Area Forecast Discussion
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000 FXUS61 KPBZ 130111 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 911 PM 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 SUNDAY/...
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THE LATE EVE UPDATE FEATURED ALTERATIONS TO HOURLY TRENDS OF POPS AND TEMPS. WARM...MOIST ADVCTN CONTS TO INCRS CLD COVER THIS EVE WITH THE ADVN OF AN UPR LVL SHRTWV. ALTHOUGH BTR DYNAMICS ARE PROGGED N OF THE AREA WITH THE LOW PRES CNTR...ENOUGH MOISTURE AND LIFT ARE INDICATED TO SPPRT SOME SCT...BUT ELEVATED SHWRS LATE TNGT/SUN MORNING...MAINLY TO THE N AND W OF PITTSBURGH. HAVE THUS MAINTAINED CHC POPS OVR THOSE AREAS WHERE CNVRG MSTR IN THE TROF AXIS WL HAVE BTR POTENTIAL TO FORCE THE INCRSG MID LVL WARMTH. A MORE POTENT DISTURBANCE IS PROJECTED ACRS THE SRN GREAT LAKES ON SUNDAY...ACCOMPANIED BY A 40-50KT MID LVL JET WHILE A CORRIDOR OF MODERATE INSTABILITY IS FORECAST ALONG AND JUST NORTH OF THE OHIO RIVER VALLEY BY AFTERNOON...WITH MAGNITUDE DEPENDANT ON EVENTUAL SFC DEWPOINT VALUES AND HEATING UNDR THE INCRSD CLD COVER. THE STORM PREDICTION CENTER HAS INCLUDED THE UPR OH VALLEY REGION IN A SLGT SVR RISK...I.E. 15 PERCENT...AND A HAZARDOUS WEATHER OUTLOOK MENTION HAS BEEN MAINTAINED. THE PRECIPITAL WATER PROGNOSIS FOR SUNDAY IS WORTH MENTIONING IN THAT VALUES NR 2 INCHES ARE PROJECTED WITH A SUFFICIENTLY DEEP WARM CLD LYR TO PROMOTE RAINFALL EFFICIENCY. LOCALLY HEAVY RAINFALL MAY LEAD TO FLOODING OF POOR DRAINAGE AREAS...BUT OVRALL FLASH FLOOD POTENTIAL IS LOW GIVEN EXPECTED ELEMENT MOVEMENT IN THE IMPROVING WIND FIELD...AS WELL AS THE RELATIVELY HIGH FLASH FLOOD GUIDANCE READINGS AFTER SEVERAL DAYS WITHOUT RAIN.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... EXPECTING THE SEVERE THREAT TO WANE DURING THE EVENING HOURS AS INSTABILITY AND SHEAR WEAKEN. HOWEVER...THE HEAVY RAINFALL THREAT WILL CONTINUE WITH CONTINUED STRONG H250 DIVERGENCE FROM UPPER JET AND PWATS NEAR OR JUST ABOVE 2 INCHES THROUGH AT LEAST 06Z. THE SOUTHERN CWA IS WHERE THESE FACTORS MIX THE BEST...AND ALSO WHERE LIKELY POPS LINGER THE LONGEST. EXPECT SOME DECREASE IN COVERAGE TO THE NORTH WITH TIME. FRONTAL BOUNDARY ADVANCES INTO NORTHERN PA SUNDAY NIGHT BUT THEN HANGS UP THERE. CONTINUED WITH HIGH CHANCE POPS FOR MONDAY AND MONDAY NIGHT...WITH PLACEMENT OF HIGHER VALUES STILL TRICKY. THE STRONGEST SHORTWAVE OF THE SERIES WILL SWEEP ACROSS THE GREAT LAKES MONDAY AFTERNOON AND EVENING...WHICH WILL FINALLY PUSH THE FRONT EAST ON TUESDAY. ANOTHER THREAT OF SEVERE STORMS IS INDICATED FOR MONDAY. THE BEST CHANCE FOR THIS APPEARS TO BE ACROSS THE SOUTHERN CWA...WHERE HIGHER INSTABILITY AHEAD OF THE FRONT WILL BETTER COMBINE WITH STRONG FLOW ALOFT...MORE UNIDIRECTIONAL THAN SUNDAY. THE THREAT OF ISOLATED WATER PROBLEMS WILL CONTINUE INTO MONDAY NIGHT AS WELL. FRONT FINALLY EXITS TO THE EAST TUESDAY MORNING AS H500 TROUGH AXIS PASSES. ALLOW POPS TO DRY OUT SLOWLY THROUGH THE DAY. COOLER AIR PUSHES IN BEHIND...HERALDING THE WELL-ADVERTISED COOLDOWN. TEMPERATURES WILL NOT GET PAST THE MID 70S ON TUESDAY...ALONG WITH LOWER DEWPOINTS. CL && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... BROAD CANADIAN HIGH WILL KEEP AREA DRY AND COMFORTABLE THROUGH THE END OF THE LONG TERM. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... VFR CONDS EXPD THRU TNGT WITH INCRG AC/CI. AN ADVNG SHRTWV WL CROSS THE AREA SUN WITH SHWRS AND TSTMS EXPD TO DVLP THRU THE DAY...WITH SITES FM PIT S NOT EXPG CNVCTN UNTIL MID TO LT AFTN. WL MAINTAIN A VCTS OR TSTM MENTION IN THE TAFS FOR THE MOST LIKELY TIME OF CNVCTN. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... OCNL RSTRNS WL BE PSBL UNTIL THE PASSAGE OF A MON NGT-TUE CDFNT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ 15/07

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