Area Forecast Discussion
Issued by NWS Charleston, WV

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551 FXUS61 KRLX 121054 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 554 AM EST FRI FEB 12 2016 .SYNOPSIS... ARCTIC FRONT CROSSES THIS EVENING...ACCOMPANIED BY SNOW SHOWERS INTO SATURDAY...AND BITTERLY COLD WEATHER FOR THE WEEKEND. A COMPLEX SYSTEM COULD BRING MIXED PRECIPITATION EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/...
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UPDATED... 545 AM UPDATE... TWEAKED POPS THIS AFTERNOON TO LOWER A BIT OUTSIDE OF THE MOUNTAINS. LOW CONFIDENCE ON EXTENT OF ANY SNOW SHOWER ACTIVITY BEHIND DEPARTING S/W AND AHEAD OF ARCTIC FRONT. PREVIOUS DISCUSSION BELOW... A FAST MOVING UPPER LEVEL IMPULSE WILL ROUND THE BASE OF THE MEAN TROF OVER THE E CONUS TODAY. THIS WILL BRING A SWATH OF MAINLY LIGHT SNOW TO S KY/SW VA/AND PORTIONS OF SE WV. QPF AMOUNTS LOOK LIGHT...RANGING A FEW HUNDREDTHS TO AROUND A TENTH. AFTER INCORPORATING THE LATEST RAP/HRRR RUNS FOR QPF AND CONVERTING TO SNOW USING NAM SNOW RATIOS RESULTED IN MAINLY ONE INCH AMOUNTS OVER THOSE LOCATIONS WITH UP TO 2 INCHES ON THE E RIDGE OF DICKENSON COUNTY. SINCE HEADLINES ARE ALREADY OUT SURROUNDING SW VA AND THE FORECAST AMOUNTS OF 1 TO 2 INCHES...ELECTED TO HOIST A WINTER WX ADV UNTIL THIS AFTERNOON FOR THOSE COUNTIES. ELSEWHERE...THINKING IT WILL BE HARD FOR MEASURABLE PRECIP TO MAKE IT N ASIDE FROM THE MOUNTAINS. THUS ANTICIPATE A PARTLY TO MOSTLY CLOUDY DAY ELSEWHERE WITH TEMPS RECOVERING INTO THE UPPER 20S TO LOWER 30S. ATTENTION THEN TURNS TO AN ARCTIC FRONT WHICH WILL USHER IN THE COLDEST TEMPERATURES OF THE SEASON FOR THE WEEKEND. SOME SNOW SHOWERS MAY BREAK OUT AHEAD OF THE FRONT LATE THIS AFTERNOON BUT OVERALL WILL WAIT FOR FROPA WHICH WILL BRING WITH IT A HEALTHY DOSE OF SQUALLS WITH PLUMMETING TEMPERATURES AND GUSTY WINDS. THESE LOOKS TO PUT DOWN A SKIFF WITH SOME LOLLIPOP AMOUNTS TO AN INCH IN THE LOWLANDS. HAVE THE FRONT CROSSING IN THE 00Z TO 06Z TIME FRAME FROM NW TO SE ACROSS THE REGION. WITH PLUMMETING H85 TEMPS AND CROSS FLOW...THINK EFFICIENT MOMENTUM TRANSFER WILL BE REALIZED TO CREATE VERY GUSTY WINDS. HAVE CODED UP SOME 20 TO 30 KT GUSTS OVERNIGHT...WITH GUSTS TO 40 KTS OVER THE HIGHER ELEVATIONS OF THE WV MOUNTAINS. SURFACE TEMPERATURES WILL BOTTOM OUT IN THE SINGLE DIGITS TO LOWER TEENS OUTSIDE OF THE MOUNTAINS BY 12Z SATURDAY...WITH BLO ZERO READINGS IN THE HIGHER ELEVATIONS. WIND CHILL CONUNDRUMS WILL BE REALIZED OVER THE HIGH TERRAIN AND ADJACENT COUNTIES. AFTER COORDINATION WITH SURROUNDING OFFICES WE ELECTED TO RAISE A WIND CHILL WATCH FOR RANDOLPH/POCAHONTAS AND A WIND CHILL ADVISORY FROM RALEIGH TO TAYLOR COUNTIES IN WV. MENTIONED THE HIGH WINDS IN THE HEADLINE. SNOW SHOWERS WILL CONTINUE BEHIND THE FRONT...MOST NUMEROUS IN THE MOUNTAINS WHERE A GENERAL 2 TO 4 INCHES ARE FORECASTED WHICH FALLS SHORT OF ADVISORY LEVEL AMOUNTS. SNOW SHOWERS WILL DIMINISH OUTSIDE OF THE MOUNTAINS LATE TONIGHT...BECOMING CONFINED TO MOISTURE STREAMS FROM LAKE MICHIGAN CONTRIBUTIONS.
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&& .SHORT TERM /SATURDAY THROUGH MONDAY/... SAT MORNING FINDS THE FCST AREA IN THE DEEP FREEZE AND DEEP LAYER NW UPSLOPE FLOW. HIGH PRESSURE REPRESENTING THE CENTER OF THE ARCTIC AIR MASS BUILDS OVER THE AREA LATE DAT NT...BEFORE MOVING ON TO THE E ON SUNDAY. THE APPROACHING HIGH WILL CUT OFF THE NW FLOW...KILLING ANY LAKE PLUMES SAT MORNING...AND THEN THE UPSLOPE SNOW SHOWERS SAT NT. FLUFFY BUT MINOR ADDITIONAL ACCUMULATIONS ARE POSSIBLE UNTIL THEN WITH TEMPERATURES ALOFT FAVORING DENDRITIC GROWTH IF NOT ALMOST TOO LOW...-22C AT H85. AS THE DEEP L/W TROUGH STARTS TO LIFT OUT...AND A S/W TROUGH APPROACHES FROM THE NW...THE AREA GETS INTO A WARM ADVECTION PATTERN THAT WILL BRING ON INCREASING CLOUDINESS SUNDAY...FOLLOWED BY SNOW LATE IN THE DAY AND AT NT. THE WARM ADVECTION COULD TAKE TEMPERATURES HIGH ENOUGH FOR A CHANGE OVER TO RAIN OVER THE LOWLANDS MON AFTERNOON. INTRODUCED AN HWO MENTION FOR POSSIBLE MIXED WINTRY PRECIPITATION MON AND TUE ALTHOUGH TEMPERATURES ON THE COLD SIDE OF THE SYSTEM ARE PROGGED TO BE MARGINAL FOR SNOW VS RAIN. BLENDED IN MOSTLY RAW MODEL DATA FOR TEMPERATURES SAT IN THE ARCTIC AIR AND THE BIAS CORRECTED MAV FOR LOWS SAT NT...THE HIGHER RIDGES LEVELING OFF AND EVEN RISING A TAD TOWARD DAWN SUNDAY. HIGHS SUNDAY WERE MAINLY BETWEEN MOS AND RAW MODEL OUTPUT AND WERE ACCEPTED. AFTER FALLING INITIALLY SUNDAY NT...TEMPERATURES RISE OVERNIGHT...AND GUIDANCE SUGGESTED HIGHER TEMPERATURES FOR MON. IN THE ARCTIC AIR...TEMPERATURES DO NOT RISE MUCH ON SAT...SO THE WIND CHILL ADVISORIES AND WATCHES CONTINUE THROUGH THE DAY SAT AND SAT NT INTO SUNDAY MORNING IN AND NEAR THE MOUNTAINS. THE WINDS DO DIE DOWN THERE SAT NT BUT NOT UNTIL VERY LATE...AND LASTLY ON THE RIDGES WHERE WIND CHILL VALUES WILL BE CLOSEST TO WARNING CRITERIA. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... STILL LOTS OF UNCERTAINTY IN THE EXTENDED PERIOD...ALTHOUGH MODELS ARE GRADUALLY TRYING TO COME TOGETHER. SERIES OF POTENT WAVES TO AFFECT THE AREA EARLY NEXT WEEK. FIRST SUNDAY NIGHT INTO MONDAY...AS WAVE MOVES INTO GREAT LAKES REGION...SPREADING MAINLY LIGHT SNOWFALL INTO THE REGION. THE SECOND MORE POWERFUL WAVE AND ASSOCIATED LOW WILL MOVE NORTHEAST OUT OF THE SOUTHERN U.S. TOWARDS THE REGION BY MONDAY NIGHT INTO TUESDAY. DEPENDING ON THE TRACK OF THE LOW...WILL DETERMINE WHETHER AREA IS LOOKING AT AN ALL SNOW EVENT...OR A WINTRY MIX AT TIMES. AT THIS POINT...LOOKS LIKE A WINTRY MIX CAN BE EXPECTED AT TIMES...PARTICULARLY ACROSS THE LOWLANDS...WHICH OF COURSE WILL LIMIT SNOWFALL POTENTIAL. WITH THE OVERALL UNCERTAINTY IN THE MODELS AT THIS TIME...WILL KEEP A MENTION OUT OF THE HWO FOR ONE MORE DAY...AND ALLOW FOCUS TO REMAIN ON SYSTEMS AND IMPACTS EXPECTED THIS WEEKEND. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/...
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GENERALLY VFR CONDITIONS THRU THIS MORNING. AFTER 15Z...LOWERING CLOUD BASES AS DISTURBANCE RACES EASTWARD WITH IFR CONDITIONS IN -SN IN SE WV AND SW VA TO INCLUDE KBKW. AN ARCTIC FRONT PASSES THIS EVENING WITH IFR SQUALLS POSSIBLE ALONG WITH GUSTY WINDS 20 TO 35 KTS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SATURDAY... FORECAST CONFIDENCE...MEDIUM. ALTERNATE SCENARIOS: THERE MAY BE SOME BREAKS BETWEEN THE SNOW FROM THE DISTURBANCE AND THE ARRIVING ARCTIC FRONT LATER IN THE EVENING WHICH WOULD ALLOW TERMINALS TO MAINTAIN VFR CONDITIONS AT LEAST WITH VSBY ONCE UPPER LEVEL DISTURBANCE PASSES. 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 FRI 02/12/16 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 H H HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H H H H H H H M M L L M EKN CONSISTENCY H H H H H H H H H M L L PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H M M L L AFTER 12Z SATURDAY... IFR CONDITIONS IN SNOW...RAIN...OR MIXED PRECIP MONDAY AND TUESDAY AREAWIDE.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EST SUNDAY FOR WVZ032-035>040. WIND CHILL WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR WVZ046-047. OH...NONE. KY...NONE. VA...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR VAZ003-004. && $$ SYNOPSIS...TRM/SL/30 NEAR TERM...30 SHORT TERM...TRM/JW LONG TERM...SL AVIATION...30

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