Area Forecast Discussion
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000 FXUS61 KPBZ 281944 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 344 PM EDT THU APR 28 2016 .SYNOPSIS... LOW PRESSURE WILL BRING RAIN TODAY INTO TOMORROW. MORE RAIN WILL ARRIVE LATE SATURDAY INTO SUNDAY. && .NEAR TERM /THROUGH FRIDAY/... RAIN SHOWERS WILL CONTINUE TO MOVE THROUGH THE NORTHERN 1/3 OF THE FORECAST AREA ALONG A MID-LEVEL FRONT WITH ISENTROPIC LIFT ACROSS. THIS HAS MET SOME RESISTANCE WITH DRY AIR NORTH OF I-80...BUT OBSERVATIONS REVEAL THAT THE LOWER COLUMN HAS SINCE SATURATED. SURFACE LOW PRESSURE APPROACHING FROM THE WEST WILL GENERATE ADDITIONAL SHOWERS AND PERHAPS A FEW THUNDERSTORMS...BUT COVERAGE SHOULD BE RELEGATED TO SOUTH OF I-70. FORCING WILL THEN BE WEAK OVERNIGHT...AS THE CENTER OF THE LOW MOVES OVER...SO RAIN CHANCES SHOULD BE LIMITED. DESPITE THIS...NOT EXPECTING A COMPLETELY DRY FORECAST AS A DEEP LAYER OF NEAR SURFACE MOISTURE WILL BE RESIDENT THROUGH EARLY FRIDAY. TEMPERATURES HAVE VARIED GREATLY FROM NORTH TO SOUTH AS LOCATIONS SOUTH OF I-70 HAVE PARTIAL CLEARING ALLOWING TEMPERATURES TO RISE INTO THE MID 60S ALREADY. FURTHER NORTH AND ALONG THE EAST COOL AIR IS POOLING UP AGAINST THE HIGHER ELEVATIONS AND WRAPPING NORTH OF I-80. TEMPERATURES HERE WILL HAVE TROUBLE GETTING OUT OF THE MID 40S. WHILE MUCH OF FRIDAY WILL REMAIN DRY...THE OPENING LOW PRESSURE SYSTEM WILL OPEN UP AND PASS ALONG OUR NORTH. THIS WILL BRING ADDITIONAL SCATTERED SHOWERS...PRIMARILY IN THE NORTHERN HALF OF THE FORECAST AREA. TAX && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
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A FEW SHOWERS MAY LINGER IN THE EAST FRIDAY EVENING AS THE LOW AND ITS ASSOCIATED MOISTURE/LIFT EXIT. HUNG ON TO AT LEAST SOME CLOUDS THROUGH THE NIGHT THOUGH...AS THERE IS SOME POTENTIAL FOR LOW LEVEL MOISTURE TO BECOME TRAPPED NEAR THE SURFACE...AND FOR MID/HIGH CLOUDS TO START INCREASING AGAIN TOWARDS MORNING. THE FASTER TREND IN BRINGING BACK PRECIPITATION ON SATURDAY CONTINUES AS ISENTROPIC LIFT BEGINS SPREADING IN FROM THE SOUTHWEST BY MIDDAY. CONTINUED THE POP INCREASE TREND OF THE PREVIOUS SHIFT AND HAVE LIKELY VALUES CLOSE TO PITTSBURGH BY 00Z SATURDAY. THEREAFTER...MODELS CONTINUE TO SHOW LOW PRESSURE MOVING INTO THE CWA BY SUNDAY. THERE ARE STILL DIFFERENCES REGARDING THE EXACT TRACK. HOWEVER...IN ANY CASE SOUTHWESTERLY FLOW WILL BE AIDED BY A SHORTWAVE DROPPING ACROSS THE GREAT LAKES SATURDAY NIGHT AND INTO THE OHIO VALLEY SUNDAY. THIS WILL RESULT IN A DECENT MOISTURE FEED AND PLENTY OF SUPPORT FOR LIFT...AND SO WILL CONTINUE WITH LIKELY/LOW CATEGORICAL POPS. THERE COULD BE A LULL IN ACTIVITY BETWEEN PASSAGE OF THE LOW AND THE APPROACH OF THE SHORTWAVE INFLUENCE...BUT TIMING THAT REMAINS TRICKY. TEMPERATURES WILL REMAIN FAIRLY SEASONABLE DURING THIS PERIOD...WITH SOME SLOW WARMING INTO SUNDAY IN SOUTHWEST FLOW. CL
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&& .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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KEPT LIKELY POPS GOING INTO SUNDAY NIGHT...BUT SHOWERS WILL BECOME MORE SCATTERED BY MONDAY AS H500 SHORTWAVE CROSSES REGION. A DRY PERIOD APPEARS LIKELY TUESDAY. THERE CONTINUES TO BE UNCERTAINTY WITH THE TIMING/DEPTH OF A DEVELOPING EASTERN TROUGH FROM WEDNESDAY ON...AS A DEVELOPING WESTERN RIDGE ELICITS A RESPONSE DOWNSTREAM. CHANCE POPS APPEAR WISE FOR WEDNESDAY AND THURSDAY AS THE POTENTIAL FOR SOME INSTABILITY-DRIVEN SHOWERS INCREASES...AND TOUGH-TO-TIME WAVES DROP IN FROM THE NORTHWEST. USED SUPERBLEND SUGGESTIONS AS A STARTING POINT AND TWEAKED FROM THERE. DID REDUCE SUPERBLEND TEMPERATURES A COUPLE OF DEGREES IN SOME CASES GIVEN THE DEVELOPING TROUGH PATTERN. CL
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&& .AVIATION /19Z THURSDAY THROUGH TUESDAY/... CONDITIONS WILL CONTINUE TO DETERIORATE ALONG THE NORTH AS LOW- LEVEL SATURATION CONTINUES. ONCE TERMINALS NORTH OF KPIT DROP BELOW 10KFT CIGS...THEY SHOULD REMAIN THERE THROUGH THE DURATION OF THE TAF PERIOD. SOME CLEARING SOUTH OF PITTSBURGH WILL ALLOW MVFR/VFR SCATTERING TO OCCUR...BUT THIS SHOULD BE TEMPORARY. HAVE THESE TERMINALS DROPPING TO IFR AGAIN TONIGHT AS THE LOW POSITIONS OVERHEAD. TERMINALS IN BETWEEN...KPIT/KBVI/KAGC...WILL CONTINUE TO BOUNCE AROUND THIS AFTERNOON...BUT ARE EXPECTED TO ALSO DROP TO IFR OR WORSE TONIGHT. LITTLE IMPROVEMENT WILL BE ACHIEVED THROUGH THE DAY FRIDAY. LIGHT NORTHEASTERLY SURFACE FLOW WILL DISSIPATE TO LIGHT AND VARIABLE TONIGHT WITH SURFACE LOW IN THE AREA. SURFACE WINDS WILL THEN REMAIN UNDER 10KTS FROM THE WEST-NORTHWEST AS THE LOW MOVES EAST. TAX .OUTLOOK /THURSDAY NIGHT THROUGH MONDAY/... RESTRICTIONS ARE LIKELY INTO FRIDAY...AND AGAIN SAT NIGHT/SUN...AS AREAS OF LOW PRESSURE CROSS THE REGION. BASED OFF TOP ANALOGS...IFR AND POSSIBLY SOME LIFR MAY BE POSSIBLE ON SUNDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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