Area Forecast Discussion
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000 FXUS61 KPBZ 220215 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 1015 PM EDT THU MAY 21 2015 .SYNOPSIS... COOL TEMPERATURES WILL REMAIN THROUGH LATE WEEK. A WEAK DISTURBANCE WILL BRING SHOWERS MAINLY FROM PITTSBURGH SOUTH THIS MORNING. && .NEAR TERM /THROUGH FRIDAY/... LATE EVENING UPDATE TO SPEED UP THE EXODUS OF THE CLOUDS AND LIGHT RAIN/SPRINKLES THAT HAVE LINGERED AS A RESULT OF THE PASSING UPPER LEVEL WAVE. MOISTURE CONTINUES TO ERODE...BUT WITH MOST OF THE RESIDUAL MOISTURE BELOW 800MB...SOME DAMMING OF CLOUDS AND DRIZZLE MAY OCCUR UP AGAINST THE HIGHER TERRAIN OF PA/WV/MD FOR THE NEXT FEW HOURS. TEMPERATURES WILL BE A BIT TRICKY TONIGHT AS A LARGE CLOUDLESS VOID WILL MOVE OVER THE FORECAST AREA...ALLOWING MANY LOCATIONS TO RADIATE DOWN. BUT THE NEXT...MUCH WEAKER...WAVE WILL SWING DOWN FROM THE WESTERN GREAT LAKES NEAR DAY BREAK. THIS WAVE WILL BRING AT LEAST CLOUDS BACK TO THE AREA...AND SOME POSSIBLE LIGHT RAIN SHOWERS AS WELL. DIDNT REALLY SEE ANY REASON TO MODIFY THE CURRENT FORECAST FOR FRIDAY THAT INCLUDES A MENTION OF ISOLATED RAIN SHOWERS. REGARDLESS OF PRECIPITATION...THE OPPORTUNITY FOR AT LEAST SOME SUNSHINE GROWS THROUGH FRIDAY AFTERNOON AS THE WAVE DEPARTS. TAX && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... WITH SKIES CLEARING OUT QUICKLY FRIDAY EVENING AND HIGH PRESSURE RESIDING OVER WESTERN PENNSYLVANIA BY SUNRISE SATURDAY...CONDITIONS WILL BE PRIME FOR A NIGHT OF RADIATIONAL COOLING. RAW MODEL GUIDANCE FROM THE 12Z GFS IS NEARLY 10 DEGREES COLDER THAN THE NAM/SREF...ALTHOUGH MOS LOWS BETWEEN THE NAM AND GFS ARE RELATIVELY SIMILAR. WITH THE IDEAL RADIATIONAL COOLING CONDITIONS...HAVE NUDGED THE FORECAST IN THE DIRECTION OF THE RAW GFS FORECAST. OVERALL...THIS GENERALLY BROUGHT FRIDAY NIGHT LOWS DOWN 2-3 DEGREES...BUT DID NOT NEED TO EXPAND MENTION OF FROST TOO MUCH FROM PREVIOUS FORECAST. CONSIDERING LOW TEMPERATURE FORECAST ALONG THE INTERSTATE 80 CORRIDOR IS RIGHT AROUND FREEZING...DECIDED TO ISSUE A FREEZE WATCH FOR SEVERAL COUNTIES. HIGH PRESSURE WILL MOVE OFFSHORE SATURDAY NIGHT...AND LOW PRESSURE DEVELOPING ACROSS THE CENTRAL PLAINS WILL SPREAD A WIDE SWATH OF SHOWERS AND THUNDERSTORMS ACROSS THE CENTRAL UNITED STATES. HIGH CLOUDS WILL MOVE INTO THE AREA SATURDAY AND SATURDAY NIGHT...WITH LOWER CLOUDS MOVING IN FOR SUNDAY. HOWEVER...APPEARS THAT ANY LIFTING MECHANISM WILL REMAIN TOO FAR WEST TO PRODUCE ANY SHOWERS LOCALLY. SUNSHINE ON SATURDAY WILL ALLOW HIGHS TO RISE A FEW DEGREES WARMER THAN FRIDAY...WITH SOUTHERLY WINDS ON SUNDAY BRINGING ANOTHER INCREASE TO HIGHS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... UPPER RIDGING OVER THE SOUTHEAST CONUS IS EXPECTED TO DEVELOP BY EARLY NEXT WEEK...AS SHORTWAVES ADVANCE ALONG THE NORTHERN PERIPHERY OF THE RIDGE. MAINTAINED CHANCE POPS FOR THE HOLIDAY FORECAST AS THE STRENGTH OF RIDGING AND PLACEMENT OF A SURFACE BOUNDARY ACROSS THE AREA REMAIN IN QUESTION. SOUTHWEST FLOW IS PROGGED TO DEVELOP THEREAFTER WITH OCCASIONAL WEAK EMBEDDED CROSSING SHORTWAVES. THIS WILL CONTINUE PERIODIC CHANCES FOR SHOWERS/STORMS. USED WPC BASED ENSEMBLE MEAN GUIDANCE WITH DOWNWARD ADJUSTMENTS TO POPS TO HELP SMOOTH OUT INDIVIDUAL MODEL DIFFERENCES...ESPECIALLY FOR MONDAY. TEMPERATURES SHOULD AVERAGE ABOVE SEASONAL LEVELS. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... HIGH PRESSURE AND DRIER AIR ARE QUICKLY MOVING IN FROM THE WEST. VFR CIGS WILL BREAK UP TO SCT CLOUDS DURING THE EVENING HOURS...AND VFR WITH LIGHT WINDS WILL CONTINUE THROUGH THE NIGHT. A FRONT SINKS INTO THE AREA ON FRIDAY. MOISTURE IS LIMITED...AND GUIDANCE INDICATES THAT SHRA SHOULD REMAIN WIDELY SCATTERED AND CIGS SHOULD REMAIN VFR. WINDS WILL KICK UP OUT OF THE WEST AS THE FRONT APPROACHES...AND NORTHWEST WINDS GUSTING TO 15-25 KNOTS ARE EXPECTED BEHIND THE FRONT. SKIES WILL THEN CLEAR TOWARDS SUNSET. CL .OUTLOOK.../FRIDAY THROUGH TUESDAY/... RESTRICTIONS ARE POSSIBLE WITH A LATE SUNDAY AND MONDAY WARM FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR PAZ007>009-015-016. WV...NONE. && $$

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