Area Forecast Discussion
Issued by NWS

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000 FXUS61 KPBZ 111843 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 243 PM EDT FRI JUL 11 2014 .SYNOPSIS... HIGH PRESSURE WILL KEEP THE AREA DRY THROUGH MOST OF SATURDAY. THE NEXT COLD FRONT WILL ARRIVE LATE SUNDAY AND INTO EARLY MONDAY. && .NEAR TERM /THROUGH SATURDAY/...
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CURRENT SATELLITE IMAGERY SHOWS DIURNAL CU FIELD OVER THE ENTIRE CWA. NEAR TERM MODELS CONTINUE TO DEVELOP ISOLATED AFTERNOON SHOWERS ACROSS THE RIDGES IN RESPONSE TO A PASSING WEAK UPPER WAVE BARELY VISIBLE IN WV IMAGERY. THIS DOESNT SEEM UNREASONABLE...WILL CONTINUE TO CARRY ISOLATED SHOWERS THROUGH THE EVENING. OTHERWISE A DRY FORECAST THROUGH THE NIGHT AND INTO SATURDAY AS HIGH PRESSURE SLOWLY LOOSENS ITS GRIP. WITH ADDITIONAL MOISTURE POOLING IN THE RIDGES SATURDAY AFTERNOON...DIFFERENTIAL HEATING COULD AGAIN PRODUCE ISOLATED SHOWERS.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/... SURFACE HIGH WILL DRIFT EASTWARD TONIGHT AND SATURDAY. WITH THE AREA ON THE BACK SIDE OF THE HIGH AND RIDGING IN THE UPPER LEVELS...OVERALL FLOW WILL BECOME SOUTHWESTERLY. THIS WILL ALLOW FOR TEMPS TO WARM AND HUMIDITY LEVELS TO RISE. MODELS ARE NOW SHOWING A DIFFERENT STORY FOR THE TIMING AND STRENGTH OF A SHORTWAVE EXPECTED TO SWING THROUGH SATURDAY NIGHT. MODELS ARE WEAKENING THE WAVE OVER THE UPPER OHIO VALLEY AND FOCUSING ON A STRONGER WAVE OVER THE NORTHERN GREAT LAKES. THE WEAKENING OF THE SOUTHERN WAVE IS LIKELY DUE TO A STRONGER RIDGE THAT WILL BE IN PLACE OVER THE REGION ON SATURDAY. AS THIS WAVE FORCES IT WAY INTO THE RIDGE IT WASTES MUCH OF ITS ENERGY. THE STRONGER WAVE WILL BE WELL TO THE NORTH AND WILL MOVE EASTWARD IN THE ZONAL FLOW. THIS SCENARIO WILL SLOW THE ONSET OF POPS SAT NIGHT AND PUSH THE MORE LIKELY TIME FOR SHOWERS/STORMS INTO THE DAYTIME HOURS ON SUNDAY. UNTIL MODELS FIND A CONSISTENT SOLUTION FOR SAT NIGHT/SUNDAY... FORECAST WILL BE ON THE LOW CONFIDENCE SIDE. THE TIMING AND PLACEMENT OF THE WAVES WILL BE THE CRUCIAL ELEMENT FOR THE FORECAST FOR THE END OF THE WEEKEND. SUNDAY COULD BE A DAY TO KEEP AN EYE ON AS ATMOSPHERE DESTABILIZES AND DEEP MOISTURE INCREASES. HOWEVER...MORNING CLOUD COVER WILL BE IMPORTANT...POSSIBLY HOLDING TEMPS DOWN BELOW CONVECTIVE LEVELS. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... SHWR AND TSTM CHCS WL CONT AS A SERIES OF UPR LVL DISTURBANCES CROSSES THE RGN AHD OF A SLOW MOVG CDFNT. THE FNT WILL FINALLY CROSS THE AREA TUE. SFC HIGH PRES WL THEN BLD IN THRU THU UNDER A GT LKS UPR TROF WITH COOLER AND DRIER CONDS. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
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VFR CONDITIONS EXPECTED TO PREVAIL WITH DIURNAL CU FIELD BASED AT NEAR 5KFT. SFC FLOW WILL REMAIN LIGHT AND VARIABLE. .OUTLOOK.../SATURDAY THROUGH WEDNESDAY/... LOCAL RESTRICTIONS DUE TO SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE SUNDAY THROUGH TUESDAY...FOLLOWED BY A PERIOD OF VFR CONDITIONS.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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