Area Forecast Discussion
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000 FXUS61 KPBZ 271456 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 1056 AM EDT WED MAY 27 2015 .SYNOPSIS... WARM AND HUMID CONDITIONS WILL CONTINUE TODAY WITH PERIODIC SHOWER AND THUNDERSTORM CHANCES. DRIER WEATHER IS EXPECTED THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AFTER SHOWERS EXIT THE WV/MD RIDGES..MUCH OF THE DAY SHOULD BE DRY WITH SUBSIDENCE BEHIND A DEPARTING SHORTWAVE...WITH THE MORNING INSTABILITY CHART SHOWING RELATIVELY STABLE AIR. LATER THIS AFTERNOON...ANOTHER SHORTWAVE AND SURFACE BOUNDARY IS PROGGED TO ADVANCE ACROSS THE GREAT LAKES AND UPPER OHIO VALLEY REGION BRINGING INCREASING SHOWER AND THUNDESTORM CHANCES INTO TONIGHT. MARGINAL SHEAR AND INSTABILITY WITH WARM AIR ALOFT IS PROGGED ESPECIALLY ACROSS NORTHWEST PA INTO OHIO...THOUGH WITH SOME DRY MID LEVEL AIR SOME POTENTIAL EXISTS FOR DAMAGING WIND GUSTS WITH ANY OF THE STRONGER STORMS. THE SHOWERS AND STORMS SHOULD DECREASE LATER THIS EVENING AS INSTABULITY DIMINISHES AND UPPER SUPPORT EXITS. TEMPERATURES SHOULD CONTINUE AROUND 10 DEGREES ABOVE SEASONAL LEVELS. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... UPPER-LEVEL WAVE PASSES EAST OF THE AREA THURSDAY MORNING WITH BRIEF RIDGING ALOFT RESULTING IN A DRYING TREND FOR THE LATTER PART OF THE WEEK. THE AXIS OF THE UPPER RIDGE MOVES EAST BY MIDDAY FRIDAY ALLOWING DEEP SOUTHWESTERLY FLOW TO KICK IN. THIS...AND INCREASED SUNSHINE WILL FUEL TEMPERATURES PUSHING WELL INTO THE 80S...AT LEAST 10 DEGREES HIGHER THAN NORMAL. THE DRY WEATHER FADES AWAY QUICKLY HEADING INTO THE WEEKEND AS THE NEXT LOW PRESSURE SYSTEM MOVES INTO THE GREAT LAKES REGION. AS THE FRONT APPROACHES...SOUTHERLY MOISTURE WILL FEED SATURDAY AFTERNOON SHOWER AND THUNDERSTORM CHANCES. TEMPERATURES SATURDAY WILL STILL BE WELL ABOVE NORMAL...BUT THE INCREASED CLOUD COVER ASSOCIATED WITH THE APPROACHING SYSTEM MAY KEEP HIGHS A FEW DEGREES LOWER THAN FRIDAYS MARKS. TAX && .LONG TERM /SATURDAY THROUGH TUESDAY/... FRONTAL BOUNDARY CLEARS A MAJORITY OF THE FORECAST AREA LATE SATURDAY NIGHT...BUT MEETS RESISTANCE CROSSING THE APPALACHIANS. WITH SOME TIMING DIFFERENCES ACROSS LONG-RANGE MODELS...DECIDED TO TAKE THE SLOWER FRONTAL PROGRESSION...ULTIMATELY LINGERING RAIN CHANCES IN THE HIGHER TERRAIN SUNDAY AFTERNOON. ELSEWHERE...SOME RELIEF FROM THE WELL ABOVE NORMAL TEMPERATURES WILL COME SUNDAY INTO MONDAY AS A DRY HIGH PRESSURE SYSTEM BUILDS TO THE NORTH. HEADING INTO NEXT WEEK...LONG-RANGE GUIDANCE HAD MAJOR DIFFERENCES WITH THE RETURN OF SOUTHERLY MOISTURE ON THE BACKSIDE OF THE HIGH. THE LATEST 00Z GFS HAS COME INTO BETTER AGREEMENT WITH ITS ECMWF AND GFS ENSEMBLE BRETHREN...KEEPING THE RETURN OF MOISTURE SUPPRESSED THROUGH THE EARLY PART OF THE WEEK. HAVE LOWERED MONDAY AND TUESDAY POPS TO REFLECT THIS. AS THE HIGH PUSHES OFF THE COAST TOWARDS THE MIDDLE OF NEXT WEEK THE ENHANCED SOUTHERLY FLOW WILL ONCE AGAIN BRING WARM AND WET BACK INTO THE FORECAST. TAX && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... MVFR CLOUD DECK HAS DEVELOPED OVER MOST TERMINALS WITH ABUNDANT LOW LEVEL MOISTURE. EXPECT THIS TO PERSIST UNTIL IT MIXES OUT INTO A BKN CU DECK THIS AFTERNOON. AN ISOLATED SHOWER OR STORM IS POSSIBLE THIS AFTERNOON WITH SOME DAYTIME INSTABILITY...BUT PROBABILITY TOO LOW TO MENTION IN TAF. ANY STORM COULD PRODUCE BRIEF IFR IN A DOWNPOUR. A MORE GENERAL CHANCE OF RAIN ARRIVES WITH A MORE POTENT MIDLEVEL DISTURBANCE TONIGHT. BEST CHANCES OF TSRA LIE FROM ZZV THROUGH PHD TO FKL. LESSER CHANCE TO THE EAST BUT SHRA/VCSH STILL EXPECTED. KEEPING MOST LOCATION VFR AFTER 00Z...SAVE FOR LATE NIGHT FOG AT ZZV...AS TIMING OF ANY RESTRICTIONS REMAINS PROBLEMATIC. .OUTLOOK.../THURSDAY THROUGH SUNDAY/... OVERALL IMPROVEMENT IS INDICATED AS PRECIP CHANCES DECLINE THROUGH FRIDAY. HOWEVER...PRECIP...AND RESTRICTION CHANCES WILL AGAIN INCREASE WITH AN ENCROACHING FRONTAL SYSTEM THIS WEEKEND. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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