSE...SO WILL CONTINUE WITH NO WATCH AND USE WARNINGS AS NEEDED. TONIGHT...MODELS TRY TO TAKE BOUNDARY NORTH INTO MI THROUGH THE NIGHT. SOME CONCERN THAT WITH ONGOING CONVECTION TODAY THAT BOUNDARY MAY STRUGGLE TO WORK NORTH. 4KM WRF REDEVELOPS CONVECTION DURING THE EVENING HOURS MUCH LIKE HAS OCCURRED PAST FEW NIGHTS. AM INCLINED TO GIVE IT A NOD...AND WOULD LIKE TO MAKE CHANGES BUT SINCE ENOUGH ISSUES WITH 1ST PERIOD LET ALONE 2ND PERIOD WILL LEAVE TNGT FORECAST INTACT. TEMPS WILL HAVE A MASSIVE BUST POTENTIAL TODAY WITH TIGHT GRADIENT POSSIBLE N TO S. HAVE LOWERED TEMPS INTO THE LOWER 70S N TO LOW 80S SOUTH. ANY SUNSHINE WILL QUICKLY ALLOW THEM TO CLIMB AND ALSO CREATE ADDITIONAL ISSUES IN TERMS OF CONVECTION AND INCREASING HEAT INDICES. LONG TERM... WEDNESDAY THROUGH MONDAY. UNSETTLED AND STORMY PATTN TO CONT UNTIL SAT. LTL CHG IN OVERALL FLAT WESTERLY FLW ALOFT W/STATIONARY FNTL BNDRY STRETCHED OUT ACRS THE MIDWEST. SFC WAVE OVR KS WILL CONT TO LIFT NEWD TWD LK HURON BY WED EVENING AND ALLOW SFC BNDRY TO MIX WELL NWD AND PLACE CWA SQUARELY WITHIN WHAT SHLD BE A VRY UNSTABLE WARM SECTOR WED AFTN. 00Z MODEL SOLUTIONS CERTAINLY FLOUNDERING W/MESOSCALE DETAILS...MOST NOTABLY THE FAILURE OF CAPTURING MCS OVR ERN IA/NE MO THIS MORNING. SUSPICION AT THIS POINT IS RENEWED MCS/MCV GENERATION UPSTREAM ACRS THE PLAINS WILL OCCUR TONIGHT ACRS IA AND PROGRESS EWD INTO THE AREA BY AFTN. HWVR GIVEN ABUNDANT MSTR HERE AND CONTD LL WAA IN PLACE...CERTAINLY COULD SEE OTHER STORMS POP IN DIFFERENTIAL HEATING. LTL CHG XPCD THU/THU NIGHT OTHER THEN A MORE DEFINED LARGE SCALE TRIGGER AS SECONDARY STRONGER FNTL WAVE KICKS NEWD INTO THE WRN LAKES BY AFTN W/VRY UNSTABLE AIRMASS IN PLACE ONCE AGAIN. HOWEVER GFS MOS TEMPS ARE RIDICULOUS AND DISCARDED IN FVR OF MORE PALATABLE MET NUMBERS AND SAME FOR FRI. THIRD AND FINAL SFC WAVE TO KICK OUT SOMETIME FRI ALTHOUGH MED RANGE MODEL SOLUTIONS QUITE LARGE AND UNCERTAIN. CONSENSUS WOULD BRING CDFNT THROUGH CWA SOMETIME FRI NIGHT W/SFC RIDGING BLDG THROUGH THE WEEKEND AND A NEEDED DRYING OUT. WILL MAKE FEW CHGS TO GOING GRIDS WHICH HAVE A GOOD HANDLE ON THINGS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...HOLSTEN LONG TERM....FISHER AVIATION...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 315 PM EDT TUE AUG 21 2007 .SYNOPSIS...AN UPPER LEVEL WAVE ASSOCIATED WITH THE REMNANTS OF TROPICAL CYCLONE ERIN WILL CROSS CENTRAL NORTH CAROLINA THIS EVENING AND EARLY TONIGHT...BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... SFC ANALYSIS THIS AFTERNOON SHOWS A THERMAL BOUNDARY ASSOC/W DIFFERENTIAL HEATING FROM PERVASIVE LOW STRATUS THIS MORNING ACROSS CENTRAL/SOUTHERN VA. TEMPS SOUTH OF THE BOUNDARY WERE IN THE UPPER 90S...WHILE TEMPS NORTH OF THE BOUNDARY IN CENTRAL VA WERE IN THE UPPER 70S TO LOWER 80S. THE TRUE WEDGE FRONT SEEMS TO HAVE RETREATED NORTH AND IS NOW LOCATED IN NORTHERN VA. A SFC TROUGH AXIS WAS LOCATED ACROSS THE PORTIONS OF NC/VA. DEWPOINTS ACROSS NORTH CAROLINA WERE IN THE LOWER 60S (WEST) TO UPPER 60S (EAST). ALOFT...A SHORTWAVE/VORTMAX ASSOC/W THE REMNANTS OF TS ERIN WAS LOCATED OVER EASTERN KENTUCKY THIS AFTERNOON. THIS FEATURE SHOWS UP ON RAOB ANALYSIS...RUC H5 HEIGHT/VORT FIELDS...AND IN WV IMAGERY WHICH CAN BE USED TO CLEARLY TRACE THIS FEATURE BACK OVER OK/MO AS ERIN`S REMNANTS. FOR THIS AFTERNOON...A FEW THINGS HAVE CHANGED COMPARED TO YESTERDAY. THE MOST NOTICEABLE CHANGE IS THAT WE WILL HAVE SOME GOOD UPPER LEVEL SUPPORT IN THE FORM OF A SHORTWAVE ASSOC/W THE REMNANTS OF TS ERIN CROSSING INTO THE AREA LATER THIS EVENING. THIS UPPER LEVEL FEATURE IS CURRENTLY FORCING SHOWERS/STORMS OVER EASTERN KY AND THE NC/VA MOUNTAINS...AND THE LATEST RUC MODEL RUN SHOWS THE SHORTWAVE AND ASSOC 20-25/S VORT ADVECTING INTO W/SW VIRGINIA AND NORTHWEST NC BY 00Z THIS EVENING...AND THROUGH THE AREA BY 06Z. GFS/NAM BUFR AND RUC40 FCST SOUNDINGS ALL SHOW AN AIRMASS THAT IS MORE UNSTABLE THAN YESTERDAY...WITH AFTERNOON PWAT VALUES IN THE 1.50-2.00" RANGE. IN FACT...THE 12Z GSO SOUNDING THIS MORNING HAD A 33F DEWPOINT AT 700MB...IN CONTRAST TO A 14F DEWPOINT AT 700MB 12Z YESTERDAY. ALTHOUGH SFC DEWPOINTS HAVE CRASHED AGAIN THIS AFTERNOON INTO THE LOWER 60S...SOME PORTIONS OF THE COASTAL PLAIN WILL LIKELY SEE DEWPOINTS REMAIN IN THE UPPER 60S TO NEAR 70F. EVEN WITH DEWPOINTS IN THE LOWER 60S...ALL THE FCST MODELS MENTIONED SHOW AFTERNOON SFC BASED CAPE VALUES AROUND 1500 J/KG WITH STEEP DRY ADIABATIC LAPSE RATES UP TO 750-700 MB. OBVIOUSLY IF DEWPOINTS ARE HIGHER...THIS VALUE GOES UP AND IF DEWPOINTS ARE LOWER...THIS VALUE GOES DOWN. BEST CHANCE FOR CONVECTION THIS EVENING WILL BE IN NORTHERN PORTIONS OF THE CWA AFTER 20Z...CLOSER TO THE TRACK OF THE UPPER LEVEL SHORTWAVE/VORT WHICH WILL CROSS THROUGH CENTRAL NC AFTER 00Z THIS EVENING. CONVECTION CURRENTLY FIRING ALONG THE FOOTHILLS AND MOUNTAINS WILL ADVECT EASTWARD TOWARD THE VA/NC PIEDMONT VIA 30KT MID-LEVEL WESTERLY FLOW. HAVE UPPED POPS TO LIKELY IN THE NW PIEDMONT THE REST OF THIS AFTERNOON...WITH THE BETTER CHANCES OVERALL IN THE NORTH AND LOWER CHANCES IN THE SOUTH...CONTINUING AFTER SUNSET AS THE UPPER LEVEL WAVE SWINGS THROUGH. WITH STEEP LOW-LEVEL LAPSE RATES FROM THE SFC THROUGH 750MB...INVERTED-V SOUNDING PROFILES...AND 30KT MID LEVEL FLOW...DAMAGING WINDS APPEAR TO BE THE PRIMARY SEVERE THREAT WITH ANY CONVECTION THAT DEVELOPS THIS EVENING. A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM FOR THE NW PIEDMONT...AND AN ADDITIONAL WATCH MAY BE NEEDED FOR AREAS TO THE EAST LATER THIS AFT/EVE. WILL TAPER POPS OFF FROM WEST TO EAST BEHIND THE UPPER LEVEL WAVE DURING THE OVERNIGHT PERIOD. LOW TEMPS WILL BE IN THE LOWER/MID 70S. -VINCENT && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... BOTH THE GFS/NAM SHOW SFC RIDGING ASSOC/W HIGH PRESSURE IN NEW ENGLAND CONTINUING TO EXTEND SOUTHWARD INTO NORTHERN VA. THE NAM APPEARS MORE AGGRESSIVE IN TRYING TO BRING THE SFC RIDGING AND ASSOC COLD POOL FURTHER SOUTH INTO SOUTHERN VA DURING THE DAY WED...AND EVEN INTO NORTHERN NC WED NIGHT AND THU MORNING. THE UPPER LEVEL RIDGE WILL REMAIN CENTERED OVER THE DEEP SOUTH WED...AND THE HIGHEST THICKNESSES WILL REMAIN IN SOUTH/SW PORTIONS OF THE CWA. THEREFORE...THE WARMEST MAX TEMPS ON WED WILL LIKELY BE IN S/SW PORTIONS OF THE AREA...IN THE UPPER 90S TO NEAR 100F...AND THE LOWEST WILL BE IN NORTHEAST PORTIONS OF THE CWA...WHERE A BLEND OF MAV/MET GUIDANCE YIELDS HIGH TEMPS IN THE LOWER 90S. AS FAR AS PRECIP IS CONCERNED...BOTH THE GFS/NAM DO SHOW AN UPPER LEVEL WAVE DROPPING THROUGH CENTRAL NC IN NW FLOW ALOFT WED AFTERNOON...AND FCST SOUNDINGS SHOW HIGH PWAT VALUES (1.75-2.00") AND AROUND 1500 J/KG OF SFC BASED INSTABILITY EVEN IF DEWPOINTS FALL INTO THE LOWER 60S...THEREFORE...WILL ADD A SLIGHT CHANCE OF SHOWERS/STORMS TO THE FORECAST WED AFTERNOON THROUGH WED NIGHT. -VINCENT && .LONG TERM /THURSDAY THROUGH TUESDAY/... MID LEVEL RIDGING PERSISTS THROUGH THE PERIOD OVER THE SOUTHEAST AND TEMPERATURES WILL CONTINUE ABOVE NORMAL WITH BELOW NORMAL RAINFALL. AFTERNOON TEMPERATURES OF 90 TO 97 THURSDAY AND 96 TO 101 FORECAST FRIDAY BEFORE A SLOW COOLING TREND DROPS HIGHS TO NORMAL TUESDAY. HOWEVER WITH ABOVE MENTIONED RIDGING IN PLACE...CONFIDENCE IN THIS COOLING TREND IS NOT HIGH. THE GFS MODEL FORECAST OF A WEAK TROUGH DROPPING DOWN THE BACK SIDE OF THE MID LEVEL RIDGE INTO NORTH CAROLINA IS SUSPECT AND WILL IGNORE THIS FEATURE AT THIS TIME. WITH THE MID LEVEL RIDGE TO OUR WEST...THERE IS THE POTENTIAL FOR SOME EAST TO SOUTHEAST FLOW INTO CENTRAL NORTH CAROLINA PERHAPS INCREASING MOISTURE ENOUGH TO BRING CLIMATOLOGICAL RAIN CHANCES TO THE AREA LATE IN THE WEEK. HOWEVER WILL CONTINUE TO PLAY THIS CONSERVATIVE AND RESPECT THE DROUGHT AND BE PESSIMISTIC FOR THE TIME BEING. -RLH && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... BROKEN LINE OF CONVECTION CROSSED THE MOUNTAINS IN THE EARLY AFTERNOON. WILL MONITOR THE PROGRESS OF THE LINE BUT IT DOES LOOK LIKE THIS LINE WILL HOLD TOGETHER AND CROSS CENTRAL NORTH CAROLINA DURING THE LATE AFTERNOON AND EVENING. HAVE ADDED CUMULONIMBUS TO THE WESTERN SITES AND WILL MONITOR THE FORECAST FOR THE EASTERN SITES AS FAR AS SUNSET AND ITS AFFECT ON CONVECTION. OTHER THAN IN THE VICINITY OF CONVECTION CEILINGS SHOULD BE VFR. A WETTING RAIN WILL LIKELY PRODUCE SOME MORNING FOG. HAVE ADDED THIS THREAT TO THE WEST BUT WILL REEVALUATE THE WEST WITH THE NEXT REGULAR FORECAST PACKAGE. && .CLIMATE... HERE ARE THE RECORD HIGHS FOR TODAY THROUGH FRIDAY: RDU- AUG 21: 101 IN 1983 AUG 22: 101 IN 1983 AUG 23: 103 IN 2002 AUG 24: 100 IN 2002 GSO- AUG 21: 100 IN 1983 AUG 22: 100 IN 1983 AUG 23: 99 IN 1983 AUG 24: 98 IN 1968 THE MODERATE AND SEVERE DROUGHT CONDITIONS ACROSS CENTRAL ARE NOT NOT EXPECTED TO SEE ANY SIGNIFICANT IMPROVEMENT THROUGH THE 7 DAY FORECAST AS THERE REMAINS NO APPARENT WEATHER FEATURE TO SUPPORT WIDESPREAD RAINFALL. AS OF AUGUST 20TH...THE MONTH TO DATE RAINFALL AT GSO AND RDU IS 0.34" AND 0.26" RESPECTIVELY. THIS WILL RESULT IN SIGNIFICANT AUGUST RAINFALL DEFICITS LEADING INTO THE LAST WEEK OF AUGUST AND A STRONG LIKELIHOOD OF BEING ONE OF THE DRIEST AUGUSTS ON RECORD. LISTED BELOW IS THE DRIEST AUGUST AT GSO AND RDU ON RECORD. TOP 5 DRIEST AUGUSTS ON RECORD. GSO RDU (SINCE 1928) (SINCE 1944) 1) 0.71/1972 0.81/1950 2) 1.13/1979 1.01/1997 3) 1.19/1962 1.13/1984 4) 1.40/1932 1.31/1956 5) 1.44/1983 1.52/1976 HOT AND DRY CONDITIONS HAVE LED TO RECORD WARMTH THIS MONTH ACROSS CENTRAL NORTH CAROLINA. IN FACT... IF WE EXPERIENCE NORMAL TEMPERATURES FOR THE REMAINDER OF THE MONTH RDU WOULD BREAK THE RECORD FOR THE WARMEST AUGUST ON RECORD... AND GSO WOULD FALL A TENTH OF A DEGREE SHORT OF THE WARMEST AUGUST ON RECORD. HOWEVER... TEMPERATURES THROUGH THE END OF AUGUST LOOK TO BE AT OR ABOVE NORMAL. THUS... THE RECORDS LISTED BELOW ARE LIKELY TO FALL. THE CURRENT MEAN AVERAGE TEMPERATURE AT RDU AND GSO AS OF AUGUST 20TH IS 84.4F AND 83.6F RESPECTIVELY. TOP 5 WARMEST AVERAGE TEMPERATURES FOR AUGUST ON RECORD. GSO RDU (SINCE 1929) (SINCE 1944) 1) 80.0/1975 80.6/1995 2) 79.7/1988 80.5/2006 3) 79.4/2006 80.3/1988 4) 79.4/1995 80.2/2005 5) 79.3/2005 80.0/1999 && .RAH WATCHES/WARNINGS/ADVISORIES... && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT LONG TERM...RLH AVIATION...RLH CLIMATE...CBL nc