Area Forecast Discussion
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000 FXUS61 KPBZ 020814 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 414 AM EDT TUE SEP 2 2014 .SYNOPSIS... A COLD FRONT WILL BRING WIDESPREAD SHOWERS AND STORMS TODAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A WEAK BOUNDARY WILL CROSS THE REGION THIS AFTERNOON. LOOKING AT CURRENT DATA...MORE CONCERNED WITH THE POTENTIAL FOR HEAVY RAIN THEN SEVERE. ATMOSPHERIC INSTABILITY DOES NOT STAND OUT WITH SB CAPES GENERALLY LESS THEN 1000J/KG AND LIFTED INDEXES AROUND -1. ADDITIONALLY...MID CLOUDS WILL RAPIDLY INCREASE AHEAD OF FRONTAL PASSAGE. MODELS ARE SHOWING A PRETTY DESCENT SHORTWAVE TROUGH RIDING ALONG THE BOUNDARY...BUT IT WEAKENS AND GETS SHEARED APART AS IT REACHES THE AREA. CANNOT TOTALLY RULE OUT ISOLATED STRONG/SEVERE STORMS AS A LINE OF STRONG LOW LEVEL FORCING WILL DEVELOP WITH FROPA AND 0-6KM BULK SHEAR VALUES WILL RISE TO NEAR 50KTS. MY GREATER CONCERN WILL BE THE THREAT FOR HEAVY DOWNPOURS. MOISTURE CONVERGENCE IN THE LOWER LEVELS STRENGTHENS EARLY THIS AFTERNOON AND PWATS RISE TO ALMOST 2 INCHES. SURFACE DEWPOINTS WILL STILL BE AROUND 70...WHICH WILL BE CLOSE TO A TROPICAL REGIME IN WHICH THE RAIN DROPS WILL BE CREATED. FRONT DOES GET TRUCKING ALONG ONCE THE TROUGH SWINGS THROUGH...WHICH WILL HELP TO LIMIT THE AMOUNT OF TIME HEAVIER RAIN CAN FALL OVER THE SAME AREAS. WILL CONTINUE WITH HIGH POPS WITH FROPA AND THE MENTION OF HEAVY DOWNPOURS. TEMPS WILL BE A BIT TRICKY WITH PRE-FRONTAL CLOUDS AND SHOWERS... SO HAVE LOWERED TEMPS JUST A BIT FROM PREVIOUS FORECAST. EXPECT ANOTHER VERY HUMID DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... FRONT QUICKLY EXITS THIS EVENING AS SHORTWAVE TROUGH SWINGS THROUGH. IT WILL TAKE MOST OF THE NIGHT...BUT LOWER SURFACE DEWPOINTS WILL EVENTUALLY SINK SOUTHWARD. AT THIS POINT...NOT QUITE SURE SHOW LONG THE LESS HUMID AIRMASS CAN REMAIN IN PLACE. WITH THE SURFACE HIGH DRIFTING EASTWARD...THE LOW LEVEL FLOW WILL BECOME SOUTHERLY ONCE AGAIN ON THURSDAY. BECAUSE OF THIS...SEE WEDNESDAY AS BEING COMFORTABLE...BUT THE HUMIDITY CREEPS BACK IN ON THURSDAY. SURFACE HIGH AND WEAK RIDGING ALOFT SHOULD PROVIDE ENOUGH SUBSIDENCE TO KEEP THE AREA ACTIVITY FREE WEDNESDAY AND THURSDAY. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... LATEST MODEL DATA IS SPEEDING UP THE CROSSING OF THE NEXT REAL COLD FRONT. WILL SPEED UP THE ENTRANCE OF POPS FRIDAY AFTERNOON. FRONT WILL TAKE ITS TIME CROSSING THE REGION...MEANING SHOWER AND STORM CHANCES WILL BE PUSHED INTO SATURDAY. MUCH COOLER AND DRIER AIR FOR THE END OF THE LONG TERM WITH BROAD SURFACE HIGH BUILDING IN FROM THE NORTHWEST. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... SUFFICIENT SFC WIND AND MID LVL CLDS ARE EXPECTED TO PRECLUDE SERIOUS RESTRICTIONS EARLY THIS MRNG...ALTHOUGH SCT SHWRS MAY DEGRADE CONDITIONS ESPECIALLY AT PORTS N OF PIT. SHWRS AND TSTMS WL BECOME MORE NMRS AFTR DAYBREAK AS A WEAK CDFNT ENCROACHES ON THE UPR OH REGION. EXPECT IFR VSBY IN THE STRONGER CELLS. OUTLOOK.../TONIGHT THROUGH SATURDAY/... RESTRICTIONS IN FOG AND ST ARE POSSIBLE WEDNESDAY MORNING. MORE RESTRICTIONS ARE POSSIBLE WITH A LATE WEEK CDFNT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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