Area Forecast Discussion
Issued by NWS

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000 FXUS61 KPBZ 010813 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 413 AM EDT FRI AUG 1 2014 .SYNOPSIS... TEMPERATURES WILL MOVE TO NEAR AVERAGE WITH DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS TODAY THROUGH SUNDAY. DRY AND MILD CONDITIONS TO RETURN BY THE BEGINNING OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... MOSTLY CLEAR SKIES AND CALM WINDS EARLY THIS MORNING ALLOWING TEMPS TO RADIATE DOWN TO DEWPOINT TEMPS GIVING RISE TO PATCHY VALLEY FOG. HIGH CLOUDS BEGINNING TO AMASS SOUTH AND EAST OF THE AREA IN RESPONSE TO A SYSTEM THAT WILL RIDE NORTH ALONG THE ERN PERIPHERY OF THE BROAD TROF THIS MORNING. AS THE MID-LEVEL WAVE TRANSLATES NORTH-NORTHEAST ALONG THE SPINE OF THE APPALACHIANS...LOW TO MID LEVEL FLOW WILL BE SOUTHEASTERLY POOLING COPIOUS AMOUNTS OF ATLANTIC MOISTURE ALONG THE ERN SLOPES. H85-H7 FLOW REMAINS PRIMARILY OUT OF THE SOUTH AND EAST THROUGH MIDDAY WRINGING OUT A VAST MAJORITY OF THE MOISTURE BEFORE IT CAN CROSS THE HIGHER TERRAIN. BY ABOUT 18Z THE DEEPER MOISTURE ARRIVES ALONG OUR RIDGES AS NOTED BY THE LOW H5 DEWPOINT DEPRESSIONS PROGGED BY 00Z RUNS OF THE NAM/GFS. HAVE CONTINUED TO FOLLOW THIS FOR TIMING OF THE LIKELY POPS ENTERING THE CWA. HI-RES WRF MODELS HAVE CONSISTENTLY SHOWN A BAND OF QPF MOVING SE TO NW ACROSS THE AREA THIS AFTERNOON. WHILE DIFFICULT TO PICK THIS FEATURE OUT OF THE BROAD MODELS...THE 00Z NAM MID-LEVEL FIELDS SHOW A WEAK BOUNDARY PUSHING AWAY FROM THE RIDGES APPROACHING THE ERN OH NEAR 00Z. THE NWRN 1/2 OF THE CWA SHOULD WARM QUICKLY THIS MORNING BEFORE THE THICKER CLOUDS STREAM IN. 00Z NAM/GFS SHOWING A CORRIDOR OF CAPE VALUES NEAR 1000J/KG AND NAM BUFR SOUNDINGS HAVE LAPSE RATES IN THE -8 TO -10 C/KM RANGE THROUGH H7. AM EXPECTING AT LEAST SCT SHRA/TSRA ALONG THIS BOUNDARY PUSHING E TO W...HAVE BOLSTERED POPS FOR THIS FEATURE. THE MID-LEVEL WAVE PUSHES NE OF THE AREA QUICKLY OVERNIGHT USHERED OUT BY A 50KT H5 JET. HOWEVER...RESIDUAL ATLANTIC MOISTURE WILL KEEP RAIN CHANCES IN HEADING INTO SAT AS THE MEAN TROF REMAINS IN THE NEIGHBORHOOD. TAX && .SHORT TERM /SATURDAY THROUGH SUNDAY/...
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SUFFICIENT MOISTURE WILL BE IN PLACE SATURDAY AND SUNDAY FOR DAILY SHOWERS AND THUNDERSTORMS AS TEMPERATURES REMAIN RIGHT AROUND NORMAL. MINOR TIMING DIFFERENCES STILL EVIDENT IN GUIDANCE IN REGARDS TO A SHORTWAVE PROGGED TO PASS OVER THE REGION THIS WEEKEND WHICH WOULD INCREASE SHOWER/THUNDERSTORM CHANCES AND COVERAGE BUT ATTM LATE SATURDAY AFTERNOON THROUGH SUNDAY MORNING LOOKS TO BE THE BEST CHANCE FOR SEEING MORE WIDESPREAD ACTIVITY.
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&& .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
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THE BEGINNING OF NEXT WEEK WILL START OFF DRY AS MOISTURE DECREASES BEHIND A SHORTWAVE TROUGH AND PWATS DROP BACK BELOW ONE INCH. THIS HOWEVER WILL BE BRIEF AS MOISTURE ADVECTION INCREASES TUESDAY AHEAD OF THE NEXT TROUGH APPROACHING THE REGION. MINIMAL CHANGE WAS NEEDED TO THE EXTENDED GRIDS AS MODELS SHOW GOOD CONTINUITY WITH THIS FEATURE BUT FROM WEDNESDAY ON DIVERGE IN HANDLING THE DEPTH OF THE FEATURE AS IT CONTINUES TO THE EAST AND ALSO SHOW MINIMAL AGREEMENT IN PROGGING THE NEXT MAJOR SHORTWAVE TOWARDS THE END OF THE WEEK. LEFT THE MIDDLE OF THE ROAD FORECAST IN PLAY CALLING FOR SLIGHT CHANCES MAINLY DURING THE DAY OVER THE SECOND HALF OF NEXT WEEK...BUT WILL NEED TO ADJUST AS SOON AS A TREND IS ESTABLISHED. TEMPERATURES WILL REMAIN RIGHT AROUND CLIMO NORMS FOR THIS TIME OF YEAR THROUGH THE PERIOD.
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&& .AVIATION /07Z FRIDAY THROUGH TUESDAY/... MAINLY MVFR FOG DEVELOPING CURRENTLY AS TEMPS CONTINUE TO DROP UNDER MOSTLY CLEAR SKIES. SOME TERMINALS COULD DROP TO IFR/LIFR RANGE BRIEFLY...DECIDED TO HANDLE THESE WITH TEMPO GROUPS THROUGH 12Z. AN INCREASE IN SOUTHERLY MOISTURE AND INSTABILITY SHOULD RESULT IN SOME SHOWERS AND THUNDERSTORMS SCATTERED ABOUT THE REGION BY FRIDAY AFTERNOON. TEMPORARY RESTRICTIONS MAY OCCUR IN ANY STRONGER SHOWER/THUNDERSTORMS...BUT MOSTLY VFR WILL PREVAIL THIS AFTERNOON/EVENING. OUTLOOK.../FRIDAY NIGHT THROUGH TUESDAY/... A LOW PRESSURE SYSTEM COULD BRING RESTRICTIONS THROUGH THE BALANCE OF THE WEEKEND. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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