Area Forecast Discussion
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000 FXUS61 KPBZ 021634 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 1234 PM EDT THU JUL 2 2015 .SYNOPSIS... A CROSSING UPPER DISTURBANCE WILL INCREASE RAIN CHANCES FOR THE START OF THE HOLIDAY WEEKEND. && .NEAR TERM /THROUGH FRIDAY/... MID AND HIGH CLOUD COVER REMAINS FAIRLY PERVASIVE AWAY FROM I-80 INTO THE EARLY AFTERNOON HOURS...EVEN AS DIURNAL CUMULUS DEVELOPS IN AREAS THAT HAD SEEN BREAKS PREVIOUSLY. THIS SHOULD KEEP THE SKIES RATHER CLOUDY GOING INTO THE AFTERNOON...WHICH WILL ALSO KEEP A LID ON TEMPERATURE RISES THROUGH THE DAY. RAIN SHOWERS SHOULD GENERALLY BE RELEGATED TO THE AREAS CLOSER TO THE HIGHER DEWPOINTS ACROSS THE SOUTHERN TIER OF THE CWA UNTIL A SURFACE LOW IS SET TO RIDE UP THE QUASI-STATIONARY BOUNDARY CURRENTLY ACROSS WEST VIRGINIA. THIS WILL ALLOW FOR A BIT OF NORTHWARD MIGRATION OF THE FRONT GOING INTO FRIDAY...HOWEVER THE MODELS ARE HAVING A TOUGH TIME PINNING DOWN EXACTLY HOW FAR NORTHWARD THAT WILL BE. THE GFS SEEMS TO BE A NORTHERN OUTLYING SOLUTION...WITH THE ECMWF AND ESPECIALLY NAM/CANADIAN A BIT MORE SUPPRESSED WITH IT. GIVEN THE AXIS OF THE UPPER JET STREAK ON THE GFS...IT TOO SEEMS THAT WHILE IT SPREADS QPF FARTHER INTO THE AREA...THAT IT REALLY FAVORS MOSTLY THE SOUTHEASTERN HALF OF THE CWA. THIS IS BASED PURELY ON WHERE THE UPPER DIVERGENCE IN THE RIGHT ENTRANCE OF THE WEAK JET STREAK TRACKS. WITH THAT IN MIND...THE POPS WERE FOCUSED PRIMARILY ON AREAS EAST AND SOUTH OF PITTSBURGH FOR THE AFTERNOON. INSTABILITY PARAMETERS REALLY A FAIRLY MEAGER ON FRIDAY. SHEAR IS WEAK...INSTABILITY IS PRETTY PALTRY AS WELL...HOWEVER THE NAM DOES MANAGE TO GENERATE A FEW HUNDRED J/KG...SO JUST SLIGHT CHANCES FOR THUNDER WERE CARRIED PRIMARILY OVER THE RIDGES AND AROUND MORGANTOWN. ABUNDANT CLOUDS WILL KEEP TEMPERATURES IN A FAIRLY TIGHT WINDOW OVER THE NEXT DAY OR SO...WIDESPREAD 60S AT NIGHT...AND 70S DURING THE DAY. THIS LOOKS JUST A TAD BELOW NORMAL FOR EARLY JULY. FRIES && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... MODELS HAVE BEEN CONSISTENT IN ADVANCING ANOTHER WEAK SHORTWAVE ACROSS THE FRONTAL ZONE ON FRIDAY...WITH GFS AND SREFS AGAIN PROGGING MORE EXTENSIVE PRECIP PROBABILITIES ALTHOUGH NAM AGAIN PROJECTS LIKELY NUMBERS OVER THE WV RIDGES. ANY PRECIP WOULD DIMINISH WITH SLOW EASTWARD PROGRESS OF THE SUPPORTING DISTURBANCE ON FRIDAY NIGHT AND POPS HAVE BEEN THUS CONSTRUCTED. LOW...DIURNALLY SUPPORTED POPS ARE APPROPRIATE FOR SATURDAY WITH YET ANOTHER SHORTWAVE GFS/NAM PROGGED ACROSS THE AREA WHILE ALL BUT SOUTHEASTERN COUNTIES SHOULD BE DRY ON SUNDAY WITH BUILDING HIGH PRESSURE. TEMPERATURES UNDER THIS PATTERN ARE LIKELY TO REMAIN JUST UNDER THE SEASONAL AVERAGES...ALTHOUGH FURTHER RECOVERY IS POSSIBLE ON SUNDAY SHOULD HEIGHTS RISE AS PROJECTED. EITHER WAY...FEW CHANGES WERE NEEDED FOR SHORT TERM TEMPS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... COMPARED TO 24 HOURS AGO...MODELS ARE IN MUCH BETTER AGREEMENT WITH THE BROAD SCALE FEATURES OF THE EXTENDED FORECAST. STILL CANNOT RULE OUT THE POSSIBILITY THAT THE SEEMINGLY-PERMANENT FRONTAL BOUNDARY WILL LINGER NEAR SOUTHERN COUNTIES FOR ONE MORE DAY AND ALLOW FOR ISOLATED/SCATTERED SHOWERS ON MONDAY. OTHERWISE THE REGION SHOULD BE DRY. THE PROGGED COLD FRONT THAT PREVIOUSLY HAD WIDELY VARYING PROJECTED TIMES FOR PASSAGE NOW HAS SOME AGREEMENT FROM DETERMINISTIC AS WELL AS ENSEMBLE MODELS OF A TUESDAY NIGHT AND WEDNESDAY PASSAGE. HAVE CHANGED THE FORECAST ACCORDINGLY. WITH THE COLD FRONT TO THE WEST MONDAY AND TUESDAY...THIS SHOULD ALLOW FOR MORE SUNSHINE AND HAVE ALSO BUMPED UP HIGH TEMPERATURES THOSE TWO DAYS. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... A SURFACE FRONT TO OUR SOUTH WILL SLOWLY WANDER NORTHWARD OVERNIGHT...ALLOWING FOR CLOUDS TO STICK AROUND OVER MOST SITES. GENERALLY VFR CONDITIONS WILL PREVAIL HOWEVER...WHICH SHOULD KEEP OVERNIGHT FOG FROM GETTING TOO OUT OF HAND TONIGHT. HOWEVER...AS THE FRONT RIDES NORTHWARD ON FRIDAY...A FEW SHOWERS WILL BE POSSIBLE AROUND KMGW BY AFTERNOON. FRIES .OUTLOOK.../FRIDAY THROUGH MONDAY/... AFTERNOON SHOWERS/STORMS SATURDAY COULD PROVIDE ADDITIONAL RESTRICTIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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