Area Forecast Discussion
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000 FXUS61 KPBZ 282215 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 515 PM EST FRI NOV 28 2014 .SYNOPSIS... A WARM FRONT CROSSES TONIGHT BRINGING SNOW SHOWERS ALONG AND NORTH OF INTERSTATE 80. A WARM UP IS IN STORE THIS WEEKEND AS WINDS ORIGINATE FROM THE SOUTH ALLOWING DAYTIME HIGHS TO CLIMB INTO THE 40S SATURDAY AND 50S SUNDAY. THERE WILL BE AN ABUNDANCE OF CLOUDS AND POSSIBILITY OF LIGHT RAIN SATURDAY NIGHT INTO SUNDAY. && .NEAR TERM /THROUGH SATURDAY/...
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WITH 5PM UPDATE...HAVE BUMPED UP POPS TO LIKELY FOR MUCH OF THE AREA THANKS TO A BAND OF SNOW CURRENTLY TRACKING ACROSS CENTRAL OHIO. THE BAND IS QUICKLY MOVING TO THE EAST AND WILL NOT LINGER MUCH MORE THAN AN HOUR IN ANY GIVEN LOCATION...BUT IT COULD DROP A QUICK QUARTER TO HALF INCH OF SNOW. THERE WILL BE LITTLE BREAK IN THE ACTIVE WEATHER REGIME WITH FAST MID LEVEL WINDS STEERING SYSTEMS THROUGH AT LESS THAN 12 HOUR INTERVALS. WARM FRONT RACES SE CLIPPING NORTHERN REACHES OF CWA OVERNIGHT. INCREASED CONSENSUS AMONGST 12Z NCEP CHAIN HAS YIELDED AN INCREASED IN POPS TO LKLY FOR I-80 REGION AFTER MIDNIGHT. THERE WILL BE A SHARP CUTOFF AS LOCATIONS ALONG AND SOUTH OF I-76 SHOULD REMAIN PRECIP FREE AFTER MIDNIGHT. ATMOSPHERE THERMAL PROFILE ILLUSTRATES ALL SNOW WITH THE ENTIRE COLUMN BELOW 0C. BEST CHANCE FOR MEASURABLE QPF WILL BE AROUND MIDNIGHT. ANY SNOW ACCUMULATION SHOULD BE AROUND AN INCH OR LESS. AS AREA GETS IN WARM SECTOR DURING THE PREDAWN HOURS...FORECAST A NON DIURNAL TEMPERATURE TREND...AS WINDS WILL PICK UP WHILE ANY INVERSION IS SCOURED OUT EVEN IN THE DEEPEST VALLEYS DUE TO BL FLOW OF 15KTS. BROAD SOUTHERLY FLOW IN THE LOWER LEVELS OF THE ATMOSPHERE PUMP MOISTURE FROM THE SOUTH...THUS DESPITE BEING IN THE WARM SECTOR OVERCAST OR NEAR OVERCAST SKY COVER IS PREDICTED FOR SATURDAY...ESPECIALLY IN THE AFTERNOON. ANY PCPN ARRIVES FIRST IN EASTERN OHIO BY AFTERNOON. BUFKIT SOUNDINGS DO NOT SHOW ANY THREAT OF MIXED PRECIPITATION FROM WAA ALOFT...SO LIGHT RAIN IS FORECAST. TEMPERATURES WERE CONSTRUCTED INITIALLY FROM THE GRIDDED LAMP TONIGHT THEN A BLEND OF THE EXISTING FORECAST AND ADJ MET BIAS CORRECTED GRIDS SATURDAY.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... WEATHER DOES NOT CHANGE MUCH SATURDAY NIGHT COMPARED TO DURING THE DAY AS BROAD LOW LEVEL SOUTHERLY FLOW CONTINUES TO BACK BUILD ALL THE WAY TO THE LOWER MISSISSIPPI RIVER VALLEY. CROSS SECTIONS OF POTENTIAL TEMPERATURE INDICATES UPGLIDE / POSITIVE PRESSURE ADVECTION FROM THE SURFACE TO 775MB. SPECIFIC HUMIDITY ARE SURPRISINGLY MODEST FOR THIS EVENT WITH VALUES REACHING 6GKG-1 SATURDAY NIGHT AT 290K. QPF VALUES WILL NOT BE THAT GREAT GIVEN LACK OF ANY SYNOPTIC SCALE WEATHER FEATURE. AMOUNTS WILL RUN ON THE ORDER OF FIVE HUNDREDTHS OR LESS...WHICH WARRANTS LIGHT RAIN ATTRIBUTE IN WEATHER GRIDS. INCREASED POPS TO LKLY FOR EASTERN OHIO AND NORTHWEST PA WHILE MAINTAINING CHANCE POPS ELSEWHERE. THE WEAK COLD FRONT WILL GRADUALLY MAKE IT`S APPROACH BY LATE SUNDAY. WHILE THE GREATEST CHANCE FOR MEASURABLE PRECIPITATION WILL NOT COME UNTIL THE FRONTS PASSAGE SUNDAY NIGHT...A STRONG MID- LEVEL JET SHOULD SUPPORT THE DEVELOPMENT OF SOME SHOWERS IN ADVANCE OF THE FRONT. THUS...LIKELY POPS WERE CARRIED OVER OHIO DURING THE DAY SUNDAY...WITH HIGH CHANCE ELSEWHERE. OUT AHEAD OF THE FRONT...STRONG W-SW FLOW SHOULD ALLOW FOR TEMPERATURES TO WARM ABOVE SEASONAL AVERAGES. THE MODELS GENERALLY AGREE THAT THE FRONT WILL BE THROUGH THE REGION BY MONDAY AFTERNOON...SO THE HIGH TEMPERATURES FOR THE DAY WILL BE REALIZED EARLY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... COOL TEMPERATURES WILL ONLY LINGER FOR A DAY BEFORE SOUTHWESTERLY FLOW RETURNS ON TUESDAY. NEARLY ZONAL PATTERN WILL SUPPORT FOR WEAK...FAST MOVING STORM SYSTEMS AND SHOWER CHANCES THROUGH THE END OF THE LONG TERM. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
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PREVAILING VFR ARE EXPECTED TO BE INTERRUPTED BY A PD OF RESTRICTIONS...MAINLY MVFR...TNGT AS A FAST SHRTWV INTERACTS WITH AN ADVNG WARM FRONT. THOSE RESTRICTIONS MAY LINGER UNTIL ABOUT DAYBREAK AT FKL AND DUJ WITH THE WARM FRONT IN VCNTY. OTHERWISE EXPECT A LGT SFC WIND BACKING FM SW TO S AS THESE FEATURES PROGRESS. OUTLOOK.../SATURDAY THROUGH WEDNESDAY/... THE NEXT CHANCE FOR WIDESPREAD RESTRICTIONS IS WITH THE ADVN AND PASSAGE OF A CDFNT DURING THE LATE SATURDAY THROUGH MONDAY PD.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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