AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 210 PM MDT THU AUG 24 2006 .SHORT TERM (TONIGHT THROUGH SATURDAY)... WEAK VORT MAXES TRAVELING OVER NORTHWEST CO AND SW CO WILL CONTINUE PRODUCING LINES OF CONVECTION OVER THE SAN JUANS AND TAVAPUTS/ROAN PLATEAUS THROUGH THE REST OF THIS AFTERNOON AND EARLY EVENING. ANOTHER VORT MAX OVER NORTHERN AZ WILL TRAVEL TO THE NE AND HELP PRODUCE MORE WIDESPREAD CONVECTION LATER THIS EVENING AND IN THE EARLY MORNING. RUC SEEMS TO BE HANDLING IT WELL AND HAVE INCREASED POPS/CLOUDS/AND WX FROM ABOUT 04Z TO 09Z. TIME-HEIGHTS OF NAM DATA SHOW GOOD UVV AND A DIV/CONV COUPLET OVER THE AREA DURING THAT TIME PERIOD AS WELL. SUBSIDENCE ALOFT AND DRIER AIR IN THE LOWER AND MID LEVELS SHOULD MOVE ACROSS SE UT AND WRN CO FRI. NE UTAH WILL CATCH ANOTHER WEAK SHORTWAVE IN THE AFTERNOON...AS A CLOSED LOW MOVES INTO IDAHO. HAVE LOWERED POPS IN THE SOUTH AND MAINTAINED HIGHER POPS OVER NE UT AND EXTREME NW CO. MOST OF THE AREA APPEARS TO REMAIN SOMEWHAT DRY- SLOTTED SAT...THEN THE IDAHO CLOSED LOW AND SURFACE COLD FRONT ARE PROGGED TO STRENGTHEN AND MOVE INTO SRN WYOMING SAT AFTERNOON. SURFACE WINDS SHOULD INCREASE THROUGHOUT THE DAY AND HAVE KEPT THE CURRENT POPS SOLUTION. TEMP PROGS HAVE NOT CHANGED MUCH AND HAVE ONLY TWEAKED A FEW NUMBERS HERE AND THERE. GENERAL MAX/MIN TEMP TREND IS DOWN THE NEXT TWO DAYS. .LONG-TERM (SATURDAY NIGHT THROUGH THURSDAY)... TROUGH/COLD FRONT PASSES SAT NIGHT FOR AN ACTIVE NIGHTTIME PERIOD. THE MODELS PUT THE TROUGH AXIS OVER NORTHEAST UT/NORTHWEST CO AT 12Z...THE WRF WAS JUST A LITTLE FASTER. THEREFORE EXPECT SOME ACTIVITY TO LINGER INTO SUN MORNING...WITH DIURNAL HEATING RESULTING IN ADDITIONAL ACTIVITY DURING THE AFTERNOON. DRIER NORTHWEST FLOW BEHIND THE TROUGH WILL DOMINATE THROUGH THE MIDWEEK. HOWEVER...WILL STILL KEEP LOW DIURNAL POPS FOR THE MOUNTAINS...ESPECIALLY SOUTH. BY WED...THE GFS SHOWS A WEAK TROUGH WILL BRUSH THE AREA. AHEAD OF THIS FEATURE FLOW WILL BECOME A LITTLE MORE SOUTHWEST FOR AN INCREASE IN MOISTURE. THE BETTER MOISTURE AND THE LIFT FROM DISTURBANCE WILL RESULT IN INCREASED POPS ON WED. TEMPS WILL BE AROUND NORMAL. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...NONE. .UT...NONE. && CJC/EH co AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PEACHTREE CITY GA 910 PM EDT THU AUG 24 2006 .UPDATE... ADJUSTED POPS SLIGHTLY FOR TONIGHT TO ACCOUNT FOR CURRENT AND EXPECTED TRENDS. KEPT CHANCE POPS IN THE SOUTHEAST IN THE VICINITY OF THE BEST MOISTURE AND SURFACE CONVERGENCE. KEPT SLIGHT CHANCE POPS MOST OTHER PLACES EXCEPT FOR THE NORTHWEST CORNER WHERE DRY AIR HAS MADE AT LEAST A LITTLE INROADS. NO OTHER MAJOR CHANGES MADE. && .PREV DISCUSSION... (ISSUED 615 PM EDT THU AUG 24 2006) SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT) CURRENT SATELLITE IMAGES CONTINUE TO SHOW LARGE MOISTURE PLUME ASSOCIATED WITH SURFACE FRONTAL BOUNDARY OVER MOST OF GEORGIA THIS AFTERNOON. ABUNDANT TROPICAL MOISTURE WITH PWS IN THE 2 TO 2.5 INCH RANGE COMBINED WITH THE FRONT AND DIURNAL HEATING HAVE CAUSED SLOW MOVING SCATTERED SHRA/TSRA WITH PERIODS OF HEAVY RAIN ALONG AND NORTH OF THE FRONT INTO THE ATL...AHN AREA. THIS CONVECTION WILL GRADUALLY DIMINISH BY SUNSET. THE SYNOPTIC PATTERN WILL CHANGE LITTLE THROUGH SATURDAY AS THE FRONTAL BOUNDARY GRADUALLY DISSIPATES. PRIMARILY AFTERNOON AND EARLY EVENING SHRA/TSRA WILL CONTINUE INTO SATURDAY. MAX TEMPS WILL REMAIN A FEW DEGREES ABOVE NORMAL. LONG TERM...(SUNDAY THROUGH THURSDAY) A SURFACE RIDGE WILL BUILD DOWN THE EAST COAST BRINGING A DRIER AIRMASS INTO NORTH AND CENTRAL GA SUNDAY. AT THE SAME TIME AN UPPER LEVEL RIDGE BUILDS ACROSS THE REGION FROM THE WEST AND PARKS ITS SELF OVER THE SOUTHEASTERN U.S. THROUGH THE MIDDLE OF NEXT WEEK. THIS UPPER LEVEL RIDGE WILL GRADUALLY SHIFT SOUTH WITH A SERIES OF UPPER LEVEL DISTURBANCES MOVING FROM WEST TO EAST OVER GEORGIA. THIS PATTERN COMBINED WITH DIURNAL HEATING WILL KEEP A CHANCE OF SHRA/TSRA ACROSS THE STATE THROUGH THURSDAY. TEMPS WILL REMAIN SEASONABLY WARM. AVIATION... LEADING EDGE OF WEDGE...TYPE FRONT SEEN ON SATELLITE FROM NEAR AHN TO NEAR VDI MOVING WEST. SCATTERED SHOWERS ARE DEVELOPING IN THE VICINITY OF THE FRONT ACROSS NORTH GEORGIA AND WILL HAVE TO INCLUDE EITHER TEMPO SHRA OR VCSH IN THE ATL AND AHN TAFS. THE CONVECTION IS A BIT MORE VIGOROUS ACROSS CENTRAL GA AHEAD OF THE FRONT AND WILL NEED TO INCLUDE TEMPO TSRA IN MCN. AFTER SUNSET THE CONVECTION SHOULD DIMINISH WITH A FEW SHOWERS LINGERING...HOWEVER WILL LEAVE TAFS DRY AFTER 5 OR 6Z. LATEST GFS AND RUC INDICATE THE FRONT ACROSS NORTHWEST GA INTO NORTHERN AL STALLS WHERE IT IS AT THEREFORE KEEPING HIGH LOW LEVEL MOISTURE OVER THE TAF SITES. RUC AND GFS BRING BOUNDARY LAYER MOISTURE TO HIGHER THAN 95 PERCENT BY 12Z FRI. FEEL LARGE AREA OF STRATUS WILL DEVELOP AFTER 06Z AND WILL ALSO GO WITH 1 TO 3 SM BR MOST AREAS. FOG AND STRATUS WILL LIFT FRIDAY MORNING WITH SCATTERED THUNDERSTORMS DEVELOPING AGAIN ACROSS THE REGION. WILL GO WITH VCTS ALL TAFS AFTER 18Z FRI. .PRELIMINARY POINT TEMPS/POPS... ATLANTA 70 87 71 89 / 20 20 20 30 ATHENS 69 87 67 90 / 20 20 10 20 GAINESVILLE 69 87 68 88 / 20 20 10 20 ROME 69 91 70 93 / 20 10 10 30 COLUMBUS 73 92 72 90 / 30 30 20 30 MACON 72 91 71 92 / 40 30 20 30 PEACHTREE CITY 68 87 70 89 / 20 20 20 30 CARTERSVILLE 67 89 67 89 / 20 20 10 30 && && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 20 ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 615 PM EDT THU AUG 24 2006 .SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT) CURRENT SATELLITE IMAGES CONTINUE TO SHOW LARGE MOISTURE PLUME ASSOCIATED WITH SURFACE FRONTAL BOUNDARY OVER MOST OF GEORGIA THIS AFTERNOON. ABUNDANT TROPICAL MOISTURE WITH PWS IN THE 2 TO 2.5 INCH RANGE COMBINED WITH THE FRONT AND DIURNAL HEATING HAVE CAUSED SLOW MOVING SCATTERED SHRA/TSRA WITH PERIODS OF HEAVY RAIN ALONG AND NORTH OF THE FRONT INTO THE ATL-AHN AREA. THIS CONVECTION WILL GRADUALLY DIMINISH BY SUNSET. THE SYNOPTIC PATTERN WILL CHANGE LITTLE THROUGH SATURDAY AS THE FRONTAL BOUNDARY GRADUALLY DISSIPATES. PRIMARILY AFTERNOON AND EARLY EVENING SHRA/TSRA WILL CONTINUE INTO SATURDAY. MAX TEMPS WILL REMAIN A FEW DEGREES ABOVE NORMAL. .LONG TERM...(SUNDAY THROUGH THURSDAY) A SURFACE RIDGE WILL BUILD DOWN THE EAST COAST BRINGING A DRIER AIRMASS INTO NORTH AND CENTRAL GA SUNDAY. AT THE SAME TIME AN UPPER LEVEL RIDGE BUILDS ACROSS THE REGION FROM THE WEST AND PARKS ITS SELF OVER THE SOUTHEASTERN U.S. THROUGH THE MIDDLE OF NEXT WEEK. THIS UPPER LEVEL RIDGE WILL GRADUALLY SHIFT SOUTH WITH A SERIES OF UPPER LEVEL DISTURBANCES MOVING FROM WEST TO EAST OVER GEORGIA. THIS PATTERN COMBINED WITH DIURNAL HEATING WILL KEEP A CHANCE OF SHRA/TSRA ACROSS THE STATE THROUGH THURSDAY. TEMPS WILL REMAIN SEASONABLY WARM. && .AVIATION... LEADING EDGE OF WEDGE-TYPE FRONT SEEN ON SATELLITE FROM NEAR AHN TO NEAR VDI MOVING WEST. SCATTERED SHOWERS ARE DEVELOPING IN THE VICINITY OF THE FRONT ACROSS NORTH GEORGIA AND WILL HAVE TO INCLUDE EITHER TEMPO SHRA OR VCSH IN THE ATL AND AHN TAFS. THE CONVECTION IS A BIT MORE VIGOROUS ACROSS CENTRAL GA AHEAD OF THE FRONT AND WILL NEED TO INCLUDE TEMPO TSRA IN MCN. AFTER SUNSET THE CONVECTION SHOULD DIMINISH WITH A FEW SHOWERS LINGERING...HOWEVER WILL LEAVE TAFS DRY AFTER 5 OR 6Z. LATEST GFS AND RUC INDICATE THE FRONT ACROSS NORTHWEST GA INTO NORTHERN AL STALLS WHERE IT IS AT THEREFORE KEEPING HIGH LOW LEVEL MOISTURE OVER THE TAF SITES. RUC AND GFS BRING BOUNDARY LAYER MOISTURE TO HIGHER THAN 95 PERCENT BY 12Z FRI. FEEL LARGE AREA OF STRATUS WILL DEVELOP AFTER 06Z AND WILL ALSO GO WITH 1 TO 3 SM BR MOST AREAS. FOG AND STRATUS WILL LIFT FRIDAY MORNING WITH SCATTERED THUNDERSTORMS DEVELOPING AGAIN ACROSS THE REGION. WILL GO WITH VCTS ALL TAFS AFTER 18Z FRI. && .PRELIMINARY POINT TEMPS/POPS... ATLANTA 70 87 71 89 / 20 20 20 30 ATHENS 69 87 67 90 / 20 20 10 20 GAINESVILLE 69 86 68 88 / 20 20 10 20 ROME 69 91 70 93 / 20 10 10 30 COLUMBUS 73 91 72 90 / 20 30 20 30 MACON 72 91 71 92 / 30 30 20 30 PEACHTREE CITY 68 87 70 89 / 20 20 20 30 CARTERSVILLE 67 89 67 89 / 20 20 10 30 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 16 ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 801 PM EDT THU AUG 24 2006 .AVIATION/UPDATE... MCS CONTS TO WKN ACRS SRN LWR MI AS IT RUNS EWD INTO MORE STABLE ENVIRONMENT AND EAST OF LLJ SUPPORT CURRENTLY. HWVR EVOLVING UPSCALE MCS OVR SRN MN/WRN WI QUITE ORGANIZED AND BEGINNING TO TURN SEWD. SHRT TERM MODEL GUIDANCE CONTS TO SUGGEST THIS WILL STAY MAINLY NORTH OF CWA OVERNIGHT SUSTAINED BY INCREASING LL MASS FLUX OVERTOP NWD RTNG WARM FRONT. CURRENT POP ORIENTATION PROBABLY SHADED TOO FAR SWD OVERNIGHT YET REALISTIC ACRS SRN MI COUNTIES. OTHERWISE VFR XPCD AT TERMINALS THROUGH THE FCST PD W/SFC WIND GUSTS UP TO 20KTS BY LATE FRI AM AND AFTN AS WARM SECTOR SPREADS NE INADV OF SFC LOW OVR SD THIS EVENING SHIFTING EWD INTO WI TOMORROW. && .SHORT TERM... TONIGHT AND FRIDAY CIRRUS SHIELD FROM DECAYING MCS HAS THINNED NICELY THIS AFTERNOON ALLOWING FOR INCREASING AMOUNTS OF SUNSHINE. THIS HAS ALLOWED SURFACE TEMPS TO RECOVER TO NEAR 80 AT 19Z. REGIONAL RADAR AND SATELLITE ANALYSIS SHOWING MCS EVOLVING UPSTREAM OVER SOUTHERN WISCONSIN FROM CONVECTION THAT ORIGINALLY FIRED NEAR KMSP THIS MORNING. 12Z RAOB ANALYSIS SUGGESTS THIS CLUSTER HAS FORMED WITHIN REGION OF LOW LEVEL WAA AND SIGNIFICANT MASS FLUX CONVERGENCE ALONG WARM FRONT...AIDED BY RIGHT ENTRANCE REGION JET DYNAMICS OF A MID/UPPER LEVEL JET STREAK OVER THE GREAT LAKES. 12Z NAM-WRF HAS TOTALLY FAILED TO INITIALIZE THIS FEATURE AND IS NOT A USABLE SOLUTION. GFS/CANADIAN GEM NOT MUCH BETTER WITH NEITHER MODEL DEPICTING SUCH AN ORGANIZED MCS. PARTIAL THICKNESS SCHEMES SUGGEST IF THIS MCS DOES HOLD TOGETHER IT WILL CONTINUE TO MOVE SE INTO THE CWA OVERNIGHT. SPC OBJECTIVE RUC ANALYSIS SUGGESTS AIRMASS IS STARTING TO RECOVER AND DESTABILIZE DOWNSTREAM FROM MCS. OVERALL FORECAST CONFIDENCE LOW...BUT POTENTIAL IS THERE FOR MCS TO CONTINUE TO MOVE/DEVELOP SE DOWN THE DEEP LAYER BAROCLINIC ZONE INTO THE CWA OVERNIGHT. HAVE THROWN OUT MODEL GUIDANCE AND SIMPLY USED EXTRAPOLATION OF CURRENT RADAR/SATELLITE TRENDS FOR FIRST PERIOD FORECAST. WILL CARRY CHANCE POPS OVER THE NW COUNTIES THIS EVENING...THEN EVERYWHERE OVERNIGHT GIVEN UNCERTAINTY. BEST CHANCE FOR ORGANIZED STORMS IS OVER OUR NW COUNTIES. IF A FORWARD PROPAGATING MCS DEVELOPS THERE IS AT LEAST A SMALL CHANCE OF DAMAGING WINDS...BUT THIS IS OF COURSE STRICTLY CONDITIONAL ON THE MCS SURVIVING THE TRIP INTO THE CWA. ON FRIDAY DEVELOPING SURFACE LOW WITHIN REGION OF LARGE SCALE ASCENT OVER THE PLAINS WILL MOVE EAST TO WISCONSIN BY LATE AFTERNOON PER NAM/CANADIAN GEM. INCREASING DEEP LAYER SOUTHERLY FLOW AHEAD OF SURFACE LOW WILL PUSH SYNOPTIC SCALE WARM FRONT NORTH AND ALLOW CWA TO FULLY BREAK OUT INTO THE WARM SECTOR. PENDING UPSTREAM MCS EVOLUTION...ANY CONVECTIVE DEBRIS CLOUD IN THE MORNING SHOULD DISSIPATE AND ALLOW FOR A GOOD AMOUNT OF SUNSHINE DURING THE AFTERNOON. TEMPS WILL CLIMB INTO THE MID/UPPER 80S WITH INCREASING HUMIDITY IN THE WARM SECTOR. BULK OF THE WARM SECTOR WILL BE CAPPED BY WELL DEFINED EML PLUME ALOFT. THAT SAID...WITH APPROACH OF THE SURFACE LOW AND ATTENDANT FRONT LARGE SCALE ASCENT MAY INCREASE ENOUGH TO BREACH THE CAP BY LATE AFTERNOON OVER THE NW CORNER OF THE CWA. CANADIAN GEM IS MOST AGGRESSIVE WITH CONVECTIVE DEVELOPMENT BY LATE AFTERNOON. FRICTIONAL CONVERGENCE OF WIND FIELD ALONG THE SE LAKE MICHIGAN LAKESHORE MAY ALSO INCREASE CONVECTIVE POTENTIAL. HAVE INTRODUCED LOW CHANCE POPS OVER FAR NW INDIANA AND SW LOWER MICHIGAN TO COVER POTENTIAL. && .LONG TERM... FRIDAY NIGHT THROUGH THURSDAY. SHORT RANGE AND LONG RANGE MODELS ARE OFFERING VARIOUS SOLUTIONS IN THE IMMEDIATE LONG TERM RANGE...AND THUS...THERE IS LOW CONFIDENCE IN THIS PART OF THE EXTENDED. AT THIS POINT IN TIME...S/WV ENERGY ACRS ERN MT/NE WY/WRN DAKOTAS IS FCST TO SHIFT EAST INTO THE GREAT LAKES REGION FRIDAY NIGHT AND SATURDAY. THIS ENERGY WILL LIKELY SWING A FRONTAL BOUNDARY INTO THE REGION. WHAT REMAINS PROBLEMATIC AT THIS POINT IS HOW FAR SOUTH AND EAST THIS BOUNDARY WILL GET. BELIEVE FRONT WILL AT LEAST GET THROUGH SOME OF THE CWFA...ON SATURDAY...SO HAVE LOWERED TEMPS A TAD IN THE NW. OTHERWISE...WITH MUCH UNCERTAINTY ON WHERE THE FRONT WILL STOP...HAVE KEPT LOW CHC POPS ACRS THE REGION FRIDAY NIGHT INTO SATURDAY NIGHT. ON SUNDAY...LONG RANGE MODELS HINT AT A POSSIBLE WAVE OF LOW PRESSURE RIDING NORTHEAST ACRS THE FCST AREA DUE TO S/WV ENERGY EJECTING OUT OF THE INTERMOUNTAIN WEST INTO THE CNTRL PLAINS. BELIEVE THE BEST CHC FOR PCPN WILL BE ON SUNDAY...SO HAVE MAINTAINED 40 POPS AT THIS TIME. PCPN CHC/S MAY VERY WELL BE NEEDED INTO MONDAY. BUT AGAIN...WITH MUCH UNCERTAINTY...JUST ADDED POPS INTO SUNDAY NIGHT...AND WILL HOPE THAT MODELS WILL HONE IN ON A DEFINITIVE SOLUTION. LONG RANGE MODELS APPEAR TO HAVE A CONSENSUS SOLUTION FOR MID TO LATE NEXT WEEK. MID LVL TROFINESS IS FCST TO DEVELOP ACRS THE PAC NW/BRITISH COLUMBIA...AND ALSO ACRS NE CANADA/NRN NEW ENGLAND. IN BETWEEN THESE FEATURES WILL BE MID LVL RIDING FROM THE CENTRAL PLAINS INTO S CNTRL CANADA. THIS UPPER LEVEL PATTERN WILL RESULT IN SFC HIGH PRESSURE UNDERNEATH THE EAST SIDE OF AFOREMENTIONED MID LVL RIDGE AXIS. THUS...DRY WEATHER WITH NEAR SEASONAL TEMPERATURES CAN BE EXPECTED MID TO LATE NEXT WEEK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ AVIATION/UPDATE...HOLSTEN SHORT TERM...HITCHCOCK LONG TERM....HICKMAN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 317 PM EDT THU AUG 24 2006 .SHORT TERM... TONIGHT AND FRIDAY CIRRUS SHIELD FROM DECAYING MCS HAS THINNED NICELY THIS AFTERNOON ALLOWING FOR INCREASING AMOUNTS OF SUNSHINE. THIS HAS ALLOWED SURFACE TEMPS TO RECOVER TO NEAR 80 AT 19Z. REGIONAL RADAR AND SATELLITE ANALYSIS SHOWING MCS EVOLVING UPSTREAM OVER SOUTHERN WISCONSIN FROM CONVECTION THAT ORIGINALLY FIRED NEAR KMSP THIS MORNING. 12Z RAOB ANALYSIS SUGGESTS THIS CLUSTER HAS FORMED WITHIN REGION OF LOW LEVEL WAA AND SIGNIFICANT MASS FLUX CONVERGENCE ALONG WARM FRONT...AIDED BY RIGHT ENTRANCE REGION JET DYNAMICS OF A MID/UPPER LEVEL JET STREAK OVER THE GREAT LAKES. 12Z NAM-WRF HAS TOTALLY FAILED TO INITIALIZE THIS FEATURE AND IS NOT A USABLE SOLUTION. GFS/CANADIAN GEM NOT MUCH BETTER WITH NEITHER MODEL DEPICTING SUCH AN ORGANIZED MCS. PARTIAL THICKNESS SCHEMES SUGGEST IF THIS MCS DOES HOLD TOGETHER IT WILL CONTINUE TO MOVE SE INTO THE CWA OVERNIGHT. SPC OBJECTIVE RUC ANALYSIS SUGGESTS AIRMASS IS STARTING TO RECOVER AND DESTABILIZE DOWNSTREAM FROM MCS. OVERALL FORECAST CONFIDENCE LOW...BUT POTENTIAL IS THERE FOR MCS TO CONTINUE TO MOVE/DEVELOP SE DOWN THE DEEP LAYER BAROCLINIC ZONE INTO THE CWA OVERNIGHT. HAVE THROWN OUT MODEL GUIDANCE AND SIMPLY USED EXTRAPOLATION OF CURRENT RADAR/SATELLITE TRENDS FOR FIRST PERIOD FORECAST. WILL CARRY CHANCE POPS OVER THE NW COUNTIES THIS EVENING...THEN EVERYWHERE OVERNIGHT GIVEN UNCERTAINTY. BEST CHANCE FOR ORGANIZED STORMS IS OVER OUR NW COUNTIES. IF A FORWARD PROPAGATING MCS DEVELOPS THERE IS AT LEAST A SMALL CHANCE OF DAMAGING WINDS...BUT THIS IS OF COURSE STRICTLY CONDITIONAL ON THE MCS SURVIVING THE TRIP INTO THE CWA. ON FRIDAY DEVELOPING SURFACE LOW WITHIN REGION OF LARGE SCALE ASCENT OVER THE PLAINS WILL MOVE EAST TO WISCONSIN BY LATE AFTERNOON PER NAM/CANADIAN GEM. INCREASING DEEP LAYER SOUTHERLY FLOW AHEAD OF SURFACE LOW WILL PUSH SYNOPTIC SCALE WARM FRONT NORTH AND ALLOW CWA TO FULLY BREAK OUT INTO THE WARM SECTOR. PENDING UPSTREAM MCS EVOLUTION...ANY CONVECTIVE DEBRIS CLOUD IN THE MORNING SHOULD DISSIPATE AND ALLOW FOR A GOOD AMOUNT OF SUNSHINE DURING THE AFTERNOON. TEMPS WILL CLIMB INTO THE MID/UPPER 80S WITH INCREASING HUMIDITY IN THE WARM SECTOR. BULK OF THE WARM SECTOR WILL BE CAPPED BY WELL DEFINED EML PLUME ALOFT. THAT SAID...WITH APPROACH OF THE SURFACE LOW AND ATTENDANT FRONT LARGE SCALE ASCENT MAY INCREASE ENOUGH TO BREACH THE CAP BY LATE AFTERNOON OVER THE NW CORNER OF THE CWA. CANADIAN GEM IS MOST AGGRESSIVE WITH CONVECTIVE DEVELOPMENT BY LATE AFTERNOON. FRICTIONAL CONVERGENCE OF WIND FIELD ALONG THE SE LAKE MICHIGAN LAKESHORE MAY ALSO INCREASE CONVECTIVE POTENTIAL. HAVE INTRODUCED LOW CHANCE POPS OVER FAR NW INDIANA AND SW LOWER MICHIGAN TO COVER POTENTIAL. && .LONG TERM... FRIDAY NIGHT THROUGH THURSDAY. SHORT RANGE AND LONG RANGE MODELS ARE OFFERING VARIOUS SOLUTIONS IN THE IMMEDIATE LONG TERM RANGE...AND THUS...THERE IS LOW CONFIDENCE IN THIS PART OF THE EXTENDED. AT THIS POINT IN TIME...S/WV ENERGY ACRS ERN MT/NE WY/WRN DAKOTAS IS FCST TO SHIFT EAST INTO THE GREAT LAKES REGION FRIDAY NIGHT AND SATURDAY. THIS ENERGY WILL LIKELY SWING A FRONTAL BOUNDARY INTO THE REGION. WHAT REMAINS PROBLEMATIC AT THIS POINT IS HOW FAR SOUTH AND EAST THIS BOUNDARY WILL GET. BELIEVE FRONT WILL AT LEAST GET THROUGH SOME OF THE CWFA...ON SATURDAY...SO HAVE LOWERED TEMPS A TAD IN THE NW. OTHERWISE...WITH MUCH UNCERTAINTY ON WHERE THE FRONT WILL STOP...HAVE KEPT LOW CHC POPS ACRS THE REGION FRIDAY NIGHT INTO SATURDAY NIGHT. ON SUNDAY...LONG RANGE MODELS HINT AT A POSSIBLE WAVE OF LOW PRESSURE RIDING NORTHEAST ACRS THE FCST AREA DUE TO S/WV ENERGY EJECTING OUT OF THE INTERMOUNTAIN WEST INTO THE CNTRL PLAINS. BELIEVE THE BEST CHC FOR PCPN WILL BE ON SUNDAY...SO HAVE MAINTAINED 40 POPS AT THIS TIME. PCPN CHC/S MAY VERY WELL BE NEEDED INTO MONDAY. BUT AGAIN...WITH MUCH UNCERTAINTY...JUST ADDED POPS INTO SUNDAY NIGHT...AND WILL HOPE THAT MODELS WILL HONE IN ON A DEFINITIVE SOLUTION. LONG RANGE MODELS APPEAR TO HAVE A CONSENSUS SOLUTION FOR MID TO LATE NEXT WEEK. MID LVL TROFINESS IS FCST TO DEVELOP ACRS THE PAC NW/BRITISH COLUMBIA...AND ALSO ACRS NE CANADA/NRN NEW ENGLAND. IN BETWEEN THESE FEATURES WILL BE MID LVL RIDING FROM THE CENTRAL PLAINS INTO S CNTRL CANADA. THIS UPPER LEVEL PATTERN WILL RESULT IN SFC HIGH PRESSURE UNDERNEATH THE EAST SIDE OF AFOREMENTIONED MID LVL RIDGE AXIS. THUS...DRY WEATHER WITH NEAR SEASONAL TEMPERATURES CAN BE EXPECTED MID TO LATE NEXT WEEK. && .AVIATION... OVERNIGHT MCS HAS DISSIPATED AS EXPECTED EARLY THIS AFTERNOON AS DIURNAL EFFECTS HAVE ALLOWED NOCTURNAL LLJ TO DISSIPATE. SKIES ARE NOW CLEARING NICELY OVER THE CWA WITH HIGH CIRRUS SHIELD QUICKLY THINNING AND ERODING. MAIN CONCERN FOR 18Z TAF CYCLE IS MOVEMENT/EVOLUTION OF UPSTREAM CONVECTION. 12Z NAM HAS TOTALLY FAILED TO CAPTURE ONGOING CONVECTION UPSTREAM OVER SW WISCONSIN. SPC OBJECTIVE MESOANALYSIS SUGGESTS AIRMASS IS STARTING TO RECOVER DOWNSTREAM FROM WISCONSIN MCS...AND THIS WILL LIKELY CONTINUE WITH INCREASING SUNSHINE. NAM/GFS PARTIAL THICKNESS SCHEMES SUGGEST IF UPSTREAM ACTIVITY HOLDS TOGETHER...IT WILL BE DIRECTED SE TOWARDS THE KSBN TERMINAL THIS EVENING. HAVE GONE WITH A VCTS QUALIFIER FOR THIS EVENING AT KSBN. DRY THEREAFTER FROM LATE TONIGHT INTO FRIDAY MORNING AS DEVELOPING SURFACE LOW OVER THE PLAINS FORCES WARM FRONT TO LIFT NORTH WITH CWA BREAKING SOLIDLY INTO THE CAPPED WARM SECTOR. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM/AVIATION...HITCHCOCK LONG TERM....HICKMAN in AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE GOODLAND KS 831 PM MDT THU AUG 24 2006 .DISCUSSION...ABOUT TO SEND OUT A MINOR UPDATE. THIS WILL BE MAINLY FOR WIND DIRECTION. NUMEROUS BOUNDARIES NEAR OR OVER THE FORECAST AREA. SO ADJUSTED BASED ON REALITY AND RUC13. ALSO ADJUSTED HOURLY TEMPERATURE AND DEW POINT GRIDS. DID NOT TOUCH THE MINS DUE TO THE VARIABILITY IN WINDS AND CLOUD COVER. WILL KEEP THE SLIGHT CHANCE POPS THROUGH THE NIGHT WITH SURFACE BOUNDARIES...UPSLOPE...AND WEAK MID AND UPPER LIFT AROUND. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 PM EDT THU AUG 24 2006 .DISCUSSION... MAIN FCST CONCERNS ARE SHRA/TSRA CHANCES TONIGHT INTO SAT. WV IMAGERY AND RUC ANALYSIS INDICATED A RDG INTO THE UPR MS VALLEY AND MANITOBA BTWN A TROF OVER ERN NOAM AND ANOTHER TROF FROM SASK INTO THE WRN PLAINS. AT THE SFC...LOW PRES WAS LOCATED OVER SE SD WITH A FRONT EXTENDING TO THE E THROUGH SRN WI INTO SRN LWR MI WITH HIGH PRES TO THE NORTH FROM HUDSON BAY AND NRN ONTARIO INTO THE UPPER GREAT LAKES. A VIGOROUS UPSTREAM SHRTWV AND 90 KT 250 MB JET STREAK AS MOVING THROUGH NE SD WHILE ANOTHER SHRTWV WAS LOCATED UPSTREAM OVER OREGON. DOWNSTREAM FROM THE RDG ANOTHER 95 KT H25 JET STREAK EXTENDED FROM E UPR MI INTO LWR MI. COMBINATION OF UPR LVL DIV AND ASSOCIATED FGEN WITH THE RIGHT ENTRANCE JET STREAK AND WAA FGEN VCNTY 850 MB FRONT SUPPORTED TSTM CLUSTERS FROM CNTRL MN INTO WRN WI. THE 12Z NAM WAS PREFERRED IN THE SHORT TERM (TIL SAT) AS THE 12Z GFS DISPLAYED SIGNIFICANT CONTINUITY PROBLEMS DUE TO CONVECTIVE FEEDBACK. TONIGHT INTO FRI...EXPECT THAT THE PCPN SUPPORTED BY WAA/ISENTROPIC LIFT AND ASSOCIATED UPR LVL DIV WITH THE H25 JET WILL CONTINUE TO GRADUALLY SPREAD TO THE NORTH. CONTINUED DRY ERLY LOW LVL FLOW MAY DELAY THE SPREAD OF THE PCPN TO THE NORTH A BIT COMPARED TO THE 12Z NAM. IN ADDITION...MCS DEVELOPMENT...WHICH SHOULD SPREAD INTO WI...WILL ALSO LIKELY DISRUPT FLOW OF MOISTURE TOWARD UPR MI. NEVERTHELESS...SYNOPTIC SCALE LIFT WITH THE WARM FRONT SHOULD STILL BE FAVORABLE ENOUGH FOR AT LEAST LIKELY POPS INTO SRN UPR MI EARLY FRI AND INTO MUCH OF THE REST OF UPR MI BY MIDDAY...ESPECIALLY IF IMPACTS OF NOCTURNAL MCS TO THE SOUTH DIMINISH SIGNIFICANTLY DURING THE DAY. WITH MAINLY ELEVATED CONVECTION NORTH OF THE WARM FRONT...ONLY ISOLD EMBEDDED TSRA ARE EXPECTED...PER NAM FCST SNDGS AND MUCAPE FCST. FRI NIGHT INTO SAT...AS THE MORE FAVORABLE UPR LVL SUPPORT AND WAA SHIFTS TO THE EAST THE PCPN WILL DIMINISH. HOWEVER...LOW LVL CONV ASSOCIATED WITH THE SFC TROF MOVING INTO UPR MI COMBINED WITH ABUNDANT LOW LVL MOISTURE AND DRYING ABV 700 MB COULD LEAD TO AREAS OF DRIZZLE ALONG WITH AREAS OF FOG. EXPECT DRY ADVECTION BEHIND THE TROF AXIS ALONG WITH INCREASING QVECTOR DIV WILL SUPPORT A CLEARING TREND DURING THE AFTERNOON. SUN-THU...MDLS WERE IN REASONABLE AGREEMENT THAT MID LVL CONFLUENT FLOW WITH SFC HIGH PRES WILL DOMINATE EARLY IN THE WEEK WITH DRY WEATHER. THE ECMWF WAS PREFERRED BY MIDWEEK (PER HPC) WITH A SLOWER PROGRESSION AND MORE AMPLIFIED PATTERN. SO...ANY SIGNIFICANT WARMUP WOULD DELAYED COMPARED TO THE 06Z/12Z GFS WHICH WOULD SUGGEST TEMPS INTO THE 80S. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1040 AM EDT THU AUG 24 2006 .UPDATE...14Z SURFACE/SATELLITE/RUC MODEL ANALYSIS SHOWS QUASI-STATIONARY FRONT STRETCHING EAST/WEST FROM SOUTHERN LOWER MICHIGAN TO A DEVELOPING AREA OF LOW PRESSURE ACROSS SOUTH DAKOTA. SCATTERED SHOWERS AND STORMS CONTINUE TO FIRE IN DEFORMATION AXIS NORTH OF WEAK MCS INDUCED LOW OVER SOUTHWEST MICHIGAN. NORTHWEST FRINGE OF SHOWER ACTIVITY REMAINS JUST SOUTH OF OUR CWA AND CONTINUES TO SLIDE OFF TO THE SOUTHEAST AS RIDGE OF HIGH PRESSURE BUILDS INTO NORTHERN MICHIGAN. LOCAL AREAS OF DENSE FOG SHOWING RAPID DISSIPATION AS LOW LEVEL MIXING COMMENCES. FORECAST CONCERNS FOR THE REMAINDER OF THE DAY CENTER AROUND LAKE BREEZE INDUCED CONVECTION POTENTIAL FOR THIS AFTERNOON. 12Z APX SOUNDING SHOWING 2 WARM LAYERS TO OVERCOME FOR SIGNIFICANT CONVECTIVE DEVELOPMENT TO OCCUR THIS AFTERNOON...ONE LAYER STRETCHING FROM 800MB TO 700MB WITH ANOTHER UP AROUND 600MB. NEW 12Z NAM-WRF POINT MODEL SOUNDING FOR THE EASTERN UPPER THIS AFTERNOON INDICATING NEARLY DRY ADIABATIC LOW LEVEL LAPSE RATES WITH ONLY 55J/KG SB CAPE CAPPED BY IMPRESSIVE WARM LAYER AROUND 775MB...SUBSTANTIALLY LOWER THAN 00Z SOUNDINGS INDICATED. ACROSS OUR SOUTHWEST CWA...MODEL SOUNDINGS SHOWING SLIGHTLY HIGHER CAP AT 675MB WITH UPWARDS OF 240 J/KG SB CAPE. SYNOPTICALLY SPEAKING...BEST MASS CONVERGENCE/UPPER LEVEL SUPPORT REMAINS FAR SOUTH IN VICINITY OF STATIONARY FRONT. ANY CHANCE OF OVERCOMING CAP IN OUR VICINITY WILL RELY ON LAKE BREEZE INDUCED CONVERGENCE. WILL LEAVE ONGOING 20 POPS FOR INTERIOR REGIONS OF THE EASTERN UPPER FOR THIS AFTERNOON ALTHOUGH FEELING IS CAP WILL BE HARD TO OVERCOME. ELSEWHERE...JUST NOT ENOUGH CONVINCING EVIDENCE TO INTRODUCE POPS. EVEN WITH CONVECTION REACHING CAP AT 675 MB ACROSS THE SOUTHWEST...WARM TEMPERATURES AT THIS ALTITUDE NOT SUPPORTIVE OF MUCH ICE GENERATION TO AID IN PRECIPITATION PRODUCTION. WILL THEREFORE MAKE JUST DO A MINOR UPDATE TO ACOUNT FOR CURRENT TEMPERATURES/CLOUD COVER AND TO CLEAN UP MORNING WORDING. UPDATED ZONES/GRIDS WILL BE OUT SHORTLY. MSB && .PREV DISCUSSION...ISSUED AT 352 AM EDT THU AUG 24 2006 HIGH PRESSURE CONTINUES TO HOLD DOWN THE FORT IN NORTHERN ONTARIO. A STALLED OUT FRONTAL ZONE WAS OVER EXTREME SOUTHERN LOWER MI. TO THE WEST THE FRONT WAS WOBBLING NORTHWARD A BIT INTO SOUTHERN WI. DEEP CONVECTION WAS OCCURRING NORTH OF THE FRONT IN THE SOUTH HALVES OF WI/LAKE MI/LOWER MI (INCLUDING A VERY IMPRESSIVE 3-INCH DIAMETER HAIL REPORT IN VAN BUREN CO AT 125AM). FOR OUR FORECAST AREA...SHOWERS/STORMS WERE GRAZING BY THE SW ZONES SOUTH OF M-115. SYNOPTIC PATTERN WILL NOT CHANGE MUCH TODAY...BUT A SURGE OF WARM MOIST AIR APPEARS LIKELY TONIGHT. OVER THE NEXT 24 HOURS...PRECIP CHANCES ARE THE MAIN CONCERN. TODAY...MAIN FOCUS FOR PRECIP IN THE REGION IS THE FRONT...AND THAT WILL STAY SOUTH OF I-96 TODAY. ONGOING ACTIVITY TO THE SOUTH WILL GRADUALLY THIS FIZZLE...WITH REDEVELOPMENT THIS AFTERNOON MOST LIKELY WEST OF LAKE MI WITH STRONGER SOUTHERLY FLOW IN THE WARM SECTOR. WILL MONITOR RADAR TRENDS THRU ISSUANCE TO SEE IF ANY PRECIP IS NEEDED IN THE FAR SOUTH EARLY ON. WILL ALSO BE MONITORING EARLY MORNING FOG TRENDS. PATCHY MID/HIGH ARE KEEPING THINGS SOMEWHAT IN CHECK...AND THERE/S LITTLE RHYME OR REASON TO FOGGY VS NON-FOGGY PLACES. NO HEADLINES FOR NOW. THE NAM/WRF HAS BEEN CONSISTENTLY SIGNALING FOR THE POSSIBILITY OF LAKE BREEZE-FORCED...DIURNAL CONVECTION THIS AFTERNOON. THIS WILL BE QUITE A CHALLENGE GIVEN THE VERY STRONG CAP AT 700MB....THOUGH THERE IS A REASONABLE AMOUNT OF INSTABILITY BELOW THE CAP (ML CAPES 100-150J/KG). WILL TOSS IN ISOLATED PM SHOWERS WHERE LOCAL FORCING WILL BE STRONGEST...AND THAT WOULD BE THE LAKE BREEZE COLLISION ZONE IN INLAND PORTIONS OF EASTERN UPPER MI. OTHERWISE...A PARTLY SUNNY DAY IS EXPECTED WITH CONSIDERABLE CU DEVELOPMENT...AND MAX TEMPS IN THE 70S. TONIGHT...AFTER A DIP SOUTHWARD LATE TODAY...THE FRONT WILL START TO RETURN NORTHWARD AGAIN...BUT STILL STAYING WELL SOUTH OF THE FORECAST AREA. SW 850MB WINDS WILL INCREASE FROM THE MID MS VALLEY INTO THE LAKES REGION...AS A 1000MB SURFACE LOW LIFTS INTO MN. THIS WILL TRIGGER MCS DEVELOPMENT IN MN/WI...WHICH WILL EVENTUALLY TRANSLATE EASTWARD INTO LOWER MI. NAM/GFS ARE IN REASONABLY GOOD AGREEMENT IN THIS SCENARIO...WITH SHRA/TSRA MOVING INTO CENTRAL LOWER MI OVERNIGHT...AND THIS MAKES SENSE SYNOPTICALLY. INSTABILITY LOOKS TO BE LIMITED...WITH MUCAPES LESS THAN 750J/KG. THIS WILL LIMIT ANY SVR THREAT. WILL HAVE LIKELY POPS OVERNIGHT SOUTH OF A FRANKFORT/HTL/STANDISH LINE...AND CHANCE AS FAR NORTH AS PETOSKEY/ ATLANTA/HARRISVILLE. ZOLTOWSKI LATER PERIODS...PRECIPITATION CHANCES WILL BE THE MAIN CONCERN FOR FRIDAY AND SATURDAY...WITH WARM FRONT PASSAGE ON FRIDAY...THEN A COLD FRONT FOR SATURDAY. A SURFACE RIDGE WILL BRING A RETURN TO PRECIPITATION FREE CONDITIONS FROM SUNDAY ONWARD. MODELS ARE IN FAIRLY GOOD AGREEMENT...SO WILL GO WITH A BLEND. FRIDAY AND FRIDAY NIGHT...SHORTWAVE MOVES OUT OF WISCONSIN AND CROSSES NORTHERN MICHIGAN. AT THE SAME TIME...WARM FRONTAL BOUNDARY WILL LIFT NORTHWARD ACROSS THE AREA. NORTHERN MICHIGAN WILL ALSO BE LOCATED IN THE RIGHT ENTRANCE REGION TO UPPER LEVEL JET TO THE EAST...PROVIDING DECENT UPPER LEVEL DIVERGENCE. WITH ALL THIS SAID...LOOKS LIKE A GOOD SCENARIO TO GET SOME MUCH NEEDED RAIN ACROSS THE AREA. WILL BUMP POPS UP TO LIKELY ACROSS NORTHERN LOWER MICHIGAN...AS THIS AREA IS MOST LIKELY GOING TO SEE WIDESPREAD MEASURABLE PRECIPITATION DURING THE DAY. THUNDERSTORM POTENTIAL IS NOT GREAT EARLY IN THE DAY WITH VERY WEAK LAPSE RATES. THE BETTER LAPSE RATES WILL BE SEEN SOUTH IN THE WARM SECTOR. HOWEVER...MAY BE JUST ENOUGH ELEVATED INSTABILITY TO GET A FEW THUNDERSTORMS TO DEVELOP. POTENTIAL EXISTS FOR SOME VERY HEAVY RAIN WITH PW VALUES JUST OVER AN INCH AND A HALF...AND FREEZING LEVELS AT 14.5 KFT. WITH STRONG STEERING FLOW...STORMS ARE NOT LIKELY TO REMAIN STATIONARY. INSTEAD...TRAINING STORMS MAY BE POSSIBLE IF THE FRONT SLOWS DOWN OVER THE AREA...WHICH IS ENTIRELY POSSIBLE. SEVERE THREAT DOES NOT LOOK PROMISING AT LEAST DURING THE MORNING HOURS SINCE STORMS ARE NOT LIKELY TO BECOME SURFACE BASED (WIND THREAT) AND FREEZING LEVELS MAY BE TOO HIGH TO GET SEVERE HAIL. BIGGER THREAT FOR SEVERE WEATHER WILL COME LATER IN THE DAY ACROSS THE SOUTH...AS WARM SECTOR STORMS MAY DEVELOP OUT OVER SOUTHERN WISCONSIN...THEN TRACK INTO CENTRAL PORTIONS OF LOWER MICHIGAN. WITH BULK SHEAR VALUES 50-55 KNOTS...POTENTIAL EXISTS FOR DAMAGING WINDS. LARGE HAIL ALSO MAY BE POSSIBLE IF STORMS DEVELOP STRONG ENOUGH UPDRAFTS. SHOWERS AND STORMS WILL LINGER INTO THE NIGHT TIME HOURS...BUT SHOULD BEGIN TO TAPER OFF TOWARDS SATURDAY MORNING AS THE GOOD DYNAMICS SHIFT TO THE NORTH AND EAST. SATURDAY...NEXT WEATHER MAKER...A COLD FRONT...PROGRESSES ACROSS NORTHERN MICHIGAN...WITH DECENT DRY AND COOL AIR IN ITS WAKE. IN ADVANCE OF THE FRONT...MODELS SHOW A FAIRLY STRONG CAP TO OVERCOME WITH 700MB TEMPS AROUND +12C. LIFTING A PARCEL IN ADVANCE OF THE FRONT (80/62) ONLY PRODUCES 400J/KG OF MLCAPE...BUT MORE IMPORTANTLY 150J/KG OF CIN. THUS...IT WILL BE VERY TOUGH IF NOT IMPOSSIBLE TO GET CONVECTION TO FIRE AWAY FROM THE COLD FRONT BOUNDARY. WILL LEAVE A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE FORECAST FOR SATURDAY...WITH STRONG FRONT COMING THROUGH...POSSIBLY ERODING THE CAP. MODEL QG FIELDS ALSO CONTINUE TO REMAIN FAVORABLE. SATURDAY NIGHT AND SUNDAY...00Z GFS HAS TRENDED FURTHER SOUTH WITH SURFACE LOW/FRONTAL POSITION. RIDGING TO THE NORTH OF THE FRONTAL BOUNDARY WILL REMAIN OVER THE NORTHERN GREAT LAKES...PRODUCING COOL AND DRY CONDITIONS ACROSS NORTHERN MICHIGAN. THUS...WILL KEEP SATURDAY NIGHT AND SUNDAY DRY WITH COOL NORTHWESTERLY FLOW. BEYOND SUNDAY...NO MAJOR CHANGES MADE. HOWEVER...00Z GFS BRINGS A SHORTWAVE THROUGH THE GREAT LAKES REGION ON MONDAY...BUT WITH LIMITED MOISTURE AROUND...WILL NOT INTRODUCE A CHANCE OF PRECIPITATION AT THIS TIME. OTHERWISE...EXPECT PARTLY TO MOSTLY SUNNY SKIES WITH NEAR SEASONAL TEMPERATURES. KAS && .APX...WATCHES/WARNINGS/ADVISORIES...NONE && $$ mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE ALBANY NY 957 PM EDT THU AUG 24 2006 .SHORT TERM /REST OF TONIGHT/... QUICK UPDATE TO CUT THE POPS OUT NORTH AND WEST OF THE CAPITAL DISTRICT BASED ON THE RADAR TRENDS AND THE LATEST 40 KM RUC. THE RUC SHOWS AN H500 VORT MAX CONTINUES TO MOVE ACROSS SRN NY AND NRN NJ. THE CYCLONIC VORTICITY ADVECTION TO THE SHORT WAVE HAS SPAWNED SOME OPEN CELLULAR SHOWERS AND ISOLD TSRA ACTIVITY. WE TAPERED THE POPS OFF GRADUALLY FROM 04Z-10Z FROM LOW CHANCE TO SLIGHT CHANCE VALUES. THE MAIN STATIONARY FRONT OR RETURNING WARM FRONT OVER THE NEXT 24 HOURS REMAINS ALIGNED OVER THE PA/MD BORDER OVERNIGHT. HOURLY T/TD FCST TRENDS WERE REDONE BASED ON THE LAST 4-5 HOURLY OBSERVATIONS. WASULA && .PREV DISCUSSION... /ISSUED 359 PM EDT THU AUG 24 2006/ SHORT TERM /TONIGHT THROUGH SUNDAY/... IF THERE IS ANY CASE FOR PROMOTING PROBABILISTIC FORECASTS...THE FORECAST THROUGH THE BEGINNING OF NEXT WEEK IS DEFINITELY ONE. IT SEEMS EACH SOURCE OF GUIDANCE KEEPS CHANGING ITS OWN TIMING... TRACK AND AREAL EXTENT OF PRECIPITATION...BASED ON DIFFERENT DEPICTIONS OF CONNECTIVELY INDUCED UPSTREAM SYSTEMS. THAT IS JUST A LONG AND COMPLICATED WAY OF SAYING IT WAS AN INTERESTING TIME TRYING TO MAKE SENSE OF ALL THE DIFFERENT GUIDANCE...PAST AND CURRENT. THE DETERMINISTIC FORECAST IS A LOW CONFIDENCE FORECAST THROUGH THE BEGINNING OF NEXT WEEK. BASED ON CURRENT DATA...AT LEAST LOOKING AT TRENDS FROM UPSTREAM FOR TONIGHT...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS SOUTH AND ISOLATED SHOWERS NORTH...WITH PERIODS OF CLOUDINESS...JUST AVERAGING PARTLY CLOUDY NORTH AND MOSTLY CLOUDY SOUTH. TEMPERATURES IN 50S...COOLER IN ADIRONDACKS. TOMORROW THROUGH SUNDAY...LOOKS LIKE AT LEAST SOME BROAD AGREEMENT FROM SOURCES OF GUIDANCE THAT A SYSTEM TRACKING OUT OF THE GREAT LAKES AND OHIO VALLEY TRACKS THROUGH THE REGION...BRINGING CLOUDINESS AND RAIN CHANCES INTO WESTERN AREAS BY AFTERNOON AND EVERYWHERE ELSE BY LATE FRIDAY AFTERNOON. ALSO SOME AGREEMENT THAT STRENGTHENING WARM ADVECTION...MOISTURE ADVECTION...ISENTROPIC LIFT AND LOW LEVEL WIND SPEED MAXIMUM WILL ENHANCE FORCING. RAIN CHANCES CONTINUE THROUGH FRIDAY NIGHT AND SATURDAY MORNING. ANY CHANCES FOR THUNDER LOOK TO BE WEST AND SOUTH OF OUR AREA...AS SOME DEGREE OF STABILITY NORTH OF LOW LEVEL BOUNDARY...AND WARM ADVECTION INDUCED RAINFALL WILL NOT HELP SURFACE BOUNDARY TRACK VERY MUCH NORTH. TIMING OF OVERCAST SKY ON FRIDAY IN QUESTION...BUT SOME SUNSHINE SHOULD HELP ALL AREAS TO AROUND 70...LOWER TO MID 70S SOUTH...AND COOLER IN MOUNTAINS. ON SATURDAY...WITH LIGHT EAST TO SOUTHEAST WINDS...QUITE A BIT OF LINGERING CLOUDINESS...BUT SOME OCCASIONAL BREAK POSSIBLE IN NORTHERN AND CENTRAL AREAS...BUT STILL... TEMPERATURES LIKELY TO STRUGGLE ABOVE THE UPPER 60S TO NEAR 70...BUT STAY TUNED...DEPENDING ON TIMING OF EXIT OF THE RAIN. KEEPING SMALL CHANCES AND CLOUDINESS SATURDAY NIGHT AND SUNDAY WITH THE UNCERTAINTIES IN THE APPROACH OF THE NEXT POTENTIAL SYSTEM. LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... NEXT BATCH OF RAIN CURRENTLY TIMED FOR SUNDAY AND SUNDAY NIGHT...BASED ON MREF GUIDANCE. LOOKS LIKE THE HEAVIEST RAIN MAY BE OVER SOUTHERN AREAS. THEN ONE FINAL SYSTEM TRACKS THROUGH MONDAY NIGHT AND EXITS TUESDAY. AGAIN...TIMING AND LOCATION OF HEAVIEST RAIN SUBJECT TO CHANGE AS WE HEAD THROUGH THE WEEKEND AND INTO THE BEGINNING OF NEXT WEEK. BY WEDNESDAY AND THURSDAY...COOLING AND DRYING AS MEAN NORTHERN STREAM UPPER TROUGH AXIS GETS JUST EAST OF THE AREA. HOWEVER...SOME HINTS THAT ACTIVE SOUTHERN STREAM MAY POTENTIALLY PUT SOME WRINKLES IN THE DAY 5-7 TIME RANGE...WILL WATCH. AVIATION... PLENTY OF CLOUDS WILL BE AROUND THRU THE PERIOD...BUT WITH VARYING HEIGHT. FOR THE REST OF THE DAYLIGHT HOURS...A SCT-BKN CU DECK AROUND 4-6 KFT WILL BE PREVALENT. SOME SCT -SHRA ARE ALSO POSSIBLE AS A DISTURBANCE MOVES THRU THIS AFTN/EVENING. AFTER SUNSET THE CU WILL TEND TO DISSIPATE...BUT A BKN DECK OF MID LVL STRATUS WILL LIKELY BE AROUND. AFTER 06Z...MOS GUIDANCE HINTING AT SOME LOW LVL STRATUS FORMING ESPECIALLY ACROSS THE MID HUDSON VALLEY. WITH A LOW LVL SE WIND COMPONENT BANKING OFF THE CATSKILLS THIS SCENARIO SEEMS REASONABLE. KEPT CIGS IN MVFR RANGE FOR NOW AT KPOU EARLY FRI MORNING...THEN LIFTING A BIT TO VFR A FEW HOURS AFTER SUNRISE. DID NOT GO FOR LOWER THAN 3500 FT CIGS AT KGFL/KALB FOR NOW...AS THE BEST MOISTURE WILL BE FURTHER SOUTH. SFC WINDS WILL BE GENERALLY NE AND LESS THAN 5 KTS THRU THE PERIOD. HYDROLOGY... THERE STILL EXISTS A GREAT DEAL OF UNCERTAINTY REGARDING THE TRACK OF MAIN FEATURES AND RESULTANT TIMING OF POTENTIAL RAINFALL OVER THE NEXT FEW DAYS. THERE WILL LIKELY NOT BE ANY HYDRO PROBLEMS THROUGH AT LEAST FRIDAY...WITH MAINLY LIGHT PRECIPITATION THIS AFTERNOON AND EVENING AVERAGING LESS THAN ONE QUARTER INCH. HOWEVER...SEVERAL BATCHES OF RAIN MAY MOVE THROUGH THE AREA STARTING FRIDAY NIGHT AND LASTING THROUGH THE WEEKEND. DETERMINISTIC FORECASTS ARE HIGHLY UNCERTAIN AT THIS TIME...SINCE SOME OF THE FEATURES ASSOCIATED WITH RAINFALL BEING DEPICTED MAY OR MAY NOT MATERIALIZE. WITH MOISTURE INCREASING THROUGH THE PERIOD AND A SURFACE BOUNDARY SETTING UP SOMEWHERE IN THE VICINITY...SPORADIC BOUTS OF MODERATE TO POTENTIALLY HEAVY RAINFALL ARE POSSIBLE. CONFIDENCE IS TOO LOW FOR QPF ESTIMATIONS AT THIS TIME. A STALLED FRONTAL BOUNDARY MAY LINGER INTO NEXT WEEK...WITH THE POTENTIAL FOR MORE RAINFALL. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NY...NONE. VT...NONE. && $$ ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BINGHAMTON NY 1020 AM EDT WED AUG 23 2006 .SHORT TERM /TODAY - FRI NGT/... UPDATE...HIGH PRESSURE OOZING SOUTH FROM CANADA HAS PUSHED INTO NEW ENGLAND THIS MORNING WITH ANOTHER HIGH CENTER ACROSS MID-ATLANTIC REGION. IN BETWEEN...SFC LOW OVER SD WITH STATIONARY BOUNDARY REMAINING DRAPED ACROSS MIDWEST EXTENDING INTO NORTHERN OH/PA. BOUNDARY BECOMES DIFFUSE AS IT HEADS TOWARD EASTERN SEABOARD...BUT SFC CONVERGENCE WOULD SUGGEST IT IS SOMEWHERE VC OF NEPA. SUBTLE S/WAVES ABOUND IN EASTERN U.S. TROF...GENERATING SHRAS OVER WNY AND ALSO OVER NORTHERN CWA. WAVES ARE BEING PICKED UP ON LATEST RUC SOLN BUT ARE EXTREMELY HARD TO PICK UP IN WV IMAGERY. LARGER WAVE OVER MI/OH WILL ROTATE THRU CPA THIS AFTERNOON AND HELP GENERATE SHRA AND THUNDERSTORMS WITH FRONT SERVING AS FOCUSING MECHANISM. INSTABILITY WILL INCREASE ACROSS FA TODAY WITH MAXES RISING INTO M-U 70S AND MOISTURE INCREASING INTO MID-50S. THIS GIVES CAPE VALUES ACROSS NE PA OF 500-1000 J/KG. 5H FLOW OF 40-50KTS MAY BE SUFFICIENT TO PRODUCE STRONG WIND GUSTS IF STORMS CAN DEVELOP IN THIS AREA THIS AFTERNOON. EXPECT THUNDER TO DEVELOP BTWN 18-21Z TODAY WITH MOST LIKELY AREA BEING SOUTHERN HALF FA...GENERALLY NY/PA BORDER AND SOUTH. WILL STILL RETAIN SCTD POPS ELSEWHERE BUT LOWER TO LO CHC. WILL ISSUE UPDATE TO TWEAK SKY/WIND AND REWORK AFTERNOON POPS. UPDATED GRIDS AND TEXT PRODUCTS WILL HIT THE ROAD BY 15Z. -PB PREV DISCUSSION... POLLUTED HIGH MEANDERING OVER CENTRAL AND EASTERN CANADA WILL MOVE LITTLE OVER THE NEXT 24H. A STALLED BOUNDARY OVER PA AND NEW ENGLAND WILL INTERACT WITH A SERIES OF WAVES DRIFTING SOUTHWARD FROM ONTARIO. THIS WILL KEEP OUR WX VERY UNSETTLED THROUGH FRIDAY NIGHT. MOISTURE REMAINS LIMITED ACROSS THE REGION BUT IT IS ON THE INCREASE. CONVECTIVE REMNANTS ARE SLIDING EASTWARD THIS MORNING WITH MOST OF ACTIVITY OVER EXTREME NORTHERN AND SOUTHERN SECTIONS OF FA. THIS WILL FILL IN TODAY AND YIELD SCT SHOWERS FOR MUCH OF THE DAY. AS TEMPS WARM INTO THE LOWER 70S INSTABILITY WILL INCREASE ALLOWING FOR A FEW THUNDERSTORMS, THOUGH NO SEVERE CONVECTION IS EXPECTED. THE ACTIVITY WILL SLOWLY PULL EAST OVERNIGHT SO WE HAVE FORECAST SOME SHOWERS TO HANG UP FROM THE NY/PA BORDER SOUTHEASTWARD. SERIES OF SHORTWAVES WILL CONTINUE TO TRAVERSE WESTERN NY FRIDAY AND FRIDAY NIGHT. HAVE ADDED POPS FOR A SHOWER OF THUNDERSTORM TO BOTH PERIODS OVER WESTERN FA. DJP && .EXTENDED (FRI NIGHT-WEDNESDAY)... WARM FRONT MOVES UP OVER AREA BRINGING SOME CLOUDS AND SLIGHT CHC POPS WITH GREATEST THREAT REMAINING TO W AND N. SFC LOW MOVES FROM WRN GREAT LAKES EAST TO N OF MONTREAL BY SUNDAY EVENING WITH SFC COLD FRONT APPROACHING WRN NY. CHANCE OF SHWRS AND TSTMS INCREASES TO LIKELY BY SUN EVENING. FRONT PASSES THROUGH BY MONDAY MORNING. SOME MOISTURE AROUND FOR AFTN STRATOCU BUT NO POPS. SHORT WAVES PASSES TO THE N ON TUES WITH FEW CLDS AND ONLY SLGT CHC POPS. HI PRES BUILDS IN WED. -BMW && .AVIATION (24/06Z TO 25/06Z)... WILL STICK WITH VFR FORECAST THIS PERIOD AS MID LEVEL CLOUDS AND LIGHT SHOWERS SHOULD KEEP TEMPS UP THIS MORNING, PREVENTING FOG FORMATION. SHOWERS WILL BE LIGHT THIS MORNING, WITH THE DECK BETWEEN 6000 AND 10000 FEET. ISOLATED HEAVIER SHOWERS OR THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON BUT CONFIDENCE IS LOW DUE TO LIMITED COVERAGE. DJP && .BGM WATCHES/WARNINGS/ADVISORIES... .NY...NONE. .PA...NONE. $$ ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1039 PM EDT THU AUG 24 2006 .SYNOPSIS... WEAK HIGH PRESSURE (1016 MB) WAS CENTERED JUST OFFSHORE OF THE OUTER BANKS LATE EVENING WITH A WESTWARD EXTENSION OVER NC. A WEAK LEE TROUGH WAS NOTED OVER THE NC/VA FOOTHILLS. A LIGHT SOUTHERLY RETURN FLOW WAS NOTED OVER THE NW PIEDMONT && .SHORT TERM /REST OF TONIGHT/... MADE ANOTHER CALL TO THE FAA TONIGHT CONCERNING A FEW AWOS SITES IN OUR REGION DUE TO POSSIBLE ERRORS IN TEMP OR IN DEW POINT TEMP. THE LOUISBURG AWOS DATA WAS NOT AVAILABLE DUE TO ONGOING T/TD ERRORS WHICH WERE BEING WORKED ON. OTHER AWOS SITES IN WHICH TICKETS WERE OPENED THIS EVENING BY THE FAA DUE TO POSSIBLE DATA QUALITY ISSUES INCLUDED... EMPORIA... FRANKLIN... AND HILLSVILLE/GALAX VA... AND MOUNT AIRY... WILKESBORO AND ERWIN-DUNN NC. 1000 PM TEMPERATURES RANGED FROM 69-75 NORTH... AND MID 70S SOUTH. THE WARMEST TEMP REPORTED WAS 79 AT MOUNT AIRY (DISCARDED AS OTHER OBSERVATIONS FROM THAT AREA INDICATED LOWER 70S THERE). ERWIN-DUNN ALSO REPORTED 79 (WHICH ALSO APPEARS 5 DEGREES WARMER THAN SURROUNDING SITES). THE DEW POINTS AT EMPORIA AND FRANKLIN VA (72-75) WERE 5-9 DEGREES ABOVE EVERYONE ELSE. THE DEW POINT AT HILLSVILLE/GALAX VA WAS POSSIBLE 10+ DEGREES HIGHER THAN OTHER SURROUNDING AREAS. BOTTOM LINE... USE THE AWOS DATA FOR T/TD WITH STRONG SCRUTINY. THE UPPER RIDGE CENTERED OVER TEXAS REMAINS NEARLY A STATIONARY FEATURE. A WEAK H5 TROUGH WAS LOCATED ALONG THE EASTERN SEABOARD... WITH THE TROUGH AXIS JUST OFFSHORE. SOME MOISTENING HAD OCCURRED WITHIN THE NW FLOW ALOFT OVER NC SINCE 12Z TODAY... BUT NOT ENOUGH TO GENERATE CLOUDINESS DUE TO THE STRONG SUBSIDENCE DRYING SEEN ON THE WATER VAPOR IMAGERY CROSSING THE APPALACHIANS. CURRENT SATELLITE AND SURFACE REPORTS INDICTED CLEAR SKIES NW AND SCATTERED TO THIN BROKEN HIGH LEVEL CLOUDS OVER THE SE THIS EVENING. SKIES SHOULD CONTINUE CLEAR NW TO PARTLY CLOUDY SE OVERNIGHT. GOOD RADIATIONAL COOLING IS EXPECTED OVER THE COASTAL PLAIN AND SANDHILLS THROUGH DAYBREAK... DUE TO THE RIDGE AXIS OVERHEAD AND RESULTANT LIGHT WIND. T/TD SPREAD WAS ALREADY LESS THAN 5 DEGREES AT SEVERAL LOCATIONS. PATCHY FOG WILL BE LIKELY THERE WITH LOWS 65-70. FOR THE PIEDMONT... THE LIGHT RETURN FLOW HAS KEPT TEMPS UP A BIT... WITH THE T/TD SPREAD STILL 10-15 DEGREES. THUS... LOWS WILL NEED TO BE BUMPED UP A FEW DEGREES ESPECIALLY OVER THE TRIAD REGION. LOWS 65-70 APPEAR REASONABLE THERE TOO. NO OTHER CHANGES AT THIS TIME. && .PREV DISCUSSION... (ISSUED 205 PM EDT THU AUG 24 2006) SHORT TERM /TONIGHT THROUGH SUNDAY/... TONIGHT...LOW LEVEL FLOW REMAINS VERY WEAK WITH MODELS DEPICTION OF HIGH PRESSURE AT 850 MB DIRECTLY OVER CENTRAL NC. NAM SOUNDINGS SHOW A BIT MORE LOWER LEVEL MOISTURE IN THE WESTERN BORDER COUNTIES THAN GFS TOWARD MORNING WHICH COULD LEAD TO SOME SPREADING STRATOCU OR ALTOCU IN THE TRIAD. BUT OTHERWISE MOSTLY CLEAR. ONCE AGAIN WE SHOULD SEE SOME AREAS OF FOG NEAR DAYBREAK..THOUGH MODEL SURFACE DEWPOINT DEPRESSION FORECASTS ARE SOMEWHAT GREATER THAN FOR THIS PAST MORNING. LOWS 65-69. FRI-SUN...THE RIDGE ALOFT EXPANDS EASTWARD FROM THE SOUTHERN PLAINS AND PUMPS UP OVER THE SOUTHEASTERN U.S. THIS SHOULD LEAD TO A GENERALLY RAINLESS PERIOD OF ABOVE NORMAL HEAT ACROSS CENTRAL NC. FORECAST SOUNDINGS SHOW PERSISTENT MID LEVEL SUBSIDENCE WARMING AND DRYING ACROSS THE AREA WITH PRECIPITABLE WATER GENERALLY LESS THAN 1.5 THROUGH THE PERIOD. ONE POTENTIAL FLY IN THE OINTMENT IS LOW PRESSURE ASSOCIATED WITH CONVECTION SOUTH OF CAPE FEAR THAT THE GFS LATCHES ONTO AND DRIFTS SLOWLY WEST. IF THIS SCENARIO PANS OUT... ADDITIONAL MARITIME HUMIDITY AND DESTABILIZATION COULD LEAD TO CONVECTIVE RAIN POTENTIAL IN THE COASTAL PLAIN SUNDAY. SUNDAY POPS WILL BE EDGED UPWARD IN THE SOUTHEAST TIER...BUT CONSISTENCY WILL BE SOUGHT IN THE SUBSEQUENT MODEL RUNS TO INCLUDE ANY ACTUAL MENTION OF SHOWERS. HIGHS EACH DAY 90-95. LOWS 66-70. -RFG LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... UNDER RIDGING ALOFT...DRY CONDITIONS SHOULD PERSIST THROUGH SUNDAY NIGHT. LOW-LEVEL MOISTURE WILL START TO INCREASE MONDAY AHEAD OF A POSITIVELY-TILTED FRONT THAT WILL APPROACH THE CAROLINAS TUESDAY. PRIMARY GUIDANCE DIFFERENCES LIE IN TIMING OF MOISTURE RETURN BEFORE THE FRONT GETS CLOSE ON TUESDAY. CANADIAN AND UKMET MODELS MAINTAIN THE MID-LEVEL RIDGE OVER THE CAROLINAS LONGER THAN THE GFS...WHICH LOWERS HEIGHTS MORE DURING THE EARLY PART OF THE NEXT WORK WEEK. IF THE CANADIAN VERIFIES...THE CHANCES FOR SHOWERS EVEN INTO TUESDAY ARE LIMITED WITH SUCH A STRONG RIDGE AND THE SURFACE FRONT REMAINING FARTHER NORTH THAN THE GFS. THE TREND OF THE GFS IS A LITTLE MORE MOIST...HOWEVER...00Z ENSEMBLE MOS POPS WERE ALMOST ALL AT OR BELOW CLIMATOLOGY. WILL COMPROMISE BETWEEN THE SLIGHTLY MORE MOIST GFS AND THE DRIER...SLOWER CANADIAN AND UKMET MENTIONING IN THE GRIDDED FORECAST AN ISOLATED THUNDERSTORM WEST ON MONDAY IN A WEAK SURFACE TROUGH...DRY EAST. FROM TUESDAY INTO WEDNESDAY...GFS SUGGESTS THE POSITIVELY-TILTED FRONT WILL SLOWLY MOVE SOUTH INTO CENTRAL NORTH CAROLINA. CHANCES FOR PRECIPITATION WILL INCREASE FROM NORTH TO SOUTH FROM TUESDAY AFTERNOON THROUGH TUESDAY NIGHT. GFS PORTRAYS A WET SCENARIO...AND THIS COULD VERIFY GIVEN THE SLOW SPEED OF THE FRONT. SOME CONCERN EXISTS REGARDING THE EVENTUAL SPEED OF THE FRONT DUE TO DIFFERENCES IN THE STRENGTH OF THE RIDGE AND THE GENERALLY WEST-SOUTHWEST FLOW ALOFT THROUGH MID-WEEK. HIGHEST POPS WILL BE TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING...AND IN SOME DEFERENCE TO THE GFS WILL BEGIN TO DIMINISH POPS LATE WEDNESDAY AS THE FRONT SLOWLY SLIPS SOUTH AND WEAKENS. CONTINUED SLIGHT CHANCE POPS INTO THURSDAY ESPECIALLY IF THE PROGRESS OF THE FRONT IS SLOW AS SHOWN ON THE LATEST 12Z RUN OF THE GFS. ABOVE NORMAL TEMPERATURES TO BE THE RULE FOR THE EARLY PART OF THE LONG-TERM PERIOD. INCREASING MOISTURE AND CHANCES FOR PRECIPITATION BY MID-WEEK WILL HELP DAYTIME HIGHS FALL BACK TO NEAR NORMAL FOR THIS TIME OF YEAR. THANKS TO AKQ AND RNK FOR COLLABORATION ON THIS PART OF THE FORECAST. AVIATION... RUC FORECASTS THE SCATTERED-TO-BROKEN CIRRUS TO GRADUALLY DIMINISH SOUTH DURING THE REST OF THE AFTERNOON AND EARLY EVENING HOURS. WINDS SHOULD GENERALLY BE LIGHT THROUGH THE PERIOD WITH A SLACK GRADIENT AND BOUNDARY LAYER WINDS FORECAST JUST ABOVE THE SURFACE LESS THAN 10KT. FORECAST CHALLENGES COME WITH POTENTIAL FOR FOG OVERNIGHT AND AN ISOLATED SHOWER OR A FEW CLOUDS FROM THE TRIAD EASTWARD. BOTH THE NAM AND THE GFS FORECAST A RELATIVELY DRY AREA OVER CENTRAL NORTH CAROLINA COMPARED TO DEW POINTS IN ADJACENT LOCATIONS...AND AT LEAST THE GFS MOS GUIDANCE SUPPORTS THIS WITH DEW POINTS A FEW DEGREES BELOW THE NAM MOS GUIDANCE. HIGHER DEW POINTS ACTUALLY ARE FORECAST LATE TONIGHT IN WESTERN ZONES...WHERE VISIBILITIES EARLY THIS MORNING WERE GENERALLY HIGHER THAN ELSEWHERE IN CENTRAL NORTH CAROLINA. DEW POINTS CURRENTLY OVER MOST OF CENTRAL NORTH CAROLINA ARE IN THE LOWER-TO-MID 60S...WITH EVEN SOME MID 50S READINGS IN ISOLATED SPOTS NEAR THE VIRGINIA BORDER. GIVEN THE LIGHT WIND AND THE POTENTIAL FOR TEMPERATURES TO GET CLOSE TO THE DEW POINT LATE UNDER A MOSTLY CLEAR SKY...ANTICIPATE SOME LIGHT FOG FORMATION AND AT ALL TAF SITES FORECAST A PERIOD OF IFR VISIBILITY FOR A COUPLE OF HOURS OR SO AROUND SUNRISE. SINCE THE DEW POINTS WERE LOWER THIS AFTERNOON...DID NOT FORECAST THE VISIBILITIES TO GET AS LOW AND TO DIMINISH AS RAPIDLY AS THEY DID EARLY THIS MORNING. BEST LOW-LEVEL CONVERGENCE IS ALONG THE NORTH CAROLINA VIRGINIA BORDER NORTH OF THE TRIAD...AND WITH DEW POINTS LOWERING FROM THE EAST IT SHOULD BE TOUGH FOR ANY ISOLATED SHOWER TO APPROACH THE TRIAD. WILL WATCH IT THOUGH...BUT FOR THE OVERNIGHT HOURS HAVE THE MENTION OF JUST A FEW HIGH SC OR LOW AC NORTH GIVEN A SMALL AREA OF POTENTIAL INSTABILITY BETWEEN 700MB AND 850MB ON THE NAM SOUNDINGS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS... SHORT TERM...BADGETT nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 205 PM EDT THU AUG 24 2006 .SHORT TERM /TONIGHT THROUGH SUNDAY/... TONIGHT...LOW LEVEL FLOW REMAINS VERY WEAK WITH MODELS DEPICTION OF HIGH PRESSURE AT 850 MB DIRECTLY OVER CENTRAL NC. NAM SOUNDINGS SHOW A BIT MORE LOWER LEVEL MOISTURE IN THE WESTERN BORDER COUNTIES THAN GFS TOWARD MORNING WHICH COULD LEAD TO SOME SPREADING STRATOCU OR ALTOCU IN THE TRIAD. BUT OTHERWISE MOSTLY CLEAR. ONCE AGAIN WE SHOULD SEE SOME AREAS OF FOG NEAR DAYBREAK..THOUGH MODEL SURFACE DEWPOINT DEPRESSION FORECASTS ARE SOMEWHAT GREATER THAN FOR THIS PAST MORNING. LOWS 65-69. FRI-SUN...THE RIDGE ALOFT EXPANDS EASTWARD FROM THE SOUTHERN PLAINS AND PUMPS UP OVER THE SOUTHEASTERN U.S. THIS SHOULD LEAD TO A GENERALLY RAINLESS PERIOD OF ABOVE NORMAL HEAT ACROSS CENTRAL NC. FORECAST SOUNDINGS SHOW PERSISTENT MID LEVEL SUBSIDENCE WARMING AND DRYING ACROSS THE AREA WITH PRECIPITABLE WATER GENERALLY LESS THAN 1.5 THROUGH THE PERIOD. ONE POTENTIAL FLY IN THE OINTMENT IS LOW PRESSURE ASSOCIATED WITH CONVECTION SOUTH OF CAPE FEAR THAT THE GFS LATCHES ONTO AND DRIFTS SLOWLY WEST. IF THIS SCENARIO PANS OUT... ADDITIONAL MARITIME HUMIDITY AND DESTABILIZATION COULD LEAD TO CONVECTIVE RAIN POTENTIAL IN THE COASTAL PLAIN SUNDAY. SUNDAY POPS WILL BE EDGED UPWARD IN THE SOUTHEAST TIER...BUT CONSISTENCY WILL BE SOUGHT IN THE SUBSEQUENT MODEL RUNS TO INCLUDE ANY ACTUAL MENTION OF SHOWERS. HIGHS EACH DAY 90-95. LOWS 66-70. -RFG && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... UNDER RIDGING ALOFT...DRY CONDITIONS SHOULD PERSIST THROUGH SUNDAY NIGHT. LOW-LEVEL MOISTURE WILL START TO INCREASE MONDAY AHEAD OF A POSITIVELY-TILTED FRONT THAT WILL APPROACH THE CAROLINAS TUESDAY. PRIMARY GUIDANCE DIFFERENCES LIE IN TIMING OF MOISTURE RETURN BEFORE THE FRONT GETS CLOSE ON TUESDAY. CANADIAN AND UKMET MODELS MAINTAIN THE MID-LEVEL RIDGE OVER THE CAROLINAS LONGER THAN THE GFS...WHICH LOWERS HEIGHTS MORE DURING THE EARLY PART OF THE NEXT WORK WEEK. IF THE CANADIAN VERIFIES...THE CHANCES FOR SHOWERS EVEN INTO TUESDAY ARE LIMITED WITH SUCH A STRONG RIDGE AND THE SURFACE FRONT REMAINING FARTHER NORTH THAN THE GFS. THE TREND OF THE GFS IS A LITTLE MORE MOIST...HOWEVER...00Z ENSEMBLE MOS POPS WERE ALMOST ALL AT OR BELOW CLIMATOLOGY. WILL COMPROMISE BETWEEN THE SLIGHTLY MORE MOIST GFS AND THE DRIER...SLOWER CANADIAN AND UKMET MENTIONING IN THE GRIDDED FORECAST AN ISOLATED THUNDERSTORM WEST ON MONDAY IN A WEAK SURFACE TROUGH...DRY EAST. FROM TUESDAY INTO WEDNESDAY...GFS SUGGESTS THE POSITIVELY-TILTED FRONT WILL SLOWLY MOVE SOUTH INTO CENTRAL NORTH CAROLINA. CHANCES FOR PRECIPITATION WILL INCREASE FROM NORTH TO SOUTH FROM TUESDAY AFTERNOON THROUGH TUESDAY NIGHT. GFS PORTRAYS A WET SCENARIO...AND THIS COULD VERIFY GIVEN THE SLOW SPEED OF THE FRONT. SOME CONCERN EXISTS REGARDING THE EVENTUAL SPEED OF THE FRONT DUE TO DIFFERENCES IN THE STRENGTH OF THE RIDGE AND THE GENERALLY WEST-SOUTHWEST FLOW ALOFT THROUGH MID-WEEK. HIGHEST POPS WILL BE TUESDAY AFTERNOON THROUGH WEDNESDAY MORNING...AND IN SOME DEFERENCE TO THE GFS WILL BEGIN TO DIMINISH POPS LATE WEDNESDAY AS THE FRONT SLOWLY SLIPS SOUTH AND WEAKENS. CONTINUED SLIGHT CHANCE POPS INTO THURSDAY ESPECIALLY IF THE PROGRESS OF THE FRONT IS SLOW AS SHOWN ON THE LATEST 12Z RUN OF THE GFS. ABOVE NORMAL TEMPERATURES TO BE THE RULE FOR THE EARLY PART OF THE LONG-TERM PERIOD. INCREASING MOISTURE AND CHANCES FOR PRECIPITATION BY MID-WEEK WILL HELP DAYTIME HIGHS FALL BACK TO NEAR NORMAL FOR THIS TIME OF YEAR. THANKS TO AKQ AND RNK FOR COLLABORATION ON THIS PART OF THE FORECAST. && .AVIATION... RUC FORECASTS THE SCATTERED-TO-BROKEN CIRRUS TO GRADUALLY DIMINISH SOUTH DURING THE REST OF THE AFTERNOON AND EARLY EVENING HOURS. WINDS SHOULD GENERALLY BE LIGHT THROUGH THE PERIOD WITH A SLACK GRADIENT AND BOUNDARY LAYER WINDS FORECAST JUST ABOVE THE SURFACE LESS THAN 10KT. FORECAST CHALLENGES COME WITH POTENTIAL FOR FOG OVERNIGHT AND AN ISOLATED SHOWER OR A FEW CLOUDS FROM THE TRIAD EASTWARD. BOTH THE NAM AND THE GFS FORECAST A RELATIVELY DRY AREA OVER CENTRAL NORTH CAROLINA COMPARED TO DEW POINTS IN ADJACENT LOCATIONS...AND AT LEAST THE GFS MOS GUIDANCE SUPPORTS THIS WITH DEW POINTS A FEW DEGREES BELOW THE NAM MOS GUIDANCE. HIGHER DEW POINTS ACTUALLY ARE FORECAST LATE TONIGHT IN WESTERN ZONES...WHERE VISIBILITIES EARLY THIS MORNING WERE GENERALLY HIGHER THAN ELSEWHERE IN CENTRAL NORTH CAROLINA. DEW POINTS CURRENTLY OVER MOST OF CENTRAL NORTH CAROLINA ARE IN THE LOWER-TO-MID 60S...WITH EVEN SOME MID 50S READINGS IN ISOLATED SPOTS NEAR THE VIRGINIA BORDER. GIVEN THE LIGHT WIND AND THE POTENTIAL FOR TEMPERATURES TO GET CLOSE TO THE DEW POINT LATE UNDER A MOSTLY CLEAR SKY...ANTICIPATE SOME LIGHT FOG FORMATION AND AT ALL TAF SITES FORECAST A PERIOD OF IFR VISIBILITY FOR A COUPLE OF HOURS OR SO AROUND SUNRISE. SINCE THE DEW POINTS WERE LOWER THIS AFTERNOON...DID NOT FORECAST THE VISIBILITIES TO GET AS LOW AND TO DIMINISH AS RAPIDLY AS THEY DID EARLY THIS MORNING. BEST LOW-LEVEL CONVERGENCE IS ALONG THE NORTH CAROLINA VIRGINIA BORDER NORTH OF THE TRIAD...AND WITH DEW POINTS LOWERING FROM THE EAST IT SHOULD BE TOUGH FOR ANY ISOLATED SHOWER TO APPROACH THE TRIAD. WILL WATCH IT THOUGH...BUT FOR THE OVERNIGHT HOURS HAVE THE MENTION OF JUST A FEW HIGH SC OR LOW AC NORTH GIVEN A SMALL AREA OF POTENTIAL INSTABILITY BETWEEN 700MB AND 850MB ON THE NAM SOUNDINGS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RFG LONG TERM...DJF AVIATION...DJF nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE RALEIGH NC 1108 AM EDT THU AUG 24 2006 .SHORT TERM /REST OF TODAY/... A MINOR UPDATE TO THE FORECAST GRIDS HAS BEEN DONE TO ACCOUNT FOR MORE HIGH CLOUDINESS ACROSS THE SOUTHERN TIER OF THE RAH CWA RESULTING IN A SLIGHTLY LOWER MAX TEMPERATURE PREDICTION IN THE SOUTHERN COUNTIES AND SOMEWHAT HIGHER SURFACE DEWPOINTS IN THE SOUTHERN AND WESTERN BORDER COUNTIES. THIS IS GENERALLY SUPPORTED BY THE RUC OUTPUT AS WELL. -RFG && .PREV DISCUSSION... (ISSUED 857 AM EDT THU AUG 24 2006) SHORT TERM /REST OF TODAY/... LITTLE CHANGE TO THE FORECAST PARAMETERS IS EXPECTED FOR TODAY. THICKNESS NUMBERS OFF 12Z RAOBS AND PROJECTED FOR THIS EVENING SUGGEST MAX FULL SUN READINGS IN THE LOWER 90S...BUT SIMILAR NUMBERS YESTERDAY YIELDED UPPER 80S TO NEAR 90 AND A COOLER START THIS MORNING PLUS A THIN CIRRUS SHIELD THIS MORNING SHOULD KEEP OUR PEAK READINGS CONFINED TO THE 88-91 RANGE AS PREVIOUSLY FORECAST. THE GSO MORNING SOUNDING SHOWS MODERATE MOISTURE IN THE LOWEST 50 MB WITH SURFACE DEWPOINTS IN THE MID 60S. MODELS SUGGEST SOME DRYING DURING THE DAY WITH NE FLOW AND MIXING SHOULD ALLOW SURFACE DEWPOINTS TO DROP INTO THE LOWER 60S THIS AFTERNOON...A MINOR DOWNWARD ADJUSTMENT. SURFACE WINDS SHOULD REMAIN LIGHT STARTING OUT FROM THE NE AND VEERING TO ESE THIS AFTN. -RFG PREV DISCUSSION... (ISSUED 215 AM EDT THU AUG 24 2006) SHORT TERM /TODAY THROUGH SATURDAY/... BOUNDARY SOUTH OF THE AREA WILL CONTINUE TO BE PUSHED SOUTH AS HIGH PRESSURE BUILDS OVER THE REGION FROM THE NORTHEAST. RESIDUAL MOISTURE IN THE EAST AND SOUTH WILL LEAD TO PATCHY FOG. SOUNDING DATA INDICATING DRIER AIR WORKING INTO THE AREA LATE MORNING TO EARLY AFTERNOON...ESPECIALLY ALOFT...SOME MID TO LOW LEVEL MOISTURE STILL POSSIBLE TODAY DUE TO THE EASTERLY FLOW. 500MB RIDGE BUILDING OVER THE AREA THROUGH THE WEEKEND WHICH WILL AID IN KEEPING US DRY. WITH RIDGE BUILDING OVER THE EAST COAST...TEMPERATURES SHOULD RISE AS INDICATED BY GUIDANCE...SO MAY RAISE ACCORDINGLY. WILL CONTINUE MENTION OF PATCHY MORNING FOG. LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... LITTLE ADJUSTMENT NEEDED DURING THIS PERIOD. CURRENT FORECAST TRENDS ON TRACK. AVIATION... WEAK HIGH PRESSURE BUILDING INTO THE AREA WITH DRIER AIR WORKING IN FROM THE NORTH. SOME DEBRIS MID/HIGH LEVEL CLOUDS FROM TENNESSEE VALLEY SPREADING INTO CWA...MAINLY ABOVE 12KFT AS MOST LOCATIONS REPORTING SKC. VSBYS 4-6 MI IN PATCHY FOG EXCEPT OCNL LIFR CONDITIONS IN FOG RWI VCNTY. FOG BECOMING MORE WIDESPREAD AFTER 08Z THROUGH 12 WITH MVFR VSBYS IN FOG WITH OCNL IFR/LIFR CONDITIONS IN FOG FAY-RWI VICINITIES. CONDITIONS GRADUALLY IMPROVING AFTER 13Z TO VFR EXCEPT BRIEF MVFR CONDITIONS RWI VCNTY UNTIL 14Z. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RFG nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 149 PM EDT THU AUG 24 2006 .AVIATION /18Z-18Z/... EMBEDDED SHORTHWAVE IN NWRLY FLO ACRS THE GREAT LAKES/OHIO VALLEY DROPPING SE THROUGH THE SRN GREAT LAKES. AN AXIS OF LO LEVEL CONVERGENCE TO DROP INTO NRN OH THIS AFTN. THIS WL BE THE FOCUS FOR SCTD CONVECTION WITH BOUNDARY LAYER INSTABILITY EXPECTED TO BE BETWEEN 1000-1500 J/KG. HAVE CONTD MENTION OF TSTMS IN CNTRL OH TAF SITES. FURTHER SOUTH...LACK OF SIGNIFICANT FORCING ALONG WITH CAP SHUD INHIBIT THE DEVELOPMENT OF DEEP CONVECTION. WITH INCREASED SFC DEWPOINTS...LIGHT WINDS AND SOME CLEARING TNGT HAVE MENTION OF FOG AT ALL TAF SITES TNGT. FRONT TO SHIFT NORTH ON FRIDAY WITH ALL TAF SITES DRY. && .PREV DISCUSSION... /ISSUED 1122 AM EDT THU AUG 24 2006/ SHORT TERM /REST OF TODAY/... UPPER LEVEL RIDGE CENTERED OVER THE PLAINS WITH NWRLY FLO ACRS THE GREAT LAKES/OHIO VALLEY. EMBEDDED SHORT WAVE DROPPING SE THROUGH THE SRN GREAT LAKES. AN AXIS OF LO LEVEL CONVERGENCE TO DROP INTO NRN OH TDA. THIS WL BE THE FOCUS FOR SCTD CONVECTION WITH BOUNDARY LAYER INSTABILITY EXPECTED TO BE BETWEEN 1000-1500 J/KG. HAVE CONTD MENTION OF CHC/SLIGHT CHC OF AFTN/ERLY EVENING CONVECTION ACRS THE NORTH. FURTHER SOUTH...LACK OF SIGNIFICANT FORCING ALONG WITH CAP SHUD INHIBIT THE DEVELOPMENT OF DEEP CONVECTION. HAVE ADJUSTED CLOUD COVER INCREASING CLDS WITH A GOOD DEAL OF DEBRIS CLOUDINESS EXPECTED. OTHERWISE...LITTLE CHANGE TO CURRENT FORECAST. PREV DISCUSSION... /ISSUED 346 AM EDT THU AUG 24 2006/ SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... WARM FRNTL BNDRY LOCATED FROM SRN MINNESOTA/WISCONSIN SE INTO NRN PORTIONS OF INDIANA AND OHIO EARLY THIS MRNG. SVRL TSTM CLUSTERS MOVING SE ALONG BNDRY...AIDED BY MID LVL S/WV WITH ELONGATED VORT LOBE ACRS LK MICHIGAN AND WEAK 850 LLJ. TSTMS HAVING A HARD TIME SUSTAINING INTENSITY AS THEY MOVE INTO A RELATIVELY DRY AIRMASS WITH DEWPTS IN THE 50S IN PLACE OVER NRN OHIO. SKIES WERE MSTLY CLR TO THE SOUTH OF THE FRNTL BNDRY. TEMPS WERE GENERALLY IN THE L/M60S ATTM. HAVE SEEN SOME OBS REPORTING VSBY RESTRICTIONS ALONG AND EAST OF I-71 WHERE DEWPTS ARE RUNNING SLIGHTLY HIGHER THIS MRNG. HAVE INSERTED PTCHY FOG IN THESE AREAS THRU 13Z TO ACCOUNT. OTHERWISE...FRNTL BNDRY WILL ACT AS FOCUSING MECHANISM FOR TSTM ACTIVITY INTO AFTN HOURS. MAIN S/WV RIDING ALONG FRNTL BNDRY WILL DROP SE INTO NRN OHIO BY ERLY THIS AFTN. MUCH OF THE MODEL DATA THIS MRNG INDCG FRNTL BNDRY TO MOVE LITTLE FROM ITS CURRENT POSN...WITH MUCH OF THE TSTM ACTIVITY AFFECTING NRN OHIO. 00Z NAM WAS ONLY MODEL RUN THAT BROUGHT PCPN CHANCES SOUTH INTO CNTRL PORTIONS OF FCST AREA...POSSIBLY ALONG AN OUTFLOW BNDRY THIS AFTN. WITH SOME WEAK CAPPING IN PLACE ACRS SRN 2/3 FCST AREA TODAY AND DRIER AIR WITHIN THE BNDRY LYR...FEEL PCPN WILL HAVE A HARD TIME DVLPG MUCH FURTHER SOUTH THAN I-70. GFS...RUC AND SREF ALL FOCUS HEAVIEST PCPN THIS MRNG INTO THE AFTN ACRS NRN 1/2 OF OHIO. INSTABILITY AXIS WILL SET UP ALONG AND NORTH OF A WAPAKONETA... COLUMBUS...ZANESVILLE LINE BY LATE MRNG. THIS LINES UP WITH SFC/LO LVL CONV AXIS AS S/WV AND UPR JET PASS TO NORTH. HAVE THUS CONTINUED PCPN CHANCES ACRS NRN 1/3 FCST AREA...INCREASING POPS A BIT AND EXTENDING SCHC POPS A LITTLE FURTHER SOUTH INTO AREAS SE OF CMH METRO. BEST CHANCES THOUGH SHOULD EXIST FROM MERCER CO SE INTO LICKING CO. MUCH OF THE ACTIVITY LATER THIS MRNG INTO AFTN SHOULD REMAIN BELOW SVR LIMITS. PCPN CHANCES WILL END BY LATE AFTN AS S/WV PULLS OFF TO EAST OF REGION. FRNTL BNDRY THEN WILL START TO SLOWLY LIFT NORTH OVERNIGHT IN RESPONSE TO A SFC LO MOVING INTO UPR MISSISSIPPI VLY...AND AN EXPANSION OF THE MID LVL RIDGE FROM THE SOUTHWEST. MID LVL VORT POISED TO SWING THRU SRN LWR MICHIGAN AFT MIDNIGHT...AND MAY SPARK AN ISOLD -SHRA ALONG THE FAR NRN FRINGE OF FCST AREA. CHANCES FOR THIS REMAIN LO ENUF TO KEEP OUT OF ZONE FCST ATTM. FRI WILL SEE RIDGE EXPAND ACRS ENTIRE FCST AREA AS FRNTL BNDRY LIFTS WELL TO NORTH OF REGION. A MOIST SRLY FLOW WILL DVLP BTWN THE AFOREMENTIONED SFC LO TO NW OF REGION AND SFC HI ACRS THE CAROLINAS. THIS WILL BRING A MORE HUMID AIRMASS BACK INTO THE REGION FOR FRI AND EXTNDG INTO SAT. MODEL SOUNDINGS INDCG FAIRLY EXTENSIVE CAP WILL DVLP BY FRI AFTN...AND THIS SHOULD KEEP ANY ISOLD TSTMS FROM DVLPG FRI AND SAT. 00Z MODELS (WITH EXCEPTION OF NAM) NOW A LITTLE MORE PROGRESSIVE WITH COLD FRONT APPCHG FROM NW OVER THE WEEKEND. WHILE GFS SEEMS A LITTLE AGGRESSIVE IN BRINGING FRNTL BNDRY INTO NRN INDIANA AND OHIO BY LATE SAT AFTN...BOTH UKMET AND ECMWF ARE INDCG RIDGE WILL GET SUPPRESSED A BIT TO THE SOUTH SAT NIGHT. FRNTL BNDRY WILL LAY OUT AS IT BECOMES PARALLEL TO UPR FLO. BROUGHT PCPN CHANCES INTO NRN FCST AREA LATE SAT NIGHT AS A RESULT. TEMPS...TRENDED TOWARDS WARM END OF TEMP GUID TODAY...ESPECIALLY ACRS SRN FCST AREA WITH PLENTY OF SUNSHINE EXPECTED. LEANED TOWARDS WARMER MET GUID THIS EVNG...THEN FOLLOWED MAV GUID FOR REMAINDER OF SHORT TERM AS 850 TEMPS CLIMBING TO NEAR 20C SHOULD ENSURE MANY LOCATIONS HITTING 90 DEG FRI AND SAT. RYAN LONG TERM /SUNDAY THROUGH WEDNESDAY/... BROUGHT PCPN CHANCES UP A BIT SUNDAY TO BLEND INTO HIGHER POPS ACRS NRN FCST AREA LATE SAT NIGHT. PCPN LIKELY TO LINGER ACRS FCST AREA INTO FIRST PART OF NEXT WEEK AS BNDRY GETS HUNG UP ACRS OH VLY. RYAN PREV DISCUSSION... /ISSUED 220 PM EDT WED AUG 23 2006/ LONG TERM /SATURDAY THROUGH TUESDAY/... MODELS APPEAR TO BE TRENDING SLOWER WITH APPROACH OF FRONT FOR THIS WEEKEND WITH THE 12Z GFS NOW EVEN SLOWER. HAVE THEREFORE PUSHED BACK TIMING OF PCPN ONSET TO AT LEAST SUNDAY AND AM AFRAID THIS MAY EVEN BE A LITTLE TOO FAST. AHEAD OF THE FRONT...WAA ALLOWING 8H TEMPS TO CLIMB UP CLOSE TO +20 DEGREES CELSIUS SO WILL NUDGE UP HIGHS FOR SATURDAY A TAD. OTHERWISE...WILL GO WITH CHANCE POPS FOR SUNDAY AND SUNDAY NIGHT AND THEN ALLOW FOR PCPN TO TAPER OFF FROM NORTHWEST TO SOUTHEAST THROUGH THE DAY ON MONDAY. HIGH PRESSURE SHOULD THEN BUILD DOWN INTO THE REGION THROUGH THE REST OF THE LONG TERM FORECAST... PROVIDING DRY CONDITIONS AND A RETURN TO MORE SEASONABLE TEMPERATURES. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OHIO 120 PM EDT THU AUG 24 2006 .AVIATION(18Z-18Z)... XPCT STNRY FNT TO RMN OVR OR NR XTRM NRN OH NEXT 24 HRS AS MODELS AGREE ON HOLDING THE FNT STNRY. WK IMPULSES RIDING ESE ALG THE FNT WL CAUSE ON AND OFF CHANCES FOR SHRA AND TSRA THRUT THE PD...ALTHO BETTER CHCS SHUD BE MAINLY THIS AFTN WITH DCR TNGT DUE TO DIURNAL COOLING. THE CURRENT TRACK OF THE ONGOING CONVECTION SHUD KP MOST OF THE NEAR TERM ACTIVITY NE OF TOL...FDY...MFD AND PROB CLE AND CAK ALSO. WIDESPREAD MID AND UPR DEBRIS CLDS MOVG SE ALG THE FRONTAL BAND MAY ACT TO LIMIT INSTABILITY TO KP MOST IF NOT ALL OF THE CONVECTION FROM BCMG STG TO SVR. INCR IN LLVL MSTR WL PROB LEAD TO MVFR FOG TNGT AND CUD EVEN DROP TO IFR IF MORE BREAKS IN CLDS OCCUR THAN EXPECTED ATTM. && .SHORT TERM (TODAY THRU FRI NIGHT)... BOUNDARY EXTENDING FROM LOW IN THE NORTHERN PLAINS ACROSS WESTERN/CENTRAL OHIO MAIN FOCUS OF MCS MOVING ACROSS SOUTHERN WI AND SW LOWER MICHIGAN. TSRA HAVING A HARD TIME PUSHING INTO THE MORE STABLE AIR ACROSS NRN OH. THINGS DESTABLIZE SOME THIS EARLY THIS AFTERNOON WITH CAPES UP TO 1500 J/KG AND SOME LIFT FROM A 500 MB VORT MAX MOVING ACROSS NRN OHIO AND DIVERGENCE FROM THE UPPERL LEVEL JET...BUT MSC ACTIVITY WILL PUSH SOUTH BY MID AFTERNOON BRINING SOME RELIEF. STATIONARY FRONT LINGERS ACROSS OHIO THROUGH THE END OF THE WORK WEEK PROVIDING CONTINUING CHC FOR TSRA. FRONT FINALLY LIFTS NE OF THE FORECAST AREA FRIDAY NIGHT. && .AVIATION(06Z-06Z)... THE FRONT IS GENERALLY FROM SRN LK MI INTO CENTRAL OH. STRONG TO SEVERE STORMS OVR FAR SW LOWER MI ARE BEING FED BY A MOIST/UNSTABLE LAYER AT 850MB AND ARE AT THE NOSE OF THE WEST-EAST ORIENTATED THETA-E RIDGE. ALL OF THE STORMS THAT HAVE MOVED EAST OF KAZO HAVE GENERALLY DISSIPATED DUE TO THE DRY AND STABLE ATMOSPHERE OVER SE LOWER MI INTO NW OH/NE IN. HOWEVER...AS THE FRONT MOVES NORTH TONIGHT AND THE RR QUAD OF THE UPR JET OVR THE NRN LAKES MOVES EAST...EXPECT THE THUNDERSTORM ACTIVITY TO ALSO SPREAD EAST-SOUTHEAST ALONG THE INSTABILITY GRADIENT. THIS WILL TAKE SOME TIME DUE TO DRY AIR IN PLACE ACROSS OHIO...BUT EXPECT THE BEST CHANCE FOR STORMS IN TOL/FDY AFT 10Z AND SPREADING ACROSS THE ENTIRE FORECAST AREA BY 14Z. LOOKS LIKE ERI MAY BE FAR ENOUGH NE AND AWAY FROM THE INSTABILITY GRADIENT TO KEEP OUT THUNDER. WL NEED TO WATCH THE STORMS AS THE APPROACH TOL...AS THE RUC SHOWS AN ELEVATED UNSTABLE LAYER AND 40-50KT DEEP SHEAR WHICH MAY SUGGEST SOME LARGE HAIL ESPECIALLY WITH FREEZING LEVELS AROUND 12KFT. OTHERWISE...CONDITIONS SHOULD IMPROVE THIS AFTN AS THE MCS ACTIVITY MOVES SE. WITH MANY PLACES SEEING RAINFALL TODAY AND CLEARING THIS EVENING...EXPECT SOME MVFR TYPE FOG TO DEVELOP THU EVENING. && .LONG TERM (FRI NIGHT THRU WED)... DRY WARMER AND MORE HUMID CONDITONS ARE EXPECTED SATURDAY WITH A CHANCE OF STORMS FOR SUNDAY AND SUNDAY NGT. THE GFS AND ECMWF APPEAR TO BE FAIRLY SIMILAR THRU THE PERIOD. A COLD FRONTAL PASSAGE IS EXPECTED SUNDAY NIGHT WITH FAIR WEATHER EXPECTED INTO THE MIDDLE OF NEXT WEEK. BY WEDNESDAY A RATHER COOL HIGH PRESSURE AREA IS CURRENTLY FORECAST TO BUILD INTO THE EASTERN LAKES. && .CLE WATCHES/WARNINGS/ADVISORIES... .OH...NONE. .PA...NONE. && $$ SHORT TERM...DJB LONG TERM...REL AVIATION...ADAMS oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1122 AM EDT THU AUG 24 2006 .SHORT TERM /REST OF TODAY/... UPPER LEVEL RIDGE CENTERED OVER THE PLAINS WITH NWRLY FLO ACRS THE GREAT LAKES/OHIO VALLEY. EMBEDDED SHORT WAVE DROPPING SE THROUGH THE SRN GREAT LAKES. AN AXIS OF LO LEVEL CONVERGENCE TO DROP INTO NRN OH TDA. THIS WL BE THE FOCUS FOR SCTD CONVECTION WITH BOUNDARY LAYER INSTABILITY EXPECTED TO BE BETWEEN 1000-1500 J/KG. HAVE CONTD MENTION OF CHC/SLIGHT CHC OF AFTN/ERLY EVENING CONVECTION ACRS THE NORTH. FURTHER SOUTH...LACK OF SIGNIFICANT FORCING ALONG WITH CAP SHUD INHIBIT THE DEVELOPMENT OF DEEP CONVECTION. HAVE ADJUSTED CLOUD COVER INCREASING CLDS WITH A GOOD DEAL OF DEBRIS CLOUDINESS EXPECTED. OTHERWISE...LITTLE CHANGE TO CURRENT FORECAST. && .PREV DISCUSSION... /ISSUED 643 AM EDT THU AUG 24 2006/ AVIATION /12Z-12Z/... LATEST GUIDANCE SUGGESTS THAT TERMINALS WILL PRIMARILY BE AFFECTED BY HIGH CLOUDS COMING FROM CONVECTION PASSING TO THE NORTH OF THE AREA. BUT IT DOES NOT APPEAR THAT THUNDERSTORMS WILL OCCUR AT THE TAF SITES. STILL A BIT OF UNCERTAINTY FOR THE COLUMBUS AREA SO LEFT CB QUALIFIER IN THERE. WINDS WILL REMAIN AT LESS THAN 10 KNOTS BUT VEER TO THE WEST SOUTHWEST. AFTER SUNSET SOME MIST/FOG DEVELOPMENT CAN BE EXPECTED PRIMARILY AT KLUK AND KILN. PREV DISCUSSION... /ISSUED 346 AM EDT THU AUG 24 2006/ SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... WARM FRNTL BNDRY LOCATED FROM SRN MINNESOTA/WISCONSIN SE INTO NRN PORTIONS OF INDIANA AND OHIO EARLY THIS MRNG. SVRL TSTM CLUSTERS MOVING SE ALONG BNDRY...AIDED BY MID LVL S/WV WITH ELONGATED VORT LOBE ACRS LK MICHIGAN AND WEAK 850 LLJ. TSTMS HAVING A HARD TIME SUSTAINING INTENSITY AS THEY MOVE INTO A RELATIVELY DRY AIRMASS WITH DEWPTS IN THE 50S IN PLACE OVER NRN OHIO. SKIES WERE MSTLY CLR TO THE SOUTH OF THE FRNTL BNDRY. TEMPS WERE GENERALLY IN THE L/M60S ATTM. HAVE SEEN SOME OBS REPORTING VSBY RESTRICTIONS ALONG AND EAST OF I-71 WHERE DEWPTS ARE RUNNING SLIGHTLY HIGHER THIS MRNG. HAVE INSERTED PTCHY FOG IN THESE AREAS THRU 13Z TO ACCOUNT. OTHERWISE...FRNTL BNDRY WILL ACT AS FOCUSING MECHANISM FOR TSTM ACTIVITY INTO AFTN HOURS. MAIN S/WV RIDING ALONG FRNTL BNDRY WILL DROP SE INTO NRN OHIO BY ERLY THIS AFTN. MUCH OF THE MODEL DATA THIS MRNG INDCG FRNTL BNDRY TO MOVE LITTLE FROM ITS CURRENT POSN...WITH MUCH OF THE TSTM ACTIVITY AFFECTING NRN OHIO. 00Z NAM WAS ONLY MODEL RUN THAT BROUGHT PCPN CHANCES SOUTH INTO CNTRL PORTIONS OF FCST AREA...POSSIBLY ALONG AN OUTFLOW BNDRY THIS AFTN. WITH SOME WEAK CAPPING IN PLACE ACRS SRN 2/3 FCST AREA TODAY AND DRIER AIR WITHIN THE BNDRY LYR...FEEL PCPN WILL HAVE A HARD TIME DVLPG MUCH FURTHER SOUTH THAN I-70. GFS...RUC AND SREF ALL FOCUS HEAVIEST PCPN THIS MRNG INTO THE AFTN ACRS NRN 1/2 OF OHIO. INSTABILITY AXIS WILL SET UP ALONG AND NORTH OF A WAPAKONETA... COLUMBUS...ZANESVILLE LINE BY LATE MRNG. THIS LINES UP WITH SFC/LO LVL CONV AXIS AS S/WV AND UPR JET PASS TO NORTH. HAVE THUS CONTINUED PCPN CHANCES ACRS NRN 1/3 FCST AREA...INCREASING POPS A BIT AND EXTENDING SCHC POPS A LITTLE FURTHER SOUTH INTO AREAS SE OF CMH METRO. BEST CHANCES THOUGH SHOULD EXIST FROM MERCER CO SE INTO LICKING CO. MUCH OF THE ACTIVITY LATER THIS MRNG INTO AFTN SHOULD REMAIN BELOW SVR LIMITS. PCPN CHANCES WILL END BY LATE AFTN AS S/WV PULLS OFF TO EAST OF REGION. FRNTL BNDRY THEN WILL START TO SLOWLY LIFT NORTH OVERNIGHT IN RESPONSE TO A SFC LO MOVING INTO UPR MISSISSIPPI VLY...AND AN EXPANSION OF THE MID LVL RIDGE FROM THE SOUTHWEST. MID LVL VORT POISED TO SWING THRU SRN LWR MICHIGAN AFT MIDNIGHT...AND MAY SPARK AN ISOLD -SHRA ALONG THE FAR NRN FRINGE OF FCST AREA. CHANCES FOR THIS REMAIN LO ENUF TO KEEP OUT OF ZONE FCST ATTM. FRI WILL SEE RIDGE EXPAND ACRS ENTIRE FCST AREA AS FRNTL BNDRY LIFTS WELL TO NORTH OF REGION. A MOIST SRLY FLOW WILL DVLP BTWN THE AFOREMENTIONED SFC LO TO NW OF REGION AND SFC HI ACRS THE CAROLINAS. THIS WILL BRING A MORE HUMID AIRMASS BACK INTO THE REGION FOR FRI AND EXTNDG INTO SAT. MODEL SOUNDINGS INDCG FAIRLY EXTENSIVE CAP WILL DVLP BY FRI AFTN...AND THIS SHOULD KEEP ANY ISOLD TSTMS FROM DVLPG FRI AND SAT. 00Z MODELS (WITH EXCEPTION OF NAM) NOW A LITTLE MORE PROGRESSIVE WITH COLD FRONT APPCHG FROM NW OVER THE WEEKEND. WHILE GFS SEEMS A LITTLE AGGRESSIVE IN BRINGING FRNTL BNDRY INTO NRN INDIANA AND OHIO BY LATE SAT AFTN...BOTH UKMET AND ECMWF ARE INDCG RIDGE WILL GET SUPPRESSED A BIT TO THE SOUTH SAT NIGHT. FRNTL BNDRY WILL LAY OUT AS IT BECOMES PARALLEL TO UPR FLO. BROUGHT PCPN CHANCES INTO NRN FCST AREA LATE SAT NIGHT AS A RESULT. TEMPS...TRENDED TOWARDS WARM END OF TEMP GUID TODAY...ESPECIALLY ACRS SRN FCST AREA WITH PLENTY OF SUNSHINE EXPECTED. LEANED TOWARDS WARMER MET GUID THIS EVNG...THEN FOLLOWED MAV GUID FOR REMAINDER OF SHORT TERM AS 850 TEMPS CLIMBING TO NEAR 20C SHOULD ENSURE MANY LOCATIONS HITTING 90 DEG FRI AND SAT. RYAN LONG TERM /SUNDAY THROUGH WEDNESDAY/... BROUGHT PCPN CHANCES UP A BIT SUNDAY TO BLEND INTO HIGHER POPS ACRS NRN FCST AREA LATE SAT NIGHT. PCPN LIKELY TO LINGER ACRS FCST AREA INTO FIRST PART OF NEXT WEEK AS BNDRY GETS HUNG UP ACRS OH VLY. RYAN PREV DISCUSSION... /ISSUED 220 PM EDT WED AUG 23 2006/ LONG TERM /SATURDAY THROUGH TUESDAY/... MODELS APPEAR TO BE TRENDING SLOWER WITH APPROACH OF FRONT FOR THIS WEEKEND WITH THE 12Z GFS NOW EVEN SLOWER. HAVE THEREFORE PUSHED BACK TIMING OF PCPN ONSET TO AT LEAST SUNDAY AND AM AFRAID THIS MAY EVEN BE A LITTLE TOO FAST. AHEAD OF THE FRONT...WAA ALLOWING 8H TEMPS TO CLIMB UP CLOSE TO +20 DEGREES CELSIUS SO WILL NUDGE UP HIGHS FOR SATURDAY A TAD. OTHERWISE...WILL GO WITH CHANCE POPS FOR SUNDAY AND SUNDAY NIGHT AND THEN ALLOW FOR PCPN TO TAPER OFF FROM NORTHWEST TO SOUTHEAST THROUGH THE DAY ON MONDAY. HIGH PRESSURE SHOULD THEN BUILD DOWN INTO THE REGION THROUGH THE REST OF THE LONG TERM FORECAST... PROVIDING DRY CONDITIONS AND A RETURN TO MORE SEASONABLE TEMPERATURES. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OHIO 730 AM EDT THU AUG 24 2006 .AVIATION(12Z-12Z)... IT LOOKS LIKE THE FRONT IS NOW RIGHT ALONG SRN LAKE ERIE SHORELINE. THERE ARE TWO AREAS OF PCPN...ONE AREA ASSOCIATED WITH THE LOW LVL JET OVER SE LOWER MI/NW OH...AND THE OTHER AREA OVER LKERI INTO ERIE PA ASSOCIATED WITH THE WARM ADVECTION N OF THE FRONT. THE MODELS HAVE A DECENT HANDLE ON THE SE MI PCPN...BUT THEY DO NOT HAVE A CLUE ABOUT THE PCPN OVR LKERI. WITH THAT IN MIND...HAVE LOW CONFIDENCE IN THE MODEL SOLNS TODAY. WITH THE FRONT STAYING NEARBY ALL DAY...IT SEEMS HARD TO BELIEVE THAT THERE IS NOT AT LEAST A CHANCE OF SHOWERS/STORMS ALL DAY FOR THE ENTIRE REGION. IN FACT...THE NAM DOES SUGGEST THAT STORMS WILL DEVELOP THIS AFTN ESPECIALLY WHERE DAYTIME HEATING OCCURS ACROSS THE SOUTH. WL THEREFORE KEEP A CHC OF STORMS FOR INLAND SITES THIS AFTN. NONE OF THE UPSTREAM OBS HAVE CIGS TOO LOW ATTM...AND IT IS EXPECTED THAT CIGS WILL NOT BECOME TOO LOW TODAY ACROSS THE AREA...GENERALLY MVFR AT TIMES. AS THE FRONT MOVES N TONIGHT...SCT STORMS MAY DEVELOP AND MOVE ACROSS THE REGION. WL ADD PROB30 GROUPS TO ACCT FOR THIS. && .SHORT TERM (TODAY THRU FRI NIGHT)... BOUNDARY EXTENDING FROM LOW IN THE NORTHERN PLAINS ACROSS WESTERN/CENTRAL OHIO MAIN FOCUS OF MCS MOVING ACROSS SOUTHERN WI AND SW LOWER MICHIGAN. TSRA HAVING A HARD TIME PUSHING INTO THE MORE STABLE AIR ACROSS NRN OH. THINGS DESTABLIZE SOME THIS EARLY THIS AFTERNOON WITH CAPES UP TO 1500 J/KG AND SOME LIFT FROM A 500 MB VORT MAX MOVING ACROSS NRN OHIO AND DIVERGENCE FROM THE UPPERL LEVEL JET...BUT MSC ACTIVITY WILL PUSH SOUTH BY MID AFTERNOON BRINING SOME RELIEF. STATIONARY FRONT LINGERS ACROSS OHIO THROUGH THE END OF THE WORK WEEK PROVIDING CONTINUING CHC FOR TSRA. FRONT FINALLY LIFTS NE OF THE FORECAST AREA FRIDAY NIGHT. && .AVIATION(06Z-06Z)... THE FRONT IS GENERALLY FROM SRN LK MI INTO CENTRAL OH. STRONG TO SEVERE STORMS OVR FAR SW LOWER MI ARE BEING FED BY A MOIST/UNSTABLE LAYER AT 850MB AND ARE AT THE NOSE OF THE WEST-EAST ORIENTATED THETA-E RIDGE. ALL OF THE STORMS THAT HAVE MOVED EAST OF KAZO HAVE GENERALLY DISSIPATED DUE TO THE DRY AND STABLE ATMOSPHERE OVER SE LOWER MI INTO NW OH/NE IN. HOWEVER...AS THE FRONT MOVES NORTH TONIGHT AND THE RR QUAD OF THE UPR JET OVR THE NRN LAKES MOVES EAST...EXPECT THE THUNDERSTORM ACTIVITY TO ALSO SPREAD EAST-SOUTHEAST ALONG THE INSTABILITY GRADIENT. THIS WILL TAKE SOME TIME DUE TO DRY AIR IN PLACE ACROSS OHIO...BUT EXPECT THE BEST CHANCE FOR STORMS IN TOL/FDY AFT 10Z AND SPREADING ACROSS THE ENTIRE FORECAST AREA BY 14Z. LOOKS LIKE ERI MAY BE FAR ENOUGH NE AND AWAY FROM THE INSTABILITY GRADIENT TO KEEP OUT THUNDER. WL NEED TO WATCH THE STORMS AS THE APPROACH TOL...AS THE RUC SHOWS AN ELEVATED UNSTABLE LAYER AND 40-50KT DEEP SHEAR WHICH MAY SUGGEST SOME LARGE HAIL ESPECIALLY WITH FREEZING LEVELS AROUND 12KFT. OTHERWISE...CONDITIONS SHOULD IMPROVE THIS AFTN AS THE MCS ACTIVITY MOVES SE. WITH MANY PLACES SEEING RAINFALL TODAY AND CLEARING THIS EVENING...EXPECT SOME MVFR TYPE FOG TO DEVELOP THU EVENING. && .LONG TERM (FRI NIGHT THRU WED)... DRY WARMER AND MORE HUMID CONDITONS ARE EXPECTED SATURDAY WITH A CHANCE OF STORMS FOR SUNDAY AND SUNDAY NGT. THE GFS AND ECMWF APPEAR TO BE FAIRLY SIMILAR THRU THE PERIOD. A COLD FRONTAL PASSAGE IS EXPECTED SUNDAY NIGHT WITH FAIR WEATHER EXPECTED INTO THE MIDDLE OF NEXT WEEK. BY WEDNESDAY A RATHER COOL HIGH PRESSURE AREA IS CURRENTLY FORECAST TO BUILD INTO THE EASTERN LAKES. && .CLE WATCHES/WARNINGS/ADVISORIES... .OH...NONE. .PA...NONE. && $$ SHORT TERM...DJB LONG TERM...REL AVIATION...MRD oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 643 AM EDT THU AUG 24 2006 .AVIATION /12Z-12Z/... LATEST GUIDANCE SUGGESTS THAT TERMINALS WILL PRIMARILY BE AFFECTED BY HIGH CLOUDS COMING FROM CONVECTION PASSING TO THE NORTH OF THE AREA. BUT IT DOES NOT APPEAR THAT THUNDERSTORMS WILL OCCUR AT THE TAF SITES. STILL A BIT OF UNCERTAINTY FOR THE COLUMBUS AREA SO LEFT CB QUALIFIER IN THERE. WINDS WILL REMAIN AT LESS THAN 10 KNOTS BUT VEER TO THE WEST SOUTHWEST. AFTER SUNSET SOME MIST/FOG DEVELOPMENT CAN BE EXPECTED PRIMARILY AT KLUK AND KILN. && .PREV DISCUSSION... /ISSUED 346 AM EDT THU AUG 24 2006/ SHORT TERM /TODAY THROUGH SATURDAY NIGHT/... WARM FRNTL BNDRY LOCATED FROM SRN MINNESOTA/WISCONSIN SE INTO NRN PORTIONS OF INDIANA AND OHIO EARLY THIS MRNG. SVRL TSTM CLUSTERS MOVING SE ALONG BNDRY...AIDED BY MID LVL S/WV WITH ELONGATED VORT LOBE ACRS LK MICHIGAN AND WEAK 850 LLJ. TSTMS HAVING A HARD TIME SUSTAINING INTENSITY AS THEY MOVE INTO A RELATIVELY DRY AIRMASS WITH DEWPTS IN THE 50S IN PLACE OVER NRN OHIO. SKIES WERE MSTLY CLR TO THE SOUTH OF THE FRNTL BNDRY. TEMPS WERE GENERALLY IN THE L/M60S ATTM. HAVE SEEN SOME OBS REPORTING VSBY RESTRICTIONS ALONG AND EAST OF I-71 WHERE DEWPTS ARE RUNNING SLIGHTLY HIGHER THIS MRNG. HAVE INSERTED PTCHY FOG IN THESE AREAS THRU 13Z TO ACCOUNT. OTHERWISE...FRNTL BNDRY WILL ACT AS FOCUSING MECHANISM FOR TSTM ACTIVITY INTO AFTN HOURS. MAIN S/WV RIDING ALONG FRNTL BNDRY WILL DROP SE INTO NRN OHIO BY ERLY THIS AFTN. MUCH OF THE MODEL DATA THIS MRNG INDCG FRNTL BNDRY TO MOVE LITTLE FROM ITS CURRENT POSN...WITH MUCH OF THE TSTM ACTIVITY AFFECTING NRN OHIO. 00Z NAM WAS ONLY MODEL RUN THAT BROUGHT PCPN CHANCES SOUTH INTO CNTRL PORTIONS OF FCST AREA...POSSIBLY ALONG AN OUTFLOW BNDRY THIS AFTN. WITH SOME WEAK CAPPING IN PLACE ACRS SRN 2/3 FCST AREA TODAY AND DRIER AIR WITHIN THE BNDRY LYR...FEEL PCPN WILL HAVE A HARD TIME DVLPG MUCH FURTHER SOUTH THAN I-70. GFS...RUC AND SREF ALL FOCUS HEAVIEST PCPN THIS MRNG INTO THE AFTN ACRS NRN 1/2 OF OHIO. INSTABILITY AXIS WILL SET UP ALONG AND NORTH OF A WAPAKONETA... COLUMBUS...ZANESVILLE LINE BY LATE MRNG. THIS LINES UP WITH SFC/LO LVL CONV AXIS AS S/WV AND UPR JET PASS TO NORTH. HAVE THUS CONTINUED PCPN CHANCES ACRS NRN 1/3 FCST AREA...INCREASING POPS A BIT AND EXTENDING SCHC POPS A LITTLE FURTHER SOUTH INTO AREAS SE OF CMH METRO. BEST CHANCES THOUGH SHOULD EXIST FROM MERCER CO SE INTO LICKING CO. MUCH OF THE ACTIVITY LATER THIS MRNG INTO AFTN SHOULD REMAIN BELOW SVR LIMITS. PCPN CHANCES WILL END BY LATE AFTN AS S/WV PULLS OFF TO EAST OF REGION. FRNTL BNDRY THEN WILL START TO SLOWLY LIFT NORTH OVERNIGHT IN RESPONSE TO A SFC LO MOVING INTO UPR MISSISSIPPI VLY...AND AN EXPANSION OF THE MID LVL RIDGE FROM THE SOUTHWEST. MID LVL VORT POISED TO SWING THRU SRN LWR MICHIGAN AFT MIDNIGHT...AND MAY SPARK AN ISOLD -SHRA ALONG THE FAR NRN FRINGE OF FCST AREA. CHANCES FOR THIS REMAIN LO ENUF TO KEEP OUT OF ZONE FCST ATTM. FRI WILL SEE RIDGE EXPAND ACRS ENTIRE FCST AREA AS FRNTL BNDRY LIFTS WELL TO NORTH OF REGION. A MOIST SRLY FLOW WILL DVLP BTWN THE AFOREMENTIONED SFC LO TO NW OF REGION AND SFC HI ACRS THE CAROLINAS. THIS WILL BRING A MORE HUMID AIRMASS BACK INTO THE REGION FOR FRI AND EXTNDG INTO SAT. MODEL SOUNDINGS INDCG FAIRLY EXTENSIVE CAP WILL DVLP BY FRI AFTN...AND THIS SHOULD KEEP ANY ISOLD TSTMS FROM DVLPG FRI AND SAT. 00Z MODELS (WITH EXCEPTION OF NAM) NOW A LITTLE MORE PROGRESSIVE WITH COLD FRONT APPCHG FROM NW OVER THE WEEKEND. WHILE GFS SEEMS A LITTLE AGGRESSIVE IN BRINGING FRNTL BNDRY INTO NRN INDIANA AND OHIO BY LATE SAT AFTN...BOTH UKMET AND ECMWF ARE INDCG RIDGE WILL GET SUPPRESSED A BIT TO THE SOUTH SAT NIGHT. FRNTL BNDRY WILL LAY OUT AS IT BECOMES PARALLEL TO UPR FLO. BROUGHT PCPN CHANCES INTO NRN FCST AREA LATE SAT NIGHT AS A RESULT. TEMPS...TRENDED TOWARDS WARM END OF TEMP GUID TODAY...ESPECIALLY ACRS SRN FCST AREA WITH PLENTY OF SUNSHINE EXPECTED. LEANED TOWARDS WARMER MET GUID THIS EVNG...THEN FOLLOWED MAV GUID FOR REMAINDER OF SHORT TERM AS 850 TEMPS CLIMBING TO NEAR 20C SHOULD ENSURE MANY LOCATIONS HITTING 90 DEG FRI AND SAT. RYAN LONG TERM /SUNDAY THROUGH WEDNESDAY/... BROUGHT PCPN CHANCES UP A BIT SUNDAY TO BLEND INTO HIGHER POPS ACRS NRN FCST AREA LATE SAT NIGHT. PCPN LIKELY TO LINGER ACRS FCST AREA INTO FIRST PART OF NEXT WEEK AS BNDRY GETS HUNG UP ACRS OH VLY. RYAN PREV DISCUSSION... /ISSUED 220 PM EDT WED AUG 23 2006/ LONG TERM /SATURDAY THROUGH TUESDAY/... MODELS APPEAR TO BE TRENDING SLOWER WITH APPROACH OF FRONT FOR THIS WEEKEND WITH THE 12Z GFS NOW EVEN SLOWER. HAVE THEREFORE PUSHED BACK TIMING OF PCPN ONSET TO AT LEAST SUNDAY AND AM AFRAID THIS MAY EVEN BE A LITTLE TOO FAST. AHEAD OF THE FRONT...WAA ALLOWING 8H TEMPS TO CLIMB UP CLOSE TO +20 DEGREES CELSIUS SO WILL NUDGE UP HIGHS FOR SATURDAY A TAD. OTHERWISE...WILL GO WITH CHANCE POPS FOR SUNDAY AND SUNDAY NIGHT AND THEN ALLOW FOR PCPN TO TAPER OFF FROM NORTHWEST TO SOUTHEAST THROUGH THE DAY ON MONDAY. HIGH PRESSURE SHOULD THEN BUILD DOWN INTO THE REGION THROUGH THE REST OF THE LONG TERM FORECAST... PROVIDING DRY CONDITIONS AND A RETURN TO MORE SEASONABLE TEMPERATURES. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ oh AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 1000 AM CDT THU AUG 24 2006 .DISCUSSION... WRMFNT LOCATED FM HON-BKX-MML AT 15Z WITH SFC LOW NR MHE. RUC LIFTS WRMFNT N OF A BKX/MML LINE THIS AFTN WHILE LATEST ANM PUSHES IT BACK S OF I90. THE NAM SOLUTION LOOKS UNREASONABLE AND FEEL FNT WL PBLY REMAIN FAIRLY STNRY THRU THE AFTN. S OF WRMFNT...AIRMASS IS CAPPED WITH +14 DEG AT H7 THRU 00Z. MAY EVEN BE CAPPED OFF ACRS NRN CWA THRU AFTN. IF ANYTHING DOES GET GOING...EXPECT IT TO BE N OF WRMFNT AND FEEL MOD RISK A TAD TOO FAR SOUTH. TOR POT WL EXIST THRU THIS EVE MAINLY NE OF A BKX-MWM LINE. TO S OF FNT...ANY THRW THAT DO FIRE UP WL HAVE TO BE ALONG CDFNT AND WL BE DEPENDENT ON WHETHER CAP WL BREAK. IF THIS DOES OCCUR...CHC OF TRW WL LIKELY BE AFT 23Z/00Z. FOR NOW WL KEEP HIGHEST POPS N OF WRMFNT THRU THIS EVE...WITH ONLY A CHC TO THE S. MADE A FEW ADJUSTMENTS TO TEMPS ACRS NRN CWA WHERE STRATUS HAS FORMED N OF WRMFNT...AND ALSO LOWERED A FEW DEG FAR WEST WHERE SFC TROF HAS SHIFTED WINDS TO THE NW AND THICKER MID AND HIGH CLOOUDS WL PERSIST. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SALT LAKE CITY UT 955 PM MDT THU AUG 24 2006 .SYNOPSIS...A PACIFIC TROUGH WILL GRADUALLY MOVE THROUGH THE NORTHERN GREAT BASIN TONIGHT THROUGH SATURDAY...PUSHING A COLD FRONT THROUGH THE AREA. HIGH PRESSURE WILL BUILD ACROSS THE REGION SUNDAY THROUGH EARLY NEXT WEEK. && .DISCUSSION...SHORTWAVE TROUGH EVIDENT IN EVENING WATER VAPOR IMAGERY CONTINUES TO ROTATE OVER EASTERN OREGON/WESTERN ID...WITH ASSOCIATED SURFACE FRONT STRETCHING STRETCHING FROM EASTERN ID BACK INTO NORTHWEST UT. JET ON DOWNSTREAM SIDE OF TROUGH EXTENDS ACROSS WY WITH ENTRANCE REGION ACROSS CENTRAL UT. NAM/RUC MODELS HAVE BEEN FORECASTING AREA OF CONVECTION TO DEVELOP WITH ENTRANCE REGION TO JET THIS EVENING ACROSS EAST CENTRAL NV THEN SPREAD ACROSS THE WASATCH FRONT AFTER MIDNIGHT. HOWEVER THIS AREA OF PRECIPITATION HAS YET TO DEVELOP...WITH BROAD CLOUD SHIELD ASSOCIATED WITH APPROACHING TROUGH AXIS CURRENTLY SPREADING ACROSS NORTHEAST NV. THINK MOST LIKELY SCENARIO IS FOR CONVECTION TO CONTINUE TO FIRE A LITTLE FURTHER SOUTH NEAR STALLED FRONTAL BOUNDARY ACROSS CENTRAL UT...ROUGHLY ALONG A LINE FROM DELTA TO DUCHESNE. HAVE UPDATED FORECAST TO INCLUDE CHANCE POPS ACROSS THIS AREA. FURTHER SOUTH WHERE BETTER MOISTURE RESIDES EXPECT TO SEE SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE ACROSS SOUTHEAST CWA THROUGH THE OVERNIGHT HOURS. TROUGH PROGGED TO SLOWLY DEEPEN AS IT GRADUALLY SPREADS ACROSS THE REGION THROUGH SUNDAY. THIS WILL ALLOW MUCH COOLER AIR TO FILTER INTO THE AREA...WITH 700MB TEMPS SUNDAY PROGGED NEAR 7C ON THE NAM. AS THIS TROUGH GRADUALLY TRANSLATES AWAY FROM THE REGION BROAD RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE AREA FOR THE LATTER HALF OF THE WEEKEND INTO EARLY NEXT WEEK RESULTING IN DRY CONDITIONS. && .FIRE WEATHER...COLD FRONT CURRENTLY MOVING INTO NORTHWEST UT WILL RESULT IN GUSTY NORTHWEST WINDS OVERNIGHT. THIS COMBINED WITH LOW RH MAY RESULT IN NEAR CRITICAL FIRE WEATHER CONDITIONS ACROSS ZONE 420 AT TIMES THIS EVENING. OTHERWISE A COOLER AND MORE STABLE AIRMASS WILL SLOWLY SPREAD ACROSS THE DISTRICT FOR THE WEEKEND INTO EARLY NEXT WEEK. && .AVIATION...NORTH WINDS CURRENTLY OBSERVED AT KSLC SHOULD PERSIST THROUGH MUCH OF THE NIGHT AS SURFACE FRONT MOVES SOUTH OF THE TERMINAL. SOUTHERLY DRAINAGE WINDS EXPECTED TO REDEVELOP LATE TONIGHT. OTHERWISE EARLY LAKE BREEZE EXPECTED AGAIN FRIDAY WITH NORTHERLY PRESSURE GRADIENT. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...NONE. WY...NONE. && $$ SEAMAN ut AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BLACKSBURG VA 848 PM EDT THU AUG 24 2006 .SHORT TERM /REST OF TONIGHT/... SCENARIO THIS EVENING SIMILAR TO THE PAST FEW NIGHTS WITH DEWPOINT GRADIENT ACROSS THE SOUTH AND THETA-E RIDGE SW PROVIDING FOCUS/INSTABILITY FOR ISOLATED CONVECTION. AGAIN WITH THE AREA UNDER WEAK RIDGING BETWEEN FRONTS...AND LACK OF SUPPORT ALOFT...WOULD EXPECT MOST SHRA/TSRA TO FADE BY MIDNIGHT SIMILAR TO THE LATEST RUC. POSSIBLE TO SEE AN ISOLATED SHRA DRIFT SE ACROSS THE FAR NORTH LATER GIVEN TRAJECTORIES BUT LIKELY JUST MORE CLOUDS AT THIS POINT. OTHERWISE MORE VALLEY FOG AROUND AGAIN TONIGHT GIVEN SOME NORTHWARD INCREASE IN DEWPOINTS AND LIGHT WINDS. WILL ALSO RAISE TEMPS A LITTLE SOUTHERN ZONES WHERE THINGS REMAIN A BIT MORE MOIST FOR NOW. && .PREV DISCUSSION... (ISSUED 718 PM EDT THU AUG 24 2006) AVIATION... BIGGEST CONCERN THRU THE TAF PERIOD IS OVERNIGHT FOG. WITH WEAK SFC RIDGE DRIFTING OVR THE REGION WILL SEE LIGHT/CALM WINDS OVERNIGHT AND RIVER/VALLEY FOG LIKELY TO DEVELOP. HAVE PLAYED THINGS QUITE SIMILAR TO WHAT OCCURRED LAST NIGHT FOR THE NEW SET OF TAFS...WITH THE MOST DENSE FOG LIKELY TO BE FOUND AROUND KLWB WITH VLIFR CONDITIONS LIKELY LATE TONIGHT. ELSEWHERE...MAINLY A COMBO OF MVFR/IFR EXCEPT AROUND KROA WHERE VISBYS SHOULD STAY VFR. COULD SEE A BRIEF PERIOD OF LOWER CLDS ACRS NORTHWEST NORTH CAROLINA AND FAR SOUTHWEST VIRGINIA GIVEN CONTINUED WEAK UPSLOPE REGIME...ALTHOUGH ANTICIPATE AS FLOW BEGINS TO TURN MORE SOUTHWEST THINGS WILL SCOUR OUT OVERNIGHT. OTHERWISE...JUST A TAD MORE WIND TOMORROW AS RIDGE SLIDES EAST OF THE AREA BUT VFR CONDITIONS EXPECTED. PREV DISCUSSION... (ISSUED 319 PM EDT THU AUG 24 2006) SHORT TERM /TONIGHT/... CURRENT ISOLATED SHOWERS AND STORMS HAVE FORMED ALONG A WEST-EAST DEW POINT GRADIENT DURING THE PEAK HEATING OF THE DAY...ALONG AND NEAR THE KMTV-KDAN AREA. EXPECT THESE ISOLATED CELLS TO CONTINUE THROUGH AROUND SUNSET THEN DISSIPATE. OTHER ISOLATED CELLS HAVE FORMED ALONG THE MOUNTAINS OF NORTHWEST NORTH CAROLINA DUE TO BOTH HEATING AND WIND CONVERGENCE. ALSO EXPECT THESE TO CONTINUE THROUGH AROUND SUNSET. THERE WAS EARLIER CONCERN THAT CONVECTION IN ASSOCIATION WITH A SHORTWAVE TROUGH MOVING THROUGH PA/MD/NORTHERN VA MIGHT CLIP NORTHERN AND NORTHEASTERN PARTS OF THE REGION. HAVE REMOVED PRECIPITATION CHANCES THIS EVENING FROM THIS AREA. BELIEVE ANY PRECIPITATION ASSOCIATED WITH THE FEATURE WOULD ENCOUNTER STRONG STABLE LAYER ONCE THE INVERSION FORMS...AND NOT MAKE IT INTO THE REGION. HAVE ADDED THE POTENTIAL FOR VALLEY FOG PARTS OF THE AREA. LONG TERM /FRIDAY THROUGH THURSDAY/... GOING WITH A DRY FORECAST FRIDAY THROUGH EARLY SUNDAY WITH HIGH PRESSURE KEEPING A STRONG HOLD ON OUR WEATHER PATTERN. WILL FAVOR TEMPERATURES A FEW DEGREES WARMER THAN THE MAV MOS GUIDANCE IN MOST LOCATIONS. EARLY NEXT WEEK A COLD FRONT WILL APPROACH AND THEN MOVE THROUGH THE AREA. HAVE FOLLOWED THE HPC DEPICTION AND GRIDS ASSOCIATED WITH THE FRONTAL PASSAGE. THIS PLACES THE GREATEST CHANCE OF SHOWERS AND STORMS MONDAY NIGHT INTO TUESDAY...WITH DECREASING CHANCES HEADING INTO WEDNESDAY AND THURSDAY AS THE FRONT MOVES SOUTH OF THE AREA. AVIATION... AN ISOLATED SHOWER IS NEAR THE DANVILLE AIRPORT AT THIS TIME...AND LOOKS LIKE IT MAY BRING A SHOWER RIGHT AROUND 18Z...SO I INCLUDED A 1 HOUR TEMPO GROUP THERE. OTHERWISE...LOOKS LIKE ANY AFT/EVE CONVECTION WILL STAY EITHER WELL TO THE NORTH...OR TO THE SOUTH...OF OUR 5 SITES. WILL BE ANOTHER MOSTLY CLEAR NIGHT WITH LIGHT WINDS...SO I INCLUDED A PERIOD OF MVFR FOG AT BLF...LYH AND DAN...WITH A BRIEF PERIOD OF IFR FOG AT DAN SIMILAR TO THIS MORNING. LWB SHOULD ONCE AGAIN DROP DOWN TO LIFR TOWARD MORNING WITH RIVER FOG. ALL FOG IS EXPECTED TO BURN OFF BY A FEW HOURS AFTER SUNRISE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ JH va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 910 PM EDT THU AUG 24 2006 .SHORT TERM /REST OF TONIGHT/... ISOLD RW/TRW CONT TO PASS JUST N OF THE FCST AREA...WHILE SCT-BKN CI CONT TO FILTER IN FM UPSTREAM MCS WHICH IS RAPIDLY DIMINISHING. VLY FG WL ONCE AGAIN DEVELOP DURING THE PREDAWN HRS WITH NO PCPN FCST OVRNGT. UPDATED GRIDS AND ZFP TO REMOVE SCHC POPS ACR FAR N. TEMPS ON TARGET...THEREFORE NO CHANGES NEEDED. && .PREV DISCUSSION... /ISSUED 730 PM EDT THU AUG 24 2006/ AVIATION /00Z TO 00Z/... NEARLY A REPEAT OF LAST NGT WITH LIFR/IFR FG DEVELOPING OVRNGT AT CRW/EKN/PKB/HTS UNDER A MCLR SKY AND LGT WINDS. DIFFERENCE BEING BLOW OFF CLDS FM UPSTREAM TRW COMPLEX DAMPENING ONSET OF FG UNTIL 6Z OR SO...A FEW HRS LTR THAN YDY AT EKN. FG LIFTS BY 12-13Z GIVING WAY TO CAVU THE BALANCE OF THE MRNG. WITH MID LVL HIGH PRES NEARBY...LTL IN THE WAY OF CU XPCTD OUTSIDE TRI STATE AREA AND MTNS IN THE AFTN. PREV DISCUSSION... /ISSUED 257 PM EDT THU AUG 24 2006/ SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... NEW CONVECTION IS NOW DEVELOPING JUST NORTH OF THE CWA NEAR ZANESVILLE OH. NAM AND GFS CONTINUE TO KEEP PRECIP OUT OF CWA...WHILE THE LATEST RUC AND THE LOCAL WRF MODEL IS NOW SUGGESTING A NORTHERN CWA SKIMMING. HAVE CONTINUED SLIGHT CHANCE POPS IN THE NORTHERNMOST ZONES...BUT THIS WILL NEED TO BE WATCHED CLOSELY. THE ACTIVITY WILL QUICKLY MOVE EAST THIS EVENING. AS FOR FOG...I EXPECT A SIMILAR BEHAVIOR TO IT AS WITH LAST NIGHT. ELKINS WILL PROBABLY DROP BELOW A MILE /AS USUAL/. FOG SHOULD BE PATCHY...AND RESTRICTED TO THE RIVER VALLEYS. SOME CLOUDS IN THE NORTH WILL AGAIN PREVENT FOG FROM GETTING DENSE. NO MAJOR CHANGES TO ONGOING FORECAST OTHER THAN SLIGHT TEMPERATURE TWEAKS. HUMIDITY DOES LOOK TO INCREASE A BIT TOMORROW AS FLOW TURNS TO SOUTHWEST. ALTHOUGH NAM LOOKS TO BE TOO FAR SOUTH WITH INSTABILITY AND FEATURES ON SATURDAY...DID ADD 20 POP FOR SE OHIO AND SOME OF THE NE HIGHLANDS OF WEST VIRGINIA SATURDAY NIGHT...ALTHOUGH NOT MUCH MOISTURE TO WORK WITH. MODEL SOUNDINGS SEEM TO INDICATE THAT MOST CIN AND STRONGEST CAP WOULD BE JUST SOUTH OF A HTS TO CRW LINE...BUT AGAIN MID LEVELS ARE DRY. A RENEGADE OUTFLOW BOUNDARY MAY BE ENOUGH TO GET A STORM TO POP IN THE NORTH...WITH NO OTHER TRIGGERS AVAILABLE. THESE POPS MAY HAVE TO BE EXPANDED FURTHER SOUTH CLOSER TO THE EVENT...BUT WOULD LIKE TO SEE MORE MODEL CONSISTENCY IN REGARDS TO THE SHRTWV FROM THE UPPER MIDWEST BEFORE EXPANDING POPS ANY FURTHER SOUTH. NAM HAS MANY WEAK DISTURBANCES COMING THROUGH INTO 12Z SUNDAY WHICH LOOK SUSPICIOUS. MORE MOISTURE TO WORK WITH ON SUNDAY...BUT WITH H7-H5 LAPSE RATES UNDER 6C/KM...NOT TOO EXCITED ABOUT STORMS...WITH NO REAL TRIGGER AGAIN...AND THE NAM STILL LOOKING SUSPICIOUS IN TERMS OF ITS VORTICITY PANEL. RESULT IN THE GRIDS WAS TO LEAVE CHC POPS MAINLY NORTH OF CRW AND JUST SE OF THE OHIO RIVER UNTOUCHED. FEW MORE CLOUDS SHOULD GIVE MAX TEMPS NEAR OR SLIGHTLY BELOW WHAT OCCURS ON SATURDAY. PREV DISCUSSION... /ISSUED 1250 PM EDT THU AUG 24 2006/ LONG TERM /MONDAY THROUGH FRIDAY MORNING/... STATIONARY BOUNDARY ALONG NORTHERN COUNTIES WILL BE FOCUS FOR PRECIP ON MONDAY. HARD TO PINPOINT ITS EXACT LOCATION THIS FAR OUT...AS OPERATIONAL AND ENSEMBLES HAVE BEEN FLOATING NORTH AND SOUTH OVER THE PAST FEW RUNS. CONSIDERING WIND PROFILES...ANY STORMS THAT DO FIRE NORTH AND WEST...WILL CURVE TO THE RIGHT OR FURTHER SOUTH...INTO THE GREATER H5 HEIGHTS OF THE CENTRAL AND SOUTH. SO WILL CARRY AT LEAST SLT CHC POPS. INTERESTING TO NOTE THAT MOST OF THE GFS ENSEMBLES AND ECMWF ARE STRONGER WITH THE UPPER RIDGE IN THE SOUTHEASTERN AND SOUTHCENTRAL CONUS..THUS THE BOUNDARY TAKES ON MORE OF A SOUTHWEST TO NORTHEAST ORIENTATION AS OPPOSED TO THE WEST TO EAST SETUP FROM THE OPERATIONAL GFS. THIS WOULD ALSO INDICATE WARMER MIDLEVELS AND A STRONGER CAP IN PLACE IF THE GFS ENSEMBLE/ECMWF ARE TO BE FOLLOWED...AND A SMALLER CHANCE FOR PRECIP THAN THE GFS. DID REDUCE LIKELY AND CATEGORICAL POPS GIVEN BY HPC ON MONDAY...ESPECIALLY FOR CENTRAL AND SOUTHERN COUNTIES. WITH 18C AT H85 FROM CRW SOUTH AND LESS CLOUDS EXPECTED THAN HPC GRIDS...DID INC MAXT GRIDS A FEW DEGREES THERE ON MONDAY. BOUNDARY SLOWLY SINKS THROUGH THE REGION MONDAY NIGHT INTO TUESDAY. MREF PROB FOR 0.1 OF PRECIP GOES TO 60 LATE TUESDAY FOR EXTREME SOUTH SO WILL TRY TO LEAVE POPS THERE TUES PM...WITH THE POSSIBILITY OF A WAVE RIDING ALONG THE FRONT...WHILE CUTTING BACK POPS FURTHER NORTH. HIGH PRESSURE BUILDS SOUTH THEN THROUGH DAY 7...DID ELIMINATE HPC POPS FROM WED ONWARDS. MREF H850 TEMPS FROM ABOUT 11-15C NORTH TO SOUTH SHOULD PROVIDE TEMPS NEAR OR SLIGHTLY BELOW NORMAL ACROSS THE CWA...WITH A PLEASANT END TO AUGUST. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SHORT TERM...29 wv AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 730 PM EDT THU AUG 24 2006 .AVIATION /00Z TO 00Z/... NEARLY A REPEAT OF LAST NGT WITH LIFR/IFR FG DEVELOPING OVRNGT AT CRW/EKN/PKB/HTS UNDER A MCLR SKY AND LGT WINDS. DIFFERENCE BEING BLOW OFF CLDS FM UPSTREAM TRW COMPLEX DAMPENING ONSET OF FG UNTIL 6Z OR SO...A FEW HRS LTR THAN YDY AT EKN. FG LIFTS BY 12-13Z GIVING WAY TO CAVU THE BALANCE OF THE MRNG. WITH MID LVL HIGH PRES NEARBY...LTL IN THE WAY OF CU XPCTD OUTSIDE TRI STATE AREA AND MTNS IN THE AFTN. && .PREV DISCUSSION... /ISSUED 257 PM EDT THU AUG 24 2006/ SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... NEW CONVECTION IS NOW DEVELOPING JUST NORTH OF THE CWA NEAR ZANESVILLE OH. NAM AND GFS CONTINUE TO KEEP PRECIP OUT OF CWA...WHILE THE LATEST RUC AND THE LOCAL WRF MODEL IS NOW SUGGESTING A NORTHERN CWA SKIMMING. HAVE CONTINUED SLIGHT CHANCE POPS IN THE NORTHERNMOST ZONES...BUT THIS WILL NEED TO BE WATCHED CLOSELY. THE ACTIVITY WILL QUICKLY MOVE EAST THIS EVENING. AS FOR FOG...I EXPECT A SIMILAR BEHAVIOR TO IT AS WITH LAST NIGHT. ELKINS WILL PROBABLY DROP BELOW A MILE /AS USUAL/. FOG SHOULD BE PATCHY...AND RESTRICTED TO THE RIVER VALLEYS. SOME CLOUDS IN THE NORTH WILL AGAIN PREVENT FOG FROM GETTING DENSE. NO MAJOR CHANGES TO ONGOING FORECAST OTHER THAN SLIGHT TEMPERATURE TWEAKS. HUMIDITY DOES LOOK TO INCREASE A BIT TOMORROW AS FLOW TURNS TO SOUTHWEST. ALTHOUGH NAM LOOKS TO BE TOO FAR SOUTH WITH INSTABILITY AND FEATURES ON SATURDAY...DID ADD 20 POP FOR SE OHIO AND SOME OF THE NE HIGHLANDS OF WEST VIRGINIA SATURDAY NIGHT...ALTHOUGH NOT MUCH MOISTURE TO WORK WITH. MODEL SOUNDINGS SEEM TO INDICATE THAT MOST CIN AND STRONGEST CAP WOULD BE JUST SOUTH OF A HTS TO CRW LINE...BUT AGAIN MID LEVELS ARE DRY. A RENEGADE OUTFLOW BOUNDARY MAY BE ENOUGH TO GET A STORM TO POP IN THE NORTH...WITH NO OTHER TRIGGERS AVAILABLE. THESE POPS MAY HAVE TO BE EXPANDED FURTHER SOUTH CLOSER TO THE EVENT...BUT WOULD LIKE TO SEE MORE MODEL CONSISTENCY IN REGARDS TO THE SHRTWV FROM THE UPPER MIDWEST BEFORE EXPANDING POPS ANY FURTHER SOUTH. NAM HAS MANY WEAK DISTURBANCES COMING THROUGH INTO 12Z SUNDAY WHICH LOOK SUSPICIOUS. MORE MOISTURE TO WORK WITH ON SUNDAY...BUT WITH H7-H5 LAPSE RATES UNDER 6C/KM...NOT TOO EXCITED ABOUT STORMS...WITH NO REAL TRIGGER AGAIN...AND THE NAM STILL LOOKING SUSPICIOUS IN TERMS OF ITS VORTICITY PANEL. RESULT IN THE GRIDS WAS TO LEAVE CHC POPS MAINLY NORTH OF CRW AND JUST SE OF THE OHIO RIVER UNTOUCHED. FEW MORE CLOUDS SHOULD GIVE MAX TEMPS NEAR OR SLIGHTLY BELOW WHAT OCCURS ON SATURDAY. PREV DISCUSSION... /ISSUED 147 PM EDT THU AUG 24 2006/ AVIATION... THERE IS A SLIGHT CHANCE OF THUNDERSTORMS NORTH OF KCKB AND KPKB UNTIL ABOUT 02Z. OTHERWISE...THE ONLY CONCERN IS FOG. I EXPECT A SIMILAR BEHAVIOR TO IT TONIGHT AS OCCURRED LAST NIGHT. SOME CLOUDS IN THE NORTH WILL PREVENT DENSE FOG...SO KCKB AND KPKB WILL ONLY DROP TO MVFR VISIBILITY BEGINNING AROUND 10Z. OTHER VALLEY TAF SITES /KCRW AND KHTS/ WILL SEE A REDUCTION TO IFR...WHILE THE USUAL FOG TRAP OF KEKN COULD REACH BRIEF LIFR CONDITIONS. PREV DISCUSSION... /ISSUED 1250 PM EDT THU AUG 24 2006/ LONG TERM /MONDAY THROUGH FRIDAY MORNING/... STATIONARY BOUNDARY ALONG NORTHERN COUNTIES WILL BE FOCUS FOR PRECIP ON MONDAY. HARD TO PINPOINT ITS EXACT LOCATION THIS FAR OUT...AS OPERATIONAL AND ENSEMBLES HAVE BEEN FLOATING NORTH AND SOUTH OVER THE PAST FEW RUNS. CONSIDERING WIND PROFILES...ANY STORMS THAT DO FIRE NORTH AND WEST...WILL CURVE TO THE RIGHT OR FURTHER SOUTH...INTO THE GREATER H5 HEIGHTS OF THE CENTRAL AND SOUTH. SO WILL CARRY AT LEAST SLT CHC POPS. INTERESTING TO NOTE THAT MOST OF THE GFS ENSEMBLES AND ECMWF ARE STRONGER WITH THE UPPER RIDGE IN THE SOUTHEASTERN AND SOUTHCENTRAL CONUS..THUS THE BOUNDARY TAKES ON MORE OF A SOUTHWEST TO NORTHEAST ORIENTATION AS OPPOSED TO THE WEST TO EAST SETUP FROM THE OPERATIONAL GFS. THIS WOULD ALSO INDICATE WARMER MIDLEVELS AND A STRONGER CAP IN PLACE IF THE GFS ENSEMBLE/ECMWF ARE TO BE FOLLOWED...AND A SMALLER CHANCE FOR PRECIP THAN THE GFS. DID REDUCE LIKELY AND CATEGORICAL POPS GIVEN BY HPC ON MONDAY...ESPECIALLY FOR CENTRAL AND SOUTHERN COUNTIES. WITH 18C AT H85 FROM CRW SOUTH AND LESS CLOUDS EXPECTED THAN HPC GRIDS...DID INC MAXT GRIDS A FEW DEGREES THERE ON MONDAY. BOUNDARY SLOWLY SINKS THROUGH THE REGION MONDAY NIGHT INTO TUESDAY. MREF PROB FOR 0.1 OF PRECIP GOES TO 60 LATE TUESDAY FOR EXTREME SOUTH SO WILL TRY TO LEAVE POPS THERE TUES PM...WITH THE POSSIBILITY OF A WAVE RIDING ALONG THE FRONT...WHILE CUTTING BACK POPS FURTHER NORTH. HIGH PRESSURE BUILDS SOUTH THEN THROUGH DAY 7...DID ELIMINATE HPC POPS FROM WED ONWARDS. MREF H850 TEMPS FROM ABOUT 11-15C NORTH TO SOUTH SHOULD PROVIDE TEMPS NEAR OR SLIGHTLY BELOW NORMAL ACROSS THE CWA...WITH A PLEASANT END TO AUGUST. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ AVIATION...29 wv AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 257 PM EDT THU AUG 24 2006 .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... NEW CONVECTION IS NOW DEVELOPING JUST NORTH OF THE CWA NEAR ZANESVILLE OH. NAM AND GFS CONTINUE TO KEEP PRECIP OUT OF CWA...WHILE THE LATEST RUC AND THE LOCAL WRF MODEL IS NOW SUGGESTING A NORTHERN CWA SKIMMING. HAVE CONTINUED SLIGHT CHANCE POPS IN THE NORTHERNMOST ZONES...BUT THIS WILL NEED TO BE WATCHED CLOSELY. THE ACTIVITY WILL QUICKLY MOVE EAST THIS EVENING. AS FOR FOG...I EXPECT A SIMILAR BEHAVIOR TO IT AS WITH LAST NIGHT. ELKINS WILL PROBABLY DROP BELOW A MILE /AS USUAL/. FOG SHOULD BE PATCHY...AND RESTRICTED TO THE RIVER VALLEYS. SOME CLOUDS IN THE NORTH WILL AGAIN PREVENT FOG FROM GETTING DENSE. NO MAJOR CHANGES TO ONGOING FORECAST OTHER THAN SLIGHT TEMPERATURE TWEAKS. HUMIDITY DOES LOOK TO INCREASE A BIT TOMORROW AS FLOW TURNS TO SOUTHWEST. ALTHOUGH NAM LOOKS TO BE TOO FAR SOUTH WITH INSTABILITY AND FEATURES ON SATURDAY...DID ADD 20 POP FOR SE OHIO AND SOME OF THE NE HIGHLANDS OF WEST VIRGINIA SATURDAY NIGHT...ALTHOUGH NOT MUCH MOISTURE TO WORK WITH. MODEL SOUNDINGS SEEM TO INDICATE THAT MOST CIN AND STRONGEST CAP WOULD BE JUST SOUTH OF A HTS TO CRW LINE...BUT AGAIN MID LEVELS ARE DRY. A RENEGADE OUTFLOW BOUNDARY MAY BE ENOUGH TO GET A STORM TO POP IN THE NORTH...WITH NO OTHER TRIGGERS AVAILABLE. THESE POPS MAY HAVE TO BE EXPANDED FURTHER SOUTH CLOSER TO THE EVENT...BUT WOULD LIKE TO SEE MORE MODEL CONSISTENCY IN REGARDS TO THE SHRTWV FROM THE UPPER MIDWEST BEFORE EXPANDING POPS ANY FURTHER SOUTH. NAM HAS MANY WEAK DISTURBANCES COMING THROUGH INTO 12Z SUNDAY WHICH LOOK SUSPICIOUS. MORE MOISTURE TO WORK WITH ON SUNDAY...BUT WITH H7-H5 LAPSE RATES UNDER 6C/KM...NOT TOO EXCITED ABOUT STORMS...WITH NO REAL TRIGGER AGAIN...AND THE NAM STILL LOOKING SUSPICIOUS IN TERMS OF ITS VORTICITY PANEL. RESULT IN THE GRIDS WAS TO LEAVE CHC POPS MAINLY NORTH OF CRW AND JUST SE OF THE OHIO RIVER UNTOUCHED. FEW MORE CLOUDS SHOULD GIVE MAX TEMPS NEAR OR SLIGHTLY BELOW WHAT OCCURS ON SATURDAY. && .PREV DISCUSSION... /ISSUED 147 PM EDT THU AUG 24 2006/ AVIATION... THERE IS A SLIGHT CHANCE OF THUNDERSTORMS NORTH OF KCKB AND KPKB UNTIL ABOUT 02Z. OTHERWISE...THE ONLY CONCERN IS FOG. I EXPECT A SIMILAR BEHAVIOR TO IT TONIGHT AS OCCURRED LAST NIGHT. SOME CLOUDS IN THE NORTH WILL PREVENT DENSE FOG...SO KCKB AND KPKB WILL ONLY DROP TO MVFR VISIBILITY BEGINNING AROUND 10Z. OTHER VALLEY TAF SITES /KCRW AND KHTS/ WILL SEE A REDUCTION TO IFR...WHILE THE USUAL FOG TRAP OF KEKN COULD REACH BRIEF LIFR CONDITIONS. PREV DISCUSSION... /ISSUED 1250 PM EDT THU AUG 24 2006/ LONG TERM /MONDAY THROUGH FRIDAY MORNING/... STATIONARY BOUNDARY ALONG NORTHERN COUNTIES WILL BE FOCUS FOR PRECIP ON MONDAY. HARD TO PINPOINT ITS EXACT LOCATION THIS FAR OUT...AS OPERATIONAL AND ENSEMBLES HAVE BEEN FLOATING NORTH AND SOUTH OVER THE PAST FEW RUNS. CONSIDERING WIND PROFILES...ANY STORMS THAT DO FIRE NORTH AND WEST...WILL CURVE TO THE RIGHT OR FURTHER SOUTH...INTO THE GREATER H5 HEIGHTS OF THE CENTRAL AND SOUTH. SO WILL CARRY AT LEAST SLT CHC POPS. INTERESTING TO NOTE THAT MOST OF THE GFS ENSEMBLES AND ECMWF ARE STRONGER WITH THE UPPER RIDGE IN THE SOUTHEASTERN AND SOUTHCENTRAL CONUS..THUS THE BOUNDARY TAKES ON MORE OF A SOUTHWEST TO NORTHEAST ORIENTATION AS OPPOSED TO THE WEST TO EAST SETUP FROM THE OPERATIONAL GFS. THIS WOULD ALSO INDICATE WARMER MIDLEVELS AND A STRONGER CAP IN PLACE IF THE GFS ENSEMBLE/ECMWF ARE TO BE FOLLOWED...AND A SMALLER CHANCE FOR PRECIP THAN THE GFS. DID REDUCE LIKELY AND CATEGORICAL POPS GIVEN BY HPC ON MONDAY...ESPECIALLY FOR CENTRAL AND SOUTHERN COUNTIES. WITH 18C AT H85 FROM CRW SOUTH AND LESS CLOUDS EXPECTED THAN HPC GRIDS...DID INC MAXT GRIDS A FEW DEGREES THERE ON MONDAY. BOUNDARY SLOWLY SINKS THROUGH THE REGION MONDAY NIGHT INTO TUESDAY. MREF PROB FOR 0.1 OF PRECIP GOES TO 60 LATE TUESDAY FOR EXTREME SOUTH SO WILL TRY TO LEAVE POPS THERE TUES PM...WITH THE POSSIBILITY OF A WAVE RIDING ALONG THE FRONT...WHILE CUTTING BACK POPS FURTHER NORTH. HIGH PRESSURE BUILDS SOUTH THEN THROUGH DAY 7...DID ELIMINATE HPC POPS FROM WED ONWARDS. MREF H850 TEMPS FROM ABOUT 11-15C NORTH TO SOUTH SHOULD PROVIDE TEMPS NEAR OR SLIGHTLY BELOW NORMAL ACROSS THE CWA...WITH A PLEASANT END TO AUGUST. PREV DISCUSSION... /ISSUED 1016 AM EDT THU AUG 24 2006/ SHORT TERM /REST OF TODAY THROUGH TONIGHT/... I TRIMMED BACK POPS AND CONFINED THEM EVEN MORE TO THE NORTHERN FRINGE OF THE CWA FOR THIS AFTERNOON...GENERALLY NORTH OF A LINE FROM NEW LEXINGTON TO PARKERSBURG TO CLARKSBURG. THE MONKEY WRENCH IS THAT WHILE ALL MODELS KEPT PRECIP NORTH OF CWA FOR LATER TODAY...THEY ALSO ALL INITIALIZED TOO FAR NORTH WITH THE UPSTREAM MCS NOW DIMINISHING IN ILLINOIS/INDIANA. HOWEVER...THE SIGNIFICANT DEBRIS CLOUDS FROM THIS FEATURE SHOULD VERY MUCH LIMIT THE ABILITY OF NEW THUNDERSTORMS TO DEVELOP. WITH THE INCOMING CLOUDS...I ALSO ADJUSTED FORECAST HIGH TEMPS DOWN SLIGHTLY FOR THE NORTHERN CWA. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SHORT TERM...MDP/KAM wv AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 925 PM CDT THU AUG 24 2006 .UPDATE...SURFACE FRONT EXTENDS FROM NEAR KMSN TO KAEL AS OF 02Z. ONGOING CONVECTION STRONGEST OVER SOUTHEAST MN...WHERE SEVERE WEATHER AND HEAVY RAIN HAVE HIT THE HARDEST. OF SPECIAL NOTE...SURFACE DEW POINTS FEEDING THE CONVECTION HAVE ACTUALLY DECREASED INTO THE LOWER TO MID 60S THIS EVENING. THIS APPEARS TO BE HAMPERING POTENTIAL FOR ADDITIONAL GROWTH IN CONVECTION...AS IT SINKS SLOWLY SOUTHWARD ACROSS THE FORECAST AREA. LATEST RUC AND NAM/WRF SUGGEST FRONT WILL LIFT NORTHWARD DURING THE NIGHT...AS SURFACE AND UPPER LEVEL WAVE LIFTS ACROSS THE UPPER MISSISSIPPI VALLEY. IN ADDITION...RUC 850MB MOISTURE TRANSPORT WILL INCREASE DURING THE NIGHT...IMPINGING ON THE FRONT AND THUS PROMOTING ADDITIONAL CONVECTION AND POTENTIAL FOR HEAVY RAIN. PLAN TO HOLD ONTO FLASH FLOOD WATCH AREAL EXTENT AS IS...BASED ON CURRENT RADAR TRENDS AND MODEL QPF. OTHERWISE...FORECAST DATA BASE APPEARS TO BE IN GENERALLY GOOD SHAPE. FLASH FLOOD WATCH STATEMENT WILL BE REFRESHED BEFORE 03Z THIS EVENING. PLEASE REFERENCE LATEST HAZARDOUS WEATHER OUTLOOK...WHICH WAS UPDATED AT 0130Z. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...FLASH FLOOD WATCH UNTIL 7 AM CDT FRIDAY FOR WIZ017-WIZ029-WIZ032- WIZ033-WIZ034-WIZ041-WIZ042-WIZ043-WIZ044. MN...FLASH FLOOD WATCH UNTIL 7 AM CDT FRIDAY FOR MNZ079-MNZ087-MNZ088. IA...NONE. && $$ THOMPSON wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 315 PM CDT THU AUG 24 2006 .SHORT TERM...TODAY THROUGH SATURDAY NIGHT MAIN FORECAST CONCERN IS HEAVY RAIN POTENTIAL TONIGHT. LATEST WATER VAPOR SATELLITE IMAGERY INDICATING VIGOROUS SHORTWAVE TROUGH OVER THE WESTERN DAKOTAS. LATEST 18Z SURFACE ANALYSIS INDICATING LOW PRESSURE OVER CENTRAL SOUTH DAKOTA. WARM/STATIONARY FRONT EXTENDING FROM LOW INTO INTO SOUTHERN WISCONSIN. LATEST MOSAIC RADAR INDICATING STRONG TO SEVERE THUNDERSTORMS ALONG AND NORTH OF SURFACE FRONT STRETCHING FROM SOUTHEAST WISCONSIN INTO SOUTHERN NORTH DAKOTA. LATEST 12Z THURSDAY NAM AND GFS ARE IN PRETTY GOOD AGREEMENT IN MOVING SURFACE LOW/UPPER LEVEL TROUGH EAST INTO FORECAST AREA TONIGHT. THE MAIN DIFFERENCE IS HOW FAR NORTH SURFACE WARM FRONT WILL MOVE...AS GFS IS SLIGHTLY FARTHER NORTH INTO SOUTHERN MINNESOTA AND INTO CENTRAL WISCONSIN THAN THE NAM. OVERALL... BOTH MODELS ARE IN GOOD AGREEMENT IN A HEAVY RAIN EVENT OVER THE NORTHERN HALF OF THE FORECAST AREA. CONFIDENCE IN FORECAST TONIGHT IS HIGH FOR HEAVY RAIN OVER NORTHERN HALF OF FORECAST AREA. TONIGHT...SURFACE LOW WILL MOVE ALONG WARM FRONT INTO EASTERN MINNESOTA AND WESTERN WISCONSIN BY 12Z FRIDAY. BOTH MODELS INDICATING GOOD STRONG LOW LEVEL JET DEVELOPING BY 06Z AND NORTHERN HALF OF FORECAST AREA TO BE ON NOSE OF LOW LEVEL JET. IN ADDITION...PARTS OF NORTHERN FORECAST AREA HAVE RECEIVED OVER 2 TO 3 INCHES OF RAIN WEDNESDAY NIGHT. FLASH FLOOD GUIDANCE VALUES RANGE IN THE 2 TO 3 INCHES IN THE ONE...THREE AND SIX HOUR CATEGORIES OVER PARTS OF NORTHERN AND EASTERN FORECAST AREA. HAVE HOISTED FLASH FLOOD WATCH ACROSS NORTHERN HALF OF FORECAST AREA THROUGH 12Z FRIDAY. SEVERE POTENTIAL WITH SYSTEM CONTINUES TO BE POSSIBLE...AS RUC INDICATES MIXED LAYER COMPUTED CAPE OF 1500 TO 3500 J/KG AND 0-3KM SHEAR ACROSS MUCH OF FORECAST AREA BY 00Z FRIDAY. WILL CONTINUE WITH SOME THUNDERSTORMS COULD BE SEVERE WORDING ACROSS MUCH OF FORECAST AREA. SHORTWAVE TROUGH/SURFACE LOW MOVES EAST INTO EASTERN WISCONSIN BY 18Z FRIDAY. WEAK MOISTURE TRANSPORT AND CONVERGENCE CONTINUE OVER EASTERN HALF OF FORECAST AREA. WILL CONTINUE WITH SMALL CHANCES OF PRECIPITATION AND TAPER OFF WEST TO EAST DURING THE DAY FRIDAY. 12Z THURSDAY NAM INDICATING SURFACE RIDGE BUILDING INTO FORECAST AREA FOR SATURDAY AND INTO SUNDAY. 12Z THURSDAY GFS INDICATING SURFACE LOW TRACKING NORTHEAST INTO NORTHEAST MISSOURI BY 18Z SUNDAY. FEEL UPPER LEVEL FLOW PATTERN DOES NOT SUPPORT SURFACE LOW TO MOVE THAT FAR NORTH...HAVE LEANED MORE TOWARDS THE NAM SOLUTION WITH SURFACE RIDGE BUILDING INTO FORECAST AREA SATURDAY NIGHT INTO SUNDAY. HAVE REMOVED PRECIPITATION CHANCES FOR SATURDAY NIGHT AND SUNDAY. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY MAIN FORECAST CONCERNS THROUGH PERIOD IS TEMPERATURES THROUGH PERIOD. BOTH THE 00Z THURSDAY GFS AND ECMWF ARE IN VERY GOOD AGREEMENT IN BUILDING UPPER LEVEL/SURFACE RIDGE INTO THE UPPER MIDWEST AND GREAT LAKES REGION EARLY NEXT WEEK. SURFACE LOW OVER OHIO RIVER VALLEY AND SURFACE RIDGE BUILDING INTO WESTERN MINNESOTA. THIS WILL ALLOW FOR COOLER AND DRIER NORTHEASTERLY FLOW ACROSS FORECAST THROUGH WEDNESDAY. THEN...SOUTHERLY FLOW ON BACKSIDE OF SURFACE HIGH WILL ALLOW FOR WARM AIR TO ADVECT INTO FORECAST FOR WEDNESDAY NIGHT INTO THURSDAY. BOTH MODELS ARE INDICATING 850MB TEMPERATURES OF PLUS 12 TO 14 ACROSS FORECAST AREA THROUGH WEDNESDAY...AND 00Z THURSDAY GFS INDICATING 1000-500MB THICKNESS VALUES OF 567 TO 570 OVER FORECAST AREA...THEN NEAR 573 1000-500MB THICKNESS VALUES AFTER 12Z THURSDAY. WILL CONTINUE DRY AND SEASONABLE TEMPERATURES THROUGH PERIOD. && .HYDROLOGY...MODELS CONTINUE TO INDICATE PRECIPITABLE WATER VALUES OF AROUND 2 INCHES FOR NORTHERN HALF OF FORECAST AREA LATE THIS EVENING AND TONIGHT. GIVEN THIS AND STRENGTH OF FORCING/MOISTURE CONVERGENCE WOULD NOT RULE OUT QPF AMOUNTS OF 2 TO 4 INCHES ACROSS PARTS OF NORTHERN FORECAST AREA. PLUS...PARTS OF NORTHERN FORECAST AREA COUNTIES 6HR FLASH FLOOD GUIDANCE VALUES OF AROUND 3 INCHES... WILL ALLOW FOR THE POTENTIAL FOR FLASH FLOODING LATE THIS EVENING AND TONIGHT. HAVE ISSUED FLASH FLOOD WATCH FOR NORTHERN HALF OF FORECAST AREA. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH FRIDAY MORNING FOR WIZ017-WIZ029-WIZ032-WIZ033-WIZ034-WIZ041- WIZ042-WIZ043-WIZ044. MN...FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH FRIDAY MORNING FOR MNZ079-MNZ087-MNZ088. IA...NONE. && $$ DTJ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 255 AM CDT FRI AUG 25 2006 DISCUSSION... 00Z SHORT RANGE MODELS HAVE NOT BEEN VERY CONSISTENT FROM PREVIOUS RUNS OR IN GOOD AGREEMENT. THIS MAKES THE FORECAST TRICKY WITH A MORE UNSETTLED WEATHER PATTERN TAKING SHAPE THIS WEEKEND INTO EARLY NEXT WEEK AFTER A DRY STRETCH THE PAST 4 TO 5 DAYS THIS WEEK. NAM/WRF AND NGM DID NOT PICK UP ON CONVECTION AROUND KANSAS CITY EARLY THIS MORNING WITH RUC AND GFS PICKING THIS UP BETTER. ONE NOTED TREND OF MODELS IS LESS QPF OVER NORTHERN AREAS FROM PEORIA NORTHWARD SAT NIGHT AND SUNDAY. WILL TRY TO BLEND THIS FORECAST WITH SOME CONSISTENCY FROM PREVIOUS PACKAGE ALONG WITH MESHING WITH SURROUNDING OFFICES. SHORT TERM...TODAY THROUGH MONDAY NIGHT... 07Z/2 AM SURFACE MAP SHOWS 1004 MB LOW PRESSURE OVER FAR NW IOWA WITH A FRONTAL BOUNDARY EXTENDING EAST ALONG THE MN/IA AND WI/IL BORDER INTO NORTHERN INDIANA WHILE WEAK HIGH PRESSURE OF 1017 MB WAS OVER THE MID ATLANTIC STATES AND RIDGING WEST INTO THE MID MS VALLEY. ANOTHER MCS UP NORTH OVER NE IA...SE MN AND INTO WI AND TRACKING ESE WITH CIRRUS BLOWOFF COVERING AREAS FROM SPRINGFIELD NE. TEMPS RANGED FROM THE LOW TO MID 60S OVER SE IL TO THE UPPER 60S AND LOWER 70S OVER CENTRAL IL FROM MATTOON NW. DEWPOINTS WERE 60 TO 65F WITH SSE WINDS 5 TO 15 MPH...EXCEPT LIGHT TO CALM OVER SE IL CLOSER TO THE HIGH PRESSURE RIDGE. ALOFT 592 DM 500 MB SUBTROPICAL HIGH PRESSURE WAS OVER TX WHILE UPPER LEVEL TROF OVER NEW ENGLAND...THE WESTERN STATES AND LAKE WINNIPEG AND MN/DAKOTAS. HIGH PRESSURE TO KEEP EASTERN IL DRY TODAY BUT ADDED 20/30 PERCENT CHANCE OF CONVECTION TO AREAS ALONG AND WEST OF I-55 THIS AFTERNOON. SHORT WAVE NEAR KANSAS CITY TO MOVE EAST ACROSS MO AND TOWARD WESTCENTRAL IL LATER THIS AFTERNOON AND MODELS HAVE BEEN QUICKER WITH THIS FEATURE THAN YESTERDAYS RUN. GETS MORE UNSTABLE ALONG AND WEST OF I-55 THIS AFTERNOON TOO WITH LIFTED INDICES MINUS 4 TO 6C AND CAPES OF 1500 TO 2500 J/KG AS DEWPOINTS ELEVATE INTO THE UPPER 60S TO AROUND 70F. LOW PRESSURE OVER FAR NW IOWA MOVES EAST INTO SOUTHERN WI THIS AFTERNOON AND INTO NORTHERN LOWER MI SAT. WILL BE INCREASING CONVECTION CHANCES FROM WEST TO EAST TONIGHT WITH SHORT WAVE MOVING ACROSS IL TOWARD THE IL/IN BORDER BY 12Z/SAT. SPC HAS SLIGHT RISK OF SEVERE NW OF THE IL RIVER LATER THIS AFTERRNOON AND EVENING FOR ISOLATED SEVERE WIND GUSTS/HAIL. HIGHS TODAY IN THE UPPER 80S WITH SW AREAS NEAR 90F AND MORE HUMID. GOOD CHANCE OF CONVECTION SAT WITH FRONTAL BOUNDARY DROPPING SOUTH INTO CENTRAL IL AND AIR MASS UNSTABLE AGAIN ESPECIALLY FROM IL RIVER SE WHERE LIFTED INDEX MINUS 4 TO 6C AND CAPES 1000 TO 2000 J/KG. SPC HAS SLIGHT RISK OF SEVERE JUST EAST OF EAST CENTRAL IL INTO CENTRAL/NORTHERN INDIANA. MODELS SHIFT QPF FURTHER SOUTH SAT NIGHT AND SUNDAY WITH FRONTAL BOUNDARY MOVING INTO SE IL WITH LESS QPF OVER AREAS FROM PEORIA NORTH...SO LOWERED CONVECTION CHANCES FROM 60 TO 30/40 PERCENT. HEAVY RAIN POSSIBLE ESPECIALLY ALONG AND SOUTH OF I-72 WITH PRECIPITITABLE WATER VALUES GOING UP FROM 1 TO 2 INCHES. SURFACE LOW PRESSURE MOVING ALONG THE FRONTAL BOUNDARY NEAR THE OHIO RIVER MON TO KEEP CHANCE OF CONVECTION OVER CENTRAL AND ESPECIALLY SE IL. AREAS NW OF THE IL MAY BE DRY AND WILL LOWER POPS THERE TO MESH UP WITH NEARBY OFFICES. CONVECTION CHANCES DIMINISH FROM NW TO SE DURING MON NIGHT. CANADIAN MODEL DEVELOP HEAVY QPF OVER IL FROM LATER SUNDAY INTO MON NIGHT...BUT IS FURTHER NORTH THAN OTHER MODELS AND NOT FOLLOWED. LONG TERM...TUESDAY THROUGH FRIDAY... EXTENDED MODEL ENSEMBLES SHIFT FRONTAL BOUNDARY FURTHER SOUTH TUE ALONG WITH CONVECTION CHANCES OVER SOUTHERN IL WHILE CENTRAL IL APPEARS DRY. DGEX IS ODD MODEL KEEPING QPF OVER IL TUE AND WED. BUT MOST EXTENDED MODELS ARE KEEPING IT DRIER DURING MID AND LATE WEEK AND WILL KEEP FORECAST DRY TOO. HIGHS CLOSER TO NORMAL FROM 80 TO 85. && ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ HUETTL il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 203 AM EDT FRI AUG 25 2006 .AVIATION... DEBRIS CLOUDS HAVE OVERSPREAD THE AREA FROM A MCS TO THE NORTHWEST. JUST HIGH LEVEL CLOUDS FROM THE MCS AND APPROACHING COLD FRONT LATER TODAY ARE EXPECTED. SOME LOWER LEVEL CLOUDS COULD BEGIN MOVING IN TOWARDS THE END OF THIS TAF PERIOD. THIS MCS IS EXPECTED TO STAY TO THE NORTH AND THE NEXT RAIN CHANCES ARE NOT TIL TOWARDS THE END OF THIS TAF PERIOD AND WITH BEING SUCH A LOW CHANCE...DID NOT MENTION ANY RAIN IN THE TAFS. THE WIND ACROSS THE AREA IS CURRENTLY LIGHT TO CALM...BUT THIS WILL INCREASE LATER THIS MORNING FROM THE SOUTH TO SOUTHWEST WITH GUSTS AND THEN CALM DOWN SOME AGAIN TONIGHT. && .UPDATE... (ISSUED 801 PM EDT THU AUG 24 2006) MCS CONTS TO WKN ACRS SRN LWR MI AS IT RUNS EWD INTO MORE STABLE ENVIRONMENT AND EAST OF LLJ SUPPORT CURRENTLY. HWVR EVOLVING UPSCALE MCS OVR SRN MN/WRN WI QUITE ORGANIZED AND BEGINNING TO TURN SEWD. SHRT TERM MODEL GUIDANCE CONTS TO SUGGEST THIS WILL STAY MAINLY NORTH OF CWA OVERNIGHT SUSTAINED BY INCREASING LL MASS FLUX OVERTOP NWD RTNG WARM FRONT. CURRENT POP ORIENTATION PROBABLY SHADED TOO FAR SWD OVERNIGHT YET REALISTIC ACRS SRN MI COUNTIES. OTHERWISE VFR XPCD AT TERMINALS THROUGH THE FCST PD W/SFC WIND GUSTS UP TO 20KTS BY LATE FRI AM AND AFTN AS WARM SECTOR SPREADS NE INADV OF SFC LOW OVR SD THIS EVENING SHIFTING EWD INTO WI TOMORROW. && .PREV DISCUSSION... (ISSUED 317 PM EDT THU AUG 24 2006) SHORT TERM... TONIGHT AND FRIDAY CIRRUS SHIELD FROM DECAYING MCS HAS THINNED NICELY THIS AFTERNOON ALLOWING FOR INCREASING AMOUNTS OF SUNSHINE. THIS HAS ALLOWED SURFACE TEMPS TO RECOVER TO NEAR 80 AT 19Z. REGIONAL RADAR AND SATELLITE ANALYSIS SHOWING MCS EVOLVING UPSTREAM OVER SOUTHERN WISCONSIN FROM CONVECTION THAT ORIGINALLY FIRED NEAR KMSP THIS MORNING. 12Z RAOB ANALYSIS SUGGESTS THIS CLUSTER HAS FORMED WITHIN REGION OF LOW LEVEL WAA AND SIGNIFICANT MASS FLUX CONVERGENCE ALONG WARM FRONT...AIDED BY RIGHT ENTRANCE REGION JET DYNAMICS OF A MID/UPPER LEVEL JET STREAK OVER THE GREAT LAKES. 12Z NAM-WRF HAS TOTALLY FAILED TO INITIALIZE THIS FEATURE AND IS NOT A USABLE SOLUTION. GFS/CANADIAN GEM NOT MUCH BETTER WITH NEITHER MODEL DEPICTING SUCH AN ORGANIZED MCS. PARTIAL THICKNESS SCHEMES SUGGEST IF THIS MCS DOES HOLD TOGETHER IT WILL CONTINUE TO MOVE SE INTO THE CWA OVERNIGHT. SPC OBJECTIVE RUC ANALYSIS SUGGESTS AIRMASS IS STARTING TO RECOVER AND DESTABILIZE DOWNSTREAM FROM MCS. OVERALL FORECAST CONFIDENCE LOW...BUT POTENTIAL IS THERE FOR MCS TO CONTINUE TO MOVE/DEVELOP SE DOWN THE DEEP LAYER BAROCLINIC ZONE INTO THE CWA OVERNIGHT. HAVE THROWN OUT MODEL GUIDANCE AND SIMPLY USED EXTRAPOLATION OF CURRENT RADAR/SATELLITE TRENDS FOR FIRST PERIOD FORECAST. WILL CARRY CHANCE POPS OVER THE NW COUNTIES THIS EVENING...THEN EVERYWHERE OVERNIGHT GIVEN UNCERTAINTY. BEST CHANCE FOR ORGANIZED STORMS IS OVER OUR NW COUNTIES. IF A FORWARD PROPAGATING MCS DEVELOPS THERE IS AT LEAST A SMALL CHANCE OF DAMAGING WINDS...BUT THIS IS OF COURSE STRICTLY CONDITIONAL ON THE MCS SURVIVING THE TRIP INTO THE CWA. ON FRIDAY DEVELOPING SURFACE LOW WITHIN REGION OF LARGE SCALE ASCENT OVER THE PLAINS WILL MOVE EAST TO WISCONSIN BY LATE AFTERNOON PER NAM/CANADIAN GEM. INCREASING DEEP LAYER SOUTHERLY FLOW AHEAD OF SURFACE LOW WILL PUSH SYNOPTIC SCALE WARM FRONT NORTH AND ALLOW CWA TO FULLY BREAK OUT INTO THE WARM SECTOR. PENDING UPSTREAM MCS EVOLUTION...ANY CONVECTIVE DEBRIS CLOUD IN THE MORNING SHOULD DISSIPATE AND ALLOW FOR A GOOD AMOUNT OF SUNSHINE DURING THE AFTERNOON. TEMPS WILL CLIMB INTO THE MID/UPPER 80S WITH INCREASING HUMIDITY IN THE WARM SECTOR. BULK OF THE WARM SECTOR WILL BE CAPPED BY WELL DEFINED EML PLUME ALOFT. THAT SAID...WITH APPROACH OF THE SURFACE LOW AND ATTENDANT FRONT LARGE SCALE ASCENT MAY INCREASE ENOUGH TO BREACH THE CAP BY LATE AFTERNOON OVER THE NW CORNER OF THE CWA. CANADIAN GEM IS MOST AGGRESSIVE WITH CONVECTIVE DEVELOPMENT BY LATE AFTERNOON. FRICTIONAL CONVERGENCE OF WIND FIELD ALONG THE SE LAKE MICHIGAN LAKESHORE MAY ALSO INCREASE CONVECTIVE POTENTIAL. HAVE INTRODUCED LOW CHANCE POPS OVER FAR NW INDIANA AND SW LOWER MICHIGAN TO COVER POTENTIAL. LONG TERM... FRIDAY NIGHT THROUGH THURSDAY. SHORT RANGE AND LONG RANGE MODELS ARE OFFERING VARIOUS SOLUTIONS IN THE IMMEDIATE LONG TERM RANGE...AND THUS...THERE IS LOW CONFIDENCE IN THIS PART OF THE EXTENDED. AT THIS POINT IN TIME...S/WV ENERGY ACRS ERN MT/NE WY/WRN DAKOTAS IS FCST TO SHIFT EAST INTO THE GREAT LAKES REGION FRIDAY NIGHT AND SATURDAY. THIS ENERGY WILL LIKELY SWING A FRONTAL BOUNDARY INTO THE REGION. WHAT REMAINS PROBLEMATIC AT THIS POINT IS HOW FAR SOUTH AND EAST THIS BOUNDARY WILL GET. BELIEVE FRONT WILL AT LEAST GET THROUGH SOME OF THE CWFA...ON SATURDAY...SO HAVE LOWERED TEMPS A TAD IN THE NW. OTHERWISE...WITH MUCH UNCERTAINTY ON WHERE THE FRONT WILL STOP...HAVE KEPT LOW CHC POPS ACRS THE REGION FRIDAY NIGHT INTO SATURDAY NIGHT. ON SUNDAY...LONG RANGE MODELS HINT AT A POSSIBLE WAVE OF LOW PRESSURE RIDING NORTHEAST ACRS THE FCST AREA DUE TO S/WV ENERGY EJECTING OUT OF THE INTERMOUNTAIN WEST INTO THE CNTRL PLAINS. BELIEVE THE BEST CHC FOR PCPN WILL BE ON SUNDAY...SO HAVE MAINTAINED 40 POPS AT THIS TIME. PCPN CHC/S MAY VERY WELL BE NEEDED INTO MONDAY. BUT AGAIN...WITH MUCH UNCERTAINTY...JUST ADDED POPS INTO SUNDAY NIGHT...AND WILL HOPE THAT MODELS WILL HONE IN ON A DEFINITIVE SOLUTION. LONG RANGE MODELS APPEAR TO HAVE A CONSENSUS SOLUTION FOR MID TO LATE NEXT WEEK. MID LVL TROFINESS IS FCST TO DEVELOP ACRS THE PAC NW/BRITISH COLUMBIA...AND ALSO ACRS NE CANADA/NRN NEW ENGLAND. IN BETWEEN THESE FEATURES WILL BE MID LVL RIDING FROM THE CENTRAL PLAINS INTO S CNTRL CANADA. THIS UPPER LEVEL PATTERN WILL RESULT IN SFC HIGH PRESSURE UNDERNEATH THE EAST SIDE OF AFOREMENTIONED MID LVL RIDGE AXIS. THUS...DRY WEATHER WITH NEAR SEASONAL TEMPERATURES CAN BE EXPECTED MID TO LATE NEXT WEEK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...66 SHORT TERM...44 LONG TERM....30 AVIATION...98 in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 315 AM CDT FRI AUG 25 2006 .DISCUSSION... APPEARS THE AREA IS IN STORE FOR SVRL ROUNDS OF CONVECTIVE RAINS. TO A POINT, THIS WILL BE GOOD. BUT HPC HAS SEVERAL INCHES OVER SVRL DAYS AND THIS COULD BE THE BIGGEST CONCERN THIS FCST CYCLE. CONVECTION THIS MRNG IS SCATTERED AND MOVING ALONG NICELY. WAVE INDICATED ON RUCII THIS MRNG SHOULD BE MOVING THROUGH THE AREA BEFORE NOON PROVIDING A BREAK IN THE ACTION. HOWEVER WITH FNT OVER NE THIS MRNG CONTS TO MOVE SOUTH TWD THE CWA THIS MRNG. THUS, A BNDRY WILL BE ADDED TO THE MIX OF POTENTIAL WEATHER MAKERS FOR LATER TODAY AND TONIGHT. PRECIPITABLE WATER VALUES CLIMB ABOVE 2 INCHES LATER TODAY AND HOLD THERE OVERNIGHT. THIS COMBINED WITH APPCHG WAVE FM THE WEST PER NAM/RUCII COULD MEAN REPEAT CELLS OVER PARTS OF THE AREA BY TNGT. THIS ALL SHOULD PRIME THE GROUND FOR SECOND WAVE OF PCPN LATER ON SUNDAY. SVRL HEAVY PCPN EPISODES COULD VERY MUCH RAISE THE FLOODING THREAT. A BIT EARLY TO HIGHLIGHT THIS YET...BUT BEARS WATCHING. TEMPERATURES TRICKY TOO RIGHT THROUGH THE WEEKEND. EXPECT MORE CLOUDS THAN SUN FOR SATURDAY AND SUNDAY. TEMPS NOT MUCH ABOVE 80 BOTH DAYS...LIKELY LESS IF CLOUDS AND PCPN PERSIST FOR A GOOD PTN OF THE DAY. ENTIRE UPPER TROF DOES NOT MAKE ITS WAY THROUGH THE CWA UNTIL LATER ON MONDAY. HOWEVER BETTER LIFT IS WELL AHEAD OF TROF SO FOR NOW WILL HOLD ONTO CURRENT FCST THAT HAS PCPN ENDING SRN CWA ON MONDAY. DRYER AND WARMER INTO MID AND LATE NEXT WEEK. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 530 AM EDT FRI AUG 25 2006 .DISCUSSION... MAIN FCST CONCERNS ARE SHRA/TSRA CHANCES TODAY INTO SAT. WV IMAGERY AND RUC ANALYSIS INDICATES A RDG INTO THE WRN GRT LAKES AND WRN ONTARIO BTWN A TROF OVER ERN NOAM AND ANOTHER TROF MOVING IN FROM SASK INTO THE NRN PLAINS. AT THE SFC...LOW PRES WAS LOCATED OVER SW MN WITH A FRONT EXTENDING TO THE E THROUGH CNTRL WI INTO SRN LWR MI WITH HIGH PRES TO THE NORTH FROM NRN LAKE SUPERIOR TO HUDSON BAY. A VIGOROUS SHRTWV MOVING THROUGH SRN MN AND CENTRAL WI ALONG WITH AN ASSOC 80 KT 250 MB JET STREAK IS HELPING SUSTAIN CONVECTION OVER SE MN AND WCNTRL WI ATTM. DECENT 700-600 MB FGEN FORCING AS NOTED ON RUC XSECTIONS HAS INITIATED A BAND OF CONVECTION OVER FAR NCNTRL WI WHICH IS MOVING INTO UPR MI BORDER COUNTIES EARLY THIS MORNING. TODAY...06Z RUC AND 00Z NAM INDICATE FGEN SHRA BAND WILL LIFT SLOWLY ENE TODAY THEN GRADUALLY DISSIPATE BY 18Z AS IT MOVES INTO DRIER AIR OVER ERN COUNTIES. EVEN SO...MODELS STILL SHOW MODEST 850-500 MB Q-VECT CONV AND 305K ISENTROPIC ASCENT SPREADING NE ACROSS THE FCST AREA THROUGH 18Z. IN SHORT...WILL KEEP LIKELY POPS IN FOR COUNTIES ALONG WI BDR AND LAKE MI...AND THEN TAPER TO LOW CHC 30 POPS FOR FAR ERN COUNTIES WHERE DRIER ERLY FLOW AROUND HUDSON BAY HIGH WILL BEAT BACK ADVANCE OF SHRA SOMEWHAT. WITH MAINLY ELEVATED CONVECTION NORTH OF THE WARM FRONT...ONLY ISOLD EMBEDDED TSRA ARE EXPECTED ALONG THE WI BDR AND LAKE MI COUNTIES...PER LIMITED INSTABILITY AS NOTED ON GFS AND NAM MLCAPE FCST. TONIGHT INTO SAT...AS MORE FAVORABLE UPR LVL SUPPORT AND WAA SHIFTS TO THE EAST THE PCPN WILL SLOWLY DIMINISH FROM THE WEST. HOWEVER...LOW LVL CONV ASSOCIATED WITH THE SFC TROF MOVING INTO UPR MI COMBINED WITH ABUNDANT LOW LVL MOISTURE AND DRYING ABV 700 MB COULD LEAD TO AREAS OF DRIZZLE ALONG WITH AREAS OF FOG. EXPECT DRY ADVECTION AND INCREASING ANTICYCLONIC FLOW BEHIND THE TROF AXIS ALONG WITH INCREASING QVECTOR DIV TO SUPPORT A CLEARING TREND DURING SAT AFTERNOON FROM THE WEST. SAT NIGHT INTO SUN...MDLS WERE IN REASONABLE AGREEMENT THAT A MID LVL CONFLUENT FLOW WILL SET UP OVER THE UPR GREAT LAKES AND BUILDING SFC HIGH PRES WILL DOMINATE AND KEEP WX DRY FOR THE REST OF THE WEEKEND. SFC RDG AXIS MOVING OVER WESTERN INTERIOR SHOULD ALLOW WINDS TO DECOUPLE AS READINGS DIP INTO THE MID 40S OVER THE TRADITIONAL COLD DRAINAGE SPOTS. EXPECT FCST 8H TEMPS OF 12C NORTH TO 13-14C SOUTH WILL ALLOW MAX TEMPS TO REBOUND INTO THE MID TO UPR 70S ON SUNDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 449 AM CDT FRI AUG 25 2006 .DISCUSSION... THE LATEST GUIDANCE IS ALL POINTING TO A RATHER WET AND ACTIVE WEATHER PATTERN AS A SLOW MOVING WEST-EAST ORIENTED FRONT SAGS THROUGH THE AREA OVER THE NEXT 3-4 DAYS. THIS SHOULD BRING US MUCH NEEDED RAINFALL...HOWEVER BEFORE ALL IS SAID AND DONE SOME AREAS COULD SEE LOCALLY HEAVY RAINFALL IN A SHORT PERIOD. PINNING DOWN THE DETAILS OF THIS FCST IS THE MOST DIFFICULT TASK AS BOTH THE GFS AND NAM-WRF APPEAR TO BE SUFFERING FROM CONVECTIVE FEEDBACK AT VARYING POINTS IN THE FCST CYCLE. IN THE NEAR TERM...THUNDERSTORMS HAVE BLOSSOMED OVER PORTIONS OF NW MO AND ERN KS SINCE 06Z IN ASSOCIATION WITH A 35+ KT SWLY LLJ. THIS ACTIVITY IS BECOMING INCREASINGLY ORGANIZED WITH TIME AND APPEARS TO BE BEST FOCUSED ON THE LEADING EDGE OF THE ELEVATED INSTABILITY. THE QUESTION IS JUST HOW FAR EAST AND SOUTH THE ACTIVITY WILL PUSH AND DEVELOP BOTH THIS MORNING AND LATER TODAY. THE LATEST RUC ANALYSIS DATA IS INDICATING DRIER AND RELATIVELY STABLE AIR LOCATED ACROSS CNTRL MO EWD INTO ILLINOIS ATTM. HOWEVER THE FCST FROM BOTH THE RUC AND WRF-NAM SHOW THE LLJ VEERING TO MORE WLY AFT 12Z WHICH TRANSPORTS THIS HIGHER THETAE/UNSTABLE AIR EWD INTO CNTRL AND NE MO. IF THIS IS INDEED THE CASE IT WUD ARGUE FOR THESE STORMS IN SOME STATE TO PUSH INTO AT LEAST NW PTNS OF THE CWA. ALL OF THE MODEL GUIDANCE ALSO GENERATES PCPN IN THIS REGION. I HAVE BOOSTED POPS INTO THE HIGH CHC RANGE IN THE AFOREMENTIONED AREA AND CUT TEMPS A TAD WITH THIS IN MIND. FOR TONIGHT INTO MONDAY THE MAIN SHOW SHOULD BE CONCENTRATED ALONG AND NORTH OF THE WEST-EAST FRONT AS A PERSISTENT SWLY LLJ REMAINS FOCUSED ALONG THE SLOPED FRONTAL ZONE. A NUMBER OF ROUNDS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED. MOISTURE CONTENT WILL BE HIGH AND WARM CLOUD DEPTHS RELATIVELY DEEP WHICH SHOULD ENHANCE PCPN EFFICIENCY. IF WE GET SOME PRONLONGED TRAINING THEN WE COULD GET INTO A FLOOD THREAT. THE POTENTIAL FOR HEAVY RAINFALL WILL BE ADDRESSED IN THE HWO. THE THREAT OF RAIN SHOULD FINALLY PUSH SE OF THE AREA ON TUESDAY AS THE MAIN UPPER LEVEL TROF MOVES EAST INTO THE OH VLY REGION. GLASS && .AVIATION... FOR THE 06Z TAFS... TROF OVER THE CENTRAL PLAINS IS DRAWING MORE MOIST AND UNSTABLE AIR UP INTO THE MISSISSIPPI VALLEY. ISOLATED CONVECTION IS ALREADY BREAKING OUT OVER EASTERN KANSAS...BUT THE ATMOSPHERE IS ALREADY QUITE UNSTABLE THERE. DON'T EXPECT THIS INSTABILITY TO AFFECT THE CWFA UNTIL AFTER 12Z SO HAVE KEPT TERMINALS PRECIP FREE. CLOUDS SHOULD LOWER AND THICKEN ESPECIALLY IF ANY ORGANIZED CONVECTIVE SYSTEM GETS GOING OVER EASTERN KANSAS OR WESTERN MISSOURI AS CLOUD DEBRIS IS PUSHED EASTWARD. DO NOT EXPECT ANYTHING BELOW 12000FT THOUGH. WITH INCREASING CLOUDS AND SURFACE WINDS STAYING BETWEEN 5-8KTS I THINK THERE'S LITTLE CHANCE OF ANY FOG TONIGHT. SCATTERED CONVECTION LOOKS PROMISING FOR FRIDAY AFTERNOON. HARD TO SAY EXACTLY WHEN OR WHERE THE STORMS WILL FORM SO HAVE STUCK WITH PROB30S INSTEAD OF TEMPOS FOR THE TIME BEING. CARNEY && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 128 AM EDT FRI AUG 25 2006 .AVIATION... SURFACE HIGH PRESSURE WITH BUILDING HEIGHTS ALOFT WILL KEEP THE AREA DRY THROUGH THE PERIOD. GOOD OVERNIGHT RADIATIONAL COOLING TO PRODUCE PATCHY MVFR FOG ACROSS THE AREA WITH LIFR FOG IN DEEPER RIVER VALLEYS (LWB) THROUGH 12Z FRI. VFR CONDITIONS RETURN SHORTLY AFTER SUNRISE. && .PREV DISCUSSION... (ISSUED 848 PM EDT THU AUG 24 2006) SHORT TERM /REST OF TONIGHT/... SCENARIO THIS EVENING SIMILAR TO THE PAST FEW NIGHTS WITH DEWPOINT GRADIENT ACROSS THE SOUTH AND THETA-E RIDGE SW PROVIDING FOCUS/INSTABILITY FOR ISOLATED CONVECTION. AGAIN WITH THE AREA UNDER WEAK RIDGING BETWEEN FRONTS...AND LACK OF SUPPORT ALOFT...WOULD EXPECT MOST SHRA/TSRA TO FADE BY MIDNIGHT SIMILAR TO THE LATEST RUC. POSSIBLE TO SEE AN ISOLATED SHRA DRIFT SE ACROSS THE FAR NORTH LATER GIVEN TRAJECTORIES BUT LIKELY JUST MORE CLOUDS AT THIS POINT. OTHERWISE MORE VALLEY FOG AROUND AGAIN TONIGHT GIVEN SOME NORTHWARD INCREASE IN DEWPOINTS AND LIGHT WINDS. WILL ALSO RAISE TEMPS A LITTLE SOUTHERN ZONES WHERE THINGS REMAIN A BIT MORE MOIST FOR NOW. PREV DISCUSSION... (ISSUED 718 PM EDT THU AUG 24 2006) AVIATION... BIGGEST CONCERN THRU THE TAF PERIOD IS OVERNIGHT FOG. WITH WEAK SFC RIDGE DRIFTING OVR THE REGION WILL SEE LIGHT/CALM WINDS OVERNIGHT AND RIVER/VALLEY FOG LIKELY TO DEVELOP. HAVE PLAYED THINGS QUITE SIMILAR TO WHAT OCCURRED LAST NIGHT FOR THE NEW SET OF TAFS...WITH THE MOST DENSE FOG LIKELY TO BE FOUND AROUND KLWB WITH VLIFR CONDITIONS LIKELY LATE TONIGHT. ELSEWHERE...MAINLY A COMBO OF MVFR/IFR EXCEPT AROUND KROA WHERE VISBYS SHOULD STAY VFR. COULD SEE A BRIEF PERIOD OF LOWER CLDS ACRS NORTHWEST NORTH CAROLINA AND FAR SOUTHWEST VIRGINIA GIVEN CONTINUED WEAK UPSLOPE REGIME...ALTHOUGH ANTICIPATE AS FLOW BEGINS TO TURN MORE SOUTHWEST THINGS WILL SCOUR OUT OVERNIGHT. OTHERWISE...JUST A TAD MORE WIND TOMORROW AS RIDGE SLIDES EAST OF THE AREA BUT VFR CONDITIONS EXPECTED. PREV DISCUSSION... (ISSUED 319 PM EDT THU AUG 24 2006) SHORT TERM /TONIGHT/... CURRENT ISOLATED SHOWERS AND STORMS HAVE FORMED ALONG A WEST-EAST DEW POINT GRADIENT DURING THE PEAK HEATING OF THE DAY...ALONG AND NEAR THE KMTV-KDAN AREA. EXPECT THESE ISOLATED CELLS TO CONTINUE THROUGH AROUND SUNSET THEN DISSIPATE. OTHER ISOLATED CELLS HAVE FORMED ALONG THE MOUNTAINS OF NORTHWEST NORTH CAROLINA DUE TO BOTH HEATING AND WIND CONVERGENCE. ALSO EXPECT THESE TO CONTINUE THROUGH AROUND SUNSET. THERE WAS EARLIER CONCERN THAT CONVECTION IN ASSOCIATION WITH A SHORTWAVE TROUGH MOVING THROUGH PA/MD/NORTHERN VA MIGHT CLIP NORTHERN AND NORTHEASTERN PARTS OF THE REGION. HAVE REMOVED PRECIPITATION CHANCES THIS EVENING FROM THIS AREA. BELIEVE ANY PRECIPITATION ASSOCIATED WITH THE FEATURE WOULD ENCOUNTER STRONG STABLE LAYER ONCE THE INVERSION FORMS...AND NOT MAKE IT INTO THE REGION. HAVE ADDED THE POTENTIAL FOR VALLEY FOG PARTS OF THE AREA. LONG TERM /FRIDAY THROUGH THURSDAY/... GOING WITH A DRY FORECAST FRIDAY THROUGH EARLY SUNDAY WITH HIGH PRESSURE KEEPING A STRONG HOLD ON OUR WEATHER PATTERN. WILL FAVOR TEMPERATURES A FEW DEGREES WARMER THAN THE MAV MOS GUIDANCE IN MOST LOCATIONS. EARLY NEXT WEEK A COLD FRONT WILL APPROACH AND THEN MOVE THROUGH THE AREA. HAVE FOLLOWED THE HPC DEPICTION AND GRIDS ASSOCIATED WITH THE FRONTAL PASSAGE. THIS PLACES THE GREATEST CHANCE OF SHOWERS AND STORMS MONDAY NIGHT INTO TUESDAY...WITH DECREASING CHANCES HEADING INTO WEDNESDAY AND THURSDAY AS THE FRONT MOVES SOUTH OF THE AREA. AVIATION... AN ISOLATED SHOWER IS NEAR THE DANVILLE AIRPORT AT THIS TIME...AND LOOKS LIKE IT MAY BRING A SHOWER RIGHT AROUND 18Z...SO I INCLUDED A 1 HOUR TEMPO GROUP THERE. OTHERWISE...LOOKS LIKE ANY AFT/EVE CONVECTION WILL STAY EITHER WELL TO THE NORTH...OR TO THE SOUTH...OF OUR 5 SITES. WILL BE ANOTHER MOSTLY CLEAR NIGHT WITH LIGHT WINDS...SO I INCLUDED A PERIOD OF MVFR FOG AT BLF...LYH AND DAN...WITH A BRIEF PERIOD OF IFR FOG AT DAN SIMILAR TO THIS MORNING. LWB SHOULD ONCE AGAIN DROP DOWN TO LIFR TOWARD MORNING WITH RIVER FOG. ALL FOG IS EXPECTED TO BURN OFF BY A FEW HOURS AFTER SUNRISE. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ RCS va AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE PUEBLO CO 601 AM MDT FRI AUG 25 2006 .SHORT TERM... (TDA AND TNGT) ...ACTIVE WX PATTERN OVER THE NEXT 24 HOURS... CURRENTLY...WATER VAPOR IMAGERY AND RUC UPPER AIR MODEL ANALYSES SHOWED SEVERAL MINOR SHORTWAVE TROUGHS MIGRATING THROUGH THE W-SWLY MIDLEVEL FLOW. THERE WAS A WAVE ABOUT TO ENTER NERN CO AND GENERATING THE ISOLD-SCT SHRA. ANOTHER WAVE WAS ABOUT TO ENTER S CNTRL CO AND GENERATING ISOLD-SCT SHRA WITH A FEW LIGHTNING STRIKES. ANOTHER WAVE WAS ABOUT TO ENTER NWRN NM WHILE ANOTHER WAS OVER NERN UT MOVING EWD. PLENTY OF MIDDLE AND HIGH LEVEL MOISTURE NOTED ON SATELLITE AND 00Z/25 UPPER AIR OBS DATA. SFC DEW POINTS ARE RESPECTABLE...HOWEVER...SOME OF THE PRECIPITATION APPEARS TO HAVE TROUBLES MAKING IT TO THE GROUND DUE A "DRY" SLOT IN THE LOW LEVELS. SFC DEW POINTS IN THE LOWER 60S WAS JUST ACROSS THE SERN CO BORDER IN SWRN KS. SFC COLD FRONT DIFFICULT TO DISCERN DUE TO PRECIPITATION OUTFLOW BOUNDARIES CONTAMINATING THE SFC DATA. THE SFC COLD FRONT LIKELY EXTENDS ACROSS SRN NE INTO NWRN KS AND INTO NERN CO. PRESSURE RISES HAVE WEAKENED BEHIND THE FRONT...SO THE SWD AND WWD PROGRESSION SHOULD BE SLOWER UNLESS SOME OF THE SHOWER ACTIVITY CAN PUSH IT FURTHER S AND W. TDA AND TNGT...VERY CHALLENGING FORECAST FOR THE NEXT 12 HOURS. THE NAM-WRF CONTINUES TO SUFFER FROM TOO MUCH CONVECTIVE PRECIPITATION AND MAKING THE SURFACE FEATURES ALMOST DIFFICULT TO FOLLOW. THE 00Z/25 AND 06Z/25 NAM-WRF LOOK TO HAVE TOO MUCH PRECIPITATION AND RESULTING IN HIGHER SFC DEW POINTS AND CAPE...ESPECIALLY EARLY THIS MORNING. GENERALLY LIKE THE 13KM RUC SOLUTION OF SLOWLY SLIDING THE SFC FRONT SWD AND WWD THROUGH TDA. GIVEN THE WEAK SHORTWAVES MOVING THROUGH THIS MORNING...WILL NEED TO MAINTAIN SOME LOW POPS FOR SHOWERS. WOULD NOT BE A BIT SURPRISED THAT MUCH OF THE ACTIVITY IS VIRGA OR JUST SPRINKLES THIS MORNING. WITH SOME HEATING...AFTN SHOWERS AND TSTMS SHOULD DEVELOP OVER THE HIGH TERRAIN AND MOVE EWD. ANOTHER TSTM GENERATION AREA WILL BE AROUND THE SFC FRONT JUST S OF BACA CO THIS AFTN/EVE. THE MOST UNSTABLE AIR MASS SHOULD BE AROUND EXTREME SERN CO WITH PROJECTED CAPE VALUES OF 1K-2K J/KG PER NAM-WRF...BUT THAT IS ASSUMING THE MODELS SFC DEW POINTS ARE CORRECT. SFC-3KM CAPE IS 100-200 J/KG AND COULD SUPPORT EXPLOSIVE TSTM DEVELOPMENT ALONG AND JUST N OF THE LOW LEVEL BOUNDARY ACROSS EXTREME SERN CO THIS AFTN. LIFTED INDICES WILL RANGE FROM -1C TO -4C...THE MOST UNSTABLE LAPSE RATES SHOULD BE IN THE FAR SERN CO PLAINS. BULK SHEAR VALUES SHOULD BE HIGHER THAN PAST WEEKS...AND WILL BE 35-50KTS GIVEN THE LOW LEVEL ELY FLOW JUXTAPOSED WITH THE MIDLEVEL WLY FLOW. THIS WOULD SUPPORT MORE ORGANIZED SUPERCELL TSTM POTENTIAL...ESPECIALLY NEAR BOUNDARIES. WET BULB ZERO HEIGHTS ARE STILL RELATIVELY HIGHER...13K-15K FT MSL...BUT STRONG UPDRAFTS COULD SUPPORT HAIL AROUND 1 INCH IN DIAMETER. DOWNDRAFT CAPE IS PROGGED TO BE AROUND 800 J/KG AND COULD SUPPORT WIND GUSTS OF 35-45KTS. MODERATE TO HEAVY RAIN WILL BE POSSIBLE GIVEN THE RELATIVELY HIGH WET BULB ZERO/FREEZING LEVEL HEIGHTS AND H7-H5 SPECIFIC HUMIDITY VALUES OF 5-6 G/KG. I HAVE ADJUSTED POPS/WX TO INCLUDE A HIGHER THREAT OVER THE MTS AND FAR SERN CO PLAINS THIS AFTN AND TNGT. THE ONE DEFINITE FORECAST ISSUE WILL BE COOLER TEMPERATURES ACROSS MUCH OF THE CWFA...ESPECIALLY SERN CO. THINK THE MET MOS IS TOO COOL GIVEN ALL THE PRECIPITATION BEING GENERATED BY THE MODEL... ESPECIALLY SINCE CURRENT TEMPERATURES ARE CLOSE TO MET MOS PREDICTED HIGHS. LEANED MORE TOWARDS THE GFS MAV MOS. MIDLEVEL WLY FLOW CONTINUES ALOFT TNGT. MUCH OF THE CONVECTIVE PRECIPITATION SHOULD DIE OUT SHORTLY AFTER SUNSET ACROSS THE MTS AND I-25 CORRIDOR. POTENTIAL MESOSCALE CONVECTIVE SYSTEM ACROSS THE FAR SERN CO PLAINS AND KS TNGT. METZE .LONG TERM... (SATURDAY THROUGH THURSDAY) UNSETTLED WEATHER TO CONTINUE THROUGH SUNDAY BEFORE DRIER/WARMER CONDITIONS RETURN FOR NEXT WEEK. UPPER LOW STILL PROGGED TO DROP INTO THE NRN GREAT BASIN ON SAT...THEN LIFT OUT ACROSS NRN CO ON SUNDAY. LATEST RUNS APPEAR TO HAVE CONTINUED THE TREND OF STRONGER AND DEEPER WITH THIS SYSTEM. UPSLOPE FLOW BEHIND THE FRONT ADVECTS UPPER 50S/LOWER 60S DEW POINTS INTO SE CO ON SAT. THIS YIELDS CAPE VALUES OF 1000-1500 J/KG ACROSS SE CO. QUESTION IS HOW MUCH CIN WILL BE IN PLACE...AND FROM MODEL SOUNDINGS...APPEAR GREATEST CIN WILL BE ACROSS KIOWA COUNTY WHERE NAM12 KEEP VALUES IN EXCESS OF 100 J/KG. FLOW ALOFT WILL BE INCREASING ON SAT AS 70 KT UPPER JET TRANSLATES OVER THE REGION. COUPLED WITH EASTERLY LOW LVL FLOW RESULTS IN 40-45 KTS OF DEEP LAYER SHEAR...WHICH SHOULD BE SUFFICIENT FOR SUPERCELL THUNDERSTORMS...WITH HAIL AND DAMAGING WINDS THE PRIMARY THREATS. WITH PRECIP WATERS RUNNING FROM 1.0 TO 1.5 INCHES...HEAVY RAIN WILL ALSO BE A CONCERN...AND WILL HAVE TO MONITOR BURN SCARS FOR FLASH FLOOD THREAT. BEST QG ASCENT ARRIVES SAT NIGHT/EARLY SUNDAY WITH BOTH GFS/NAM PRINTING OUT HIGHEST QPF VALUES DOWN AROUND THE FRONT ACROSS NRN NM/TX PANHANDLE. HOWEVER A SECONDARY MAX OCCURS ALONG THE INTERSTATE 25 CORRIDOR IN CO/SRN WY COINCIDENT WITH BEST QG LIFT AHEAD OF THE APPROACHING UPPER LOW. DIFFICULT TO SAY WHERE BULLS EYES OF QPF WILL BE POSITIONED ACROSS SE CO...SO PLAN TO KEEP BROAD BRUSH HIGH SCATTERED POPS THROUGH SAT NIGHT...WITH SOME LIKELY POPS ACROSS SRN BACA COUNTY IN PROXIMITY TO FRONTAL BOUNDARY. FOR SUNDAY UPPER TROF IS SLOW TO EXIT NE CO. SHOULD SEE DRIER CONDITIONS OUT WEST AS DRIER AIR MOVES IN ALOFT BEHIND THE TROF. EASTERN SECTIONS OF THE FORECAST AREA COULD SEE ANOTHER UNSETTLED DAY AS COOLER AIR ALOFT ASSOC WITH UPPER TROF HELPS TO STEEPEN LAPSE RATES. CAPES IN 06Z RUN LOOK A LITTLE LOWER THAN PREVIOUS RUNS...BUT CIN IS LOWER THAN ON SATURDAY...AND MODEL SOUNDINGS SHOW SOME HIGHER CAPES IN THE LOWER PORTIONS OF THE SOUNDINGS WHICH WOULD SUPPORT STRONG UPDRAFTS. DEEP LAYER SHEARS STILL RUNNING AROUND 40-50 KTS...WHICH AGAIN WOULD SUPPORT SUPERCELL THUNDERSTORMS. MUCH WILL DEPEND ON THE TIMING OF THE EXITING TROF THOUGH. MAIN CHANGE WAS TO INCREASE POPS AND INTRODUCE AREAS OF FOG TO THE SAT NIGHT/EARLY SUNDAY TIME RANGE. ALSO COOLED OFF MAX TEMPS FOR BOTH SAT AND SUNDAY. FOR THE REMAINDER OF THE EXTENDED...UPPER RIDGE TRANSLATES BACK OVER THE REGION WITH MOST OF THE MOISTURE REMAINING SUPPRESSED TO THE SOUTH. THUS...SHOULD SEE GENERALLY ISOLATED POPS OVER THE MOUNTAINS EACH DAY...WITH A GRADUAL WARMING TREND TO NEAR CLIMO VALUES BY WEEKS END. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/31 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1035 AM CDT FRI AUG 25 2006 .UPDATE... REGIONAL RADAR MOSAIC SHOWS TWO AREAS OF PRECIPITATION THREATENING THE AREA... ONE MOVING ACROSS THE MID-ILLINOIS RIVER VALLEY... ANOTHER OVER NORTHEASTERN MISSOURI. THUNDERSTORMS MOVING OVER OUR NORTHERN CWA ARE THE LEFTOVERS OF A CONVECTIVE COMPLEX WHICH MOVED OVER THE UPPER MIDWEST OVERNIGHT. THESE STORMS APPEAR TO BE FOLLOWING THE WARM FRONT... AND ARE STILL EXPECTED TO WEAKEN AS THEY MOVE EASTWARD INTO AN INCREASINGLY DRY AND CAPPED ATMOSPHERE PER 12Z KILX SOUNDING. SFC OBS SHOW A LITTLE BIT OF LOW LEVEL MOISTURE POOLING ALONG AND NORTH OF THE FRONT... SO THIS MAY ALLOW STORMS TO MAKE THEIR WAY AS FAR EAST AS MCLEAN COUNTY LATER THIS MORNING. STORMS OVER NORTHWEST MISSOURI APPEAR TO BE ASSOCIATED WITH A SFC WAVE OVER IOWA AND TRAILING TROUGH ACROSS MISSOURI. COMMA-SHAPED APPEARANCE ON RADAR INDICATES SOME MESOSCALE ORGANIZATION WITH THIS CLUSTER... ARCING BACK INTO SOUTHERN MISSOURI. HOWEVER... LATEST TRENDS HAVE SHOWN SOME WEAKENING AS THE STORMS MOVE EAST OF THE MISSISSIPPI RIVER AND SFC MOISTURE AXIS. OVERALL... POPS FROM THE PREVIOUS UPDATE LOOK TO BE IN GOOD SHAPE... KEEPING ACTIVITY THIS AFTERNOON MORE OR LESS WEST OF I-55. BETTER RISK OF PRECIP WILL COME IN TIME FOR THE WEEKEND AS THE ACTUAL SFC COLD FRONT... CURRENTLY OVER IOWA... MOVES INTO THE PICTURE. HAVE UPDATED THE GRIDS TO COOL TEMPS WITH PLENTY OF DEBRIS CLOUDS AROUND... AND MADE CLOUD GRIDS A LITTLE MORE PESSIMISTIC. UPDATED ZFP WILL BE OUT SHORTLY. && .PREV DISCUSSION... /ISSUED 255 AM CDT FRI AUG 25 2006/ 00Z SHORT RANGE MODELS HAVE NOT BEEN VERY CONSISTENT FROM PREVIOUS RUNS OR IN GOOD AGREEMENT. THIS MAKES THE FORECAST TRICKY WITH A MORE UNSETTLED WEATHER PATTERN TAKING SHAPE THIS WEEKEND INTO EARLY NEXT WEEK AFTER A DRY STRETCH THE PAST 4 TO 5 DAYS THIS WEEK. NAM/WRF AND NGM DID NOT PICK UP ON CONVECTION AROUND KANSAS CITY EARLY THIS MORNING WITH RUC AND GFS PICKING THIS UP BETTER. ONE NOTED TREND OF MODELS IS LESS QPF OVER NORTHERN AREAS FROM PEORIA NORTHWARD SAT NIGHT AND SUNDAY. WILL TRY TO BLEND THIS FORECAST WITH SOME CONSISTENCY FROM PREVIOUS PACKAGE ALONG WITH MESHING WITH SURROUNDING OFFICES. SHORT TERM...TODAY THROUGH MONDAY NIGHT... 07Z/2 AM SURFACE MAP SHOWS 1004 MB LOW PRESSURE OVER FAR NW IOWA WITH A FRONTAL BOUNDARY EXTENDING EAST ALONG THE MN/IA AND WI/IL BORDER INTO NORTHERN INDIANA WHILE WEAK HIGH PRESSURE OF 1017 MB WAS OVER THE MID ATLANTIC STATES AND RIDGING WEST INTO THE MID MS VALLEY. ANOTHER MCS UP NORTH OVER NE IA...SE MN AND INTO WI AND TRACKING ESE WITH CIRRUS BLOWOFF COVERING AREAS FROM SPRINGFIELD NE. TEMPS RANGED FROM THE LOW TO MID 60S OVER SE IL TO THE UPPER 60S AND LOWER 70S OVER CENTRAL IL FROM MATTOON NW. DEWPOINTS WERE 60 TO 65F WITH SSE WINDS 5 TO 15 MPH...EXCEPT LIGHT TO CALM OVER SE IL CLOSER TO THE HIGH PRESSURE RIDGE. ALOFT 592 DM 500 MB SUBTROPICAL HIGH PRESSURE WAS OVER TX WHILE UPPER LEVEL TROF OVER NEW ENGLAND...THE WESTERN STATES AND LAKE WINNIPEG AND MN/DAKOTAS. HIGH PRESSURE TO KEEP EASTERN IL DRY TODAY BUT ADDED 20/30 PERCENT CHANCE OF CONVECTION TO AREAS ALONG AND WEST OF I-55 THIS AFTERNOON. SHORT WAVE NEAR KANSAS CITY TO MOVE EAST ACROSS MO AND TOWARD WESTCENTRAL IL LATER THIS AFTERNOON AND MODELS HAVE BEEN QUICKER WITH THIS FEATURE THAN YESTERDAYS RUN. GETS MORE UNSTABLE ALONG AND WEST OF I-55 THIS AFTERNOON TOO WITH LIFTED INDICES MINUS 4 TO 6C AND CAPES OF 1500 TO 2500 J/KG AS DEWPOINTS ELEVATE INTO THE UPPER 60S TO AROUND 70F. LOW PRESSURE OVER FAR NW IOWA MOVES EAST INTO SOUTHERN WI THIS AFTERNOON AND INTO NORTHERN LOWER MI SAT. WILL BE INCREASING CONVECTION CHANCES FROM WEST TO EAST TONIGHT WITH SHORT WAVE MOVING ACROSS IL TOWARD THE IL/IN BORDER BY 12Z/SAT. SPC HAS SLIGHT RISK OF SEVERE NW OF THE IL RIVER LATER THIS AFTERNOON AND EVENING FOR ISOLATED SEVERE WIND GUSTS/HAIL. HIGHS TODAY IN THE UPPER 80S WITH SW AREAS NEAR 90F AND MORE HUMID. GOOD CHANCE OF CONVECTION SAT WITH FRONTAL BOUNDARY DROPPING SOUTH INTO CENTRAL IL AND AIR MASS UNSTABLE AGAIN ESPECIALLY FROM IL RIVER SE WHERE LIFTED INDEX MINUS 4 TO 6C AND CAPES 1000 TO 2000 J/KG. SPC HAS SLIGHT RISK OF SEVERE JUST EAST OF EAST CENTRAL IL INTO CENTRAL/NORTHERN INDIANA. MODELS SHIFT QPF FURTHER SOUTH SAT NIGHT AND SUNDAY WITH FRONTAL BOUNDARY MOVING INTO SE IL WITH LESS QPF OVER AREAS FROM PEORIA NORTH...SO LOWERED CONVECTION CHANCES FROM 60 TO 30/40 PERCENT. HEAVY RAIN POSSIBLE ESPECIALLY ALONG AND SOUTH OF I-72 WITH PRECIPITABLE WATER VALUES GOING UP FROM 1 TO 2 INCHES. SURFACE LOW PRESSURE MOVING ALONG THE FRONTAL BOUNDARY NEAR THE OHIO RIVER MON TO KEEP CHANCE OF CONVECTION OVER CENTRAL AND ESPECIALLY SE IL. AREAS NW OF THE IL MAY BE DRY AND WILL LOWER POPS THERE TO MESH UP WITH NEARBY OFFICES. CONVECTION CHANCES DIMINISH FROM NW TO SE DURING MON NIGHT. CANADIAN MODEL DEVELOP HEAVY QPF OVER IL FROM LATER SUNDAY INTO MON NIGHT...BUT IS FURTHER NORTH THAN OTHER MODELS AND NOT FOLLOWED. LONG TERM...TUESDAY THROUGH FRIDAY... EXTENDED MODEL ENSEMBLES SHIFT FRONTAL BOUNDARY FURTHER SOUTH TUE ALONG WITH CONVECTION CHANCES OVER SOUTHERN IL WHILE CENTRAL IL APPEARS DRY. DGEX IS ODD MODEL KEEPING QPF OVER IL TUE AND WED. BUT MOST EXTENDED MODELS ARE KEEPING IT DRIER DURING MID AND LATE WEEK AND WILL KEEP FORECAST DRY TOO. HIGHS CLOSER TO NORMAL FROM 80 TO 85. && ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ HARDIMAN/HUETTL il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1047 AM EDT FRI AUG 25 2006 .UPDATE... ISSUED AN UPDATE THIS MORNING TO ADJUST CLOUD COVER. EXPANSIVE DEBRIS CLOUD FROM UPSTREAM CONVECTION CONTINUES TO CROSS THE CWA THIS MORNING WITH MOST LOCATIONS OVERCAST AT 14Z...EXCEPT FOR THE FAR SW AND SE CORNERS OF THE CWA. MORE CONVECTIVE DEBRIS UPSTREAM WILL CROSS THE CWA THIS AFTERNOON. WOULD EXPECT AREAL EXTENT OF CLOUD COVER TO DECREASE THIS AFTERNOON FOLLOWING TYPICAL DIURNAL TRENDS. WILL WORD ZFP AS A MIX OF CLOUDS AND SUN. IF CLOUDS REMAIN THICK ENOUGH THEY WILL RETARD SURFACE HEATING. FOR NOW WILL STAY WITH CURRENT FORECAST HIGH TEMPS IN THE MID 80S AND BANK ON THINNING/DIMINISHING CLOUD COVER THIS AFTERNOON. LOW CHANCE POPS LATE THIS AFTERNOON IN THE FAR NW STILL LOOKS GOOD. REGIONAL RADARS THIS MORNING SHOWING AREAS OF CONVECTION FROM SOUTHERN WISCONSIN SOUTH THROUGH WESTERN ILLINOIS. STORMS BEING DRIVEN BY MODERATE LOW/MID LEVEL THETA-E ADVECTION AS LLJ CONTINUES TO VEER DIURNALLY TO A MORE WESTERLY COMPONENT. 12Z PROXIMITY RAOB SOUNDINGS AND SPC OBJECTIVE RUC ANALYSIS SHOWING A LARGE THETA-E MINIMUM DOMINATING THE CWA THIS MORNING. THIS WILL INITIALLY INHIBIT DEVELOPMENT OF ANY SIGNIFICANT INSTABILITY...HOWEVER 06Z NAM CONTINUES TO SUGGEST HIGHER THETA-E PLUME OVER WESTERN ILLINOIS WILL ADVECT INTO THE NW CORNER OF THE CWA BY LATE AFTERNOON/EVENING. && .PREV DISCUSSION... AVIATION... DEBRIS CLOUDS HAVE OVERSPREAD THE AREA FROM A MCS TO THE NORTHWEST. JUST HIGH LEVEL CLOUDS FROM THE MCS AND APPROACHING COLD FRONT LATER TODAY ARE EXPECTED. SOME LOWER LEVEL CLOUDS COULD BEGIN MOVING IN TOWARDS THE END OF THIS TAF PERIOD. THIS MCS IS EXPECTED TO STAY TO THE NORTH AND THE NEXT RAIN CHANCES ARE NOT TIL TOWARDS THE END OF THIS TAF PERIOD AND WITH BEING SUCH A LOW CHANCE...DID NOT MENTION ANY RAIN IN THE TAFS. THE WIND ACROSS THE AREA IS CURRENTLY LIGHT TO CALM...BUT THIS WILL INCREASE LATER THIS MORNING FROM THE SOUTH TO SOUTHWEST WITH GUSTS AND THEN CALM DOWN SOME AGAIN TONIGHT. MOS GUIDANCE IS HINTING SOME FOG EARLY TOMORROW MORNING BUT SINCE THIS IS AT THE END OF THE TAF PERIOD...WILL NOT MENTION AT THIS MOMENT. SHORT TERM... TODAY AND TONIGHT. OVERNIGHT THE MCS TO THE NORTHWEST HAS BEEN CRANKING IT OUT BUT THE ONLY EFFECTS OUR CWA HAS FELT FROM IT HAVE BEEN HIGH LEVEL DEBRIS CLOUDS. THE QUASI STATIONARY FRONT JUST TO THE NORTH WILL NOT MOVE MUCH TODAY AS THE SURFACE TROUGH CURRENTLY OVER THE CENTRAL PART OF THE U.S. GETS CLOSER. THIS WILL KEEP OUR CWA IN THE WARM SECTOR TODAY AND WITH 850MB TEMPS PROGGED TO BE AROUND 19 TO 20 DEGREES CELSIUS THIS AFTERNOON...HIGH TEMPERATURES TODAY WILL REACH INTO THE MIDDLE 80S. THE NAM/WRF HAS NOT WAVERED WITH THE POSITION OF THE TROUGH/FRONT BY THIS EVENING AND THE GFS HAS SEEMED TO BACK OFF WITH THE FRONT A LITTLE BIT AND COME MORE IN LINE WITH THE NAM/WRF. HAVE TRIMMED BACK THE LOW CHANCE POPS A TAD FOR THIS AFTERNOON IN THE WEST/NORTHWEST BUT WITH THE FRONT/TROUGH STILL PROGGED TO BE CLOSE TO THE WESTERN BORDER OF OUR CWA...DECIDED TO STAY CONSISTENT WITH PREVIOUS FORECAST AND KEEP THE INTRODUCTION OF RAIN CHANCES LATE THIS AFTERNOON. IT IS STILL A LOW POP CHANCE WHICH IS SAYING A GREATER CHANCE THAT IT WILL BE DRY. THESE ARE JUST MODELS AFTER ALL AND THE ACTUAL POSITION OF THE TROUGH/FRONT COULD STILL BE CLOSER THAN WHAT THEY ARE SAYING. THEN OVERNIGHT TONIGHT THE COLD FRONT WILL BE IN THE WESTERN PART OF THE CWA...OVERSPREADING THE CHANCE FOR RAIN TO THE REST OF THE CWA. THE BETTER POTENTIAL FOR SEVERE WEATHER TODAY AND TONIGHT EXISTS JUST TO OUR WEST TO NORTHWEST. MODEL SOUNDINGS ARE SHOWING A CAP TO BE OVER THE CWA TODAY LIMITING OUR CHANCES FOR ANY SEVERE WEATHER. THE BEST POTENTIAL LIKE MENTIONED IS CLOSER TO THE FRONT AND ANOTHER LIMITING FACTOR IS THE TIMING OF THE FRONT INTO THE CWA. AN ISOLATED SEVERE STORM IN THE WESTERN PART OF OUR CWA IS NOT OUT OF THE QUESTION WITH SUCH INSTABILITY CLOSE BY...BUT CHANCES ARE LOW. LONG TERM... SATURDAY THROUGH FRIDAY. BEST CHANCE FOR SHRA/TSRA ON SATURDAY AS POTENT SRN CANADA SHORTWAVE ENERGY DROPS ESE INTO GREAT LAKES. SOME QUESTION WITH RESPECT TO FRONTAL TIMING WITH NAM OUTLIER IN SCOURING FRONT THROUGH MUCH FASTER. PREFERENCE LIES TO MORE CONSISTENT GFS/ECMWF/UKMET. FRONT SHOULD SLOW WITH SURFACE WAVE REFLECTION ALONG FRONT IN SOUTHERN PLAINS LIKELY GIVEN LOW LEVEL JET PRESENCE FRIDAY NIGHT. WEAK FRONTAL FORCING SHOULD BE SUFFICIENT IMPETUS FOR TSRA DEVELOPMENT BY MIDDAY AS AIRMASS BECOMES MODERATELY UNSTABLE WITH SBCAPES 2000-2500 J/KG AS LOW LEVEL THETA-E POOLS AHEAD OF FRONT. 0-6KM BULK LAYER SHEAR 25-30 KTS ALSO SUFFICIENT FOR AT LEAST A MINOR SEVERE POTENTIAL. CONCERN WITH POPS SUNDAY AND SUNDAY NIGHT ESPECIALLY NRN CWA WITH LATEST GFS TAKING FRONT SOUTH OF CWA TO NEAR OHIO RIVER AND SURFACE HIGH WEDGES INTO SOUTHERN GREAT LAKES AND MUCH DRIER AIRMASS. FOR NOW THOUGH WILL MAINTAIN STATUS QUO AND DEFER TO LATER RUNS AS STILL SOME CONCERN WITH FRONTAL WAVE DEVELOPMENT EARLY NEXT WEEK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...HITCHCOCK SHORT TERM/AVIATION...LOTHAMER LONG TERM...MURPHY in AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1207 PM EDT FRI AUG 25 2006 .UPDATE... MAIN UPDATE CONCERNS ARE SHRA/TSRA CHANCES THIS AFTERNOON. VIS SAT SHOWS WIDESPREAD LOW CLOUDS ACROSS OUR CWA WITH -SHRA ACROSS THE WEST 2/3. THE NAM SEEMS TO BE HANDLING THE SHRA THE BEST. THE 12Z NAM SHOWS ISENTROPIC ASCENT FROM 300-315K AND A DEEP MOISTURE AXIS COINCIDING WITH THE MAX PRECIP AT 12-15Z. IT SHOWS THIS DEEP MOISTURE AXIS MOVING ALMOST OUT OF OUR CWA BY 18Z...EXCEPT OVER THE FAR EAST. WV SHOWS SHRTWV OVER OUR CWA AT 12Z...ALSO HELPING TO PRODUCE THE SHRA...AND THIS SHRTWV WILL ALSO EXIT BY 18Z. THUS...OUR BEST CHANCE OF PRECIP IS RIGHT NOW THROUGH EARLY AFTERNOON EAST. THE BIG QUESTION IS WHETHER OR NOT TO EXPECT MORE SHOWERS AND THUNDERSTORMS DEVELOPING BEHIND THIS MAIN SHRA. SHRTWV OVER CWA WILL EXIT AND SUBSIDENCE WILL BUILD IN BEHIND FOR A SHORT PERIOD OF TIME. WV AND KMSP/KINL SNDGS INDICATE VERY DRY AIR AT UPPER LEVELS MOVING INTO OUR CWA. HOWEVER...KRHI TAMDAR REMAINS FAIRLY MOIST AT LOW LEVELS THROUGH 700MB AND KGRB SNDG IS DRIER ABOVE 850MB. SCATTERED SHOWERS AND THUNDERSTORMS ARE PRESENT OVER CENTRAL WI...ASSOCIATED WITH THE NOSE OF A 250MB JET AND 500MB SHRTWV. THE INTERSECTION OF THIS SHRTWV AND 850MB AXIS OF MOIST AIR ACROSS CENTRAL AND SOUTHERN WI MAY BRING THUNDERSTORMS INTO MENOMINEE COUNTY THIS AFTERNOON. THE REST OF THE CWA MAY SEE A FEW SHOWERS FILLING IN WITH THE NEXT SHRTWV...SO WENT WITH SCT RW- OVER KEWEENAW AND MID LAKE...A CHANCE OF SHOWERS WITH A SLIGHT CHANCE OF THUNDERSTORMS OVER MOST OF THE U.P...AND SCATTERED SHOWERS AND THUNDERSTORMS ACROSS SOUTHERN MNM COUNTY...MAINLY SOUTH OF HWY 2. THE GOING FCST MAX TEMPS LOOKED FINE SINCE THE OVC CLOUD COVER IS HANGING IN THERE. WINDS AND WAVES ALSO SEEM TO BE ON TRACK ATTM. && .PREV DISCUSSION... MAIN FCST CONCERNS ARE SHRA/TSRA CHANCES TODAY INTO SAT. WV IMAGERY AND RUC ANALYSIS INDICATES A RDG INTO THE WRN GRT LAKES AND WRN ONTARIO BTWN A TROF OVER ERN NOAM AND ANOTHER TROF MOVING IN FROM SASK INTO THE NRN PLAINS. AT THE SFC...LOW PRES WAS LOCATED OVER SW MN WITH A FRONT EXTENDING TO THE E THROUGH CNTRL WI INTO SRN LWR MI WITH HIGH PRES TO THE NORTH FROM NRN LAKE SUPERIOR TO HUDSON BAY. A VIGOROUS SHRTWV MOVING THROUGH SRN MN AND CENTRAL WI ALONG WITH AN ASSOC 80 KT 250 MB JET STREAK IS HELPING SUSTAIN CONVECTION OVER SE MN AND WCNTRL WI ATTM. DECENT 700-600 MB FGEN FORCING AS NOTED ON RUC XSECTIONS HAS INITIATED A BAND OF CONVECTION OVER FAR NCNTRL WI WHICH IS MOVING INTO UPR MI BORDER COUNTIES EARLY THIS MORNING. TODAY...06Z RUC AND 00Z NAM INDICATE FGEN SHRA BAND WILL LIFT SLOWLY ENE TODAY THEN GRADUALLY DISSIPATE BY 18Z AS IT MOVES INTO DRIER AIR OVER ERN COUNTIES. EVEN SO...MODELS STILL SHOW MODEST 850-500 MB Q-VECT CONV AND 305K ISENTROPIC ASCENT SPREADING NE ACROSS THE FCST AREA THROUGH 18Z. IN SHORT...WILL KEEP LIKELY POPS IN FOR COUNTIES ALONG WI BDR AND LAKE MI...AND THEN TAPER TO LOW CHC 30 POPS FOR FAR ERN COUNTIES WHERE DRIER ERLY FLOW AROUND HUDSON BAY HIGH WILL BEAT BACK ADVANCE OF SHRA SOMEWHAT. WITH MAINLY ELEVATED CONVECTION NORTH OF THE WARM FRONT...ONLY ISOLD EMBEDDED TSRA ARE EXPECTED ALONG THE WI BDR AND LAKE MI COUNTIES...PER LIMITED INSTABILITY AS NOTED ON GFS AND NAM MLCAPE FCST. TONIGHT INTO SAT...AS MORE FAVORABLE UPR LVL SUPPORT AND WAA SHIFTS TO THE EAST THE PCPN WILL SLOWLY DIMINISH FROM THE WEST. HOWEVER...LOW LVL CONV ASSOCIATED WITH THE SFC TROF MOVING INTO UPR MI COMBINED WITH ABUNDANT LOW LVL MOISTURE AND DRYING ABV 700 MB COULD LEAD TO AREAS OF DRIZZLE ALONG WITH AREAS OF FOG. EXPECT DRY ADVECTION AND INCREASING ANTICYCLONIC FLOW BEHIND THE TROF AXIS ALONG WITH INCREASING QVECTOR DIV TO SUPPORT A CLEARING TREND DURING SAT AFTERNOON FROM THE WEST. SAT NIGHT INTO SUN...MDLS WERE IN REASONABLE AGREEMENT THAT A MID LVL CONFLUENT FLOW WILL SET UP OVER THE UPR GREAT LAKES AND BUILDING SFC HIGH PRES WILL DOMINATE AND KEEP WX DRY FOR THE REST OF THE WEEKEND. SFC RDG AXIS MOVING OVER WESTERN INTERIOR SHOULD ALLOW WINDS TO DECOUPLE AS READINGS DIP INTO THE MID 40S OVER THE TRADITIONAL COLD DRAINAGE SPOTS. EXPECT FCST 8H TEMPS OF 12C NORTH TO 13-14C SOUTH WILL ALLOW MAX TEMPS TO REBOUND INTO THE MID TO UPR 70S ON SUNDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ MRE (UPDATE) VOSS (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1055 AM EDT FRI AUG 25 2006 .UPDATE...14Z SURFACE/IR SATELLITE/REGIONAL RADAR/AND RUC ANALYSIS SHOWING QUASI-STATIONARY FRONT DRAPED ACROSS SOUTH CENTRAL LOWER MICHIGAN. THIS FRONT EXTENDS WEST TO A WEAK AREA OF LOW PRESSURE SITUATED OVER CENTRAL IOWA. CLOSER TO HOME...LARGE SHIELD OF RAIN...DRIVEN BY MASS CONVERGENCE ON NOSE OF 850MB LOW LEVEL JET...CONTINUES TO PROPAGATE EAST ACROSS THE NORTHEASTERN LOWER AND THE EASTERN UPPER. RAIN IS STRUGGLING TO MAKE INTO NORTHERN CHIPPEWA COUNTY...HOWEVER...AS HIGH PRESSURE CENTERED OVER JAMES BAY CONTINUES TO ADVECT DRY LOW AND MID LEVEL AIR INTO THAT AREA. EXPECT THIS RAIN SHIELD TO CONTINUE ITS ADVANCE EAST AND SLOWLY DIMINISH IN INTENSITY AS JET WEAKENS. FORECAST CONCERNS FOR THE REMAINDER OF THE DAY CENTER AROUND THE CONTINUED THREAT OF SHOWERS AND STORMS ALONG WITH THE POTENTIAL OF SEVERE WEATHER THIS AFTERNOON. SOUTHERN MICHIGAN FRONT STRUGGLING TO PUSH NORTH AS RAIN COOLED AIR HAS EFFECTIVELY STALLED ITS NORTHWARD PROGRESSION. BEST INSTABILITY WILL REMAIN SOUTH OF THIS BOUNDARY IN WARM SECTOR. GIVEN OBSERVATIONAL TRENDS OVER THE LAST SEVERAL HOURS AND LATEST RUC FORECAST...FEEL FRONT WILL NOT MAKE INTO OUR FORECAST AREA DURING THE DAY. KINEMATICS REMAIN IMPRESSIVE WITH 0-6 KM BULK SHEAR VALUES OF 45 TO 50 KNOTS AND 0-3 KM HELICITY GREATER THAN 350 M2/S2. BIGGEST LIMITING FACTOR REMAINS INSTABILITY WITH FRONT SO FAR SOUTH AND ABUNDANT CLOUD COVER. MODIFYING 12Z APX SOUNDING WITH A WORST CASE SCENARIO HIGH OF 74 AND DEWPOINT OF 63 DOES YIELD ML CAPE OF OVER 1000J/KG. A MORE CONSERVATIVE TEMPERATURE OF 71 YIELDS CAPE ON ONLY ABOUT 200J/KG. LATEST SATELLITE IMAGES DOES SHOW SOME CLEARING IN NORTHERN WISCONSIN WITH TEMPERATURES RESPONDING NICELY REACHING THE LOW 70S. WILL NEED TO MONITOR CLEARING TRENDS THIS AFTERNOON. GIVEN ABOVE MENTIONED WIND FIELDS...IT WILL NOT TAKE MUCH INSTABILITY TO GENERATE A SEVERE WIND THREAT. PRESENCE OF SUBTLE SHORTWAVE OVER NORTHERN WISCONSIN IN CONJUNCTION WITH NORTHWARD ADVECTION OF 850-700MB THETA-E RIDGE SHOULD CONTINUE THE THREAT OF SCATTERED SHOWERS AND STORMS THROUGHOUT THE REMAINDER OF THE AFTERNOON. AS FOR THE MARINE ISSUES...WILL MAINTAIN ONGOING SCA AS STIFF 15 TO 20 KNOT EASTERLY WINDS FUNNEL ACROSS THE LAKES. AM EXPECTING WINDS TO BECOME INCREASINGLY GUSTY THIS AFTERNOON AS PRESSURE GRADIENT TIGHTENS WITH APPROACH OF IOWA LOW. UPDATED GRIDS/ZONES WILL BE OUT SHORTLY TO REFRESHEN WORDING. MSB && .PREV DISCUSSION...ISSUED AT 354 AM EDT FRI AUG 25 2006 FLOW PATTERN THROUGH THE COMING WEEKEND EXPECTED TO BE SOMEWHAT FLATTER/PROGRESSIVE AS EASTERN NORTH AMERICA TROUGH GETS NUDGED FARTHER EAST...WHILE EASTERN PACIFIC RIDGE GETS FLATTENED BY APPROACHING SHORT WAVE ENERGY OVER THE GULF OF AK. SHORT WAVE TROUGH OVER THE DAKOTAS/MN THIS MORNING WILL IMPACT THE FORECAST AREA TODAY...WITH ADDITIONAL ENERGY OVER THE CANADIAN PRAIRIES PASSING NEAR/NORTH OF THE FORECAST AREA SUNDAY. SURFACE FRONT LYING FROM THE UPPER MISSISSIPPI VALLEY SOUTHEAST THROUGH THE LOWER LAKES REGION WILL LIFT SLOWLY NORTH THROUGH SATURDAY AS A WEAKENING FRONTAL WAVE ALONG MN/IA BORDER RIDES ALONG IT. MAIN FORECAST CONCERNS WILL DEAL WITH PRECIPITATION EVOLUTION IN WARM ADVECTION PATTERN NORTH OF THIS BOUNDARY TODAY THROUGH SATURDAY...AS WELL AS FORECAST POSITION OF SURFACE FRONT AS THAT WILL IMPACT ANY SEVERE WEATHER POTENTIAL TODAY. TODAY/TONIGHT...FAIRLY WIDESPREAD AREA OF RAIN/EMBEDDED CONVECTION SPREADING ACROSS NORTHERN LOWER MI EARLY THIS MORNING...FORMING AHEAD OF SHORT WAVE TROUGH CROSSING WI ALONG WITH RRQ FORCING FROM 100+KT JET STREAK CLIPPING THE NORTHEAST CORNER OF THE STATE...AND IN AN AREA OF BROAD LOW/MID LEVEL WARM ADVECTION NORTH OF STALLED FRONT RUNNING ACROSS FAR SOUTHERN MN/WI/NORTHERN IL/IN/OH PER MIDNIGHT SURFACE ANALYSIS. AXIS OF 1.50+ INCH PW VALUES ALSO POOLED ALONG THE BAROCLINIC ZONE ACROSS SOUTHERN PORTIONS OF LOWER MI/WI/ MN...ALONG WITH STEEP MID LEVEL LAPSE RATES (700-500MB LAPSE RATES 8+ C/KM) CLOSER TO THE FRONT ITSELF. BACK EDGE OF THIS RAIN CROSSING NORTHERN LAKE MICHIGAN ASSOCIATED WITH LEAD MID LEVEL TROUGH AXIS...THOUGH SOME ADDITIONAL SHOWERS DEVELOPING OVER FAR NORTHWEST WI. MAIN SHOW IS FARTHER SOUTH CLOSER TO THE BOUNDARY WHERE STRONG STORMS CONTINUE TO DEVELOP ACROSS SOUTHEAST MN/ NORTHEAST IA...WHERE OF COURSE THE GUIDANCE DOESN'T APPEAR TO BE DOING SO HOT IN PICKING UP THE QPF THERE. SO AS USUAL IN THESE SITUATIONS TRYING TO FERRET DETAILS OUT OF THE MODELS IS PROBABLY A SOMEWHAT FRUITLESS ENDEAVOR...BUT INITIAL THINKING IS THAT LEADING BAND OF PRECIPITATION WILL MOVE THROUGH THIS MORNING AS VORTICITY CENTER MOVES EAST OF THE AREA...WITH MORE SCATTERED COVERAGE DURING THE AFTERNOON AS 850MB WARM FRONT LIFTS INTO CENTRAL LOWER COUNTIES. AT THIS POINT ANTICIPATE THAT SURFACE WARM FRONT WILL REMAIN SOUTH OF THE FORECAST AREA THROUGH THE AFTERNOON...ESPECIALLY IF CONVECTION CONTINUES TO DEVELOP ALONG IT ACROSS SOUTHERN WI AND ALLOWING A BUBBLE OF RAIN-COOLED AIR TO BLUNT NORTHWARD PUSH OF THE BOUNDARY. GIVEN EXTENSIVE CLOUD COVER INSTABILITY WILL BE LIMITED...THOUGH WITH 700- 500MB LAPSE RATES AROUND 7.5C/KM ANTICIPATED WON'T REQUIRE MUCH WARMING TO GENERATE SOME CAPE (400-800 J/KG)...AND GIVEN FORECAST SHEAR MAY NOT REQUIRE A LARGE AMOUNT OF INSTABILITY TO CAUSE SOME PROBLEMS. 0-6KM SHEAR VALUES OF 40-50KT COMBINED WITH STRONG LOW LEVEL TURNING OF THE WINDS WITHIN WARM FRONTAL ZONE WOULD SUPPORT UPDRAFT ROTATION AND POTENTIAL TORNADIC DEVELOPMENT GIVEN LOW LCL HEIGHTS (IF BOUNDARY LAYER IS NOT TOO STABLE). SO POTENTIAL IS THERE...WILL HAVE TO SEE IF PERSISTENT UPSTREAM CONVECTION ENDS UP BEING MORE DETRIMENTAL OR INSTABILITY TOO MARGINAL (BRN BELOW 10...TOO MUCH SHEAR VERSUS INSTABILITY???). BEST THREAT RIGHT NOW LOOKS TO BE SOUTH OF M-72 WHERE STEEPER MID LEVEL LAPSE RATES EXPECTED TO OCCUR. CHANCES FOR SHOWERS/THUNDERSTORMS TO CONTINUE OVERNIGHT AS WARM ADVECTION PATTERN PERSISTS WITH SURFACE LOW LIFTING NORTHEAST TOWARD GREEN BAY. SATURDAY...SURFACE LOW WILL CREEP SLOWLY NORTHEAST ACROSS NORTHERN LAKE MICHIGAN...DRAGGING WARM FRONT INTO NORTHERN LOWER MI. EXPECT CONTINUED SHOWER/THUNDERSTORM CHANCES ASSOCIATED WITH THIS FEATURE... PERHAPS AUGMENTED BY DIURNAL HEATING/INSTABILITY. WILL DRAG RAIN CHANCES INTO SATURDAY EVENING...WITH SURFACE LOW/COLD FRONT NOT FORECAST TO EXIT THE AREA UNTIL AFTER MIDNIGHT. MARINE...EASTERLY GRADIENT TIGHTENS TODAY AS SURFACE LOW SLIDES INTO SOUTHERN WI. FAIRLY BRISK LOW LEVEL FLOW AS WELL (925MB WINDS 20-30KTS) SHOULD TRANSLATE TO SMALL CRAFT CONDITIONS IN MOST NEARSHORE ZONES...ENHANCED BY COASTAL CONVERGENCE ALONG SOUTHEAST UPPER SHORELINE AND FUNNELING THROUGH THE STRAITS OF MACKINAC. WILL RUN THIS THROUGH TONIGHT. ALTHOUGH WINDS EXPECTED TO DIMINISH SATURDAY...WAVE HEIGHTS MAY STILL BE AN ISSUE ON THE LAKE HURON SIDE. WINDS SHIFT TO NORTHWEST SATURDAY NIGHT AND WILL PICK UP AGAIN IN COLD ADVECTION PATTERN WITH 20KT LOW LEVEL FLOW FORECAST. JPB && .APX...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1127 AM EDT FRI AUG 25 2006 .SHORT TERM /REST OF TODAY/... WEAK BOUNDARY OVER CTRL PA IS FCST TO EDGE SLOWLY NORTH TODAY. CLOUDS ARE BREAKING NICELY OVER MOST OF THE AREA...HANGING TOUGHEST EAST OF A LINE FROM ABOUT BFD THRU RDG. WITH DEWPOINTS RISING INTO THE 60S...MODELS ARE TRYING TO DEVELOP SOME MODEST INSTABILITY WITH RUC ANALS SHOWING CAPE IN EXCESS OF 1000J OVER WRN AND SERN PA. SREF FORECASTS OF CAPE ARE MORE MODEST BUT ALSO HIGHLIGHT THESE AREAS WHERE DEWPOINTS ARE HIGHEST AND SUNSHINE IS OR WILL BE MOST ABUNDANT. WITH THE BOUNDARY MAINLY THRU THE NRN HALF OF THE STATE TODAY...THINK THAT WILL BE WHERE THE BEST CHC OF THUNDER WILL REMAIN WITH JUST SPOTTY ACTIVITY OVER THE SRN HALF OF MY FCST AREA. LA CORTE && .PREV DISCUSSION... /ISSUED 301 AM EDT FRI AUG 25 2006/ SHORT TERM /TODAY THROUGH SUNDAY/... MANY THINGS GOING ON HERE JUST NORTH OF THE WARM FRONT. WARM FRONT NOW SOMEWHERE NEAR PIT TO JUST SOUTH OF JST AND NOT MOVING AT THIS HOUR. SHOWERS ASSOCIATED WITH ONE S/WV NOW ENTERING NWRN ZNS...AND NOT REALLY DECREASING AS THEY MOVE IN. BUT COVERAGE IS NOT TOTAL...MORE LIKE 40/50 PCT. ADDITIONAL LIGHT PRECIP UPSTREAM APPEARS TO BE REMNANTS OF MASSIVE CONVECTIVE CLUSTER OV WI EARLIER THIS EVENING. WILL THEREFORE KEEP HIGH CHC POPS UP IN THE NRN THIRD THIS MORNING. PCPN THIS AFTN VERY MUCH A MORE DIFFICULT CALL. UPSTREAM CLOUDS AND MORNING PRECIP WILL KEEP US DARKER THAN NECESSARY FOR BEST DESTABILIZATION...AND MAY KEEP THE WARM FRONT FROM GOING TOO FAR NORTH TODAY. THAT ARGUES FOR TWO THINGS...BETTER HELICITY OVER SRN/CENTRAL PA...BUT ALSO FOR LOW CAPES. WILL HOLD WITH CONTINUITY AND KEEP MENTIONS OF SHOWERS TO MAINLY THIS MORNING...AND LEAVE IN A REAL LOW POP FOR THE AFTN IN THE N/C....AND THEN INCREASE AGAIN AFT 22Z /6PM/ MAINLY OVER THE NERN HALF OF CWA. WITH SO MUCH CLOUD COVER AND LIGHT PRECIP THIS MORNING...WILL HOLD MAXES IN 70S IN THE NORTH...BUT MENTION MID 80S IN SOUTH. TONIGHT...WILL GO FOR SCT/NMRS SHOWERS AND SOME THUNDER IN THE NORTH/EAST AND LESS ACTIVITY TO THE SW...WHERE WE MAY ACTUALLY BE IN THE WARM SECTOR AND DRY. CLUSTER OF CONVECTION - MAINLY ELEVATED - IS EXPECT TO DROP NW-SE ACROSS MY NE HALF. TEMPS UPPER 50S IN NORTH AND M/U60S IN SOUTH. SATURDAY MAY ALSO START OUT MAINLY DRY...ESP IN THE WEST AND CENTRAL ZNS...BUT GET BUSIER IN THE AFTN WITH PESKY SLOW MOVING WARM FRONT IN VCTY HELPING TO CREATE SOME LIFT. MOST MAX TEMPS SHOULD GO A FEW DEGS HIER SAT THAN TODAY. SAT NITE AND SUNDAY LOOK LIKE THE MOST LIKELY TIME FOR SHOWERS AND THUNDER FOR THIS ENTIRE TIME PERIOD...AND HAVE THUSLY ADJUSTED POPS UP QUITE A BIT...TO 60S FOR THE NORTH AND 40-50 FOR THE REST OF THE AREA. WITH WM FNT STILL LINGERING AND A CD FNT NEARING FROM NW...HI POPS ARE IN ORDER. FUNNY - OR MAYBE TELLING - THAT THIS TIME FRAME /SAT-SUN/ IS EXACTLY WHEN THE HIGHEST PWATS HAVE BEEN PROGGED TO AFFECT THE AREA FOR A FEW DAYS NOW BY THE GFS EPS - ENSEMBLE PREDICTION SYSTEM. LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... DRIER AIR LOOKS TO WORK IN FROM N-S ON MONDAY AND HAVE ALSO MADE INTER-OFFICE-COORDINATED DROPS IN POPS FOR MON-TUE...MAKING MUCH OF THAT TIME DRY IN ZFP WORDING...HOLDING ONLY 20 OR SO POPS FOR THEN. NEWEST DETERMINISTIC AND ENSEMBLE GUID IS IN AGREEMENT THAT SFC HIGH SHOULD WORK S IN TO PA AND PROVIDE FAIR WX. REST OF EXTENDED NOT TOUCHED. AVIATION... SHORT TERM CONCERNS WILL BE THE DEVELOPMENT OF FOG AND ASSOCIATED LOW CEILINGS. CURRENTLY KIPT HAS DROPPED INTO IFR CATEGORY WITH A OVC004 LAYER. THIS IS SIMILAR TO LAST NIGHT WITH OTHER SITES MAINLY DROPPING TO MVFR VISIBILITIES IN BR. EXPECT SIMILAR CONDITIONS THIS MORNING AND HAVE ADDED TEMPO GROUPS COVERING THIS. REMNANT CLOUDS FROM MCS OVER WISCONSIN WILL REMAIN OVER THE ENTIRE AREA THROUGH AROUND 16Z. THERE MAY EVEN BE A WIDELY SCATTERED SHOWER BUT CONFIDENCE ONLY ENOUGH TO PLACE VCSH IN THE LATE MORNING PERIOD. OTHERWISE...ALL LOCATIONS EXPECTED TO BE VFR TODAY. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 1119 AM EDT FRI AUG 25 2006 .SHORT TERM /REST OF TODAY/...MORNING WATER VAPOR IMAGERY SHOWS A VERY WELL-DEFINED PUNCH OF MID AND UPPER LEVEL DRY AIR PUSHING INTO SC AND GA. THIS IS ASSOCIATED WITH THE LEADING EDGE OF A BROAD UPPER RIDGE THAT IS BUILDING EAST. THE LOW LEVELS ARE STILL QUITE SOUPY WITH DEWPOINTS IN THE MID 70S IN MANY AREAS. A SFC TROUGH IS STILL LYING ACROSS THE AREA...SOMEWHERE NEAR THE SC/GA BORDER AND ACROSS THE WATERS ALBEIT SUBTLE. LOW CLOUDS AND LIGHT FOG HAVE PERSISTED ACROSS NEARLY THE ENTIRE CWFA THROUGH LATE MORNING...WITH AREAS OF SCATTERED TO NUMEROUS SHOWERS AND A FEW STORMS...MAINLY ACROSS THE SC COAST NEAR CHARLESTON. WEAK MOISTURE CONVERGENCE ACROSS THE TRI-COUNTY AREA HAS BEEN RESPONSIBLE FOR THIS ACTIVITY...AND SEEMS TO STILL BE SQUEEZING OUT SOME SHOWERS. IT APPEARS THAT BEYOND 2 PM OR SO THE WINDS ACROSS SOUTHEAST SC WILL BE MORE UNIDIRECTIONAL FROM THE E OR SE...WHICH SHOULD SIGNIFICANTLY DECREASE THE AMOUNT OF CONVERGENCE ACROSS SC. HOWEVER BETTER INSOLATION ACROSS SOUTHEAST GA AND CONTINUED HIGH LLVL THETA-E IN CONCERT WITH A STRONG SEABREEZE SHOULD PRODUCE SCATTERED SHOWERS AND STORMS DURING THE AFTERNOON. THUS...HAVE UPDATED POPS TO TREND FROM A SMALL AREA OF LIKELY IN THE CHS VICINITY THROUGH EARLY AFTN TO SLIGHT CHC OR CHC LATER IN THE DAY...HIGHEST S. ALSO...DUE TO THE PROLONGED LOW CLOUDINESS...HAVE DECREASED HIGH TEMPS ACROSS THE BOARD BY A FEW DEGREES AND INCREASED SKY GRIDS. NEW PRODUCTS OUT SHORTLY. && .AVIATION...SOUPY AIRMASS IN PLACE ACROSS THE COASTAL ZONES THIS MORNING. WINDS ARE SLOWLY INCREASING AND VEERING TO NE OR E...WHICH IS TRANSITIONING THE REMNANT FOG ISSUES AT SAV TO A LOW STRATUS DECK. CHS HAS HAD MVFR VSBYS FOR QUITE A WHILE...MAINLY WITH SCATTERED RAIN SHOWERS THAT HAVE PERSISTED ALONG THE COAST. CIGS HAD LIFTED TO MVFR BUT HAVE NOW COME BACK DOWN TO IFR WITH BKN009. WINDS HAVE JUST TIPPED TO SE AT CHS WHICH MAY BE THE EARLY STAGES OF THE SEABREEZE. HOWEVER THE MARINE AIRMASS IS QUITE SIMILAR TO THE LAND...THUS NO HUGE CHANGE IS EXPECTED. LUCKILY TEMPS ARE SLOWLY WARMING REGARDLESS OF THE LOW CLOUDINESS...SO TEMPS CLIMBING INTO THE LOWER 80S SHOULD YIELD SOME CIGS AROUND 1500 FT IN TWO HOURS OR SO. LATER TONIGHT MORE LOW CIGS ARE POSSIBLE IF THE DRIER SFC AIR AGAIN DOES NOT MAKE IT THIS FAR SOUTH. && .MARINE...TWEAKED SOME WIND DIRECTIONS BASED ON THE LATEST RUC GUIDANCE AND INCREASED EXPECTED WIND SPEEDS IN THE HARBOR FOR THIS AFTN TO 15 KT. ALSO ADDED MENTION OF SOME LIKELY POPS IN THE SC NEARSHORE AND HARBOR THROUGH EARLY AFTN. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ JRL sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 426 PM EDT FRI AUG 25 2006 .SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT) NAM AND GFS MODELS HAVE LINED UP BETTER THIS MODEL RUN WITH THE HIGH PRESSURE SYSTEM ALOFT OVER THE REGION THROUGH THE WEEKEND AND DRIER AIR OVER THE NORTH HALF OF GEORGIA. THE WEAK STATIONARY FRONT THAT HAS AFFECTED THE STATE FOR THE PAST FEW DAYS IS NOW OVER SOUTH GEORGIA WITH CONTINUED PWS FROM 2 TO 2.5 INCHES AND MODERATE INSTABILITY. THESE COMBINED WEATHER FEATURES WILL BE THE TRIGGERING MECHANISM FOR SCATTERED SHRA/TSRA THIS AFTERNOON AND EARLY EVENING AGAIN FOR THE SOUTH HALF OF GEORGIA. MEANWHILE WEAK SURFACE HIGH PRESSURE OVER THE CAROLINAS WILL CONTINUE TO RIDGE DOWN THE APPALACHIAN MOUNTAINS WITH FAIR WEATHER FOR THE NORTH HALF OF GEORGIA. THIS SYNOPTIC PATTERN WILL GENERALLY REMAIN IN PLACE THROUGH SUNDAY WITH AN EASTERLY FLOW. A MORE SOUTHEASTERLY FLOW LATE SUNDAY WILL CAUSE THE MOISTURE TO GRADUALLY RETURN ACROSS THE STATE AND INCREASE THE CHANCES OF CONVECTION IN THE LATE AFTERNOON AND EVENING. TEMPERATURES WILL BE NEAR OR SLIGHTLY ABOVE SEASONAL NORMALS DURING THIS FORECAST PERIOD. .LONG TERM...(MONDAY THROUGH FRIDAY) AN UPPER TROUGH OVER THE WESTERN PORTION OF THE NATION IS FORECAST TO MOVE EAST BY THE GFS AND PUSH A FRONTAL BOUNDARY INTO THE AREA BY MID WEEK. SUFFICIENT MOISTURE IN PLACE FOR AN INCREASED CHANCE OF PRECIPITATION TUESDAY AND WEDNESDAY. GFS THEN TRIES TO DRY AREA OUT BY END OF WEEK WITH SLIGHTLY COOLER AIR. && .AVIATION... ATMOSPHERE HAS DRIED OUT ALOFT PER WATER VAPOR IMAGERY. BASED ON THE MODEL STABILITY INDICES AND MOISTURE FIELD THAT SHOULD HOLD THROUGH SATURDAY. UNFORTUNATELY THE LOW LEVEL MOISTURE STAYS IN PLACE WITH DEW POINTS REMAINING IN THE UPPER 60S AND LOWER 70S. SKIES SHOULD GO MOSTLY CLEAR THIS EVENING GIVING US GOOD RADIATIONAL COOLING TONIGHT AND THE HIGH PROBABILITY OF LOW CLOUDS AND FOG DEVELOPING AFTER MIDNIGHT. RUC/GFS/ETA INDICATE LOW LEVELS BECOMING SATURATED BETWEEN 06Z AND 12Z. AFTER 12Z LOW CLOUDS WILL DISSIPATE AND BY 18Z EXPECT SKIES TO BE SCATTERED TO BROKEN BUT ABOVE 3000 FT. THERE ARE ISOLATED SHOWERS ACROSS THE CWA BUT NOT WIDESPREAD AND EXPECT TAFS TO BE DRY THROUGH 00Z SUN. && .PRELIMINARY POINT TEMPS/POPS... ATLANTA 69 88 71 89 / 10 10 10 10 ATHENS 67 89 68 89 / 5 5 10 10 GAINESVILLE 68 88 69 88 / 5 10 10 10 ROME 69 92 71 92 / 5 10 10 20 COLUMBUS 73 90 74 90 / 20 30 10 30 MACON 72 92 72 92 / 10 20 10 20 PEACHTREE CITY 67 88 70 89 / 10 20 10 20 CARTERSVILLE 66 90 68 90 / 5 10 10 20 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 16 ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 619 PM EDT FRI AUG 25 2006 .AVIATION... UPSTREAM CONVECTION OVER NORTHERN ILLINOIS CONTINUES TO STRUGGLE LATE THIS AFTERNOON IT MOVES EAST AWAY FROM RESERVOIR OF GREATER INSTABILITY ALONG THE MISSISSIPPI RIVER. GIVEN LATEST RADAR TRENDS AND 18Z MODEL GUIDANCE...CHANCES OF CONVECTION SURVIVING THE TRIP TO KSBN APPEAR SMALL AT THIS TIME. NAM/GFS BOTH SUGGEST A SLOW IMPROVEMENT IN ELEVATED INSTABILITY OVERNIGHT AS DEEPER MOISTURE AND HIGHER QUALITY THETA-E AIR CONTINUE TO ADVECT SLOWLY EAST. WILL KEEP TAFS DRY AT THIS TIME WITH CHANCES BELOW MENTIONABLE THRESHOLD. LATE TONIGHT INTO SATURDAY MORNING LOW LEVEL MOISTURE ADVECTION COUPLED WITH DIURNAL COOLING AND DIMINISHING BOUNDARY LAYER WINDS SHOULD PROMOTE BR DEVELOPMENT. HAVE GONE WITH A PERIOD OF MVFR VSBY TO COVER POTENTIAL...AND COULD POTENTIALLY SEE A BRIEF DIP TO IFR AROUND DAYBREAK AS MENTIONED AT KSBN. ON SATURDAY DEEP LAYER FRONTAL ZONE WILL ADVANCE EAST TOWARDS THE CWA. CONVECTIVE POTENTIAL HINGES ON DEGREE OF DESTABILIZATION WITH QUESTIONS REMAINING ON HOW MUCH DEBRIS CLOUD WILL EXIST. AT THIS EARLY JUNCTURE HAVE INTRODUCED A CB QUALIFIER ONLY AND WILL ALLOW LATER SHIFTS TO INCREASE MENTION IF NECESSARY WHEN MESOSCALE EVOLUTION IS MORE CERTAIN. && .SHORT TERM... TONIGHT AND SATURDAY CWA HAS BEEN SHROUDED IN A HIGH CIRRUS CANOPY ALL DAY FROM BLOWOFF OF UPSTREAM CONVECTION. DESPITE THE CLOUD COVER...ENOUGH SUNSHINE HAS FILTERED THROUGH TO ALLOW TEMPS TO CLIMB INTO THE LOW 80S AT 18Z FOR MOST SITES. CLUSTER OF EARLIER CONVECTION OVER SE WISCONSIN HAS CONTINUED TO WEAKEN AS IT BECAME OUTFLOW DOMINATED AND MOVED INTO LESS FAVORABLE ENVIRONMENT. LATEST OBJECTIVE RUC ANALYSIS CONTINUES TO SHOW AN 850MB DEWPOINT MINIMUM CENTERED OVER THE CWA WHICH... ALONG WITH CLOUD COVER...HAS EFFECTIVELY LIMITED DESTABILIZATION. AS EXPECTED...NEW CONVECTIVE DEVELOPMENT HAS BEGUN LAST HOUR OVER NW ILLINOIS AND SOUTH CENTRAL WISCONSIN IN THE WAKE OF WEAKENING ACTIVITY WHERE A BREAK IN THE CLOUD COVER HAS PROMOTED DEVELOPMENT OF MODERATE INSTABILITY. AIRMASS IN THIS REGION MUCH MORE FAVORABLE WITHIN A CHANNEL OF MORE ROBUST MOISTURE ALONG AND JUST AHEAD OF DEEP LAYER BAROCLINIC ZONE. EXPECT THIS AREA OF CONVECTION TO CONTINUE TO FILL IN THROUGH THIS EVENING. NAM/GFS BOTH SUGGEST A SLOW IMPROVEMENT OF MOISTURE/INSTABILITY TONIGHT WITH THETA-E ADVECTION ADVANCING EAST ACROSS THE CWA. OVERALL CONFIDENCE IS LOW FOR CONVECTION SURVIVING THE TRIP EAST OVERNIGHT GIVEN LACK OF ANY WELL DEFINED LARGE SCALE FORCING FOR ASCENT...AND RELATIVELY WEAK AND VEERED LOW LEVEL JET FORECAST BY THE NAM-WRF. WILL CONTINUE WITH SAME BASIC IDEA OF PREVIOUS SHIFT WITH LOW CHANCE POPS THIS EVENING WEST...THEN SPREADING EAST ACROSS THE CWA OVERNIGHT. HAVE REMOVED POPS ALTOGETHER IN THE FAR SE CORNER OF THE CWA. ON SATURDAY DEEP LAYER FRONTAL ZONE WILL CONTINUE TO MOVE SLOWLY EAST IN RESPONSE TO EJECTION OF WELL DEFINED MID LEVEL SHORTWAVE NOW OVER THE ROCKIES. SEVERAL MESOSCALE PERTURBATIONS FORECAST TO EVOLVE ALONG THE FRONT MANIFESTED AS WEAK SURFACE WAVES AND MID LEVEL VORTICITY MAXIMA. MESOSCALE EVOLUTION WILL LIKELY BE HIGHLY COMPLEX AND INTERPLAY WITH AMOUNT OF CLOUD DEBRIS AND SUBSEQUENT ABILITY TO DESTABILIZE. BOTH NAM/GFS ARE VERY NOISY WITH CONVECTIVE FEEDBACK AND BOTH HAVE HAD VERY POOR RUN TO RUN CONTINUITY WITH PLACEMENT AND TIMING OF FRONT. WITH LITTLE HELP FROM MODELS...WILL STAY THE COURSE FROM CONTINUITY AND KEEP CHANCE POPS...WITH THE GREATEST CHANCES BEING IN THE AFTERNOON/EVENING. IF ENOUGH SURFACE BASED INSTABILITY DEVELOPS...KINEMATIC PROFILES SUGGEST SHEAR WILL BE SUFFICIENT FOR ORGANIZATION INTO MULTICELL CLUSTERS...BOWING SEGMENTS...AND PERHAPS A FEW HYBRID SUPERCELL STRUCTURES. AS HAS BEEN THE CASE MANY TIMES THIS SUMMER HOWEVER...SEVERE WEATHER CHANCES ARE STRICTLY CONDITIONAL ON SUFFICIENT DESTABILIZATION. && .LONG TERM... SATURDAY NIGHT THROUGH FRIDAY. MODELS ARE STILL HAVING A HARD TIME DETERMINING CONVECTIVE COVERAGE THROUGH SUNDAY. WILL START OFF SATURDAY NIGHT WHERE SHORT TERM LEFT OFF...EMPLOYING ABOUT A 50 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS ACRS THE ENTIRE REGION DURING THE EVENING HOURS. KEY TO EVENING CONVECTION WILL BE HOW UNSTABLE SATURDAY AFTN BECOMES ...AND WHETHER ANY DISCERNIBLE/TRACEABLE SHORTWAVE CROSSES THE REGION TO PROVIDE SOME UPR LVL SUPPORT. OTHERWISE...RELYING ON THE FRONTAL BOUNDARY ITSELF WILL MAKE IT HARD PRESSED TO GO LIKELY/CATEGORICAL POPS AS GUIDANCE IS INDICATING. AT THIS POINT...AM DISCOUNTING CONVECTIVE FEEDBACK SFC WAVE ALONG THE FRONTAL BOUNDARY SATURDAY NIGHT/SUNDAY ACRS THE FCST AREA AS DEPICTED BY THE 12Z GFS. THUS...WILL LEAN MORE TOWARD THE 12Z NAM-WRF WHICH NOW SAGS THE FRONT SLOWLY SOUTH THROUGH THE REGION SATURDAY NIGHT INTO SUNDAY. WITH ELEVATED INSTABILITY LINGERING ACRS THE SOUTH SUNDAY/SUNDAY EVENING...WILL KEEP LOW CHC POPS ACRS THE SOUTH...KEEPING OUR MICHIGAN COUNTIES DRY. FOR SUNDAY NIGHT INTO MONDAY...12Z NAM-WRF HINTS AT A POSSIBLE LOW LVL DEFORMATION AXIS ACRS THE FAR SOUTH. HOWEVER...INSTABILITY IS FCST TO BE QUITE LOW (LESS THAN 200 J/KG)...SO HAVE KEPT A LOW CHC OF SHOWERS SUNDAY NIGHT (AFTER MIDNIGHT) AND MONDAY ACRS THE SRN THIRD OF THE FCST AREA. TEMPERATURES WILL BE HELD DOWN DURING THE DAY BOTH SUNDAY AND MONDAY DUE TO EXPECTED MOSTLY CLOUDY CONDITIONS. FOR THE EXTENDED PERIOD MONDAY NIGHT THROUGH TUESDAY NIGHT...LONG RANGE MODELS ARE OFFERING VARYING SOLUTIONS TO THE MOVEMENT OF AN UPR LVL CLOSED LOW CURRENTLY ACRS THE INTERMOUNTAIN WEST. AS THE UPR LVL LOW EJECTS E INTO THE CENTRAL PLAINS...THE CANADIAN MODEL DEVELOPS A SFC WAVE ALONG OLD FRONTAL BOUNDARY...TRACKING IT NORTH OF THE OHIO RIVER DURING THE PERIOD. OTHER MODELS...SUCH AS THE LATEST 12Z GFS...KEEP THE SFC REFLECTION SOUTH OF THE OHIO RIVER. AT THIS POINT...WILL KEEP REGION DRY MONDAY NIGHT INTO TUESDAY NIGHT...AND HOPE FOR A BETTER CONSENSUS WITH LATER MODEL RUNS. WILL HOWEVER...INCREASE THE CLOUD COVER AS MID AND UPR LVL FLOW WILL LIKELY EJECT MID AND HIGH LVL CLOUDINESS INTO THE REGION FROM THE SOUTHWEST. FOR THE REMAINDER OF THE EXTENDED...WEDNESDAY THROUGH FRIDAY...MOST LONG RANGE MODELS AGREE THAT THE UPR LVL PATTERN BY THE END OF THE WEEK WILL FEATURE AN UPR LVL TROF ACRS THE PAC NW AND ALSO ACRS NEW ENGLAND/NE CANADA. THIS WILL RESULT IN A MID LVL RIDGE AXIS FROM THE UPR MIDWEST INTO S CNTRL CANADA. THIS UPR LVL ORIENTATION SHOULD RESULT IN SFC HIGH PRESSURE ACRS THE LOWER GREAT LAKES. THUS...MOSTLY SUNNY DAYS AND MOSTLY CLEAR NIGHTS ALONG WITH NEAR NORMAL TEMPERATURES CAN BE EXPECTED. && .AVIATION... EXPANSIVE SHIELD OF CONVECTIVE DEBRIS CLOUD CONTINUES TO OVERSPREAD THE TERMINALS EARLY THIS AFTERNOON. NOT MANY CONCERNS FOR THE FIRST 6 HOURS OR SO WITH VFR CONDITIONS. AFTER THAT...MAIN CONCERN IS CONVECTIVE POTENTIAL. UPSTREAM CONVECTION RAPIDLY WEAKENING OVER SOUTHERN WISCONSIN AS STORMS BECOME OUTFLOW DOMINATED. EXPECT THIS TREND TO CONTINUE AS THEY MOVE INTO MORE STABLE AIRMASS DOWNSTREAM. RUC OBJECTIVE ANALYSIS CONTINUES TO INDICATE AN 850MB DEWPOINT MINIMUM CENTERED OVER THE CWA WHICH IS RESULTING IN LITTLE IF ANY INSTABILITY. THIS WILL CHANGE EVENTUALLY AS LOW/MID LEVEL MOISTURE ADVECTION SPREADS EAST ACROSS THE CWA THIS EVENING. CONFIDENCE LOW IN ANY CONVECTION TONIGHT...BUT WILL CARRY A CB QUALIFIER AT KSBN OVERNIGHT AS A START. NO MENTION AT ALL FOR KFWA WHICH SHOULD REMAIN FAR ENOUGH REMOVED FROM DEEP MOISTURE AND FORCING FOR ASCENT TO PRECLUDE ANY CONVECTION. HAVE KEPT SAT PERIOD DRY FOR NOW WITH CONVECTIVE POTENTIAL VERY UNCERTAIN ATTM OWING TO MESOSCALE EVOLUTION TONIGHT AND AMOUNT OF DEBRIS CLOUDS LEFT. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM/AVIATION...HITCHCOCK LONG TERM...HICKMAN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 311 PM EDT FRI AUG 25 2006 .SHORT TERM... TONIGHT AND SATURDAY CWA HAS BEEN SHROUDED IN A HIGH CIRRUS CANOPY ALL DAY FROM BLOWOFF OF UPSTREAM CONVECTION. DESPITE THE CLOUD COVER...ENOUGH SUNSHINE HAS FILTERED THROUGH TO ALLOW TEMPS TO CLIMB INTO THE LOW 80S AT 18Z FOR MOST SITES. CLUSTER OF EARLIER CONVECTION OVER SE WISCONSIN HAS CONTINUED TO WEAKEN AS IT BECAME OUTFLOW DOMINATED AND MOVED INTO LESS FAVORABLE ENVIRONMENT. LATEST OBJECTIVE RUC ANALYSIS CONTINUES TO SHOW AN 850MB DEWPOINT MINIMUM CENTERED OVER THE CWA WHICH... ALONG WITH CLOUD COVER...HAS EFFECTIVELY LIMITED DESTABILIZATION. AS EXPECTED...NEW CONVECTIVE DEVELOPMENT HAS BEGUN LAST HOUR OVER NW ILLINOIS AND SOUTH CENTRAL WISCONSIN IN THE WAKE OF WEAKENING ACTIVITY WHERE A BREAK IN THE CLOUD COVER HAS PROMOTED DEVELOPMENT OF MODERATE INSTABILITY. AIRMASS IN THIS REGION MUCH MORE FAVORABLE WITHIN A CHANNEL OF MORE ROBUST MOISTURE ALONG AND JUST AHEAD OF DEEP LAYER BAROCLINIC ZONE. EXPECT THIS AREA OF CONVECTION TO CONTINUE TO FILL IN THROUGH THIS EVENING. NAM/GFS BOTH SUGGEST A SLOW IMPROVEMENT OF MOISTURE/INSTABILITY TONIGHT WITH THETA-E ADVECTION ADVANCING EAST ACROSS THE CWA. OVERALL CONFIDENCE IS LOW FOR CONVECTION SURVIVING THE TRIP EAST OVERNIGHT GIVEN LACK OF ANY WELL DEFINED LARGE SCALE FORCING FOR ASCENT...AND RELATIVELY WEAK AND VEERED LOW LEVEL JET FORECAST BY THE NAM-WRF. WILL CONTINUE WITH SAME BASIC IDEA OF PREVIOUS SHIFT WITH LOW CHANCE POPS THIS EVENING WEST...THEN SPREADING EAST ACROSS THE CWA OVERNIGHT. HAVE REMOVED POPS ALTOGETHER IN THE FAR SE CORNER OF THE CWA. ON SATURDAY DEEP LAYER FRONTAL ZONE WILL CONTINUE TO MOVE SLOWLY EAST IN RESPONSE TO EJECTION OF WELL DEFINED MID LEVEL SHORTWAVE NOW OVER THE ROCKIES. SEVERAL MESOSCALE PERTURBATIONS FORECAST TO EVOLVE ALONG THE FRONT MANIFESTED AS WEAK SURFACE WAVES AND MID LEVEL VORTICITY MAXIMA. MESOSCALE EVOLUTION WILL LIKELY BE HIGHLY COMPLEX AND INTERPLAY WITH AMOUNT OF CLOUD DEBRIS AND SUBSEQUENT ABILITY TO DESTABILIZE. BOTH NAM/GFS ARE VERY NOISY WITH CONVECTIVE FEEDBACK AND BOTH HAVE HAD VERY POOR RUN TO RUN CONTINUITY WITH PLACEMENT AND TIMING OF FRONT. WITH LITTLE HELP FROM MODELS...WILL STAY THE COURSE FROM CONTINUITY AND KEEP CHANCE POPS...WITH THE GREATEST CHANCES BEING IN THE AFTERNOON/EVENING. IF ENOUGH SURFACE BASED INSTABILITY DEVELOPS...KINEMATIC PROFILES SUGGEST SHEAR WILL BE SUFFICIENT FOR ORGANIZATION INTO MULTICELL CLUSTERS...BOWING SEGMENTS...AND PERHAPS A FEW HYBRID SUPERCELL STRUCTURES. AS HAS BEEN THE CASE MANY TIMES THIS SUMMER HOWEVER...SEVERE WEATHER CHANCES ARE STRICTLY CONDITIONAL ON SUFFICIENT DESTABILIZATION. && .LONG TERM... SATURDAY NIGHT THROUGH FRIDAY. MODELS ARE STILL HAVING A HARD TIME DETERMINING CONVECTIVE COVERAGE THROUGH SUNDAY. WILL START OFF SATURDAY NIGHT WHERE SHORT TERM LEFT OFF...EMPLOYING ABOUT A 50 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS ACRS THE ENTIRE REGION DURING THE EVENING HOURS. KEY TO EVENING CONVECTION WILL BE HOW UNSTABLE SATURDAY AFTN BECOMES ...AND WHETHER ANY DISCERNIBLE/TRACEABLE SHORTWAVE CROSSES THE REGION TO PROVIDE SOME UPR LVL SUPPORT. OTHERWISE...RELYING ON THE FRONTAL BOUNDARY ITSELF WILL MAKE IT HARD PRESSED TO GO LIKELY/CATEGORICAL POPS AS GUIDANCE IS INDICATING. AT THIS POINT...AM DISCOUNTING CONVECTIVE FEEDBACK SFC WAVE ALONG THE FRONTAL BOUNDARY SATURDAY NIGHT/SUNDAY ACRS THE FCST AREA AS DEPICTED BY THE 12Z GFS. THUS...WILL LEAN MORE TOWARD THE 12Z NAM-WRF WHICH NOW SAGS THE FRONT SLOWLY SOUTH THROUGH THE REGION SATURDAY NIGHT INTO SUNDAY. WITH ELEVATED INSTABILITY LINGERING ACRS THE SOUTH SUNDAY/SUNDAY EVENING...WILL KEEP LOW CHC POPS ACRS THE SOUTH...KEEPING OUR MICHIGAN COUNTIES DRY. FOR SUNDAY NIGHT INTO MONDAY...12Z NAM-WRF HINTS AT A POSSIBLE LOW LVL DEFORMATION AXIS ACRS THE FAR SOUTH. HOWEVER...INSTABILITY IS FCST TO BE QUITE LOW (LESS THAN 200 J/KG)...SO HAVE KEPT A LOW CHC OF SHOWERS SUNDAY NIGHT (AFTER MIDNIGHT) AND MONDAY ACRS THE SRN THIRD OF THE FCST AREA. TEMPERATURES WILL BE HELD DOWN DURING THE DAY BOTH SUNDAY AND MONDAY DUE TO EXPECTED MOSTLY CLOUDY CONDITIONS. FOR THE EXTENDED PERIOD MONDAY NIGHT THROUGH TUESDAY NIGHT...LONG RANGE MODELS ARE OFFERING VARYING SOLUTIONS TO THE MOVEMENT OF AN UPR LVL CLOSED LOW CURRENTLY ACRS THE INTERMOUNTAIN WEST. AS THE UPR LVL LOW EJECTS E INTO THE CENTRAL PLAINS...THE CANADIAN MODEL DEVELOPS A SFC WAVE ALONG OLD FRONTAL BOUNDARY...TRACKING IT NORTH OF THE OHIO RIVER DURING THE PERIOD. OTHER MODELS...SUCH AS THE LATEST 12Z GFS...KEEP THE SFC REFLECTION SOUTH OF THE OHIO RIVER. AT THIS POINT...WILL KEEP REGION DRY MONDAY NIGHT INTO TUESDAY NIGHT...AND HOPE FOR A BETTER CONSENSUS WITH LATER MODEL RUNS. WILL HOWEVER...INCREASE THE CLOUD COVER AS MID AND UPR LVL FLOW WILL LIKELY EJECT MID AND HIGH LVL CLOUDINESS INTO THE REGION FROM THE SOUTHWEST. FOR THE REMAINDER OF THE EXTENDED...WEDNESDAY THROUGH FRIDAY...MOST LONG RANGE MODELS AGREE THAT THE UPR LVL PATTERN BY THE END OF THE WEEK WILL FEATURE AN UPR LVL TROF ACRS THE PAC NW AND ALSO ACRS NEW ENGLAND/NE CANADA. THIS WILL RESULT IN A MID LVL RIDGE AXIS FROM THE UPR MIDWEST INTO S CNTRL CANADA. THIS UPR LVL ORIENTATION SHOULD RESULT IN SFC HIGH PRESSURE ACRS THE LOWER GREAT LAKES. THUS...MOSTLY SUNNY DAYS AND MOSTLY CLEAR NIGHTS ALONG WITH NEAR NORMAL TEMPERATURES CAN BE EXPECTED. && .AVIATION... EXPANSIVE SHIELD OF CONVECTIVE DEBRIS CLOUD CONTINUES TO OVERSPREAD THE TERMINALS EARLY THIS AFTERNOON. NOT MANY CONCERNS FOR THE FIRST 6 HOURS OR SO WITH VFR CONDITIONS. AFTER THAT...MAIN CONCERN IS CONVECTIVE POTENTIAL. UPSTREAM CONVECTION RAPIDLY WEAKENING OVER SOUTHERN WISCONSIN AS STORMS BECOME OUTFLOW DOMINATED. EXPECT THIS TREND TO CONTINUE AS THEY MOVE INTO MORE STABLE AIRMASS DOWNSTREAM. RUC OBJECTIVE ANALYSIS CONTINUES TO INDICATE AN 850MB DEWPOINT MINIMUM CENTERED OVER THE CWA WHICH IS RESULTING IN LITTLE IF ANY INSTABILITY. THIS WILL CHANGE EVENTUALLY AS LOW/MID LEVEL MOISTURE ADVECTION SPREADS EAST ACROSS THE CWA THIS EVENING. CONFIDENCE LOW IN ANY CONVECTION TONIGHT...BUT WILL CARRY A CB QUALIFIER AT KSBN OVERNIGHT AS A START. NO MENTION AT ALL FOR KFWA WHICH SHOULD REMAIN FAR ENOUGH REMOVED FROM DEEP MOISTURE AND FORCING FOR ASCENT TO PRECLUDE ANY CONVECTION. HAVE KEPT SAT PERIOD DRY FOR NOW WITH CONVECTIVE POTENTIAL VERY UNCERTAIN ATTM OWING TO MESOSCALE EVOLUTION TONIGHT AND AMOUNT OF DEBRIS CLOUDS LEFT. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM/AVIATION...HITCHCOCK LONG TERM...HICKMAN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 140 PM EDT FRI AUG 25 2006 .AVIATION... EXPANSIVE SHIELD OF CONVECTIVE DEBRIS CLOUD CONTINUES TO OVERSPREAD THE TERMINALS EARLY THIS AFTERNOON. NOT MANY CONCERNS FOR THE FIRST 6 HOURS OR SO WITH VFR CONDITIONS. AFTER THAT...MAIN CONCERN IS CONVECTIVE POTENTIAL. UPSTREAM CONVECTION RAPIDLY WEAKENING OVER SOUTHERN WISCONSIN AS STORMS BECOME OUTFLOW DOMINATED. EXPECT THIS TREND TO CONTINUE AS THEY MOVE INTO MORE STABLE AIRMASS DOWNSTREAM. RUC OBJECTIVE ANALYSIS CONTINUES TO INDICATE AN 850MB DEWPOINT MINIMUM CENTERED OVER THE CWA WHICH IS RESULTING IN LITTLE IF ANY INSTABILITY. THIS WILL CHANGE EVENTUALLY AS LOW/MID LEVEL MOISTURE ADVECTION SPREADS EAST ACROSS THE CWA THIS EVENING. CONFIDENCE LOW IN ANY CONVECTION TONIGHT...BUT WILL CARRY A CB QUALIFIER AT KSBN OVERNIGHT AS A START. NO MENTION AT ALL FOR KFWA WHICH SHOULD REMAIN FAR ENOUGH REMOVED FROM DEEP MOISTURE AND FORCING FOR ASCENT TO PRECLUDE ANY CONVECTION. HAVE KEPT SAT PERIOD DRY FOR NOW WITH CONVECTIVE POTENTIAL VERY UNCERTAIN ATTM OWING TO MESOSCALE EVOLUTION TONIGHT AND AMOUNT OF DEBRIS CLOUDS LEFT. && .PREV DISCUSSION... UPDATE... ISSUED AN UPDATE THIS MORNING TO ADJUST CLOUD COVER. EXPANSIVE DEBRIS CLOUD FROM UPSTREAM CONVECTION CONTINUES TO CROSS THE CWA THIS MORNING WITH MOST LOCATIONS OVERCAST AT 14Z...EXCEPT FOR THE FAR SW AND SE CORNERS OF THE CWA. MORE CONVECTIVE DEBRIS UPSTREAM WILL CROSS THE CWA THIS AFTERNOON. WOULD EXPECT AREAL EXTENT OF CLOUD COVER TO DECREASE THIS AFTERNOON FOLLOWING TYPICAL DIURNAL TRENDS. WILL WORD ZFP AS A MIX OF CLOUDS AND SUN. IF CLOUDS REMAIN THICK ENOUGH THEY WILL RETARD SURFACE HEATING. FOR NOW WILL STAY WITH CURRENT FORECAST HIGH TEMPS IN THE MID 80S AND BANK ON THINNING/DIMINISHING CLOUD COVER THIS AFTERNOON. LOW CHANCE POPS LATE THIS AFTERNOON IN THE FAR NW STILL LOOKS GOOD. REGIONAL RADARS THIS MORNING SHOWING AREAS OF CONVECTION FROM SOUTHERN WISCONSIN SOUTH THROUGH WESTERN ILLINOIS. STORMS BEING DRIVEN BY MODERATE LOW/MID LEVEL THETA-E ADVECTION AS LLJ CONTINUES TO VEER DIURNALLY TO A MORE WESTERLY COMPONENT. 12Z PROXIMITY RAOB SOUNDINGS AND SPC OBJECTIVE RUC ANALYSIS SHOWING A LARGE THETA-E MINIMUM DOMINATING THE CWA THIS MORNING. THIS WILL INITIALLY INHIBIT DEVELOPMENT OF ANY SIGNIFICANT INSTABILITY...HOWEVER 06Z NAM CONTINUES TO SUGGEST HIGHER THETA-E PLUME OVER WESTERN ILLINOIS WILL ADVECT INTO THE NW CORNER OF THE CWA BY LATE AFTERNOON/EVENING. SHORT TERM... TODAY AND TONIGHT. OVERNIGHT THE MCS TO THE NORTHWEST HAS BEEN CRANKING IT OUT BUT THE ONLY EFFECTS OUR CWA HAS FELT FROM IT HAVE BEEN HIGH LEVEL DEBRIS CLOUDS. THE QUASI STATIONARY FRONT JUST TO THE NORTH WILL NOT MOVE MUCH TODAY AS THE SURFACE TROUGH CURRENTLY OVER THE CENTRAL PART OF THE U.S. GETS CLOSER. THIS WILL KEEP OUR CWA IN THE WARM SECTOR TODAY AND WITH 850MB TEMPS PROGGED TO BE AROUND 19 TO 20 DEGREES CELSIUS THIS AFTERNOON...HIGH TEMPERATURES TODAY WILL REACH INTO THE MIDDLE 80S. THE NAM/WRF HAS NOT WAVERED WITH THE POSITION OF THE TROUGH/FRONT BY THIS EVENING AND THE GFS HAS SEEMED TO BACK OFF WITH THE FRONT A LITTLE BIT AND COME MORE IN LINE WITH THE NAM/WRF. HAVE TRIMMED BACK THE LOW CHANCE POPS A TAD FOR THIS AFTERNOON IN THE WEST/NORTHWEST BUT WITH THE FRONT/TROUGH STILL PROGGED TO BE CLOSE TO THE WESTERN BORDER OF OUR CWA...DECIDED TO STAY CONSISTENT WITH PREVIOUS FORECAST AND KEEP THE INTRODUCTION OF RAIN CHANCES LATE THIS AFTERNOON. IT IS STILL A LOW POP CHANCE WHICH IS SAYING A GREATER CHANCE THAT IT WILL BE DRY. THESE ARE JUST MODELS AFTER ALL AND THE ACTUAL POSITION OF THE TROUGH/FRONT COULD STILL BE CLOSER THAN WHAT THEY ARE SAYING. THEN OVERNIGHT TONIGHT THE COLD FRONT WILL BE IN THE WESTERN PART OF THE CWA...OVERSPREADING THE CHANCE FOR RAIN TO THE REST OF THE CWA. THE BETTER POTENTIAL FOR SEVERE WEATHER TODAY AND TONIGHT EXISTS JUST TO OUR WEST TO NORTHWEST. MODEL SOUNDINGS ARE SHOWING A CAP TO BE OVER THE CWA TODAY LIMITING OUR CHANCES FOR ANY SEVERE WEATHER. THE BEST POTENTIAL LIKE MENTIONED IS CLOSER TO THE FRONT AND ANOTHER LIMITING FACTOR IS THE TIMING OF THE FRONT INTO THE CWA. AN ISOLATED SEVERE STORM IN THE WESTERN PART OF OUR CWA IS NOT OUT OF THE QUESTION WITH SUCH INSTABILITY CLOSE BY...BUT CHANCES ARE LOW. LONG TERM... SATURDAY THROUGH FRIDAY. BEST CHANCE FOR SHRA/TSRA ON SATURDAY AS POTENT SRN CANADA SHORTWAVE ENERGY DROPS ESE INTO GREAT LAKES. SOME QUESTION WITH RESPECT TO FRONTAL TIMING WITH NAM OUTLIER IN SCOURING FRONT THROUGH MUCH FASTER. PREFERENCE LIES TO MORE CONSISTENT GFS/ECMWF/UKMET. FRONT SHOULD SLOW WITH SURFACE WAVE REFLECTION ALONG FRONT IN SOUTHERN PLAINS LIKELY GIVEN LOW LEVEL JET PRESENCE FRIDAY NIGHT. WEAK FRONTAL FORCING SHOULD BE SUFFICIENT IMPETUS FOR TSRA DEVELOPMENT BY MIDDAY AS AIRMASS BECOMES MODERATELY UNSTABLE WITH SBCAPES 2000-2500 J/KG AS LOW LEVEL THETA-E POOLS AHEAD OF FRONT. 0-6KM BULK LAYER SHEAR 25-30 KTS ALSO SUFFICIENT FOR AT LEAST A MINOR SEVERE POTENTIAL. CONCERN WITH POPS SUNDAY AND SUNDAY NIGHT ESPECIALLY NRN CWA WITH LATEST GFS TAKING FRONT SOUTH OF CWA TO NEAR OHIO RIVER AND SURFACE HIGH WEDGES INTO SOUTHERN GREAT LAKES AND MUCH DRIER AIRMASS. FOR NOW THOUGH WILL MAINTAIN STATUS QUO AND DEFER TO LATER RUNS AS STILL SOME CONCERN WITH FRONTAL WAVE DEVELOPMENT EARLY NEXT WEEK. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ AVIATION/UPDATE...HITCHCOCK SHORT TERM...LOTHAMER LONG TERM...MURPHY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 PM EDT FRI AUG 25 2006 .DISCUSSION... MAIN FCST CONCERNS ARE PCPN TRENDS TONIGHT INTO SAT. WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RDG OVER NRN ONTARIO...A TROF OVER MANITOBA AND ANOTHER CLOSED LOW OVER IDAHO LEAVING WRLY FLOW FROM THE PLAINS INTO THE WRN GREAT LAKES. AT THE SFC(18Z)...LOW PRES WAS LOCATED OVER NE IA WITH A WARM FRONT EXTENDING EASTWARD THROUGH SRN WI INTO SRN LWR MI. AN INVERTED TROF ALSO EXTENDED NORTH FROM THE LOW...THROUGH WRN WI INTO NE MN. THE SHRTWV THAT SUPPORTED PCPN OVER UPR MI THIS MORNING HAD EXITED TOWARD ERN LK SUPERIOR. UPSTREAM NRN BRANCH SHRTWVS WERE LOCATED OVER SW MANITOBA AND INTO WRN SASK. OTHER SHRTWVS WERE MOVING NE OUT OF THE ROCKIES INTO NE WY AND THROUGH WRN NEB. WV IMAGERY ALSO INDICATED PROMINENT DRYING OVER NRN WI AND UPR MI. WITH THINNING MID/UPPER LVL MOISTURE PROFILE AND CONTINUED WEAK LOW LVL ISENTROPIC LIFT...PCPN HAS GIVEN WAY TO SOME PATCHY -RA/DRIZZLE...ESPECIALLY FOR LOCATIONS FAVORED BY UPSLOPE SE FLOW. TONIGHT INTO SAT...CONTINUING 295K-300K ISENTROPIC LIFT (925-850 MB) E OF THE TROF AXIS AND N OF THE WARM FRONT...PER 12Z NAM...TO SUPPORT SOME ONCL LIGHT RAIN OR DRIZZLE AGAIN WITH THE BEST CHANCE WHERE UPSLOPE ERLY FLOW PREVAILS. WITH THE SASK SHRTWV HELPING TO PUSH THE MID LVL TROF OVER MANITOBA TO THE EAST...EFFECTS OF SHRTWV ENERGY MOVING OUT OF THE PLAINS SHOULD REMAIN TO THE SOUTH OF UPR MI. HOWEVER...THE SHRTWVS WILL BE MOVE CLOSE ENOUGH TO UPR MI(ESPECIALLY THE SE) SO THAT WITH WITH 12Z NAM MUCAPE IN THE 100-300 J/KG RANGE TONIGHT INTO EARLY SAT...CANNOT RULE OUT SOME SCT SHOWERS. WITH ONLY RELATIVELY WEAK ELEVATED INSTABILITY...NO TSTMS ARE EXPECTED. PATCHY FOG MAY ALSO DEVELOP...BUT PERSISTENT 925-700 MOISTURE SHOULD KEEP MAINLY A STRATUS DECK GOING AND SHOULD KEEP FOG FROM BECOMING TOO THICK. A COMBINATION OF THE 12Z NAM 295K-300K ISENTROPIC FCST AND 925 RH AND WINDS WERE USED TO TIME THE END OF THE PCPN AND PARTIAL CLEARING AS THE SFC-925 TROF MOVE WEST TO EAST THROUGH THE CWA BTWN 09Z-21Z. PERSISTENT LOWER CLOUDS SHOULD KEEP TEMPS AOB GUIDANCE VALUES...ESPECIALLY OVER THE EAST. SAT NIGHT...700-500 QVECTOR DIV AND DRY ADVECTION TAKE OVER AND SFC RDG WILL BUILD INTO UPR MI AS THE MID LVL TROF AXIS DEPARTS. NW WINDS SHOULD REMAIN STRONG ENOUGH TO MINIMIZE FOG POTENTIAL EVEN AS TEMPS FALL AOB 50F INLAND. SUN...ACYC NRLY FLOW WILL PREVAIL AS THE SFC RDG BUILDS INTO THE AREA BENEATH CONFLUENT MID/UPPER LEVEL FLOW. MON-FRI...THE GFS AND ECMWF WERE IN DECENT AGREEMENT AND SUGGEST THAT DRY WEATHER WILL PREVAIL THROUGH THE PERIOD AS A SLOWLY PROGRESSIVE PATTERN BRINGS A TROF INTO THE WRN CONUS BY MIDWEEK AND TOWARD THE NRN PLAINS BY FRI. THE DOWNSTREAM RDG WILL BUILD INTO THE THE WRN LAKES WITH A WARMING TREND TOWARD THE END OF THE WEEK. A WEAK SHRTWV AND COLD FRONT WILL MOVE THROUGH THE UPPER GREAT LAKES BY MON NIGHT...BUT WITH THE LACK OF MOISTURE IN THE AREA AND RELATIVELY WEAK MID/UPPER LEVEL DYNAMICS...NO PCPN IS EXPECTED. THE 12Z GFS ALSO HINTS AT POSSIBILITY OF ISOLD INLAND SHRA/TSRA TUE...BUT ALSO SEEMS THAT THE LOW LVL MOISTURE AND RESULTING CAPE IS A BIT OVERDONE. A COMPROMISE BTWN THE HIGHER GFS AND LOWER ECMWF 850 MB AROUND (15C) STILL SUGGEST TEMPS WOULD CLIMB AOA GUIDANCE AROUND 80F BY THU/FRI. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1250 PM EDT FRI AUG 25 2006 .AFTERNOON UPDATE...QUICK UPDATE TO DROP HIGH TEMPERATURES THIS AFTERNOON DUE TO ABUNDANT CLOUD COVER. WILL HAVE HIGHS RANGING FROM THE LOW 70S SOUTHWEST TO THE MID 60S ACROSS THE NORTHEAST LOWER PENINSULA AND THE EASTERN UPPER. UPDATED GRIDS/ZONES OUT SHORTLY. MSB && .PREV DISCUSSION...ISSUED AT 1055 AM EDT FRI AUG 25 2006 UPDATE...14Z SURFACE/IR SATELLITE/REGIONAL RADAR/AND RUC ANALYSIS SHOWING QUASI-STATIONARY FRONT DRAPED ACROSS SOUTH CENTRAL LOWER MICHIGAN. THIS FRONT EXTENDS WEST TO A WEAK AREA OF LOW PRESSURE SITUATED OVER CENTRAL IOWA. CLOSER TO HOME...LARGE SHIELD OF RAIN...DRIVEN BY MASS CONVERGENCE ON NOSE OF 850MB LOW LEVEL JET...CONTINUES TO PROPAGATE EAST ACROSS THE NORTHEASTERN LOWER AND THE EASTERN UPPER. RAIN IS STRUGGLING TO MAKE INTO NORTHERN CHIPPEWA COUNTY...HOWEVER...AS HIGH PRESSURE CENTERED OVER JAMES BAY CONTINUES TO ADVECT DRY LOW AND MID LEVEL AIR INTO THAT AREA. EXPECT THIS RAIN SHIELD TO CONTINUE ITS ADVANCE EAST AND SLOWLY DIMINISH IN INTENSITY AS JET WEAKENS. FORECAST CONCERNS FOR THE REMAINDER OF THE DAY CENTER AROUND THE CONTINUED THREAT OF SHOWERS AND STORMS ALONG WITH THE POTENTIAL OF SEVERE WEATHER THIS AFTERNOON. SOUTHERN MICHIGAN FRONT STRUGGLING TO PUSH NORTH AS RAIN COOLED AIR HAS EFFECTIVELY STALLED ITS NORTHWARD PROGRESSION. BEST INSTABILITY WILL REMAIN SOUTH OF THIS BOUNDARY IN WARM SECTOR. GIVEN OBSERVATIONAL TRENDS OVER THE LAST SEVERAL HOURS AND LATEST RUC FORECAST...FEEL FRONT WILL NOT MAKE INTO OUR FORECAST AREA DURING THE DAY. KINEMATICS REMAIN IMPRESSIVE WITH 0-6 KM BULK SHEAR VALUES OF 45 TO 50 KNOTS AND 0-3 KM HELICITY GREATER THAN 350 M2/S2. BIGGEST LIMITING FACTOR REMAINS INSTABILITY WITH FRONT SO FAR SOUTH AND ABUNDANT CLOUD COVER. MODIFYING 12Z APX SOUNDING WITH A WORST CASE SCENARIO HIGH OF 74 AND DEWPOINT OF 63 DOES YIELD ML CAPE OF OVER 1000J/KG. A MORE CONSERVATIVE TEMPERATURE OF 71 YIELDS CAPE ON ONLY ABOUT 200J/KG. LATEST SATELLITE IMAGES DOES SHOW SOME CLEARING IN NORTHERN WISCONSIN WITH TEMPERATURES RESPONDING NICELY REACHING THE LOW 70S. WILL NEED TO MONITOR CLEARING TRENDS THIS AFTERNOON. GIVEN ABOVE MENTIONED WIND FIELDS...IT WILL NOT TAKE MUCH INSTABILITY TO GENERATE A SEVERE WIND THREAT. PRESENCE OF SUBTLE SHORTWAVE OVER NORTHERN WISCONSIN IN CONJUNCTION WITH NORTHWARD ADVECTION OF 850-700MB THETA-E RIDGE SHOULD CONTINUE THE THREAT OF SCATTERED SHOWERS AND STORMS THROUGHOUT THE REMAINDER OF THE AFTERNOON. AS FOR THE MARINE ISSUES...WILL MAINTAIN ONGOING SCA AS STIFF 15 TO 20 KNOT EASTERLY WINDS FUNNEL ACROSS THE LAKES. AM EXPECTING WINDS TO BECOME INCREASINGLY GUSTY THIS AFTERNOON AS PRESSURE GRADIENT TIGHTENS WITH APPROACH OF IOWA LOW. UPDATED GRIDS/ZONES WILL BE OUT SHORTLY TO REFRESHEN WORDING. MSB DISCUSSION...FLOW PATTERN THROUGH THE COMING WEEKEND EXPECTED TO BE SOMEWHAT FLATTER/PROGRESSIVE AS EASTERN NORTH AMERICA TROUGH GETS NUDGED FARTHER EAST...WHILE EASTERN PACIFIC RIDGE GETS FLATTENED BY APPROACHING SHORT WAVE ENERGY OVER THE GULF OF AK. SHORT WAVE TROUGH OVER THE DAKOTAS/MN THIS MORNING WILL IMPACT THE FORECAST AREA TODAY...WITH ADDITIONAL ENERGY OVER THE CANADIAN PRAIRIES PASSING NEAR/NORTH OF THE FORECAST AREA SUNDAY. SURFACE FRONT LYING FROM THE UPPER MISSISSIPPI VALLEY SOUTHEAST THROUGH THE LOWER LAKES REGION WILL LIFT SLOWLY NORTH THROUGH SATURDAY AS A WEAKENING FRONTAL WAVE ALONG MN/IA BORDER RIDES ALONG IT. MAIN FORECAST CONCERNS WILL DEAL WITH PRECIPITATION EVOLUTION IN WARM ADVECTION PATTERN NORTH OF THIS BOUNDARY TODAY THROUGH SATURDAY...AS WELL AS FORECAST POSITION OF SURFACE FRONT AS THAT WILL IMPACT ANY SEVERE WEATHER POTENTIAL TODAY. TODAY/TONIGHT...FAIRLY WIDESPREAD AREA OF RAIN/EMBEDDED CONVECTION SPREADING ACROSS NORTHERN LOWER MI EARLY THIS MORNING...FORMING AHEAD OF SHORT WAVE TROUGH CROSSING WI ALONG WITH RRQ FORCING FROM 100+KT JET STREAK CLIPPING THE NORTHEAST CORNER OF THE STATE...AND IN AN AREA OF BROAD LOW/MID LEVEL WARM ADVECTION NORTH OF STALLED FRONT RUNNING ACROSS FAR SOUTHERN MN/WI/NORTHERN IL/IN/OH PER MIDNIGHT SURFACE ANALYSIS. AXIS OF 1.50+ INCH PW VALUES ALSO POOLED ALONG THE BAROCLINIC ZONE ACROSS SOUTHERN PORTIONS OF LOWER MI/WI/ MN...ALONG WITH STEEP MID LEVEL LAPSE RATES (700-500MB LAPSE RATES 8+ C/KM) CLOSER TO THE FRONT ITSELF. BACK EDGE OF THIS RAIN CROSSING NORTHERN LAKE MICHIGAN ASSOCIATED WITH LEAD MID LEVEL TROUGH AXIS...THOUGH SOME ADDITIONAL SHOWERS DEVELOPING OVER FAR NORTHWEST WI. MAIN SHOW IS FARTHER SOUTH CLOSER TO THE BOUNDARY WHERE STRONG STORMS CONTINUE TO DEVELOP ACROSS SOUTHEAST MN/ NORTHEAST IA...WHERE OF COURSE THE GUIDANCE DOESN'T APPEAR TO BE DOING SO HOT IN PICKING UP THE QPF THERE. SO AS USUAL IN THESE SITUATIONS TRYING TO FERRET DETAILS OUT OF THE MODELS IS PROBABLY A SOMEWHAT FRUITLESS ENDEAVOR...BUT INITIAL THINKING IS THAT LEADING BAND OF PRECIPITATION WILL MOVE THROUGH THIS MORNING AS VORTICITY CENTER MOVES EAST OF THE AREA...WITH MORE SCATTERED COVERAGE DURING THE AFTERNOON AS 850MB WARM FRONT LIFTS INTO CENTRAL LOWER COUNTIES. AT THIS POINT ANTICIPATE THAT SURFACE WARM FRONT WILL REMAIN SOUTH OF THE FORECAST AREA THROUGH THE AFTERNOON...ESPECIALLY IF CONVECTION CONTINUES TO DEVELOP ALONG IT ACROSS SOUTHERN WI AND ALLOWING A BUBBLE OF RAIN-COOLED AIR TO BLUNT NORTHWARD PUSH OF THE BOUNDARY. GIVEN EXTENSIVE CLOUD COVER INSTABILITY WILL BE LIMITED...THOUGH WITH 700- 500MB LAPSE RATES AROUND 7.5C/KM ANTICIPATED WON'T REQUIRE MUCH WARMING TO GENERATE SOME CAPE (400-800 J/KG)...AND GIVEN FORECAST SHEAR MAY NOT REQUIRE A LARGE AMOUNT OF INSTABILITY TO CAUSE SOME PROBLEMS. 0-6KM SHEAR VALUES OF 40-50KT COMBINED WITH STRONG LOW LEVEL TURNING OF THE WINDS WITHIN WARM FRONTAL ZONE WOULD SUPPORT UPDRAFT ROTATION AND POTENTIAL TORNADIC DEVELOPMENT GIVEN LOW LCL HEIGHTS (IF BOUNDARY LAYER IS NOT TOO STABLE). SO POTENTIAL IS THERE...WILL HAVE TO SEE IF PERSISTENT UPSTREAM CONVECTION ENDS UP BEING MORE DETRIMENTAL OR INSTABILITY TOO MARGINAL (BRN BELOW 10...TOO MUCH SHEAR VERSUS INSTABILITY???). BEST THREAT RIGHT NOW LOOKS TO BE SOUTH OF M-72 WHERE STEEPER MID LEVEL LAPSE RATES EXPECTED TO OCCUR. CHANCES FOR SHOWERS/THUNDERSTORMS TO CONTINUE OVERNIGHT AS WARM ADVECTION PATTERN PERSISTS WITH SURFACE LOW LIFTING NORTHEAST TOWARD GREEN BAY. SATURDAY...SURFACE LOW WILL CREEP SLOWLY NORTHEAST ACROSS NORTHERN LAKE MICHIGAN...DRAGGING WARM FRONT INTO NORTHERN LOWER MI. EXPECT CONTINUED SHOWER/THUNDERSTORM CHANCES ASSOCIATED WITH THIS FEATURE... PERHAPS AUGMENTED BY DIURNAL HEATING/INSTABILITY. WILL DRAG RAIN CHANCES INTO SATURDAY EVENING...WITH SURFACE LOW/COLD FRONT NOT FORECAST TO EXIT THE AREA UNTIL AFTER MIDNIGHT. MARINE...EASTERLY GRADIENT TIGHTENS TODAY AS SURFACE LOW SLIDES INTO SOUTHERN WI. FAIRLY BRISK LOW LEVEL FLOW AS WELL (925MB WINDS 20-30KTS) SHOULD TRANSLATE TO SMALL CRAFT CONDITIONS IN MOST NEARSHORE ZONES...ENHANCED BY COASTAL CONVERGENCE ALONG SOUTHEAST UPPER SHORELINE AND FUNNELING THROUGH THE STRAITS OF MACKINAC. WILL RUN THIS THROUGH TONIGHT. ALTHOUGH WINDS EXPECTED TO DIMINISH SATURDAY...WAVE HEIGHTS MAY STILL BE AN ISSUE ON THE LAKE HURON SIDE. WINDS SHIFT TO NORTHWEST SATURDAY NIGHT AND WILL PICK UP AGAIN IN COLD ADVECTION PATTERN WITH 20KT LOW LEVEL FLOW FORECAST. JPB && .APX...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 504 PM CDT FRI AUG 25 2006 .DISCUSSION... MESOSCALE UPDATE... VISIBLE SATELLITE IMAGERY AND 21Z SURFACE OBSERVATIONS SHOW THAT THE COLD FRONT OVER NRN MO IS BECOMING INCREASINGLY LESS DEFINED WITH WARM SECTOR WINDS NOW SHIFTED INTO THE E/NE IN RESPONSE TO WEAK ELEVATED CONVECTION FURTHER SOUTH. CLOUD STRUCTURE IN THE VICINITY OF THE DECAYING BOUNDARY HAS BECOME INCREASINGLY STRATIFORM IN NATURE OVER THE LAST FEW HOURS...AND THE THREAT FOR SURFACE BASED CONVECTION IS LIKELY OVER. LATEST RUC 2 PROXIMITY SOUNDINGS SHOW THE REASON FOR THIS...DEPICTING AN IMPRESSIVE 750MB CAPPING INVERSION WITH TEMPS AROUND 18C. THIS CAP WAS NOT AT ALL HANDLED BY 12Z/18Z MODEL SOLUTIONS...WITH SERIOUS CONVECTIVE FEEDBACK PROBLEMS CONTINUING TO HAMPER BOTH THE NAM-WRF AND GFS. SOUTH AND EAST OF THIS ARCING BOUNDARY...AN AXIS OF ELEVATED INSTABILITY (DENOTED BY WIDESPREAD ACCAS AND EMBEDDED SHOWERS/STORMS) PRESENTLY EXTENDS FROM WEST CENTRAL MO...TO NEAR WICHITA...TO THE TEXAS PANHANDLE. THIS AREA ALSO REMAINS WITHIN A BROAD MOISTURE/WARM ADVECTION REGIME... AND WILL LIKELY BE THE FOCUS FOR RENEWED DEVELOPMENT DURING THE EVENING AND OVERNIGHT HOURS AS INCREASING NOCTURNAL LOW LEVEL JET IS ABLE TO TAP POTENTIAL INSTABILITY ABOVE 750MB. ADDITIONAL VERTICAL SUPPORT WILL LIKELY COME FROM AN ELONGATED VORTICITY MAXIMUM THAT IS PRESENTLY PROVIDING LARGE SCALE ASCENT OVER ERN CO/WRN KS. THEREFORE...I DO EXPECT TO SEE WIDESPREAD RAIN/THUNDERSTORMS OVERSPREAD THE AREA FROM THE WEST LATER THIS EVENING. STEEP 750-600MB LAPSE RATES MAY PROVIDE SOME SUPPORT FOR MARGINAL HAIL EARLY...BUT WEAK BULK SHEAR AND OVERALL WEAK INSTABILITY SHOULD PREDOMINANTLY RESULT IN MULTI-CELL CLUSTERS. NARROW CAPE PROFILES...CONTINUED WARM/MOIST LLJ INFLUX INTO AN QUASI-STATIONARY BOUNDARY...AND PRECIPITABLE WATERS APPROACHING TWO INCHES CERTAINLY FAVOR A HEAVY RAINFALL THREAT. BOOKBINDER && .PREV DISCUSSION... /ISSUED 300 PM CDT FRI AUG 25 2006/ THUNDERSTORMS WITH HEAVY RAINFALL ARE THE PRIMARY CONCERN FOR THE NEXT COUPLE OF DAYS. MODELS SIMILAR IN THE VERY SLOW EASTWARD PROGRESSION OF AN UPPER TROUGH OVER THE PAC NW AND GREAT BASIN. THE INTERACTION OF THIS UPPER TROUGH AND THE POSITION OF THE SURFACE AND ELEVATED BOUNDARIES ARE THE KEY PLAYERS. LATEST MOISTURE IMAGERY ALONG WITH THE SHORT TERM RUC INDICATE A SHORTWAVE IN ERN COLORADO. HOWEVER...IMAGERY DOES NOT LOOK AS IMPRESSIVE AS THE MODELS DEPICT. ANOTHER WEAK SHORTWAVE WAS NOTED IN EXTREME SWRN NM. THIS WAVE IS NOT HANDLED WELL BY MODELS AND COULD ENHANCE PRECIPITATION CHANCES SATURDAY OR SATURDAY NIGHT. OVERALL...PREFER THE WRF OVER THE GFS AS THE GFS HAS SERIOUS CONVECTIVE FEEDBACK WHICH HAS A SIGNIFICANT IMPACT ON THE LOW LEVEL MASS FIELDS. ALTHOUGH THE WRF HAS SOME ISSUES...IT DOES DEPICT A TYPICAL LATE SUMMER/EARLY FALL SCENARIO OF ROUNDS OF THUNDERSTORMS ALONG AND NORTH OF THE SURFACE BOUNDARY WITH THE HEAVIEST PRECIPITATION IN THE RELATIVELY TIGHT H8 BAROCLINIC ZONE. ISENTROPIC LIFT WITHIN THIS BAROCLINIC ZONE WILL BE THE PRIMARY FORCING MECHANISM WITH WEAK H3 DIVERGENCE AND QG FORCING SUPPLEMENTING THE UVV PERIODICALLY TONIGHT THROUGH SUNDAY. IN THE NEAR TERM...A COLD FRONT HAS SAGGED SOUTH TO NEAR A STJ TO LAMONIA LINE. THE FRONT IS EXPECTED TO PROGRESS VERY SLOWLY SOUTH TO NEAR A MCI TO IRK LINE BY EARLY THIS EVENING. A MOIST AND VERY UNSTABLE AIR MASS EXISTS ALONG AND IN ADVANCE OF THE FRONT...NORTH OF I-70. ESTIMATED CAPES ARE FROM 3000-4000 J/KG WITH ONLY A FEW MORE DEGREES NEEDED TO BREAK THE CAP. A FEW HIGH BASED THUNDERSTORMS HAVE DEVELOPED AHEAD OF THE FRONT IN THE KC METRO...BUT EXPECT THE BULK OF THE THUNDERSTORMS TO DEVELOP ALONG THE FRONT AFT 21Z AND PROGRESS SLOWLY SOUTHEAST THROUGH THE EVENING HOURS. ALTHOUGH THE SHEAR IS WEAK...FORECAST SOUNDINGS ALONG WITH AFTN ACCAS...DEPICT RELATIVELY STEEP MID LVL LAPSE RATES. IN ADDITION...FCST SOUNDINGS SUGGEST A DRY LAYER FROM H8 TO 550 MB. AS A RESULT...LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE. FRONTAL CONVECTION WILL GRADUALLY TRANSITION TO POST FRONTAL CONVECTION AFTER MIDNIGHT AS A MODEST LLJ ENHANCES ISENTROPIC LIFT ON THE 310K SURFACE. ALTHOUGH SEVERE THUNDERSTORMS ARE NOT EXPECTED...HEAVY RAINFALL IS POSSIBLE ALONG AND SOUTH OF INTERSTATE 70...GIVEN PRECIPITABLE WATER VALUES AROUND 1.7 INCHES. THE CDFNT SHOULD BECOME STATIONARY ACROSS SRN MO ON SATURDAY WITH WEAK TO MODERATE ISENTROPIC LIFT FROM 305-310 CONTINUING THROUGH SUNDAY NIGHT. THE ISENTROPIC LIFT WILL GENERALLY BE CONFINED TO THE SRN TWO THIRDS OF THE CWA. THERE WILL UNDOUBTEDLY BE BREAKS IN THE RAIN DURING THE WEEKEND ESPECIALLY IF A SHORTWAVE IS STRONG ENOUGH TO DEVELOP A WEAK WAVE ALONG THE FRONT. AT THIS TIME...IT IS TOUGH TO DISCERN WHEN THE BREAKS WILL OCCUR...BUT THE MOST LIKELY TIMES WILL BE DURING THE AFTN AND EARLY EVENING WHEN ISENTROPIC LIFT IS THE WEAKEST. THE MAJOR CONCERN WITH THIS EVENT WILL BE HEAVY RAINFALL. BY THE END OF THE WEEKEND...MOST AREAS SOUTH OF ROUTE 36 WILL SEE 1 TO 2 INCHES WITH SOME AREAS RECEIVING 2 TO 4 INCHES. THE SRN PORTION OF THE CWA CAN HANDLE A LOT OF RAIN. WILL ISSUE AND ESF FOR THE POTENTIAL OF LOCALIZED FLOODING. FUTURE SHIFTS WILL NEED TO MONITOR FOR THE POTENTIAL OF A FLASH FLOOD WATCH. CONFIDENCE IS NOT HIGH ENOUGH AT THIS TIME...AS FUTURE BOUNDARY LOCATIONS ARE CRITICAL. DB THE MEDIUM RANGE MODELS CONTINUE THE TREND OF HOLDING AT LEAST A PORTION OF THE SHORTWAVE TROUGH TO THE NORTH/NORTHWEST OF MISSOURI INTO EARLY NEXT WEEK. MEANWHILE...AN UPPER TROUGH IS FORECAST TO AMPLIFY OFF THE WEST COAST...WHILE RIDGING BUILDS ACROSS THE PLAINS. THERE IS SOME INDICATION THAT THE SHORTWAVE TROUGH ENERGY THAT WILL AFFECT OUR AREA THIS WEEKEND MAY BECOME TRAPPED BENEATH THE UPPER RIDGE...AND SLOWLY MEANDER EAST THROUGH THE MIDDLE OF NEXT WEEK. FOR NOW...HAVE EXTENDED PRECIPITATION CHANCES THROUGH MONDAY WITH THE UPPER TROUGH AXIS REMAINING TO THE NORTHWEST OF THE FORECAST AREA. HAVE ALSO DROPPED TEMPERATURES A FEW DEGREES ON MONDAY WITH THE ANTICIPATED CLOUD COVER AND POSSIBLE PRECIPITATION. CONTINUED WITH A SLOW WARMING TREND THROUGH THE MIDDLE OF NEXT WEEK...WITH TEMPERATURES BELOW NORMAL FOR THE FIRST PART OF THE WEEK...WARMING TO SEASONAL NORMALS BY THE END OF THE WORK WEEK. STOFLET && .AVIATION... SCATTERED THUNDERSTORMS ARE EXPECTED THROUGH THIS THIS EVENING FROM 20Z TO 02Z. CIGS AND VSBYS WILL GENERALLY BE MVFR. ADDITIONAL WIDESPREAD THUNDERSTORM DEVELOPMENT IS EXPECTED AFT 06Z FOLLOWED BY IFR CIGS AND MVFR VSBYS IN AN AREA OF RAIN AFT 11Z. CONFIDENCE IS NOT HIGH WITH REGARDS TO THE IFR CONDITIONS AS IT IS DEPENDENT UPON HOW FAR SOUTH THE FRONT PROGRESSES ALONG WITH THE INTENSITY AND COVERAGE OF THE RAIN. DB && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 300 PM CDT FRI AUG 25 2006 .DISCUSSION... THUNDERSTORMS WITH HEAVY RAINFALL ARE THE PRIMARY CONCERN FOR THE NEXT COUPLE OF DAYS. MODELS SIMILAR IN THE VERY SLOW EASTWARD PROGRESSION OF AN UPPER TROUGH OVER THE PAC NW AND GREAT BASIN. THE INTERACTION OF THIS UPPER TROUGH AND THE POSITION OF THE SURFACE AND ELEVATED BOUNDARIES ARE THE KEY PLAYERS. LATEST MOISTURE IMAGERY ALONG WITH THE SHORT TERM RUC INDICATE A SHORTWAVE IN ERN COLORADO. HOWEVER...IMAGERY DOES NOT LOOK AS IMPRESSIVE AS THE MODELS DEPICT. ANOTHER WEAK SHORTWAVE WAS NOTED IN EXTREME SWRN NM. THIS WAVE IS NOT HANDLED WELL BY MODELS AND COULD ENHANCE PRECIPITATION CHANCES SATURDAY OR SATURDAY NIGHT. OVERALL...PREFER THE WRF OVER THE GFS AS THE GFS HAS SERIOUS CONVECTIVE FEEDBACK WHICH HAS A SIGNIFICANT IMPACT ON THE LOW LEVEL MASS FIELDS. ALTHOUGH THE WRF HAS SOME ISSUES...IT DOES DEPICT A TYPICAL LATE SUMMER/EARLY FALL SCENARIO OF ROUNDS OF THUNDERSTORMS ALONG AND NORTH OF THE SURFACE BOUNDARY WITH THE HEAVIEST PRECIPITATION IN THE RELATIVELY TIGHT H8 BAROCLINIC ZONE. ISENTROPIC LIFT WITHIN THIS BAROCLINIC ZONE WILL BE THE PRIMARY FORCING MECHANISM WITH WEAK H3 DIVERGENCE AND QG FORCING SUPPLEMENTING THE UVV PERIODICALLY TONIGHT THROUGH SUNDAY. IN THE NEAR TERM...A COLD FRONT HAS SAGGED SOUTH TO NEAR A STJ TO LAMONIA LINE. THE FRONT IS EXPECTED TO PROGRESS VERY SLOWLY SOUTH TO NEAR A MCI TO IRK LINE BY EARLY THIS EVENING. A MOIST AND VERY UNSTABLE AIR MASS EXISTS ALONG AND IN ADVANCE OF THE FRONT...NORTH OF I-70. ESTIMATED CAPES ARE FROM 3000-4000 J/KG WITH ONLY A FEW MORE DEGREES NEEDED TO BREAK THE CAP. A FEW HIGH BASED THUNDERSTORMS HAVE DEVELOPED AHEAD OF THE FRONT IN THE KC METRO...BUT EXPECT THE BULK OF THE THUNDERSTORMS TO DEVELOP ALONG THE FRONT AFT 21Z AND PROGRESS SLOWLY SOUTHEAST THROUGH THE EVENING HOURS. ALTHOUGH THE SHEAR IS WEAK...FORECAST SOUNDINGS ALONG WITH AFTN ACCAS...DEPICT RELATIVELY STEEP MID LVL LAPSE RATES. IN ADDITION...FCST SOUNDINGS SUGGEST A DRY LAYER FROM H8 TO 550 MB. AS A RESULT...LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE. FRONTAL CONVECTION WILL GRADUALLY TRANSITION TO POST FRONTAL CONVECTION AFTER MIDNIGHT AS A MODEST LLJ ENHANCES ISENTROPIC LIFT ON THE 310K SURFACE. ALTHOUGH SEVERE THUNDERSTORMS ARE NOT EXPECTED...HEAVY RAINFALL IS POSSIBLE ALONG AND SOUTH OF INTERSTATE 70...GIVEN PRECIPITABLE WATER VALUES AROUND 1.7 INCHES. THE CDFNT SHOULD BECOME STATIONARY ACROSS SRN MO ON SATURDAY WITH WEAK TO MODERATE ISENTROPIC LIFT FROM 305-310 CONTINUING THROUGH SUNDAY NIGHT. THE ISENTROPIC LIFT WILL GENERALLY BE CONFINED TO THE SRN TWO THIRDS OF THE CWA. THERE WILL UNDOUBTLY BE BREAKS IN THE RAIN DURING THE WEEKEND ESPECIALLY IF A SHORTWAVE IS STRONG ENOUGH TO DEVELOP A WEAK WAVE ALONG THE FRONT. AT THIS TIME...IT IS TOUGH TO DISCERN WHEN THE BREAKS WILL OCCUR...BUT THE MOST LIKELY TIMES WILL BE DURING THE AFTN AND EARLY EVENING WHEN ISENTROPIC LIFT IS THE WEAKEST. THE MAJOR CONCERN WITH THIS EVENT WILL BE HEAVY RAINFALL. BY THE END OF THE WEEKEND...MOST AREAS SOUTH OF ROUTE 36 WILL SEE 1 TO 2 INCHES WITH SOME AREAS RECEIVING 2 TO 4 INCHES. THE SRN PORTION OF THE CWA CAN HANDLE A LOT OF RAIN. WILL ISSUE AND ESF FOR THE POTENTIAL OF LOCALIZED FLOODING. FUTURE SHIFTS WILL NEED TO MONITOR FOR THE POTENTIAL OF A FLASH FLOOD WATCH. CONFIDENCE IS NOT HIGH ENOUGH AT THIS TIME...AS FUTURE BOUNDARY LOCATIONS ARE CRITICAL. .AVIATION... SCATTERED THUNDERSTORMS ARE EXPECTED THROUGH THIS THIS EVENING FROM 20Z TO 02Z. CIGS AND VSBYS WILL GENERALLY BE MVFR. ADDITIONAL WIDESPREAD THUNDERSTORM DEVELOPMENT IS EXPECTED AFT 06Z FOLLOWED BY IFR CIGS AND MVFR VSBYS IN AN AREA OF RAIN AFT 11Z. CONFIDENCE IS NOT HIGH WITH REGARDS TO THE IFR CONDITIONS AS IT IS DEPENDENT UPON HOW FAR SOUTH THE FRONT PROGRESSES ALONG WITH THE INTENSITY AND COVERAGE OF THE RAIN. DB THE MEDIUM RANGE MODELS CONTINUE THE TREND OF HOLDING AT LEAST A PORTION OF THE SHORTWAVE TROUGH TO THE NORTH/NORTHWEST OF MISSOURI INTO EARLY NEXT WEEK. MEANWHILE...AN UPPER TROUGH IS FORECAST TO AMPLIFY OFF THE WEST COAST...WHILE RIDGING BUILDS ACROSS THE PLAINS. THERE IS SOME INDICATION THAT THE SHORTWAVE TROUGH ENERGY THAT WILL AFFECT OUR AREA THIS WEEKEND MAY BECOME TRAPPED BENEATH THE UPPER RIDGE...AND SLOWLY MEANDER EAST THROUGH THE MIDDLE OF NEXT WEEK. FOR NOW...HAVE EXTENDED PRECIPITATION CHANCES THROUGH MONDAY WITH THE UPPER TROUGH AXIS REMAINING TO THE NORTHWEST OF THE FORECAST AREA. HAVE ALSO DROPPED TEMPERATURES A FEW DEGREES ON MONDAY WITH THE ANTICIPATED CLOUD COVER AND POSSIBLE PRECIPITATION. CONTINUED WITH A SLOW WARMING TREND THROUGH THE MIDDLE OF NEXT WEEK...WITH TEMPERATURES BELOW NORMAL FOR THE FIRST PART OF THE WEEK...WARMING TO SEASONAL NORMALS BY THE END OF THE WORK WEEK. STOFLET && .PREVIOUS DISCUSSION... 328 AM... A POTENTIAL WET PATTERN IS EVOLVING ACROSS THE CENTRAL PLAINS EARLY THIS MORNING. A FLATTENED RIDGE HOLDS SWAY ACROSS THE SOUTHERN PLAINS THIS MORNING WITH AS SHARPLY POINTED TROUGH SCOOTS EAST ALONG THE CANADIAN BORDER. FARTHER WEST A LARGER SHORTWAVES FEATURE IS DIGGING INTO THE PACIFIC NORTHWEST. THIS WAVE WILL TAKE IT TIME MOVING INTO AND THROUGH THE PLAINS AS THE NORTHERN JET STREAM WILL JUST ABOUT CUT IT OFF AS IT MOVES THROUGH THE GREAT BASIN. AT THE SURFACE A COLD FRONT...WHICH IS THE REFLECTION OF THE CANADIAN BORDER SHORTWAVE...IS DRAPED FROM SOUTH DAKOTA SOUTHWEST THROUGH CENTRAL NEBRASKA. ALSO OF NOTE ARE THE DEW POINTS POOLED IN THE LOW 70S SOUTHEAST OF THE FRONT FROM CENTRAL KANSAS INTO WESTERN IOWA. EARLY MORNING CONVECTIVE ACTIVITY IS BEGINNING TO BUBBLE UP ACROSS EASTERN KANSAS ON ISENTROPIC LIFT ON THE LAYERS FROM AT LEAST 305K TO 310K. ALSO LENDING A HELPING HAND TO THE STORMS IS A WEAK UPPER LEVEL WAVE RESOLVED ON THE VORTICITY FIELD FROM 400MB TO 300MB ON BOTH THE NAM-WRF AND GFS. THIS SMALL WAVE HAS ALLOWED FOR CONVECTION TO POP UP ALL THE WAY BACK INTO THE TEXAS PANHANDLE AS A RESULT. 00Z/26 UPPER AIR SOUNDINGS FROM TOPEKA AND SPRINGFIELD SHOWED A FAIRLY DRY BOUNDARY LAYER....BUT MID LEVEL LAYERS AROUND 800MB TO 700MB INDICATE A NICE MOIST PLUME ALOFT. CONVECTION HAS STARTED OUT FAIRLY SCATTERED IN NATURE...BUT IS EXPECTED TO CONGEAL AS THE LOW LEVEL JET FOCUSES ON WEST CENTRAL MISSOURI THROUGH THE EARLY MORNING HOURS. ALSO AT PLAY IS A BOUNDARY PUSHING SOUTHEAST THROUGH NEBRASKA AHEAD OF THE FRONT. THIS BOUNDARY CAN BE SEEN ON OMAHA'S RADAR THIS MORNING. NAM-WRF HAS THIS HANDLED BY PAINTING WIDESPREAD PRECIP ACROSS MUCH OF THE FORECAST AREA FOR THE 12Z TO 15Z TIME PERIOD...WHICH SEEMS KIND OF SLOW WHEN COMPARED TO THE TIMING OF THE BOUNDARY. STILL...HAVE ADDED LIKELY POPS TO EASTERN KANSAS AND WESTERN MISSOURI THROUGH 15Z AS A RESULT. KEPT THE HIGHEST POPS RESTRICTED TO THE WESTERN SIDE OF THE CWA WHERE THE BEST MOISTURE IS FOUND. WILL LIKELY NEED TO MAKE ADJUSTMENTS TO THIS MORNINGS FORECAST BASED ON TRENDS. THE GENERAL PICTURE FOR THIS TODAY HAS THE FRONT IN NEBRASKA MOVING INTO THE NORTHWEST MISSOURI AFTER SUNRISE. MODELS THEN START TO DIVERGE ON HOW FAR INTO NORTHERN MISSOURI THE FRONT WILL PENETRATE. NAM-WRF HANGS THE FRONT IN NORTHWEST MISSOURI...WHILE THE GFS MOVES IT TO OUR SOUTHEASTERN EDGE. BOTH MODELS ARE SUSPECT DUE TO THE AMOUNT OF CONVECTIVE FEEDBACK. STILL...THE PREVAILING IDEA THAT THE FRONT WILL BE IN THE CWA WITH LOW 70 DEGREE DEW POINTS IS A VALID ONE. HOWEVER...WILL KEEP AFTERNOON POPS IN THE CHANCE CATEGORY DUE TO CLOUD COVER AND DEBRIS LEFT OVER FROM THE MORNINGS ACTIVITY. FOR LATER TONIGHT THROUGH SATURDAY...WITH A STALLED BOUNDARY AND LOTS OF AVAILABLE MOISTURE IN PLACE...I HAVE PAINTED LIKELY POPS ACROSS MUCH OF THE FORECAST AREA. FOR TONIGHT THE LOW LEVEL JET WILL FOCUS AGAIN ACROSS EASTERN KANSAS AND WESTERN MISSOURI INITIATING OVERNIGHT CONVECTION. DAYLIGHT HOURS SATURDAY WILL SEE INCREASING PVA AS ANOTHER SMALL WAVE EJECTS OUT OF THE DESERT SOUTHWEST AHEAD OF THE PACIFIC NORTHWEST SHORTWAVE...WHICH IS NOT PROGGED TO MOVE THROUGH THE CENTRAL PLAINS UNTIL MONDAY. SATURDAY NIGHT SHOULD SEE HIGHEST POPS ACROSS AREAS ALONG OUR SOUTHERN AND EASTERN EDGES AS THE LOW LEVEL JET FOCUSES FARTHER SOUTH. SUNDAY WILL SEE THE TROUGH IN THE PACIFIC NORTHWEST ENTER THE CENTRAL PLAINS. LATEST RUNS OF THE GFS AND NAM-WRF INDICATE THAT THE TROUGH WILL BE PENNING UP AS IT MOVES INTO THE PLAINS. THIS LOOKS REASONABLE AS THE WAVE WILL BE MOVING INTO A CONFLUENT FLOW ACROSS THE GREAT LAKES AS IT MOVES EAST. HAVE OPTED TO KEEP CHANCE POPS FOR SUNDAY DAY...AND EVEN EXPANDED THEM A LITTLE FARTHER NORTH FOR THE NIGHTTIME HOURS DUE TO WARM AIR ADVECTION AHEAD OF THE TROUGH. WITH PRECIPITABLE WATER VALUES RANGING FROM ONE AND HALF TO TWO INCHES HEAVY RAIN WILL BE OF CONCERN FOR THE WEEKEND. THOUGHTS AT THIS TIME IS THAT THE CONVECTION SHOULD OCCUR IN SEVERAL ROUNDS IN DIFFERENT LOCATIONS AS THE ACTUAL AND EFFECTIVE BOUNDARIES GET PUSHED AROUND BY THE STORMS SHIFTING THE FOCUS OF THE ACTIVITY. THIS WILL REQUIRE MONITORING THROUGH THE WEEKEND. CUTTER && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1215 PM CDT FRI AUG 25 2006 .UPDATE... UPDATED THE GRIDS AND PRODUCTS FOR CLOUDCOVER AND TEMP TRENDS. && .DISCUSSION... HIGHER RH WITH NE FLOW PRODUCING SOME STRATOCU FOR PARTS OF ERN NEB AND WRN IA. THIS MAY HOLD TEMPS BACK...ALTHOUGH THE LOW CLDS ARE FCST TO MIX OUT BY THE NAM/RUC LATER THIS AFTERNOON. MEANWHILE...MID LEVEL MOISTURE WAS INCREASING FM THE WEST WITH SOME SPRINKLES FM CNTRL TO NRN NEB. EXPECT THESE CLDS TO HOLD BACK TEMPS IN THE 70S. SFC FNT IS TO THE S OF THE FCST AREA...HOWEVER LEFT SML POPS IN SE WHERE LINGERING H85 MOISTURE AND HEATING INTO THE UPR 80S MAY PRODUCE SOME TSRA. && .PREV DISCUSSION... (ISSUED 501 AM CDT FRI AUG 25 2006) DISCUSSION... FORECAST CONCERNS WILL BE PRECIPITATION CHANCES THROUGH MONDAY. CONVECTIVE CAP WAS BROKEN AS CDFNT PASSED SOUTH OF OMA AND LNK. EXPECT FIRST ROUND OF TSTMS TO BE CONFINED TO FAR SOUTHERN NEB EARLY THIS MORNING. ADDITIONAL DEVELOPMENT IS POSSIBLE LATER THIS AFTN AND OVERNIGHT AS A SHORT WAVE MOVES OUT OF THE SOUTHWEST U.S. AND BRINGS INCREASING MID LEVEL MOISTURE AT LEAST TO SOUTHERN SECTIONS. DRY AIR AT LOW LEVELS WILL RESTRICT NORTH EDGE OF PRECIP...AND EXPECT IT TO REMAIN S OF INTERSTATE 80 AND QUITE POSSIBLE RIGHT ALONG KS BORDER. ANOTHER CHANCE FOR PRECIP WILL COME SUNDAY INTO MONDAY AS A WAVE MOVES INTO THE AREA FROM THE PACIFIC NW. AGREE WITH NATIONAL DISCUSSION THAT NAM IS LIKELY OVERDONE WITH THE SYSTEM. GFS SOLUTION OF AN OPENING WAVE MOVING ACROSS THE AREA SEEMS MORE REASONABLE AS THE SYSTEM EJECTS ACROSS THE MEAN RIDGE POSITION. DRY AIR AT LOW LEVELS WILL CONTINUE TO BE A NEGATIVE FACTOR FOR PRECIP REACHING THE GROUND...IN ADDITION TO A LACK OF ANY SURFACE BASED INSTABILITY. 00Z GFS SEEMED TO BE RESPONDING REASONABLY WITH PRECIP AREA DECREASING IN SIZE AND INTENSITY AS IT MOVED EAST ACROSS THE AREA LATE SUN THROUGH MON MORNING. WITH A MUCH STRONGER SYSTEM ALOFT...NAM DEVELOPED A BROADER AREA OF PRECIP...ESPECIALLY THE 06Z RUN. AFTER DISCUSSION WITH NEIGHBORS...OPTED FOR FAIRLY LOW POPS SUN AND SUN NIGHT WHILE LEAVING MON DRY FOR NOW. MID AND HIGH CLOUDS WILL TEND TO KEEP DAYTIME TEMPS ON THE COOL SIDE...AT LEAST COMPARED TO RECENT DAYS...BUT THERE IS SOME UNCERTAINTY AS TO JUST HOW THICK AND PERSISTENT THE CLOUDS ARE. DO NOT EXPECT STRATOCU NOW MOVING ACROSS NORTHEAST NEBRASKA TO PERSIST FOR LONG. OVERALL...MADE LITTLE CHANGE TO TEMPS AND LEFT EXTENDED FORECAST ALONE. POLLACK && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ ZAPOTOCNY ne