Area Forecast Discussion
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000 FXUS61 KPBZ 021312 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 912 AM EDT TUE SEP 2 2014 .SYNOPSIS... A COLD FRONT WILL BRING WIDESPREAD SHOWERS AND STORMS TODAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 9 AM UPDATE...UPDATED MAINLY FOR RADAR TRENDS. STILL LOOKING AT A LOW-END SLIGHT RISK. 12Z SOUNDING SHOWS A STOUT CAP BETWEEN H800 AND H700...AND INCOMING CLOUD COVER WILL HINDER DESTABILIZATION AS WELL. STILL MAY HAVE TO WATCH RAIN AMOUNTS PARTICULARLY IN AREAS WITH LOW FFG. PREVIOUS... A WEAK FRONT 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 /13Z TUESDAY THROUGH SATURDAY/... CONDITION DETERIORATION CAN BE EXPECTED THIS MRNG AS SHWRS AND TSTMS BECOME MORE WIDESPREAD AS A WEAK CDFNT ENCROACHES ON THE UPR OH REGION. EXPECT WIDESPREAD MVFR WITH IFR VSBY IN THE STRONGER CELLS. OUTLOOK.../TONIGHT THROUGH SATURDAY/... RESTRICTIONS IN FOG AND LCL 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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