Area Forecast Discussion
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000 FXUS61 KPBZ 021824 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 224 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 NIGHT/... KEEPING FOCUS OF HIGHER PRECIPITATION PROBABILITIES ALONG THE SOUTHEASTERN FLANK OF THE FORECAST AREA...WHICH GENERALLY FAVORS THE NAM/ECMWF TRACK OF THE LOW. THE MID-ATLANTIC SURFACE LOW TAKES OVER SATURDAY MORNING...BUT THE 300MB JET CORRIDOR REMAINS OVERHEAD ALONG WITH THE UPPER-LEVEL TROF AXIS. THIS WILL KEEP RAIN SHOWERS POSSIBLE THROUGH THE EARLY INDEPENDENCE DAY MORNING...BUT WILL BE DIURANALLY LESS FAVORABLE. THE MOIST AIR MASS DOESNT COMPLETELY EVACUATE THE AREA BY SATURDAY AFTERNOON...SO RE-DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS IS POSSIBLE. THE MAIN FOCUS OF THE SYSTEM WILL BE WELL TO THE EAST AT THAT POINT...SO COVERAGE AND INTENSITY OF ANY RAIN WILL BE LIMITED. MUCH DRIER AIR INVADES FOR SUNDAY...KEEPING ANY REMAINING DIURNALLY DRIVEN SHOWERS/THUNDERSTORMS LIMITED TO OUR FAR SOUTHEASTERN ZONES. TEMPERATURES WILL REMAIN NEAR AVERAGE THROUGH THE HOLIDAY WEEKEND...SLOWLY WARMING TOWARDS EARLY NEXT WEEK. TAX && .LONG TERM /MONDAY 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 /18Z THURSDAY THROUGH TUESDAY/... 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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