Area Forecast Discussion
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000 FXUS61 KPBZ 270751 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 351 AM EDT WED MAY 27 2015 .SYNOPSIS... WARM AND HUMID CONDITIONS WILL PERSIST TODAY...WITH INCREASING SHOWER AND THUNDERSTORM CHANCES TONIGHT. DRIER WEATHER IS EXPECTED THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... SHORTWAVE CONTINUES TO LIFT ACROSS THE AREA DURING THE PREDAWN HOURS. THUNDER HAS ALL BUT CEASED WITH THE LOSS OF INSTABILITY. EASTWARD COMPONENT OF MOTION IS SLOW...SO STILL EXPECT RAIN TO LINGER ALONG THE RIDGES PAST SUNRISE. THE EXIT OF THE SHORTWAVE WILL THEN ALLOW FOR A RELATIVE LULL IN ACTIVITY FROM LATE MORNING INTO THE AFTERNOON...ALTHOUGH KEPT A LOW CHANCE ALONG THE RIDGES AS A WEAK LOBE OF VORTICITY LINGERS. ALTHOUGH SOME INSTABILITY BUILDS DURING THE AFTERNOON...THE LACK OF A TRIGGER SUGGESTS WIDELY SCATTERED AFTERNOON CONVECTION AT BEST WEST OF THE RIDGES. A MORE POTENT SHORTWAVE WILL ARRIVE IN MICHIGAN LATER TODAY...AND THEN BEGIN TO SHEAR OUT AS IT CROSSES THE EASTERN GREAT LAKES TONIGHT. ACCOMPANYING SURFACE BOUNDARY WILL LIKEWISE BE FADING AS IT APPROACHES. HAVE SKIMMED LIKELY POPS ALONG THE NORTHWEST FRINGE OF CWA...CLOSER TO SHORTWAVE. SPC HAS ANOTHER SLIGHT RISK OF SEVERE STORMS IN THIS AREA. EXPECT SOMETHING SIMILAR TO YESTERDAY. WHILE BEST SHEAR AND INSTABILITY LIE TO THE WEST...BUFKIT SOUNDINGS AT LOCATIONS LIKE ZZV AND PHD SUGGEST THAT AROUND 1000 J/KG OF CAPE MAY COMBINE WITH 30-40 KNOTS OF MIDLEVEL FLOW...ALLOWING FOR A FEW STORMS WITH STRONG TO DAMAGING WIND GUSTS. LESSER RISK TO THE EAST...WHERE CHANCE POPS ARE MAINTAINED WITH LESS POTENTIAL LIFT. ACTIVITY WILL BEGIN TO QUICKLY DIE DOWN AFTER 06Z WITH LOSS OF SUPPORT FROM EXITING SHORTWAVE. GOING TEMPERATURES WERE VERY CLOSE TO A GUIDANCE CONSENSUS...AND ONLY MADE MINOR TWEAKS. CL && .SHORT TERM /THURSDAY THROUGH SATURDAY/... 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 /08Z WEDNESDAY THROUGH SUNDAY/... SHORTWAVE MOVING ACROSS CURRENTLY...WITH MVFR/IFR VISIBILITIES IN SHRA AND DYING TSRA. THESE WILL PULL ACROSS THE RIDGES TOWARDS SUNRISE. BEHIND THE RAIN...SOME MVFR/IFR CIGS AND VIS ARE EXPECTED WITH FOG. LOW CLOUDS WILL LIFT INTO A VFR CU DECK BY MIDDAY. ANY DAYTIME SHRA/TSRA SHOULD BE QUITE SPOTTY AND DID NOT INCLUDE IN TAF AT THIS TIME. NEXT SHORTWAVE ARRIVES AFTER 00Z...WITH MORE RAIN ARRIVING FROM WEST TO EAST. KEPT VFR FOR NOW BUT BRIEF RESTRICTIONS ARE AGAIN POSSIBLE IN SHRA/TSRA. .OUTLOOK.../WEDNESDAY NIGHT 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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