Area Forecast Discussion
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000 FXUS61 KPBZ 010952 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 452 AM EST SUN FEB 1 2015 .SYNOPSIS... LOW PRESSURE WILL BRING WINTRY WEATHER SUNDAY INTO MONDAY WITH COLD TEMPERATURES FOR TUESDAY MORNING. ANOTHER COLD FRONT FOR THE WEDNESDAY NIGHT WILL REINFORCE COLD AIR FOR THE LATTER PART OF THE WEEK. && .NEAR TERM /THROUGH MONDAY/... WARMER TREND IN THE MODELS CONTINUES. SURFACE LOW TRACKS INTO THE OHIO VALLEY LATER TODAY...AND THEN ENE INTO THE CWA BY 12Z MONDAY. INITIAL LIGHT BAND OF PRECIP THIS MORNING WILL MAINLY BE IN THE FORM OF SNOW. BEST ACCUMULATION OF AN INCH OR TWO WILL BE SEEN ACROSS THE WESTERN CWA. THIS BAND LIFTS OUT BY THIS AFTERNOON...WITH A DRY SLOT THEN ENTERING THE CWA FROM THE SOUTHWEST. THIS MAY REDUCE PRECIP TO DRIZZLE FOR A TIME AS IT ROTATES ACROSS THROUGH THE EARLY EVENING. FIRST OF TWO LOW LEVEL WARM PUNCHES ALSO ARRIVES...WITH AREAS SOUTH OF I-70 TURNING TO LIQUID BY 00Z. SECOND WARM PUNCH ACCOMPANIES APPROACH OF H850 LOW TONIGHT...WHICH WILL TRACK ACROSS NORTHERN OHIO TO ERIE BY 12Z MONDAY. INCREASING SW FLOW WILL BRING A RENEWED FEED OF MOISTURE...AND ALSO THE H850 ZERO LINE TO JUST SOUTH OF I-80. THUS...SNOW WILL MIX WITH RAIN AND FREEZING RAIN...BEFORE TURNING TO ALL RAIN FOR THE MAJORITY OF THE CWA BY 06Z MONDAY. SURFACE LOW PASSES NEAR OR JUST SOUTH OF PIT LATE TONIGHT...WHICH WILL TURN WINDS TO MORE OF A WESTERLY COMPONENT AND START TO BRING COLDER AIR BACK IN. EXPECT MOST OF OHIO TO TURN BACK TO SNOW BY 12Z MONDAY...WITH REST OF CWA FOLLOWING IN QUICK ORDER LATER MONDAY MORNING. POPS DECREASE AS WELL WITH DEEPER MOISTURE BEING SHUNTED OFF TO THE EAST. AFTER COLLABORATION...ELECTED TO DOWNGRADE COLUMBIANA AND BEAVER COUNTIES TO AN ADVISORY...AND LEFT ALL OTHER HEADLINES INTACT FOR NOW. WILL NOT BE SURPRISED IF A FURTHER NORTHWARD MOVEMENT OF WARNINGS/ADVISORIES IS NEEDED LATER TODAY DEPENDING ON EVENTUAL STRENGTH OF WARM SURGE. FOREST/VENANGO/MERCER STILL PICTURED AS REMAINING MOSTLY SNOW...ALTHOUGH A BRIEF MIX WILL STILL BE POSSIBLE TONIGHT. WINTRY MIX AND RAIN WILL HOLD BACK ACCUMULATIONS SOUTH OF THERE. CL && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/... DRY SLOT WILL BEGIN PUSHING EAST OF THE CWA LINE BY MON MORNING AS WE TRANSITION TO COLD ADVECTION IN THE WAKE OF THE LOW. 12Z MON MARKS A GOOD TRANSITION POINT IN THE SYSTEM AS MOST PRECIP WILL HAVE FULLY CHANGED OVER TO SNOW AS THE SFC LOW MOVES EAST THROUGH PA. STRATIFORM SNOW WILL STILL BE PRESENT THROUGH MID-MORNING AS THE MID-LEVEL DEFORMATION BAND EVIDENT ON THE LATEST NAM SWINGS THROUGH...DESPITE A STOUT 500MB JET THAT WILL INJECT DRY AIR INTO AXIS OF THE UPPER LOW. COPIOUS MOISTURE STILL EXISTS FROM THE SFC TO 700MB AND REMAINS THROUGH THE EARLY EVENING AS THE BOTTOM DROPS OUT ON THE MID-LEVEL TEMPS. VERY STRONG CAA WILL BRING 850MB TEMPS DOWN NEARLY 20C IN THE MATTER OF 12HRS. THE DENDRITIC GROWTH ZONE WILL DROP LIKE AN ANCHOR TO THE SFC ALLOWING EVERY BIT OF MOISTURE TO PRECIPITATE OUT IN THE FORM OF SNOW. RAPID COOLING OF THE MID-LEVELS WILL TRANSLATE TO THE SFC CAUSING ADDITIONAL PROBLEMS AS SFC TEMPS ARE EXPECTED TO DECREASE THROUGH THE DAY. THIS WILL MEAN THAT UNTREATED PAVEMENT SURFACES COULD SEE FLASH FREEZING...AND THAT SLICK SPOTS COULD EXIST EVEN IN THE ABSENCE OF EARLIER HEAVY SNOW OR MIXED PRECIPITATION. SNOW SHOWERS IN COLD AIR BEHIND THE UPPER LOW COULD PRODUCE AROUND AN INCH OF FLUFFY ACCUMULATION ACROSS MUCH OF THE LOWLAND COUNTIES...WITH A LITTLE MORE IN THE RIDGES OF PA/MD/WV AND UP NORTH. EXPECTING FLUFFY SNOW SHOWERS TO FINALLY TAPER DOWN TO FLURRIES AND THEN FULLY CEASE BY MIDNIGHT MON AS THE MOISTURE DRIES UP. TEMPERATURE FORECAST TUES MORNING IS TRICKY...AS SOON AS THE COLD AIR ARRIVES...ITS GONE AND WAA BEGINS TO KICK IN BY DAY BREAK TUES. WILL REMAIN BELOW GUIDANCE TUES MORNING AS WE DECOUPLE UNDER HIGH PRESSURE WITH CLEARING SKIES AND A LINGERING SNOWPACK. CALM SFC WINDS MAY PRECLUDE THE NEED FOR A WIND CHILL ADVISORY ALONG THE NORTH TUES MORNING...BUT IT WILL BE DOWNRIGHT COLD REGARDLESS. TAX && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... THE TEMPORARY EXODUS OF HIGH PRESSURE MARKS THE BEGINNING OF THE EXTENDED AS A WEAK LOW MOVES THROUGH THE SRN GREAT LAKES BY MID-WEEK. THIS RELATIVELY DRY SYSTEM SHOULD PRODUCE LIGHT SNOW ALONG THE NRN PERIPHERY OF THE CWA WEDS INTO THURS...BUT JUST AS IMPORTANT...THE TRAILING COLD FRONT WILL REINFORCE THE UPPER LEVEL TROF AS COLD AIR POURS IN TOWARDS THE END OF THE WEEK. HIGH PRESSURE WILL ENSURE A DRY START TO THE WEEKEND...BUT ANOTHER LOW IS POISED TO IMPACT THE AREA BY NEXT SUN. TAX && .AVIATION /09Z SUNDAY THROUGH THURSDAY/... ALL SITES VFR AT THE MOMENT...BUT THIS WILL BE CHANGING OVER THE NEXT FEW HOURS. SNOW WILL SPREAD IN FROM THE WEST THROUGH THE PREDAWN HOURS....DROPPING TERMINALS TO MVFR AND THEN TO IFR BY SUNRISE. A DRY SLOT IS STILL EXPECTED TO WORK IN DURING THE AFTERNOON HOURS. MOST TERMINALS COULD SEE A PERIOD OF DZ OR VERY LIGHT RAIN...AND POSSIBLY A BRIEF PERIOD OF VFR IF CLOUDS CAN BREAK ENOUGH. FKL MAY BE THE EXCEPTION IN KEEPING STEADY PRECIPITATION. MOISTURE RETURNS WITH APPROACH OF SURFACE LOW AFTER SUNSET...BRINGING STEADY PRECIPITATION BACK. WARMER AIR WILL CONTINUE TO BLEED NORTHWARD...WITH A WINTRY MIX OR PLAIN RAIN EXPECTED AT MOST TERMINALS SOUTH OF I-80 ALONG WITH IFR CONDITIONS. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... WIDESPREAD RESTRICTIONS CAN BE EXPECTED INTO MONDAY AS A LOW PRESSURE SYSTEM CROSSES THE REGION. NEXT CHANCE FOR WIDESPREAD RESTRICTIONS WILL BE WITH A WEDNESDAY COLD FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...WINTER WEATHER ADVISORY UNTIL NOON EST MONDAY FOR OHZ039-040- 048>050-057>059. WINTER STORM WARNING UNTIL NOON EST MONDAY FOR OHZ041. PA...WINTER WEATHER ADVISORY UNTIL NOON EST MONDAY FOR PAZ021-029- 073-074. WINTER STORM WARNING UNTIL NOON EST MONDAY FOR PAZ007>009- 013>016-020-022-023. WV...WINTER WEATHER ADVISORY UNTIL NOON EST MONDAY FOR WVZ001>003. && $$

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