Area Forecast Discussion
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000 FXUS61 KPBZ 031458 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 1058 AM 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/... MID AND UPPER CLOUDS ARE RATHER SLOW TO OVERSPREAD THIS REGION LATE THIS MORNING...RESULTING IN SOME DECENT TEMPERATURE INCREASES. HOWEVER...THEY ARE LURKING IN A QUITE PERVASIVE WAY JUST TO THE SOUTHWEST OF THE AREA...AND GIVEN THE TRAJECTORY OF THE UPPER FLOW...THEY WILL ENVELOPE THE AREA WITHIN THE NEXT FEW HOURS. UPPER DIFFLUENCE IS SET TO INCREASE THROUGH THE DAY 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 AFTERNOON. 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 && .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 THURSDAY/... 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. SEAONALLY WARM TEMPERATURES ARE EXPECTED. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE MORNING. A SHORTWAVE IS PROGGED TO BRING INCREASING SHOWER CHANCES THIS AFTERNOON AND EVENING...WITH EVENTUAL CONDITION DETERIORATION SOUTH OF I 80 TO AT LEAST MVFR SPREADING IN FROM THE SOUTHWEST WITH IFR CONDITIONS LIKELY OVERNIGHT. .OUTLOOK.../SATURDAY THROUGH TUESDAY/... RESTRICTION ARE POSSIBLE THROUGH EARLY SATURDAY WITH AN EXITING SHORTWAVE. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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