Area Forecast Discussion
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000 FXUS61 KPBZ 301821 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 221 PM EDT TUE JUN 30 2015 .SYNOPSIS... UNSETTLED WEATHER AND SLIGHTLY BELOW NORMAL TEMPERATURES WILL CONTINUE THROUGH WEDNESDAY...FOLLOWED BY A WARMING TREND AND DRIER CONDITIONS AS HIGH PRESSURE SETTLES OVER THE AREA. && .NEAR TERM /THROUGH TONIGHT/... MESOSCALE CONVECTIVE VORTEX OVER WESTERN OHIO...APPARENT IN BOTH THE RADAR AND SATELLITE...WILL CONTINUE TO MAKE ITS WAY TOWARD THE REGION THIS AFTERNOON. OUT AHEAD OF THIS SYSTEM...CLOUDS HAVE SCATTERED OUT SUFFICIENTLY TO WARM AND DESTABILIZE THE AREA...WITH ABOUT 1000J/KG OF MUCAPE AS SUGGESTED BY THE MESOANALYSIS. WITH 30-35KTS OF BULK SHEAR...AND SOME COOLING ALOFT AS THE UPPER LEVEL SHORTWAVE APPROACHES...SOME STORMS SHOULD BE SUPPORTED TO STRONG OR SEVERE LEVELS. AS SUCH...THE STORM PREDICTION CENTER HAS ADDED OUR AREA TO A SLIGHT RISK AND A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED FOR THE ENTIRE REGION. DAMAGING WIND WILL BE THE PRIMARY THREAT BUT WITH FREEZING LEVELS NEAR 12KFT...SOME HAIL WILL BE POSSIBLE AS WELL. TRIED TO TIME THE HIGHEST POPS WITH THE LONE OF CONVECTION OVER OHIO THAT THE HRRR REPRESENTED WELL THIS MORNING. CURRENT TIMING HAS THE BULK OF THE CONVECTION EAST OF THE REGION BY 8PM. WEAK COLD ADVECTION WILL ENSUE OVERNIGHT BUT WITH LITTLE MIXING...TEMPERATURES SHOULD REMAIN NEAR NORMAL VALUES. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... NEW MODEL GUIDANCE SUGGESTS THAT MOST OF THE AREA SAVE FOR THE NORTHERN COUNTIES AND THE RIDGES MAY REMAIN DRY...AS SUBSIDENCE AND WARMING TAKES PLACE ALOFT AND MIXING DRIES OUT THE SURFACE. THIS MAY TAKE MOST OF THE DAY THOUGH...SO SOME SHOWERS MAY BE POSSIBLE...IN THE AFOREMENTIONED AREAS...WHERE BETTER INSTABILITY MAY BE IN PLACE PER THE LATEST NAM SOUNDINGS. IN ADDITION...THE 12Z GUIDANCE WANTS TO SHUNT MOST OF THE PRECIPITATION SOUTHWARD THROUGH THE REMAINDER OF THE SHORT TERM...WITH HIGH PRESSURE BUILDING AT THE SURFACE AND A SURFACE BOUNDARY REMAINING JUST SOUTH OF THE MASON DIXON LINE. HAVE PUSHED CHANCE POPS SOUTHWARD FROM THE PREVIOUS FORECAST WITH THESE TRENDS. HAVE INCREASED POPS SLIGHTLY OVER NORTHERN WV THURSDAY AFTERNOON AS MODEL CONSENSUS HAS A LOW PRESSURE SYSTEM RIDING ALONG THE STALLED BOUNDARY FROM KENTUCKY TO WEST VIRGINIA DURING THIS TIME FRAME. TEMPERATURES ARE FORECAST TO STAY JUST BELOW OR NEAR SEASONAL AVERAGES WITH THE UPPER TROUGH REMAINING IN PLACE. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... HAVE NOT NEEDED TO MAKE MUCH IN THE WAY OF CHANGES TO THE EXTENDED PORTION OF THE FORECAST. A STALLED FRONTAL BOUNDARY WILL CONTINUE TO PROVIDE A FOCUS FOR DAILY SHOWERS AND STORMS...BUT COMPARED TO EARLIER IN THE WEEK...THE BOUNDARY WILL BE SHIFTED FARTHER TO THE SOUTH. AS A RESULT...THE NORTHERN HALF OF THE FORECAST AREA HAS A BETTER CHANCE TO SEE SOME DRY DAYS. HARD TO PINPOINT ANY PARTICULAR POINT WHEN RAIN IS LIKELY...BUT SO FAR FRIDAY NIGHT AND SATURDAY APPEAR TO HAVE THE BEST CHANCES FOR RAIN. TEMPERATURES SHOULD NOT SHIFT MUCH DURING THE PERIOD...WITH HIGHS AROUND 80 AND LOWS IN THE MID 60S. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... UPPER LEVEL DISTURBANCE CROSSING THE UPPER OHIO VALLEY WILL BRING INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS ACROSS THE ENTIRE FORECAST AREA THIS AFTERNOON. CONFIDENCE IS INCREASING THAT MOST...IF NOT ALL OF THE TAF SITES WILL EXPERIENCE A THUNDERSTORM AS INSTABILITY IS INCREASING WITH PEAKS OF SUNSHINE. THUS...HAVE ADDED TSRA TEMPO GROUPS WITH PRIMARILY MVFR VSBY/CIG RESTRICTIONS. WIND GUSTS TO 20KTS ARE EXPECTED THROUGH THE AFTERNOON...WITH HIGHER GUSTS POSSIBLE IN THUNDERSTORMS. PRECIPITATION WILL LINGER INTO THIS EVENING AS THE UPPER TROUGH PIVOTS TO THE EAST. WHILE WE DO NOT EXPECT TO FULLY DECOUPLE OVERNIGHT...RAINFALL WILL ONCE AGAIN BRING THE CHANCE FOR MVFR AND IFR RESTRICTIONS IN STRATUS AND FOG...ESPECIALLY OVER KFKL AND KDUJ THROUGH WEDNESDAY MORNING. .OUTLOOK.../WEDNESDAY THROUGH SATURDAY/... COOL NW FLOW MAY BRING OCCASIONAL RESTRICTIONS WEDNESDAY AFTERNOON BEFORE HIGH PRESSURE BUILDS OVERHEAD FOR MOST OF THE REGION ON THURSDAY. THE NEXT CHANCE FOR WIDESPREAD RESTRICTIONS WILL BE WITH APPROACHING LOW PRESSURE THURSDAY NIGHT/FRIDAY && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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