Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 012039 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 439 PM EDT TUE SEP 1 2015 .SYNOPSIS... AN UPPER LEVEL LOW WILL DRIFT SOUTHEAST ACROSS THE AREA TONIGHT INTO WEDNESDAY. AN UPPER LEVEL RIDGE WILL THEN BUILD ACROSS THE REGION THROUGH THE REMAINDER OF THE WEEK WITH CONTINUED WARM AND HUMID CONDITIONS. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... A CLOSED UPPER LEVEL LOW EVIDENT OVER INDIANA ON WATER VAPOR IMAGERY THIS AFTERNOON CONTINUES TO SLOWLY DRIFT NORTHEASTWARD. COUPLED WITH A WARM AND MUGGY AIRMASS...ENERGY ASSOCIATED WITH THIS SYSTEM HAS TRIGGERED ISOLATED TO SCATTERED CONVECTION ACROSS MAINLY OUR NORTHWESTERN CWA THIS AFTERNOON. WITH RATHER WEAK FLOW FROM ABOUT 0-6 KM...INDIVIDUAL CELLS WILL CONTINUE TO BE SLOW MOVING AND NOT WELL ORGANIZED. THUS...MAIN ISSUE WITH STRONGER CELLS THROUGH EARLY EVENING WILL LIKELY JUST BE LOCALLY HEAVY RAINFALL. EXPECT THIS ACTIVITY AND MUCH OF THE CU FIELD TO DIMINISH WITH THE LOSS OF DAYTIME HEATING THIS EVENING. KEPT SLIGHT CHANCE POPS ACROSS MAINLY OUR NORTHWEST OVERNIGHT AS THE UPPER LOW MOVES OVER WESTERN OHIO. OVERALL FORCING FROM THIS FEATURE WILL REMAIN WEAK BUT CANNOT RULE OUT SOME ISOLATED LINGERING CONVECTION IN ITS VICINITY. VARIOUS MODEL QPF FIELDS SEEM OVERDONE BEHIND THE LOW ALONG THE IN/OH BORDER...WHICH IS PROBABLY TIED INSTEAD TO A WEAK LOW LEVEL JET AND CONVERGENCE OVER THAT AREA. CLOUD COVER OVERNIGHT IS SOMEWHAT UNCERTAIN GIVEN THE UPPER LOW OVERHEAD BUT ALSO SOME DRIER AIR MOVING IN ALOFT. HAVE GONE PARTLY CLOUDY FOR NOW WITH LOWS IN THE MID TO UPPER 60S. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... MODELS ARE IN AGREEMENT WITH THE UPPER LOW OPENING UP INTO A WEAKENING SHORTWAVE EARLY WEDNESDAY MORNING...BECOMING ABSORBED INTO MID LEVEL FLOW AND PUSHING SOUTHEAST OF THE CWA BY AFTERNOON. HAVE DISCOUNTED THE THE GFS WHICH WAS QUITE A BIT SLOWER THAN THE NAM...ECMWF AND CANADIAN IN CLEARING THE LOW OUT OF OUR AREA. A WEAK SURFACE TROUGH WILL PUSH THROUGH NORTHERN OHIO DURING THE DAY...RESULTING IN A CHANCE OF SHOWERS AND STORMS GIVEN THE CONTINUED WARM AND HUMID AIRMASS WITH TEMPERATURES RISING INTO THE MID TO UPPER 80S. PRECIP CHANCES WILL DIMINISH WITH THE LOSS OF DAYTIME HEATING WEDNESDAY EVENING. A BUILDING UPPER LEVEL RIDGE WILL THEN GRADUALLY TAKE HOLD OF THE REGION BEGINNING LATE WEDNESDAY...RESULTING IN DRY CONDITIONS FOR WEDNESDAY NIGHT. A WEAK RIDGE OF HIGH PRESSURE AT THE SURFACE WILL DEVELOP JUST WEST OF OUR AREA ON THURSDAY CAUSING WINDS TO BECOME NORTHERLY. DESPITE THIS CHANGE IN SURFACE FLOW...TEMPERATURES WILL STILL REMAIN UP THERE WITH HIGHS FLIRTING WITH 90 IN MANY SPOTS AND DEWPOINTS AROUND 70. A WEAK DISTURBANCE ALOFT MAY ALLOW FOR ISOLATED CONVECTION IN CONJUNCTION WITH DAYTIME HEATING ON THURSDAY WITH DRY CONDITIONS EXPECTED FOR THURSDAY NIGHT. && .LONG TERM /FRIDAY THROUGH TUESDAY/... WHILE SOME OF THE SPECIFICS REGARDING THE EXTENDED FORECAST REMAIN UNCERTAIN...THE LARGE SCALE PATTERN SUPPORTING ABOVE-NORMAL TEMPERATURES SHOWS NO SIGNS OF CHANGE THROUGH THE WEEKEND...WITH ONLY A SLIGHT TREND TOWARD THE MID-LEVEL RIDGE BREAKING DOWN GOING INTO THE FIRST HALF OF NEXT WEEK. ON FRIDAY MORNING...THE AXIS OF A FAIRLY STRONG RIDGE WILL EXTEND FROM THE TEXAS COAST NNE THROUGH THE NORTHERN GREAT LAKES. AT THE SURFACE..THE PRESSURE PATTERN WILL BE FAIRLY NEBULOUS...WITH WEAK HIGH PRESSURE OVER THE NORTHEASTERN STATES. THIS WILL KEEP THE OHIO VALLEY IN A REGIME OF WEAK AND MOIST LOW-LEVEL EASTERLY FLOW THROUGH THE WEEKEND. THIS IS CERTAINLY A PATTERN THAT SUPPORTS WARM CONDITIONS...AND MAX TEMPS IN THE UPPER 80S TO AROUND 90 ARE EXPECTED. GEFS 850MB/700MB TEMPERATURE AND 500MB HEIGHT ANOMALIES ARE NOT EXTREME...RANGING FROM AROUND 0.5 TO 1.5 STANDARD DEVIATIONS ABOVE NORMAL THROUGH THE FORECAST PERIOD. THIS LENDS SUPPORT TO A FORECAST FOR ABOVE NORMAL TEMPERATURES...BUT NOT AT THE HIGH END OF THE CLIMATOLOGICAL RECORD. WITH VERY LITTLE APPRECIABLE FORCING...ANY CHANCES FOR PRECIPITATION WILL BE LIMITED. BETWEEN THE GFS AND ECMWF...THE GFS HAS BEEN A LITTLE MORE WILLING TO CONVECT...BUT QPF OUTPUT IS NOT SIGNIFICANT IN EITHER CASE. A DRY FORECAST WILL BE MAINTAINED FOR MOST OF THE FORECAST PERIOD...THOUGH SLIGHT CHANCE POPS WERE KEPT IN FOR FRIDAY. ON MONDAY AND TUESDAY...THERE ARE SIGNS THAT THE RIDGE WILL BEGIN TO FLATTEN...THOUGH THE EXTENT AND QUICKNESS THAT THIS OCCURS IS NOT IN GOOD AGREEMENT. AS A SHORTWAVE MOVES ACROSS THE NORTH-CENTRAL CONUS GOING INTO TUESDAY...EVENTUALLY A COLD FRONT WILL DEVELOP AND MOVE TOWARD THE OHIO VALLEY. HOW FAR THIS PROCESS GETS IS MUCH TOO EARLY TO FORECAST...BUT THERE IS ENOUGH CONFIDENCE TO SHOW A SLIGHT DECREASE IN TEMPERATURES AND AS LIGHT INCREASE IN POPS FOR TUESDAY. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... ISOLATED THUNDERSTORMS HAVE DEVELOPED EARLY THIS AFTERNOON AHEAD OF AN UPPER LEVEL LOW MOVING VERY SLOWLY EASTWARD ACROSS INDIANA. AS THE LOW CONTINUES TO WORK TOWARD OUR FA AND WE DESTABILIZE A BIT MORE...EXPECT THUNDERSTORM COVERAGE TO BECOME A LITTLE MORE WIDESPREAD THROUGH MID TO LATE AFTERNOON. WILL COVER THIS THREAT WITH A VCTS. THE THUNDERSTORM ACTIVITY AND CU SHOULD BEGIN TO DISSIPATE AS WE HEAD INTO THIS EVENING AND START TO LOSE THE DIURNAL HEATING. THE UPPER LEVEL LOW WILL PROGRESS SLOWLY EAST SOUTHEAST ACROSS OUR AREA TONIGHT INTO WEDNESDAY MORNING. AS WE GET ON THE BACK SIDE OF THE LOW AND SOME LOW LEVEL CONVERGENCE BEGINS TO DEVELOP LATER TONIGHT...BOTH THE NAM AND GFS...ALONG WITH SOME OF THE HIGHER RES MODELS...ARE HINTING AT THE POSSIBILITY OF SCATTERED SHOWER/POSSIBLY THUNDERSTORM DEVELOPMENT ACROSS AT LEAST WESTERN PORTIONS OF OUR FA LATE TONIGHT INTO EARLY WEDNESDAY. DUE TO THE UNCERTAINTY OF THIS THOUGH...WILL JUST ALLOW FOR AN INCREASE IN VFR CIGS LATER TONIGHT ALONG WITH A VCSH AT THE WESTERN TAF SITES. WILL NOT HIT THE BR/FG RESTRICTIONS QUITE AS HARD TONIGHT...BUT THIS IS BASED ON THE ASSUMPTION THAT WE WILL HAVE AT LEAST SOME CLOUD COVER REDEVELOPMENT LATER TONIGHT. IF THIS DOES NOT OCCUR...WE WILL LIKELY SEE MORE WIDESPREAD IFR MVFR TO IFR VSBY RESTRICTIONS LATER TONIGHT INTO WEDNESDAY MORNING. OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...KURZ NEAR TERM...KURZ SHORT TERM...KURZ LONG TERM...HATZOS AVIATION...JGL

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