Area Forecast Discussion
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520 FXUS61 KPBZ 140141 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 841 PM EST SAT FEB 13 2016 .SYNOPSIS... VERY COLD TEMPERATURES AND DANGEROUS WIND CHILL INDICES CAN BE EXPECTED TONIGHT. && .NEAR TERM /THROUGH SUNDAY/... NO CHANGES WERE NEEDED FOR THE LATE EVE UPDATE AS SNOW SHOWER POTENTIAL CONTS TO FADE WITH WEAKENING FLOW. OTHERWISE...THE WIND CHILL ADVISORY HAS BEEN MAINTAINED ALTHOUGH BUILDING HIGH PRES WILL CONT TO GRADUALLY DEGRADE THE WIND COMPONENT. NO CHANGE WAS NEEDED FOR THE FRIGID TEMP PROGNOSIS. SUNDAY WILL BE GENERALLY DRY AND CONTINUED COLD...EVEN THOUGH MID AND HIGH CLOUDINESS IS EXPECTED TO RAPIDLY ENCROACH AS WARM...MOIST ADVECTION ENSUES IN ADVN OF ANOTHER SHORTWAVE TROUGH. LIGHT SNOW MAY DEVELOP NEAR ZZV AS NIGHT FALLS...CHC POPS WERE MAINTAINED IN THAT VICINITY. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... SHORTWAVE MOVING EAST ACROSS THE GREAT LAKES WILL BRING WARM ADVECTION ALONG WITH AN INCREASE IN DEEPER MOISTURE SUNDAY NIGHT INTO MONDAY. THIS WILL GIVE A PERIOD OF SNOW ESPECIALLY SOUTH OF PITTSBURGH WITH SOME ACCUMULATION POSSIBLE. TEMPERATURES LOOK TO RISE LATER SUNDAY NIGHT AND WILL PUSH TO NEAR THE SEASONAL AVERAGES MONDAY. SOUTHWARD DIGGING SHORTWAVE IN THE UPPER TROUGH AND PIVOTING UPPER LEVEL JET WILL SUPPORT A LOW PRESSURE SYSTEM THAT WILL RIDE NORTHWARD ALONG THE MID-ATLANTIC STATES MONDAY...FOLLOWED BY ANOTHER SYSTEM ON TUESDAY. THERE REMAIN SOME UNCERTAINTY IN THE TRACK OF THIS SYSTEM...WITH THE GFS MUCH FASTER AND LESS AMPLIFIED WITH THE FIRST LOW THAN THE ECMWF AT THIS TIME. BASED ON NATIONAL GUIDANCE AND CURRENT MODEL TRENDS...HAVE OPTED TO SIDE WITH THE GFS. WHILE WARM ADVECTION IS NOT AS STRONG AS IT IS ON THE ECMWF...THERE ARE SOME P-TYPE CONCERNS...ESPECIALLY ON TUESDAY AS THE SECOND LOW PRESSURE MOVES OVER THE OHIO VALLEY. MODEL SOUNDINGS...WHILE ON THE COOLER SIDE...SUPPORT LOWER SNOW RATIOS MONDAY NIGHT...WITH THE BEST LIFT PLACED BELOW THE LAYER FOR EFFICIENT SNOW GROWTH. THUS...THE CURRENT SNOWFALL FORECAST WAS DEPICTED AS SUCH. HOWEVER...IF THE QPF THAT IS FORECAST IN THE MODEL MATERIALIZES...SNOW AMOUNTS COULD REACH VALUES FOR HEADLINES. AT THIS POINT...HAVE HIGHLIGHTED THESE CONCERNS IN THE HWO. TEMPERATURES WERE CONSTRUCTED HEAVILY ON THE GFS WITH CONSIDERATION FOR ENSEMBLE GUIDANCE. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... SECOND LOW WILL BE CROSSING TUESDAY NIGHT WITH WARM ADVECTION CONTINUING. AGAIN...P-TYPE ISSUES REMAIN WITH RAIN AND SNOW CHANGING TO SNOW WITH COLD ADVECTION WEDNESDAY WITH THE SYSTEMS DEPARTURE. RIDGING AND A WARM UP LOOKS TO TAKE PLACE BY LATE IN THE PERIOD. HEAVY EMPHASIS WAS USED ON THE SUPERBLEND FOR THE LONG TERM. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... STILL CANNOT RULE OUT SOME MVFR OR EVEN IFR VISIBILITIES IN SNOW SHOWERS...ALTHOUGH SNOW SHOWER COVERAGE SHOULD RAPIDLY DECREASE THIS EVENING. WIND GUSTS WILL ALSO DIMINISH WITH NIGHTFALL. MID LEVEL CLOUDS SHOULD SCATTER OUT AS WINDS BACK TO THE WEST- SOUTHWEST...AND THE WINDS WILL CONTINUE TO BACK THROUGH THE PERIOD. ALTHOUGH HIGH LEVEL CLOUDS WILL MOVE DURING THE DAY ON SUNDAY...CONDITIONS SHOULD REMAIN VFR. CANNOT RULE OUT SNOW ARRIVING TO ZZV BY 00Z MON...BUT THE ODDS ARE LOW AT THIS TIME. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... LOW PRESSURE SYSTEMS WILL BRING WIDESPREAD RESTRICTIONS LATER SUNDAY NIGHT THROUGH WEDNESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR MDZ001. OH...WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR OHZ040-041-050. PA...WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR PAZ007>009- 013>016-020>023-029-031-073>076. WV...WIND CHILL ADVISORY UNTIL 9 AM EST SUNDAY FOR WVZ001-002-021- 509>514. && $$ 15/33

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