Area Forecast Discussion
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000 FXUS61 KPBZ 222201 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 601 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 /22Z TUESDAY THROUGH SUNDAY/... DIURNAL CUMULUS SHOULD FADE WITH SUNSET...YIELDING ANOTHER MAINLY CLEAR OVERNIGHT AT ALL SITES. SOME MVFR VIS ARE POSSIBLE AT TERMINALS NEAR WATER BODIES...OTHERWISE MOSTLY CLEAR SKIES WILL CONTINUE UNTIL THE ARRIVAL OF DEEPER CLOUD COVER DURING THE MORNING HOURS OF WEDNESDAY. RAIN SHOWERS AND THUNDERSTORMS SEEM LIKELY TO HOLD OFF UNTIL NEAR THE END OF THE TAF VALID TIME AT THE MOMENT. FRIES OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/... A COLD FRONT WILL RESULT IN RESTRICTIONS AT TIMES WEDNESDAY AND WEDNESDAY NIGHT. GENERAL VFR THURSDAY INTO SATURDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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