Area Forecast Discussion
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000 FXUS61 KPBZ 120505 AAC AFDPBZ AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PITTSBURGH PA 105 AM EDT SAT JUL 12 2014 .SYNOPSIS... AN APPROACHING COLD FRONT WILL BRING SHOWERS AND THUNDERSTORMS TO THE AREA BEGINNING SUNDAY AND CONTINUING INTO TUESDAY. && .NEAR TERM /THROUGH TODAY/... A WEAK SHORTWAVE WILL PROVIDE CIRRUS CLOUDS OVERNIGHT. AN AREA OF SCATTERED TO BROKEN MID-DECK WILL OVERSPREAD REGION TODAY. AS THE CLOUDS MOVE IN...HIGH PRESSURE AT THE SURFACE WILL DRIFT EASTWARD. THE OVERALL FLOW WILL BECOME SOUTHWESTERLY WHICH WILL PROMOTE A SLOW INCREASE IN HUMIDITY LEVELS. HIGH TEMPS MAY BE DAMPENED JUST A BIT WITH THE INCREASE IN CLOUD COVER. && .SHORT TERM /TONIGHT THROUGH MONDAY/... MODELS ARE CONTINUING A SLOWING TREND WITH THE NEXT SYSTEM. FIRST CONCERN TONIGHT WILL BE THE PASSAGE OF A WEAKENING SHORTWAVE TROUGH. STILL SOME MODEL DISAGREEMENT ON HOW MUCH AFFECT THIS UPPER LEVEL ENERGY WILL HAVE AS IT CROSSES LATE TONIGHT. EXPECT MOST OF THE ACTIVITY TO BE WELL TO OUR NORTH AND WEST CONCENTRATED ALONG A FRONTAL BOUNDARY OVER THE UPPER MIDWEST. ATMOSPHERE REMAINS STABLE TONIGHT WITH THE CONCENTRATION OF BUOYANCY TO OUR WEST. WILL CONTINUE A CHC POP FORECAST FOR TONIGHT...BUT THINK THAT WE WOULD SEE MAINLY SHOWERS DUE TO THE AFOREMENTIONED STABILITY. FRONT WILL MOVE THROUGH UPPER MIDWEST AND INTO WESTERN OHIO SUNDAY. ANOTHER SHORTWAVE TROUGH WILL MOVE EASTWARD AHEAD OF SURFACE BOUNDARY REACHING WESTERN PA SUNDAY AFTERNOON. WITH SOUTHWESTERLY FLOW INTENSIFYING...ATMOSPHERE QUICKLY DESTABILIZES. A STRONG AREA OF LOW LEVEL MOISTURE CONVERGENCE WILL DEVELOP SUNDAY AFTERNOON AS FORCING IN THE LOW LEVELS INCREASES. A SLIGHT RISK FOR SUNDAY LOOKS RIGHT ON TRACK WITH LI`S OF -4 TO -6...CAPES OF 1500 TO 2000 J/KG AND SHEAR VALUES IN EXCESS OF 30KTS. IN ADDITION TO THE SEVERE THREAT...HEAVY RAIN WILL BE A CONCERN AS THE INFLUX OF MOISTURE PUSHES PWAT NUMBERS CLOSE TO 2 INCHES. IT SHOULD BE NOTED THAT CLOUD COVER AND THE RISK FOR MORNING SHOWERS MAY HINDER CONVECTION AS THIS WILL KEEP HIGH TEMPS VERY CLOSE TO THOSE NEEDED TO INITIATE CONVECTION. ALL OF THE PREVIOUSLY MENTIONED ELEMENTS MOVE THROUGH SUNDAY EVENING...HOWEVER THE TRAILING COLD FRONT GETS HUNG UP OVER THE NORTHERN HALF OF MY FA. THIS STALLED FRONT WILL CONTINUE TO PROVIDE SHOWERS AND STORMS THROUGH MONDAY. POPS WILL BE TRICKY MONDAY...WHOLLY DEPENDENT ON THE LOCATION OF THE STALLED BOUNDARY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... STILL SEEING SOME TIMING ISSUES ON THE PASSAGE OF THE FRONT MONDAY NIGHT. WILL LEAN TOWARD THE SREF/GEFS/GFS OP HERE AS THEY ARE VERY SIMILAR WITH FRONTAL PASSAGE. THIS WILL BRING AN END TO SHOWERS LATE MONDAY NIGHT. BROAD CANADIAN HIGH WILL KEEP AREA DRY AND COMFORTABLE THROUGH THE END OF THE LONG TERM. && .AVIATION /05Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS CAN BE EXPECTED FOR THE TAF PD AS SFC HIGH PRES SLIDES ACRS THE REGION...ALTHOUGH MID AND UPR CLDINESS WL ACCOMPANY PASSAGE OF A WEAK DISTURBANCE. .OUTLOOK.../SATURDAY THROUGH WEDNESDAY/... RESTRICTIONS WL BECOME LIKELY WITH THE APPRCH AND PASSAGE OF A CDFNT LATER SUNDAY AND MONDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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