Area Forecast Discussion
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000 FXUS61 KPBZ 031748 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 148 PM EDT FRI JUL 3 2015 .SYNOPSIS... A CROSSING UPPER DISTURBANCE WILL INCREASE RAIN CHANCES FOR THE START OF THE HOLIDAY WEEKEND. WARMER WEATHER CAN BE EXPECTED FOR THE START OF THE NEW WEEK. && .NEAR TERM /THROUGH SATURDAY/...
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HIGH CLOUDS TOOK THEIR SWEET TIME ARRIVING...AND JUST A FEW CUMULUS ARE MANAGING TO POP UP UNDER THE TRANSLUCENT HIGH CLOUD DECK. TEMPERATURES DID MANAGE TO WANDER UPWARD FAIRLY STRONGLY THROUGH THE LATE MORNING AND EARLY AFTERNOON HOURS...HOWEVER THEIR TRAJECTORY HAS LIKELY REACHED ITS LID WITH INCREASING CLOUD COVER. UPPER DIFFLUENCE IS SET TO INCREASE THROUGH AFTERNOON AND EVENING AS A WEAK SHORT WAVE AND CLOSED 850 MB CIRCULATION TRACK TOWARD THE UPPER OHIO VALLEY AHEAD OF THE UPPER WAVE. THIS WILL ALLOW FOR SHOWER ACTIVITY TO INCREASE FROM SOUTH TO NORTH GOING INTO THE LATE AFTERNOON HOURS. INSTABILITY IS FAR FROM IMPRESSIVE...AND GIVEN MODEL SOUNDINGS REALLY ONLY PROJECTING POSITIVE AREA MAINTAINING ITSELF ABOVE THE FREEZING LEVEL IN THE SOUTHEASTERNMOST PORTIONS OF THE CWA...THUNDERSTORM CHANCES WERE RELEGATED GENERALLY TO THE RIDGES AND POINTS NEARBY. HOWEVER...GIVEN DECENT LIFT AND FAIRLY HEFTY LAYER RH VALUES...CHANCES OF RAIN WERE INCREASED TO CATEGORICAL ACROSS THE SOUTHEASTERN QUARTER OF THE CWA FROM LATE THIS AFTERNOON INTO THIS EVENING. THE AFOREMENTIONED UPPER WAVE IS SLOW TO MOVE EASTWARD GOING INTO THE OVERNIGHT HOURS. THIS SHOULD ALLOW FOR SOUTHERLY FLOW TO DOMINATE THE SCENE. WITH JET CURVATURE INCREASING THROUGH THE NIGHT AND THE RIGHT ENTRANCE REGION REMAINING IN THE REGION...SHOWER CHANCES WILL REMAIN QUITE HIGH...PARTICULARLY ACROSS THE EASTERN HALF OF THE CWA. HOWEVER...BY SATURDAY...THE JET AXIS STARTS TO SLINK EASTWARD...RESULTING IN AN IMPROVEMENT OF CONDITIONS FROM WEST TO EAST DURING THE DAY. FRIES
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&& .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... SCATTERED/CHANCE POP NUMBERS WERE MAINTAINED THROUGH SATURDAY AS MODELS PERSIST IN LINGERING THE UPPER TROUGH OVER THE REGION...ALBEIT WITH DRY ADVECTION IN THE MID AND UPPER LEVELS. DESPITE THE TROUGHING...MID LEVEL TEMPS IN THIS SCENARIO ARE WARM...HENCE THE LIMITED POPS AND ONLY A SLIGHT CHANCE OF THUNDER DUE TO INHIBITED INSTABILITY. BY SUNDAY...THE SURFACE REFLECTION PROGNOSIS IS SUFFICIENTLY SOUTH THAT RAIN CHANCES HAVE BEEN OMITTED WITH BUILDING HIGH PRESSURE. WARMER TEMPS WILL THEN BE THE FOCUS AS HEIGHTS RISE DRAMATICALLY FOR THE START OF THE NEW WEEK. FOR NOW...HAVE PERSISTED WITH AVERAGE READINGS FOR SUNDAY...AND A COUPLE DEGREES ABOVE FOR MONDAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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THE UPPER FLOW IS PROGGED TO FLATTEN THROUGH MUCH OF THE PERIOD. INDIVIDUAL SHORTWAVES IN THE FLOW ARE EXPECTED TO BRING PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS. USED AN ENSEMBLE BASED WPC GUIDANCE TO SMOOTH OUT DIFFERENCES IN INDIVIDUAL MODELS...WITH DOWNWARD ADJUSTMENTS TO WPC POPS. SEASONALLY WARM TEMPERATURES ARE EXPECTED.
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&& .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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VFR CONDITIONS SHOULD LARGELY CONTINUE AS SHOWERS SLOWLY ADVANCE NORTHWARD AND CLOUD HEIGHTS LOWER THROUGH THE AFTERNOON. AFTER SUNSET...CIGS WILL RAPIDLY DETERIORATE AS THE BOUNDARY LAYER SATURATES...ALLOWING FOR FAIRLY WIDESPREAD IFR CONDITIONS OVERNIGHT...DEPENDING UPON EVENTUAL RAIN COVERAGE. CONDITIONS WILL IMPROVE ON SATURDAY FROM WEST TO EAST RATHER RAPIDLY NEAR THE END OF THE TAF VALID TIME. FRIES .OUTLOOK.../SATURDAY THROUGH TUESDAY/... CONDITIONS SHOULD RAPIDLY IMPROVE ON SATURDAY. THE NEXT CHANCE OF RESTRICTIONS WILL COME WITH A FRONTAL SYSTEM ON TUESDAY OR TUESDAY NIGHT.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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