Area Forecast Discussion
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000 FXUS61 KPBZ 300518 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 118 AM EDT TUE JUN 30 2015 .SYNOPSIS... A SERIES OF DISTURBANCES WILL KEEP PERIODIC RAIN CHANCES THROUGH MUCH OF THE WEEK. && .NEAR TERM /THROUGH TODAY/... SCATTERED SHOWERS WILL PERSIST FOR THE NEXT COUPLE HOURS BEFORE STARTING TO DIMINISH BEFORE DAYBREAK. THE PRIMARY AREAS WHERE PRECIPITATION WILL CONTINUE WILL BE MAINLY EAST OF THE PA/OH BORDER...ALONG THE I80 CORRIDOR AND NORTH WHERE THE WARM FRONT IS CURRENTLY LOCATED BASED OFF LATEST SURFACE ANALYSIS AND SOUTH ACROSS WESTERN PA AS MORE SUBSTANTIAL MOISTURE OVER WEST VIRGINIA RIDES THE WARM CONVEYOR NORTH UP AND OVER THE FRONT. NO CHANGES NEEDED AT THIS TIME TO THE FORECAST AT THIS TIME. PREV DISCUSSION BELOW.. PERIODIC SHOWERS ARE EXPECTED TO CONTINUE TONIGHT AS A WARM FRONT MOVES NORTH ACROSS THE UPPER OHIO VALLEY. A FEW THUNDERSTORMS ARE POSSIBLE MAINLY SOUTH OF PIT WHERE LIMITED ELEVATED INSTABILITY IS SEEN ON MESO ANALYSIS...SO MAINTAINED A CHANCE OF THUNDERSTORMS IN THIS AREA. FURTHER NORTH WITH LACK OF LOW LEVEL JET AND SUFFICIENT INSTABILITY LEFT OUT THE MENTION OF THUNDER. A RELATIVE BREAK IN THE PRECIP IS EXPECTED TUESDAY MORNING BEFORE ANOTHER SHORTWAVE AND ASSOCIATED COLD FRONT APPROACH LATER IN THE DAY WITH INCREASING SHOWER/STORM CHANCES. MODEL PROGGED SHEAR AND INSTABILITY ARE MARGINAL...SO THE POTENTIAL FOR STRONG STORMS IS IN QUESTION. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/... BROAD UPPER TROUGH WILL DOMINATE THE EASTERN CONUS THROUGH MID- WEEK...WITH SEVERAL SHORTWAVE TROUGHS EXPECTED TO MOVE THROUGH THE FLOW. THUNDERSTORMS ARE EXPECTED AT THE START OF THE TUESDAY NIGHT PERIOD...BUT THESE SHOULD WANE QUICKLY AS THEIR SUPPORTING UPPER WAVE DEPARTS AND DRIVES THE ASSOCIATED COLD FRONT SOUTHWARD. THIS COLD FRONT WILL BECOME STALLED ACROSS THE FORECAST AREA ON WEDNESDAY...AND LIKELY WILL BE THE FOCUS FOR ADDITIONAL SHOWERS AND STORMS ON WEDNESDAY AFTERNOON AS MODEST INSTABILITY PERSISTS IN THE WARM SECTOR...AND ANOTHER SHORTWAVE TROUGH IMPINGES ON THE REGION. TEMPERATURES ON WEDNESDAY WILL NOT DEPART MUCH FROM NORMAL VALUES. AMID INCREASING CUMULUS COVER...HIGHS ARE EXPECTED IN THE UPPER 70S-LOWER 80S...WITH MINIMA IN THE LOWER 60S. && .LONG TERM /THURSDAY THROUGH MONDAY/... ALTHOUGH THE LONGWAVE TROUGH WILL FLATTEN SOMEWHAT IN THE MEDIUM RANGE...A PROGRESSIVE PATTERN WILL PERSIST...WITH SEVERAL SHORTWAVE TROUGHS EXPECTED TO IMPACT THE REGION LATE-WEEK THROUGH THE WEEKEND. A STALLED FRONTAL BOUNDARY WILL BE DIVERTED QUITE LITTLE DURING THIS TIME...AND WILL PROVIDE FOCUS FOR DAILY ROUNDS OF SHOWERS AND STORMS. MODELS DO NOT AGREE ON DETAILS AT THIS RANGE...BUT THE GENERAL PICTURE IS THAT A SHORTWAVE TROUGH FROM THE SOUTHERN PLAINS MOVES ALONG THIS STALLED BOUNDARY LATE IN THE WEEK. THE PRECISE POSITION OF THE STALLED FRONT WILL DICTATE THE COVERAGE OF ANY ASSOCIATED PRECIPITATION IN THE PITTSBURGH FORECAST AREA...BUT CONSENSUS SUGGESTS THAT THE SOUTHERNMOST PORTION OF THE AREA HAS THE GREATEST LIKELIHOOD OF MEASURABLE RAIN. THUS...POPS WERE ADJUSTED IN THE LATTER HALF OF THE WEEK TO DEPICT A BIT MORE OF A GRADIENT. THERE IS NO INDICATION THAT TEMPERATURES WILL DEVIATE FROM CLIMATOLOGICAL NORMALS BY ANY SIGNIFICANT DEGREE. MAXIMA IN THE UPPER 70S-LOWER 80S AND MINIMA IN THE LOWER 60S SHOULD BE COMMON AT LEAST THROUGH THE WEEKEND. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... GENERAL VFR THIS EVENING WITH SCATTERED MVFR IN SHOWERS THROUGH 02Z. WITH DEW POINTS RISING AND SHOWERS THIS AFTERNOON EXPECT SOME MVFR TO IFR CIGS TO DEVELOP 8-10Z NORTHERN PORTS AND AFTER 10Z ELSEWHERE. A WARM FRONT MOVING NORTH WILL HELP PUT NORTHERN PORTS IN LINE FOR MOST OF THE IFR CIGS. FRONTAL BOUNDARY WILL APPROACH LATE DAY TUESDAY WITH MIXING BRINGING GENERAL VFR BACK ACROSS ALL TERMINALS. ONLY VCTS LATE DAY TUESDAY WELL AHEAD OF FRONT. .OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/... THE BEST CHANCE FOR WIDESPREAD RESTRICTIONS WILL BE WEDNESDAY AS A WEAK FRONT PASSES...AND AGAIN ON SATURDAY WITH POSSIBLE LOW PRESSURE. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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