Area Forecast Discussion
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000 FXUS61 KPBZ 222342 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 742 PM EDT TUE JUL 22 2014 .SYNOPSIS... THE AREA WILL SEE SHOWERS AND THUNDERSTORMS ON WEDNESDAY AS COLD FRONT PASSES ACROSS THE REGION...WITH SLIGHTLY BELOW NORMAL TEMPERATURES AND DRY CONDITIONS THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 6 PM - UPDATED TO AMP UP POPS SLIGHTLY FOR THE SOUTHEAST RIDGES WHERE SHRA CONTINUE TO FIRE...THIS SHOULD CONTINUE FOR A FEW HOURS UNTIL JUST AFTER SUNSET...WHEN THESE AND ANY REMAINING CU WILL FALL APART. MINOR CHANGES OTHERWISE. PREVIOUS DISCUSSION... CUMULUS BUILDUPS CONTINUE TO BE LIMITED BY A FAIRLY STRONG CAP AROUND 10 KFT. HOWEVER...STRONG LOW LEVEL LAPSE RATES GENERATED BY INTENSE INSOLATION EARLIER TODAY AND A FAIRLY MOIST COLUMN BELOW 10 KFT HAVE MANAGED TO ALLOW FOR SAID CUMULUS TO BE QUITE WIDESPREAD AROUND THE REGION. THAT SAID...ONLY AROUND THE HIGHEST RIDGELINES DO THESE BUILDUPS SEEM TO BE CAPABLE OF REACHING SUFFICIENT VERTICAL EXTENT TO CAUSE A SHOWER OR TWO. OVERNIGHT...DIURNAL CUMULUS WILL QUICKLY FADE AS RAGGED MID-CLOUD APPROACHES FROM THE NORTHWEST. THIS WILL BE AN EARLY HARBINGER OF THE WEATHER FOR WEDNESDAY...HOWEVER THE BEST COLUMN RH VALUES FAIL TO REACH OUR CWA PRIOR TO SUNUP. AS A RESULT...GENERALLY CLEAR SKIES SEEM LIKELY TO DOMINATE THE REGION OVERNIGHT. HOWEVER...WITH STRONG WARM ADVECTION AT THE TOP OF THE BOUNDARY LAYER...RIDGETOP TEMPERATURES ARE LIKELY TO STAY WELL UP OVERNIGHT AS 17-18C IS ABOUT AS LOW AS WE WILL MUSTER AT 850 MB. RADIATIONAL COOLING WILL LIKELY BE A BIT MORE EFFECTIVE IN THE VALLEYS...HOWEVER DEWPOINTS STRADDLING 70F WILL MAKE DIURNAL FALLS DIFFICULT TO MANAGE. AS A RESULT...A WARM NIGHT IS EXPECTED ACROSS THE REGION...WITH SOME PATCHY RIVER FOG POSSIBLE BY MORNING AND AHEAD OF THE INCOMING CLOUDS FROM THE NEXT SYSTEM. FRIES && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... A COLD FRONT WILL PASS ACROSS THE FORECAST AREA WEDNESDAY AFTERNOON THROUGH WEDNESDAY NIGHT. SCATTERED THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON AHEAD OF THE FRONT WITH SFC DEWPOINTS STILL IN UPPER 60S TO LOW 70S AND MID LEVELS BEGINNING TO COOL AS HEIGHTS FALL. INSTABILITY IS NOT ENTIRELY IMPRESSIVE WITH LOCAL HI RES MODELS PROGGING THE HIGHEST LEVELS OF CAPE...AROUND 1500-1700J/KG. CONVECTION SHOULD REMAIN FAIRLY UNORGANIZED AS SHEAR STILL LOOKS TO BE MARGINAL AT BEST. SCATTERED SHOWERS WILL LINGER BEHIND THE FRONT OVERNIGHT AS THE ASSOCIATED MIDLEVEL SHORTWAVE PASSES. DRY CONDITIONS AND COOLER TEMPERATURES WILL THEN PREVAIL THE REMAINDER OF THE WEEK AS HIGH PRESSURE BUILDS IN ACROSS THE REGION. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... DRY HIGH PRESSURE WILL DOMINATE INTO SATURDAY. BY SATURDAY NIGHT INTO SUNDAY NEXT SYSTEM WILL APPROACH FROM THE GREAT LAKES WITH INCREASING DEW POINTS AND CHANCE POPS FOR SHOWERS AND THUNDERSTORMS. A SERIES OF COLD FRONTS WILL THEN BRING COOLER TEMPERATURES WITH CONTINUED SHOWER CHANCES INTO EARLY NEXT WEEK. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... CLEARING TREND CONTINUES INTO THE OVERNIGHT HOURS WITH A COLD FRONT STILL WELL TO THE WEST. TEMPERATURES AND DEWPOINTS ARE A FEW DEGREES HIGHER THAN 24 HOURS AGO...BUT THE SPREAD BETWEEN REMAINS ABOUT THE SAME. NOT EXPECTING CLOUDS ASSOCIATED WITH THE COLD FRONT TO MAKE IT INTO THE AREA UNTIL AROUND SUNRISE WEDS...SO A REPEAT OF MON NIGHT/TUES MORNING COULD BE IN STORE. IN SHORT...SHOULD SEE DEVELOPMENT OF MVFR FOG FOR MOST TERMINALS...THE MORE FOG PRONE TERMINALS COULD DROP TO IFR OR WORSE. ANY OVERNIGHT FOG SHOULD QUICKLY DISSIPATE AFTER DAYBREAK WEDS AS INCREASED SW SFC FLOW KICKS IN AHEAD OF THE COLD FRONT. RAIN SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE FRONT COULD CAUSE SOME TEMPORARY RESTRICTIONS BEGINNING AROUND MIDDAY WEST THROUGH THE LATE EVENING EAST. A WIND SHIFT WILL ALSO OCCUR WITH THE FRONT...WITH 5-10KT WINDS FROM THE NORTHWEST WEDS EVENING. TAX OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/... GENERAL VFR THURSDAY INTO SATURDAY AS HIGH PRESSURE RETURNS TO THE AREA. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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