Area Forecast Discussion
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000 FXUS61 KPBZ 280926 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 526 AM EDT THU APR 28 2016 .SYNOPSIS... LOW PRESSURE WILL BRING RAIN TODAY INTO TOMORROW. MORE RAIN WILL ARRIVE LATE SATURDAY INTO SUNDAY. && .NEAR TERM /THROUGH TONIGHT/...
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WITH 530AM UPDATE...MADE MINIMAL CHANGES TO HOURLY TEMPERATURE AND PRECIPITATION FORECASTS. PREVIOUS DISCUSSION FOLLOWS. A LINE OF SHOWERS CONTINUES TO ADVANCE FROM THE WEST...CURRENTLY STRETCHING FROM OHIO INTO TENNESSEE. THE AMOUNT OF LIGHTNING HAS DROPPED CONSIDERABLY OVER THE LAST FEW HOURS ACROSS THE NORTHERN HALF OF THE LINE. HOWEVER...HAVE DECIDED TO KEEP ISOLATED THUNDER IN THE FORECAST ALONG THE LINE AS IT MOVES INTO THE REGION...EXCEPT FOR LOCATIONS NORTH AND EAST OF PITTSBURGH WHERE MODEL FORECAST SOUNDINGS SHOW A TOTAL LACK OF INSTABILITY. WITH THE SLOW MOVEMENT OF THE LINE...RAINFALL TOTALS OF ONE QUARTER TO ONE HALF INCH ARE EXPECTED...WITH ISOLATED HIGHER AMOUNTS POSSIBLE IN ANY THUNDERSTORMS THAT DEVELOP. ALTHOUGH THERE SHOULD BE A LULL IN PRECIPITATION DURING THE LATE AFTERNOON...LOW PRESSURE CREEPING EAST ALONG INTERSTATE 70 WILL BRING A RENEWED CHANCE FOR SHOWERS OVERNIGHT. THERE SHOULD BE A WIDE SPREAD IN HIGH TEMPERATURES TODAY...WITH LOCATIONS ALONG INTERSTATE 80 REMAINING CLOUDY ALL DAY AND HIGHS ONLY IN THE LOW TO MID 50S...WHILE LOCATIONS SOUTH OF INTERSTATE 70 SHOULD HAVE PARTIAL CLEARING THIS AFTERNOON AND TEMPERATURES RISING INTO THE MID 70S.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY/... WITH LOW PRESSURE CENTERED OVER SOUTHWEST PENNSYLVANIA FRIDAY MORNING...SKIES WILL REMAIN OVERCAST UNTIL THE LOW PUSHES EAST. ALTHOUGH SCATTERED SHOWERS WILL CONTINUE FRIDAY...CONDITIONS SHOULD DRY OUT BY THE EVENING. YESTERDAYS 12Z MODELS DEPICTED PRECIPITATION MOVING INTO THE REGION MORE QUICKLY ON SATURDAY...AND TONIGHTS 00Z MODELS HAVE CONTINUED THAT TREND. SIGNIFICANTLY INCREASED POPS FOR SATURDAY AFTERNOON...ESPECIALLY ACROSS THE SOUTH. TEMPERATURES WILL BE SLIGHTLY BELOW NORMAL ON FRIDAY WITH CLOUD COVER...WITH HIGHS INCREASING ABOUT 5 DEGREES ON SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... LATEST MODEL RUNS SHOW GOOD CONTINUITY WITH PREVIOUS RUNS AND OVERALL BETTER AGREEMENT IN REGARDS TO TIMING AND TRACK OF A SURFACE LOW CENTER PROGGED TO TRACK OVER SOUTHERN PORTIONS OF THE FORECAST AREA AND RESULT IN PRECIPITATION CHANCES SATURDAY NIGHT THROUGH MONDAY. OVER THAT TIME ENSEMBLES SHOW PWAT ANOMALIES BETWEEN 1.5 AND 2 STD DEVIATIONS ABOVE NORMAL AND M-CLIMATE RETURN INTERVALS OF 1-2...SO WITH THAT ANTICIPATE A FAIR AMOUNT OF QPF AS THINGS WRAP UP ON MONDAY WITH VALUES FROM AROUND 0.75 ACROSS THE NORTH TO OVER AN INCH SOUTH OF PITTSBURGH DURING THIS TIME. THIS IS SUPPORTED BY THE RAW GEFS MEAN...DETERMINISTIC QPF FORECAST BASED OFF A RE-FORECAST OF THE TOP ANALOGS...AND LATEST CIPS ANALOGS. AT THIS POINT THERE LOOKS TO BE A BREAK MONDAY EVENING THROUGH THE DAY ON WEDNESDAY DURING WHICH TIME RIDGING OVER THE WESTERN CONUS SIGNIFICANTLY STRENGTHENS AND TROUGHING DEEPENS ACROSS THE EASTERN CONUS IN RESPONSE. THERE IS RELATIVELY HIGH CONFIDENCE IN THE LONGWAVE TROUGH DEVELOPING BASED ON MODERNITY`S AND RMOP DATA...BUT HOW DEEP AND TIMING OF SHORTWAVES REMAIN A QUESTION. THERE HAS BEEN A DEEPENING TREND OVER THE PAST 10 MODEL RUNS OF THE PARENT LOW TO THE NORTH. AND WITH THAT IN MIND OPTED TO GO COOLER THAN SUPERBLEND GUIDANCE...BUT NOT TOO FAR BELOW CLIMO NORMS AS TEMP AND HEIGHT ANOMALIES ONLY SIT BETWEEN 1.5 TO 2 AT THIS POINT. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... CONDITIONS SHOULD DETERIORATE TO MVFR...WITH PATCHY IFR THIS MORNING AS RAIN SPREADS ACROSS THE REGION. ANY THUNDERSTORMS SHOULD BE PRIMARILY SOUTH OF KPIT. .OUTLOOK /THURSDAY NIGHT THROUGH MONDAY/... RESTRICTIONS ARE LIKELY INTO FRIDAY...AND AGAIN SAT NIGHT/SUN...AS AREAS OF LOW PRESSURE CROSS THE REGION. BASED OFF TOP ANALOGS...IFR AND POSSIBLY SOME LIFR MAY BE POSSIBLE ON SUNDAY. && .EQUIPMENT... KPBZ RADAR HAS BEEN DOWN SINCE TUESDAY EVENING. WITH ADDITIONAL PARTS ON ORDER...THE RADAR WILL REMAIN DOWN UNTIL AT LEAST THIS AFTERNOON. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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