Area Forecast Discussion
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000 FXUS61 KPBZ 181914 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 314 PM EDT SAT APR 18 2015 .SYNOPSIS...
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DRY AND WARM CONDITIONS WILL GIVE WAY TO INCREASING RAIN CHANCES ON SUNDAY AND MONDAY. UNSEASONABLY COOL TEMPERATURES ARE EXPECTED FOR THE REMAINDER OF THE WEEK.
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&& .NEAR TERM /THROUGH SUNDAY NIGHT/...
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SKIES ARE MOSTLY CLEAR UNDER HIGH PRESSURE. ABUNDANT SUNSHINE THIS AFTERNOON WILL GIVE WAY TO A PLEASANT EVENING AND THE ADDITION OF A FEW MORE HIGH CLOUDS. TEMPERATURES TONIGHT WILL REMAIN ABOVE AVERAGE AS LOW- TO MID-LEVEL FLOW BEGINS TO VEER TO THE SOUTHEAST. SUNDAY WILL BEGIN DRY WITH CLOUDS INCREASING QUICKLY FROM THE SOUTH. CLOUD COVER WILL HELP KEEP TEMPERATURES IN CHECK COMPARED TO SATURDAYS MARKS...BUT ARE EXPECTED TO BE AVERAGE. A LOW PRESSURE SYSTEM CURRENTLY COMING TOGETHER OVER THE LOWER MISSISSIPPI VALLEY WILL MOVE NORTH THROUGH THE DAY ON SUNDAY... SPREADING CLOUDS AND THEN RAIN SHOWERS SOUTH TO NORTH THROUGH THE FORECAST AREA. RAIN IS EXPECTED TO BEGIN IN THE EARLY AFTERNOON ALONG OUR SOUTHERN ZONES...REACHING PITTSBURGH BY LATE AFTERNOON. AT THIS TIME...THE HEAVIEST PRECIPITATION IS EXPECTED TO FALL ALONG THE EASTERN SLOPES OF THE HIGH TERRAIN WITHIN THE UPSLOPE FLOW...AND THROUGH OHIO...CLOSER TO THE TRACK OF THE LOW AND THE STRONGER LOW-LEVEL JET. A RELATIVE MINIMUM IN PRECIPITATION IS EXPECTED JUST WEST OF THE RIDGES AS DOWNSLOPING EAST-SOUTHEASTERLY FLOW WILL WORK TO COUNTERACT SOME OF THE ASCENT ALONG THE WARM FRONT. STILL...ENOUGH MOISTURE AND LIFT EXISTS WITH THE WARM FRONT THAT EVERYONE IS EXPECTED TO GET PRECIPITATION THROUGH SUNDAY NIGHT. A LARGE UPPER-LEVEL DRY SLOT WILL MOVE IN WITH THE WARMER AIR SUNDAY NIGHT...REDUCING SHOWER CHANCES AND COVERAGE. TAX
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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SUBSIDENCE IS EXPECTED ON MONDAY MORNING IN THE WAKE OF A DEPARTING SHORTWAVE TROUGH...WHICH WILL AID IN ERODING ANY LINGERING PRECIPITATION FROM LATE SUNDAY NIGHT. THIS SUBSIDENCE WILL PROMOTE THE MODEST HEATING OF A RELATIVELY-MOIST AIRMASS ON MONDAY BENEATH 45-50KT OF 500MB SWLY FLOW. A SECOND SHORTWAVE TROUGH WILL MOVE QUICKLY NEWD THROUGH THE FLOW AND WILL CROSS THE REGION BY LATE MONDAY AFTERNOON. LIFT IN ASSOCIATION WITH THIS WAVE WILL AID IN CONVECTIVE DEVELOPMENT BY MID-AFTERNOON MONDAY. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ON THE HIGHER TERRAIN FIRST AND ALONG THE SURFACE TROUGH ASSOCIATED WITH THE UPPER WAVE LATER IN THE AFTERNOON. ALTHOUGH TEMPERATURES WILL REACH THE LOWER 70S...LOW-LEVEL LAPSE RATES WILL BE QUITE STEEP...SUPPORTING A THREAT OF GUSTY WINDS FROM ANY VIGOROUS AND DEEP CONVECTION. WIDESPREAD SEVERE THUNDERSTORMS ARE NOT EXPECTED OWING TO WEAKER MID-LEVEL LAPSE RATES. UNUSUALLY STRONG UPPER LOW PRESSURE WILL BUILD SEWD INTO THE GREAT LAKES REGION BY TUESDAY...WITH ITS ASSOCIATED COLD FRONT EXPECTED TO CROSS THE FORECAST AREA DURING TUESDAY MORNING. THIS LOW WILL PERSIST THROUGH MUCH OF THE WEEK. COLD ADVECTION BEHIND THE FRONTAL PASSAGE WILL PROVIDE INCREASED COVERAGE OF STRATOCU AND POSSIBLE LAKE ENHANCEMENT TO LIGHT PRECIPITATION...BUT ANY PRECIPITATION LIKELY WILL BE LIMITED ONLY TO THE NORTHERN ZONES OWING TO WESTERLY FETCH AND ADVECTION OF VERY DRY AIR IN THE POST-FRONTAL AIRMASS. MAXIMA ON TUESDAY WILL REACH ONLY THE MID-50S AT BEST. KRAMAR
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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UNSETTLED WEATHER IS EXPECTED TO CONTINUE THROUGH NEXT WEEK WITH A BROAD UPPER TROUGH INFLUENCING MUCH OF THE EASTERN US. CONFIDENCE IS LOW WITH DIFFERING MODEL SOLUTIONS LATER IN THE WEEK...AND POPS WERE KEPT LOW. TEMPERATURES WERE FORECAST USING WPC GUIDANCE...WHICH WERE AT...OR SLIGHTLY BELOW THE SEASONAL AVERAGES.
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&& .AVIATION /19Z SATURDAY THROUGH THURSDAY/...
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VFR CONDITIONS EXPECTED THE REMAINDER OF THE DAY UNDER HIGH PRESSURE. A SYSTEM APPROACHING FROM NEAR THE GULF OF MEXICO WILL SPREAD CLOUDS AND STRONGER SUFACE FLOW THROUGH THE FORECAST AREA SUNDAY. CLOUDS WILL GRADUALLY TRANSITION FROM AN UPPER- TO MID- LEVEL DECK BEFORE THE LOW CEILINGS AND RAIN COME IN RIGHT AT THE END OF THE CURRENT TAF PERIOD. TAX .OUTLOOK.../SATURDAY NIGHT THROUGH WEDNESDAY/... RESTRICTIONS ARE LIKELY LATER SUNDAY AND MONDAY AS LOW PRESSURE DEVELOPS TOWARD THE GREAT LAKES AND PULLS A COLD FRONT ACROSS THE REGION.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ TAX/KRAMAR

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