Area Forecast Discussion
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000 FXUS61 KPBZ 132113 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 413 PM EST SAT FEB 13 2016 .SYNOPSIS... SNOW SHOWERS TAPER OFF THIS EVENING. VERY COLD TEMPERATURES WITH DANGEROUS WIND CHILLS ARE EXPECTED OVERNIGHT. THE NEXT WINTER SYSTEM ARRIVES LATE SUNDAY NIGHT AND MONDAY. && .NEAR TERM /THROUGH SUNDAY/... SCATTERED-NUMEROUS SHSN CONTINUE IN NW LAKE ENHANCED FLOW. ACTIVITY HAS BECOME MORE CELLULAR THANKS TO STEEP LOW LEVEL LAPSE RATES...WITH CONCENTRATED BANDING HARDER TO FIND. EXPECT ACTIVITY TO BEGIN TO WANE DURING THE LATE AFTERNOON/EVENING HOURS AS INSTABILITY WANES AND SNOW GROWTH BECOMES LESS FAVORABLE. MAY BE ONE OF THOSE SITUATIONS WHERE FLAKES CONTINUE TO FALL OUT OF DISSIPATING CLOUDS. WILL CANCEL RIDGE ADVISORY AT 3 PM...AND ANTICIPATE LAKE EFFECT ADVISORY EXPIRING AT 7 PM. NW FLOW DIES DOWN OVERNIGHT...AND EXPECT THE SNOW SHOWERS TO DO LIKEWISE. SOME CLEARING SHOULD NUDGE IN FROM THE SOUTHWEST WITH TIME WITH SURFACE HIGH APPROACHING. SHOULD BE ABLE TO MAINTAIN ENOUGH WIND TO KEEP THE WIND CHILL ADVISORY GOING. DID TWEAK LOW TEMPS UPWARD SLIGHTLY IN A FEW AREAS IN RESPONSE TO LATEST GUIDANCE...BUT BELOW ZERO READINGS SHOULD STILL BE COMMON. SUNDAY WILL BE MOSTLY DRY WITH SUNSHINE IN THE MORNING...BEFORE MID AND HI CLOUDS WILL BEGIN TO INVADE DURING THE AFTERNOON. THE FIRST SNOW MAY ARRIVE NEAR ZZV JUST PRIOR TO 00Z MONDAY IN A DEVELOPING OVERRUNNING PATTERN. NOT MUCH CHANGE TO FORECAST HIGHS...STILL 15 TO 20 DEGREES BELOW NORMAL. CL && .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 /21Z SATURDAY THROUGH THURSDAY/... LAKE-ENHANCED SNOW SHOWERS WILL CONTINUE THROUGH THE AFTERNOON. MOST ORGANIZED BAND EXTENDS THROUGH BVI/PIT AT THE MOMENT BUT EXPECT ITS POSITION TO WOBBLE A BIT. MORE DISORGANIZED SHSN ARE EXPECTED ELSEWHERE. MVFR TO VFR CIGS ARE GENERALLY EXPECTED OUTSIDE OF SHSN...BUT BRIEF IFR IS POSSIBLE...OR EVEN LIFR CLOSER TO I-80. GUSTY WNW WILL CONTINUE AS WELL. BY THIS EVENING...SHSN COVERAGE WILL BE ON THE WANE AND WINDS WILL BECOME LESS GUSTY. EXPECT CIGS TO SCATTER OUT OVERNIGHT FROM PIT ON SOUTH AT LEAST. VFR CONDITIONS SHOULD BE ESTABLISHED IN MOST LOCATIONS BY SUNRISE ON SUNDAY...WITH HIGH CLOUDS ADVANCING OVER ANY REMAINING STRATUS. CL .OUTLOOK.../SATURDAY NIGHT THROUGH WEDNESDAY/... 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...LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ007>009. 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. && $$

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