Area Forecast Discussion
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000 FXUS61 KPBZ 041309 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 909 AM EDT WED MAY 4 2016 .SYNOPSIS... COOL LOW PRESSURE WILL KEEP SHOWERS IN THE FORECAST THROUGH THURSDAY. MAINLY DRY FRIDAY BEFORE SHOWER CHANCES RETURN SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... SEVERAL MINOR ADJUSTMENTS NEEDED THIS MORNING BUT OVERALL THE FORECAST LOOKS TO BE IN GOOD SHAPE. HOURLY TEMPERATURES WERE ADJUSTED DOWN SLIGHTLY TO BETTER ALIGN WITH LATEST OBSERVATIONAL TRENDS AND MENTION OF THUNDER WAS REMOVED FOR THIS AFTERNOON AS LATEST GUIDANCE PROGS MINIMAL INSTABILITY AND 12Z SOUNDINGS SHOW A WEAK CAP AT 600MB. IF DEWPOINTS STAY STEADY OR RISE SLIGHTLY AND TEMPERATURES ALOFT COOL MORE THAN FORECAST THEN THERE IS A CHANCE OF CONVECTION BUT AT THIS TIME THAT LOOKS UNLIKELY. LATEST WATER VAPOR IMAGERY SHOWS UPPER LOW DEEPENING TO OUR WEST...WHICH WILL RESULT IN SHOWERS DEVELOPING AND SPREADING FROM WEST TO EAST THIS AFTERNOON AS THE LOW CONTINUES TO SHIFT SOUTH AND THE FORECAST AREA SITS UNDER THE DEFORMATION ZONE. THIS SETUP WILL CONTINUE THROUGH THE NIGHT. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... COOL MID LEVEL CLOSED SYSTEM WILL SLOWLY TRANSLATE TOWARD THE MID ATLANTIC STATES INTO THURSDAY NIGHT. THIS WILL KEEP TEMPERATURES NEAR 10 DEGREES BELOW AVERAGE. SHORTWAVES ROTATING AROUND CLOSED LOW COMBINED WITH COLD POOL ALOFT WILL KEEP SHOWERS IN THE FORECAST INTO THURSDAY NIGHT. BY FRIDAY LOW MAY BECOME BECOME MORE ELONGATED NEAR THE COAST...ALTHOUGH NEWEST LONGER RANGE MODELS DISAGREE ON PLACEMENT AND SPEED OF LOW LIFTING OUT. HAVE KEPT LOW CHANCE POPS INTO THE RIDGES FRIDAY WITH A DRYING TREND ELSEWHERE. GENERAL MODEL AGREEMENT ON A STRONG SHORTWAVE DIVING SOUTHEAST OUT OF CENTRAL CANADA FRIDAY NIGHT TO SHUNT LOW TOWARD NEW ENGLAND. THIS TROUGH WILL BRING BACK SHOWER CHANCES SATURDAY WITH WARM ADVECTION AHEAD OF IT PUSHING TEMPERATURES BACK NEAR NORMAL. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... UPR TROF AND SFC BOUNDARY PASSAGE IS PROGGED ERLY IN THE PERIOD WITH THE BEST CHCS FOR SHOWERS. OTHERWISE...BUILDING RIDGING SHOULD RESULT IN DRY WEATHER UNTIL AN APPROACHING UPR TROF ADVANCES OUT OF THE MID WEST BY MID WEEK. TEMPS NEAR SEASONAL LVLS ARE EXPECTED TO WARM TO ABOVE AVG BY MID WEEK. THE SUPERBLEND GUIDANCE...WITH DOWNWARD MID WEEK POP ADJUSTMENT...WAS USED FOR THE LONG TERM FCST. && .AVIATION /13Z WEDNESDAY THROUGH SUNDAY/... OTHER THAN ISOLATED ERLY MRNG FOG...VFR CONDITIONS ARE EXPECTED THRU THE AFTN. APPROACHING LOW PRESSURE SHOULD RESULT IN SCT LGT SHOWERS FOR WHICH A VCSH MENTION WAS MAINTAINED TODAY...THOUGH BETTER CHCS FOR SHOWERS AND MVFR RESTRICTIONS ARE EXPECTED BY EVENING AND OVERNIGHT WHEN THE BEST MOISTURE AND LIFT IS EXPECTED. .OUTLOOK /THURSDAY THROUGH SUNDAY/... PERIODIC RESTRICTIONS ARE LIKELY THU/FRI WITH PERSISTENT LOW PRESSURE...AND AGAIN WITH A SAT NGT COLD FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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