Area Forecast Discussion
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000 FXUS61 KPBZ 011258 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 858 AM EDT SUN MAY 1 2016 .SYNOPSIS... A COUPLE OF LOW PRESSURE SYSTEMS WILL PROVIDE RAIN OVER THE REGION INTO EARLY MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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THE FIRST SURFACE WAVE ALONG A QUASI-STATIONARY BOUNDARY IS CURRENTLY PUSHING TO THE EAST OF THE THE AREA...TAKING WITH IT THE BULK OF THE DEEP MOISTURE AND LARGE SCALE LIFT. IN ITS WAKE...VIRTUALLY NIL BOUNDARY LAYER ADVECTION EXISTS...THUS SOUPY DEWPOINTS NEAR 60F WILL REMAIN. HOWEVER...SUBSTANTIAL MID-LEVEL DRYING IS EVIDENT ON WATER VAPOR IMAGERY AND THE FIRST FEW FRAMES OF VISIBLE IMAGERY INDICATE SOME DEGREE OF CLEARING CREEPING UP THE OHIO VALLEY FROM CINCINNATI AT THIS HOUR. AS THE DAY GOES ON...HRRR PROJECTIONS SUGGEST THIS SHOULD ENVELOPE THE AREA...WHILE SYNOPTIC MODELS ARE NOT AS BULLISH WITH THIS IDEA. GIVEN BOUNDARY LAYER MOISTURE...IT WOULD SEEM SUNSHINE SHOULD BE DESTRUCTIVE IF CLEARING DOES OCCUR...SO WILL JUST TREND THE FORECAST TOWARD PARTLY CLOUDY FOR A TIME. WITH COME CLOUD BREAKUP AND INSOLATION GOING INTO THE LATER MORNING AND AFTERNOON...LAPSE RATES SHOULD BECOME RAPIDLY MORE UNSTABLE. COMBINING THIS WITH ADDITIONAL MID-LEVEL DRY AIR AND MODEST SHEAR WILL MEAN A RAPID INCREASE IN INSTABILITY BY AFTERNOON AND EVENING AS A SECONDARY SURFACE WAVE APPROACHES. THUS POPS FOR SHOWERS AND THUNDERSTORMS WILL SECONDARILY INCREASE BY LATE AFTERNOON AND INTO THE EVENING HOURS. SPC STILL OUTLINES MUCH OF THE AREA IN A MARGINAL RISK FOR SEVERE WEATHER...WHICH SEEMS WARRANTED AT THIS JUNCTURE. FRIES
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&& .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... THE FRONT WILL FINALLY TRACK SOUTHEASTWARD TONIGHT AS THE MAIN SHORTWAVE TROUGH PUSHES INTO NORTHERN OHIO. WITH THE LAGGING FRONTAL BOUNDARY CROSSING THE AREA...HAVE INCREASED POPS AGAIN OVERNIGHT. IT WILL TAKE ALL NIGHT AND PART OF MONDAY MORNING...BUT THE BOUNDARY WILL FINALLY EXIT TO THE SOUTHEAST... ENDING THE RAIN THREAT. A DIGGING UPPER LEVEL TROUGH OVER THE NORTHEAST WILL HELP SUPPORT A LOW PRESSURE SYSTEM ALONG THE EAST COAST. LOW CONSENSUS IN MODEL SOLUTIONS WILL REQUIRE A BLEND OF DATA FOR THE TUESDAY FORECAST. WILL NEED TO CONTINUE WITH THE THREAT FOR SHOWERS TUESDAY AS THE TROUGH CROSSES THE REGION. TEMPERATURES TUESDAY ARE EXPECTED TO BE A BIT BELOW NORMAL. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... MODELS COMING INTO BETTER AGREEMENT THAT A LARGE TROUGH WILL SETUP OVER THE EASTERN CONUS DURING THE PERIOD. THIS WILL KEEP THE AREA COOL AND UNSETTLED INTO THE WEEKEND. && .AVIATION /13Z SUNDAY THROUGH THURSDAY/... THE PASSING SFC LOW IS VEERING WIND TO THE SW THIS MRNG AND PROVIDING IMPROVEMENT TO THE IFR CIGS FRM THE OVRNGHT. THIS TREND WILL CONTINUE THIS MRNG AS THE WARM SECTOR OF THE SYSTEMS ENGULFS THE REGION. HOWEVER...MORE SHOWERS AND POSSIBLE THUNDERSTORMS CAN BE EXPECTED AS THE AIRMASS DESTABILIZES VIA COOLING ALOFT/WARMING SFC. .OUTLOOK /MONDAY THROUGH THURSDAY/... RESTRICTIONS ARE EXPECTED THRU MON AS LOW PRESSURE COMPLETES PASSAGE OVER THE REGION. ANOTHER ROUND IS LIKELY WITH A WEDNESDAY COLD FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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