Area Forecast Discussion
Issued by NWS Charleston, WV

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507 FXUS61 KRLX 121758 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1258 PM EST FRI FEB 12 2016 .SYNOPSIS...
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ARCTIC FRONT CROSSES TONIGHT...ACCOMPANIED BY SNOW SHOWERS INTO SATURDAY...AND BITTERLY COLD WEATHER FOR THE WEEKEND. A COMPLEX SYSTEM COULD BRING MIXED PRECIPITATION EARLY NEXT WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/... 1030 UPDATE. CHANGED WIND CHILL WATCH OVER NORTHERN MOUNTAINS TO WIND CHILL ADVISORY. NO OTHER CHANGE TO HEADLINES. OTHERWISE...NO SIGNIFICANT CHANGE TO FORECAST. MOST ACCUMULATIONS OF SNOW THIS AFTERNOON WILL BE OVER SOUTHWEST VIRGINIA. 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. && .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 /18Z FRIDAY THROUGH WEDNESDAY/...
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18Z FRIDAY THRU 18Z SATURDAY... WEAK UPPER DISTURBANCE CROSSES THE AREA THIS AFTERNOON...WITH SOME SNOW MOSTLY SOUTHERN PORTIONS. AN ARCTIC FRONT DROPS SOUTHEAST ACROSS THE AREA TONIGHT...WITH BRIEF IFR SQUALLS ALONG THE FRONT POSSIBLE ALONG WITH GUSTY WINDS 20 TO 35 KTS...FOLLOWED BY MAINLY MOUNTAIN SNOW SHOWERS BEHIND THE FRONT AND GUSTY NORTHWEST WINDS INTO SATURDAY. THRU 00Z...MVFR OR LOWER CONDITIONS IN SNOW THIS AFTERNOON MOSTLY CONFINED TO FAR SOUTHERN AREAS OF WEST VIRGINIA AND SOUTHWEST VIRGINIA...AFFECTING BKW...THEN MAINLY INTO MOUNTAINS LATER THIS AFTERNOON AND TONIGHT AS UPSLOPE SNOW SHOWERS KICK IN. ELSEWHERE...GENERALLY VFR CEILINGS BUT BRIEFLY LOWER IN LIGHT SNOW. AFTER 00Z...AFOREMENTIONED SNOW SQUALL ALONG FRONT POSSIBLE... THEN SCATTERED SNOW SHOWERS BEHIND THE FRONT...BUT MUCH MORE NUMEROUS IN THE MOUNTAINS. OUTSIDE OF SNOW SHOWERS...GENERALLY VFR CEILINGS WEST OF THE OHIO RIVER AND MVFR CEILINGS REMAINDER OF LOW LANDS...MVFR TO IFR IN SNOW SHOWERS MOUNTAINS. THESE CONDITIONS WILL PERSIST SATURDAY MORNING. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY... FORECAST CONFIDENCE...MEDIUM. ALTERNATE SCENARIOS: SNOW LOOKS TO BE MORE SCATTERED THIS AFTERNOON OUTSIDE OF SOUTHWEST VIRGINIA AND SOUTHERN MOUNTAINS. 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. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY H H H H H H H H H M M L HTS CONSISTENCY H H H H H H H H H M M M BKW CONSISTENCY L M M H H H H H M L L L EKN CONSISTENCY H H H H H H H H M L L L PKB CONSISTENCY H H H H H H H H M M M M CKB CONSISTENCY H H H H H H H H M M M L AFTER 18Z 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>040-046-047. OH...NONE. KY...NONE. VA...WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR VAZ003-004. && $$ SYNOPSIS...TRM/SL/30 NEAR TERM...JMV/30 SHORT TERM...TRM/JW LONG TERM...SL AVIATION...JMV

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