Area Forecast Discussion
Issued by NWS Charleston, WV

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173 FXUS61 KRLX 141048 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 548 AM EST SUN FEB 14 2016 .SYNOPSIS... COMPLEX SYSTEM OVERRUNS SLOWLY EXITING ARCTIC AIR TODAY THROUGH MONDAY...FOR A MESSY CONCOCTION OF WINTRY WEATHER. THE SYSTEM EXITS EARLY TUESDAY...FOLLOWED BY ANOTHER TUESDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... FOCUS IN THE NEAR TERM IS ALMOST ENTIRELY ON THE UPCOMING WINTER STORM THREAT. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH SYNOPTIC PATTERN AS WELL AS LOW LEVEL THERMAL PROFILES. THIS IS ENTIRELY SNOW IN THE NEAR TERM WITH THIS UPPER LEVEL SYSTEM AND WAA EVENT. WHERE THE MODELS DIVERGE IS QPF AMOUNTS WHICH COULD MEAN THE DIFFERENCE BETWEEN 12 HR WARNING CRITERIA OR AN ADVISORY. THE NAM SEEMS TO BE THE WETTEST...ESPECIALLY ALONG AND N OF THE I64 CORRIDOR. GIVEN THE LINGERING DRY ARCTIC AIRMASS IN PLACE...ELECTED TO SIDE WITH A TAMER GFS WITH SOME INCORPORATION OF WPC GUIDANCE. NO DOUBT THE FIRST FEW HOURS OF ECHOES ON THE RADAR WILL GO TO MOISTENING THE COLUMN...SO TRIED TO SHAVE A BIT OFF THE SNOW AMOUNTS TO ACCOUNT FOR THIS ALONG WITH A LATER START TIME TO HEADLINES BY AN HOUR OR SO. AFTER COLLABORATION WITH SURROUNDING OFFICES...WE ISSUED A WINTER STORM WARNING FOR THE COAL FIELDS/SW VA/SE WV PLATEAU/POCAHONTAS COUNTY. THINKING 12 HR CRITERIA WILL BE MET WITH GENERALLY 3 TO 5 INCHES EXPECTED BY MID MORNING MONDAY AND 4 TO 6 INCHES IN RALEIGH COUNTY. POCAHONTAS WILL SEE A PROLONGED EVENT GIVEN COLD AIR DAMMING WHICH THE SHORT TERM FORECASTER WILL COVER. WE ISSUED AN ADVISORY FOR NE KY AND MOST OF SE OH AS WELL AS THE I 64 CORRIDOR IN WV. LOOKING AT PRIMARILY 1 TO 3 WITH THE HIGHER END OF THAT SPECTRUM IN NE KY AND ALONG I64 CORRIDOR IN WV LOWLANDS. WE ALSO ISSUED AN ADVISORY FOR FAYETTE/NICHOLAS/RANDOLPH FOR SNOW AND EVENTUALLY SOME FREEZING RAIN ON THE EASTERN PORTIONS OF THE THOSE COUNTIES BEYOND THE NEAR TERM. SO...EXPECT SNOW TO DEVELOP FROM SW TO NE LATE THIS AFTERNOON AND INTO THIS EVENING...BECOMING HEAVY AT TIMES IN SW VA AND S WV. TEMPERATURES WILL FALL THIS AFTERNOON WITH WETBULBING AND HOLD NEARLY STEADY IN THE 20S LOWLANDS AND TEENS MOUNTAINS TONIGHT BEFORE RISING TOWARD MORNING. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... PERIOD STARTS WITH AN ONGOING WARM ADVECTION EVENT MON MORNING THAT CONTINUES MUCH OF THE DAY. DEEP LAYER SW FLOW OVERRUNS LOW LEVEL SE FLOW AT THE SFC...IN THE WAKE OF AN UPPER LEVEL S/W TROUGH LIFTING AWAY FROM THE AREA THROUGH THE ERN GREAT LAKES AND THE UPPER OHIO VALLEY. THE WARMING BRINGS THE COLUMN ABOVE FREEZING BELOW H85...BUT WITH A SFC-BASED COLD LAYER HANGING ON MUCH OF THE DAY ACROSS THE LOWLANDS...AND THROUGH MON NT IN THE MOUNTAINS. MODELS HAVE SLOWED BACK DOWN WITH A SECOND S/W TROUGH THAT APPROACHES THE AREA MON NT AND THEN CROSSES TUE MORNING. THIS GENERATES A RELATIVELY WEAK SFC LOW OVER THE TN VALLEY MON THAT THEN TRACKS NE ACROSS THE LOWLANDS OF THE FCST AREA MON NT. THIS TAKES OUT THE SFC BASED COLD LAYER ACROSS MUCH OF THE LOWLANDS BUT THE COLD AIR DAMMING WEDGE E OF THE APPALACHIANS PERSISTS. THE TRACK OF THE SYSTEM RIGHT OVER THE AREA LEAVES THE COLUMN BELOW H85 VERY CLOSE TO FREEZING THROUGHOUT MUCH OF THE AREA MUCH OF MON...AND ACROSS NW PORTIONS OF THE AREA...AND IN THE MOUNTAINS...MON NT AND TUE. THIS GIVES RISE TO MUCH UNCERTAINTY IN THE FCST PRECIPITATION TYPES AND AMOUNTS. THE WARM ADVECTION EVENT ONGOING FROM THE NEAR TERM INTO MON FEATURES A QPF AXIS ACROSS SRN PORTIONS OF THE AREA...MOST OF IT OCCURRING WHILE THE COLUMN IS STILL COLD ENOUGH TO SUPPORT SNOW. MOST OF THE ICE IN THIS EVENT COMES MON NT AS WARM AIR ALOFT OVERRIDES THE COLD AIR IN THE DAMMING WEDGE E OF THE APPALACHIANS. HAVE UP TO A QUARTER INCH OF ICE IN THE GREENBRIER VALLEY...BUT THERE IS THE POTENTIAL FOR MORE AS THE NAM SUGGESTS. AS A RESULT...WARNINGS FOR SNOW ARE POSTED INTO MON FOR THE SRN COAL FIELDS AND THE SRN MOUNTAINS...AND FOR SNOW AND ICE IN THE GREENBRIER VALLEY INTO TUE MORNING. ADVISORIES MOSTLY FOR SNOW ARE POSTED INTO MON FOR THE CENTRAL LOWLANDS AND FOR SNOW...AND A BIT OF ICE ON THE ERN EDGES...FOR THE CENTRAL AND NRN MOUNTAINS OF WV THROUGH MON NT. AFTER A DRIER BUT OVERCAST INTERLUDE BETWEEN SYSTEMS TUE...06Z MODEL RUNS ARE FARTHER S WITH ANOTHER UPPER LEVEL S/W TROUGH AND ASSOCIATED LOW PRESSURE SYSTEM PROGGED TO CROSS TUE NT. THIS WOULD BRING COLDER AIR BACK INTO THE AREA FROM THE W THROUGHOUT THE COLUMN OVERNIGHT TUE NT...CHANGING ANY RAIN...FREEZING RAIN OR MIXED PRECIPITATION THAT RETURNS TUE EVENING...BACK TO SNOW...WITH LIGHT ADDITIONAL AMOUNTS POSSIBLE. USED MOSTLY A NAM/GFS BLEND FOR TEMPERATURES SFC AND ALOFT...ALSO INCLUDED THE ECMWF AND WPC FOR QPF. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... BEHIND THE DEPARTING LOW...ANOTHER CLIPPER TYPE SYSTEM EXPECTED TO IMPACT THE AREA...BRINGING A REINFORCING SHOT OF COOL AIR...AND CREATING LIGHT SNOW SHOWERS LATE TUESDAY NIGHT INTO WEDNESDAY. THERE ARE DIFFERENCES BETWEEN THE MODELS WITH THIS SYSTEM...WITH GFS AND NAM INDICATING A STRONGER SYSTEM THAN THE ECMWF. GENERALLY FIGURING AN INCH OR LESS ACROSS THE LOWLANDS...WITH 1 TO 3 ACROSS THE HIGHER TERRAIN. SOME LIGHT SNOW SHOWERS ARE STILL POSSIBLE THROUGH WEDNESDAY EVENING IN THE NORTHWESTERLY FLOW BEHIND THE DEPARTING SYSTEM. DRIER...AND GRADUALLY WARMING WEATHER EXPECTED BEHIND THE CLIPPER...WITH ANOTHER SYSTEM POSSIBLE LATE IN THE WEEK. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... SURFACE HIGH WILL PROVIDE FOR LIGHT WINDS THIS MORNING. VFR CONDITIONS WILL PREVAIL THRU 18Z AS MID/HI CLOUDS OVERSPREAD THE AREA. EXCEPTION BEING SOME PESKY STRATOCU OVER THE N MOUNTAINS WHICH MAY BRING KEKN/KCKB A PERIOD OF MVFR CIGS EARLY THIS MORNING. AN UPPER LEVEL SYSTEM WILL BE APPROACHING IN THE AFTERNOON WITH SNOW OVERSPREADING THE AREA FROM SW TO NE THRU THE EVENING. GIVEN DRY AIRMASS IN PLACE...VIRGA MAY BE REALIZED FOR A TIME BEFORE SNOW BEGINS TO REACH THE GROUND. HAVE USED THIS THINKING IN FORMULATING THE TAFS. AS THE SNOW REACHES THE GROUND CLOUDS BASES WILL LOWER INTO MVFR AS VSBY LOWERS INTO MVFR AND IFR. LOCALIZED LIFR VSBY IS POSSIBLE IN ANY HEAVIER SNOW BURSTS. TIMING LOOKS TO BE IN THE 21 TO 00Z TIME FRAME FOR KHTS/KBKW/KCRW AND 02 TO 04Z TIME FRAME FOR N TERMINALS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY... FORECAST CONFIDENCE: MEDIUM ALTERNATE SCENARIOS: TIMING OF SNOWFALL TOMORROW MAY VARY A FEW HOURS FROM FORECAST. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SUN 02/14/16 UTC 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 EST 1HRLY 05 06 07 08 09 10 11 12 13 14 15 16 CRW CONSISTENCY H H H H H H H H H H M M HTS CONSISTENCY H H H H H H H H H H M M BKW CONSISTENCY H H H H H H H H H H M M EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 12Z MONDAY... IFR CONDITIONS POSSIBLE IN LIGHT SNOW TOMORROW NIGHT AND MONDAY...TRANSITIONING TO A MIXED PRECIPITATION EVENT FOR MONDAY INTO TUESDAY. WESTERN SLOPES MAY IMPROVE FOR A TIME MONDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST TUESDAY FOR WVZ036>038-047. WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 1 PM EST MONDAY FOR WVZ024-025-033>035. WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST MONDAY FOR WVZ005>008-013>016-026-027. WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 10 AM EST TUESDAY FOR WVZ046. OH...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST MONDAY FOR OHZ083>087. KY...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 1 PM EST MONDAY FOR KYZ101>103-105. VA...WINTER STORM WARNING FROM 2 PM THIS AFTERNOON TO 1 PM EST MONDAY FOR VAZ003-004. && $$ SYNOPSIS...TRM/30 NEAR TERM...30 SHORT TERM...TRM LONG TERM...SL AVIATION...30

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