Area Forecast Discussion
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000 FXUS61 KPBZ 191348 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 948 AM EDT SUN APR 19 2015 .SYNOPSIS... A DRY BEGINNING TO THE DAY...BUT SHOWERS WILL OVERSPREAD THE REGION THIS AFTERNOON AND CONTINUE THROUGH MONDAY. UNSEASONABLY COOL TEMPERATURES ARE EXPECTED FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... A FEW THUNDERSTORMS DEVELOPED JUST AFTER SUNRISE IN EASTERN OHIO AND HAVE SINCE MOVED OFF INTO NORTHERN OHIO. NOT MUCH FURTHER DEVELOPMENT OF THESE SHOWERS/THUNDERSTORMS IS EXPECTED SO FAR AHEAD OF THE WARM FRONT POISED TO BRING RAIN SHOWERS TO THE AREA LATER TODAY. A LOOK AT THE 12Z UPPER AIR SOUNDING REVEALS TWO SUBSTANTIAL LAYERS OF DRY AIR...ONE NEAR THE SURFACE AND ANOTHER FROM 700MB-500MB. THIS HAS RESULTED IN A MOSTLY SUNNY MORNING FOR MUCH OF THE AREA...ALLOWING FOR TEMPERATURES TO RISE RAPIDLY AFTER MIXING BEGAN. STRONGER WINDS JUST OFF THE SURFACE HAVE MIXED DOWN RESULTING IN SOME EARLY GUSTS CLOSE TO 20KTS. THESE GUSTS ARE EXPECTED TO CONTINUE THROUGH THE DAY AS THE PRESSURE GRADIENT TIGHTENS WITH THE SYSTEM DRAWING NEAR. DAYTIME HIGHS WILL BE DEPENDENT UPON ARRIVAL OF CLOUDS AND PRECIPITATION AND THE WARMING/COOLING TREND WILL SHIFT FROM SOUTH TO NORTH AS A RESULT. TRIED TO CONVEY THIS HOURLY TEMPERATURE TRANSITION IN THE FORECAST AS MUCH AS POSSIBLE. TIMING OF THE PRECIPITATION LOOKS TO BE ON TRACK WITH EARLIER FORECASTS...WITH THE RAIN REACHING OUR SOUTHERN ZONES BY MIDDAY...PITTSBURGH BY LATE AFTERNOON. KEPT THE CATEGORICAL POPS IN FOR THIS EVENING/EARLY TONIGHT...DESPITE THE LATEST HI-RES GUIDANCE SHOWING CONSIDERABLE MOISTURE EROSION UPON ARRIVAL. THIS MAKES SOME SENSE GIVEN THE AMOUNT OF DRY AIR SAMPLED BY THE MORNING SOUNDING. WILL WAIT FOR THE REST OF THE 12Z GUIDANCE BEFORE MAKING ANY MAJOR UPDATES TO THE FORECAST. TAX && .SHORT TERM /MONDAY THROUGH TUESDAY/... SHOWER COVERAGE WILL DECREASE OVERNIGHT AS UPPER LEVEL SUPPORT SHIFTS TO THE EAST AND A LARGE UPPER LEVEL DRY SLOT OVERSPREADS THE AREA. THE RESULTING SUBSIDENCE IS EXPECTED TO CONTINUE THROUGH MONDAY MORNING...AND MAY PROMOTE MODEST HEATING OF A RELATIVELY-MOIST BOUNDARY LAYER WITH 45-50KT OF SOUTHWEST FLOW ALOFT. A SECOND SHORTWAVE TROUGH IS PROJECTED TO MOVE QUICKLY NORTHEASTWARD AND CROSS THE REGION BY LATE DAY. LIFT IN ASSOCIATION WITH THAT DISTURBANCE WOULD AID CONVECTIVE DEVELOPMENT DURING THE AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED WITH THIS SCENARIO. WIDESPREAD SEVERE THUNDERSTORMS ARE NOT EXPECTED OWING TO PROGNOSIS OF WEAK MID LEVEL LAPSE RATES. UNUSUALLY STRONG UPPER LOW PRESSURE IS FORECAST TO BUILD SEWD INTO THE GREAT LAKES REGION BY TUESDAY...WITH ITS ASSOCIATED COLD FRONT TO CROSS THE FORECAST AREA DURING THE MORNING. COLD ADVECTION BEHIND THE FRONTAL PASSAGE IS PROGGED TO PROVIDE INCREASED COVERAGE OF STRATOCU AND POSSIBLE LAKE ENHANCEMENT TO LIGHT PRECIPITATION...WITH THAT LIMITED TO THE NORTHERN ZONES WITH EXPECTATIONS OF WESTERLY FETCH AND DRY ADVECTION. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... BROAD UPPER TROUGHING WILL REMAIN OVER THE EASTERN CONUS THROUGH THE EXTENDED AND RESULT IN BELOW NORMAL TEMPERATURES EACH DAY ALONG WITH CLOUDY SKIES AND SLIGHT CHANCES FOR PRECIPITATION THROUGHOUT THE PERIOD AS SHORTWAVES TRANSITION THROUGH THE FLOW AND CAA ALOFT PERSISTS. CONFIDENCE IS HIGH IN THE GENERAL FORECAST AS MODELS HAVE BEEN FAIRLY CONSISTENT IN PROGGING THIS LONGWAVE PATTERN...REFLECTED IN LATEST RMOP AND MODTRENDS GUIDANCE. HOWEVER...CONFIDENCE IN TIMING OF ANY MORE SIGNIFICANT PERIODS OF PRECIPITATION IS RELATIVELY LOW. FORECAST MAX/MIN TEMPERATURES ARE NOT EXCEPTIONALLY COLD...BUT PERSISTENT AROUND 10 DEGREES BELOW NORMALS AS ENSEMBLE ANOMALIES ARE SHOWING TEMPS AND HEIGHTS ALOFT ONLY RANGING FROM 1-2 STANDARD DEVIATIONS BELOW NORMAL THROUGH THE PERIOD. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... NO RESTRICTIONS ARE ANTICIPATED UNTIL RAIN SHOWERS ASSOCIATED WITH THE WARM FRONT DEVELOP LATE THIS AFTERNOON. EXPECTING RAIN TO FALL OUT OF MOSTLY VFR CIGS...BUT HEADING INTO THE OVERNIGHT THE CIGS SHOULD CONTINUE THIER DESCENT TO MVFR. GUSTY EAST- SOUTHEASTERLY FLOW WILL CONTINUE THROUGH THE DAY AND OVERNIGHT...GRADUALLY RELAXING THROUGH THE EARLY MORNING MONDAY. TAX .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... PERIODIC RESTRICTIONS ARE EXPECTED THROUGH MONDAY NIGHT AS LOW PRESSURE CROSSES THE REGION. RESTRICTIONS ARE POSSIBLE WITH A MID WEEK UPPER TROUGH. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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