Area Forecast Discussion
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000 FXUS61 KPBZ 270915 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 415 AM EST THU NOV 27 2014 .SYNOPSIS... ANOTHER SHOT OF COLD AIR WILL MOVE THROUGH LATER TODAY AND TONIGHT. THIS WILL PROVIDE THE RISK FOR SNOW SHOWERS. HIGH PRESSURE WILL IMPROVE CONDITIONS ON FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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COLDER AIR WILL SLOWLY SPREAD ACROSS THE AREA TODAY. FLOW AT THE MID AND UPPER LEVELS WILL REMAIN LIGHT AND UNORGANIZED THROUGH MUCH OF THE DAY. DURING THE AFTERNOON...MIXING HEIGHTS WILL RISE AS LARGE SCALE ASCENSION INCREASES AHEAD OF A SHORTWAVE TROUGH. COLDER AIR AT 850 MB WILL MARCH EASTWARD AND THE FLOW ALOFT WILL INCREASE AND BECOME BETTER ORGANIZED. MIXING HEIGHTS WILL RISE ENOUGH TO REACH THE SNOW GROWTH ZONE. WILL SLOWLY INCREASE POPS THIS AFTERNOON...WITH THE HIGHEST NUMBERS ACROSS THE NORTH AND RIDGES.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... A SERIES OF WEAK UPPER LEVEL WAVES WILL CROSS THE AREA TONIGHT. THIS WILL DRIVE THE HEART OF THE COLD AIR SOUTHEASTWARD ACROSS THE REGION. FLOW WILL REMAIN GENERALLY OUT OF THE NORTHWEST TONIGHT...SO WILL EXPECT SNOW SHOWERS TO CONTINUE UNTIL THE SECOND WAVE EXITS AROUND DAWN FRIDAY. AGAIN...WILL FOCUS THE HIGHEST POPS ACROSS THE NORTH(LAKE INFLUENCE)...AND RIDGES(OROGRAPHIC EFFECT). SHORTWAVE WILL QUICKLY EXIT TO THE EAST FRIDAY MORNING... INVERSIONS WILL LOWER AND SUBSIDENCE WILL INCREASE AS BROAD HIGH PRESSURE MOVES EASTWARD ACROSS THE LOWER OHIO VALLEY. ANY LINGERING SNOW SHOWERS WILL QUICKLY END FRIDAY MORNING. THE COLD POOL ALOFT WILL SLOWLY EJECT TO THE NORTH WHICH WILL ALLOW FOR A DECREASE IN CLOUD COVER. WAA WILL CONTINUE SATURDAY NIGHT AS A WARM FRONT CROSSES THE AREA AND FLOW IN THE LOWER AND MID-LEVELS BECOMES SOUTH-SOUTHWESTERLY. MODELS ARE HINTING AT THE DEVELOPMENT OF ISOLATED SNOW SHOWERS DEVELOPING WITH THE PASSING FRONT. WILL INCLUDE SCHC POPS FRIDAY NIGHT. A WEAK DISTURBANCE WILL CROSS ON SATURDAY...WHICH WILL TEMPORARILY PUT THE BREAKS ON THE WAA. COULD SEE A PASSING SHOWER SATURDAY AFTERNOON...BUT DEEP MOISTURE IS LACKING AND THE WAVE IS UNIMPRESSIVE. FOR NOW WILL LEAVE SATURDAY DRY. TEMPERATURES WILL MODERATE ON SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... SHOWER CHANCES WILL INCREASE SUNDAY...AHEAD OF THE NEXT COLD FRONT. FRONT WILL CLEAR THE AREA EARLY MONDAY MORNING. SHOWERS WILL END BUT TEMPS WILL COOL DOWN ON MONDAY. HIGH PRESSURE WILL PROVIDE A DRY AND CHILLY TUESDAY...WITH TEMPS MODERATING ON WEDNESDAY. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... ALTHOUGH MOST SITES HAVE IFR CONDITIONS AS OF 00Z...DIFFICULTY WITH TONIGHTS FORECAST IS DETERMINING WHEN CONDITIONS WILL LIFT TO MVFR. THINK THAT MANY SITES WILL SEE SOME IMPROVEMENT BY MIDNIGHT...WHILE OTHERS WILL LIKELY REMAIN IFR UNTIL MORNING. LOW LEVEL MOISTURE IS SHALLOW...BUT WITH VERY LIGHT FLOW...THERE MAY NOT BE MUCH OF A MECHANISM TO PREVENT AIR FROM STAGNATING. SCATTERED LAKE EFFECT SHOWERS ARE EXPECTED TO DEVELOP BY THURSDAY AFTERNOON...BUT COVERAGE WILL NOT BE NOT HIGH ENOUGH TO WARRANT TAF MENTION AT THIS TIME. OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/... NON VFR DEVELOPING THURSDAY IN -SHSN...LINGERING ACROSS NW PA INTO FRIDAY. NON-VFR SUNDAY IN -SHRA WITH THE NEXT FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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