Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 101048 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 548 AM EST WED FEB 10 2016 .SYNOPSIS... DEEP UPPER LEVEL TROUGH LIFTS OUT OF THE AREA THURSDAY FOR A BRIEF LULL IN THE SNOW SHOWERS. TROUGH RE-ESTABLISHES FRIDAY-SATURDAY WITH RETURN OF SNOW SHOWERS AND EVEN COLDER WEATHER. && .NEAR TERM /THROUGH TONIGHT/... 600 AM UPDATE... FCST ON TRACK. PREV DISCN... A POTPOURRI OF CHANGES NEEDED TO ADVISORIES BASED ON SNOW SHOWERS PERSISTING INTO OR REGENERATING THIS AFTERNOON ACROSS THE LOWLANDS...AND LINGERING INTO THU IN THE MOUNTAINS. THE HIGHEST MOUNTAINOUS TERRAIN WILL NEED A WIND CHILL ADVISORY OVERNIGHT TONIGHT INTO THU MORNING. THE AREA REMAINS UNDER A DEEP UPPER LEVEL L/W TROUGH MOVING SLOWLY EWD THROUGH THE EASTERN U.S. IT WILL SLOWLY START TO LIFT OUT TONIGHT. THIS TROUGH HAS BECOME LARGELY DEFINED BY A NEGATIVELY TILTED AXIS THAT WILL MOVE ACROSS THE AREA TODAY. IT..AND DIURNAL HEATING...ARE LIKELY TO FILL THE RADAR SCOPE WITH A POPCORN PATTERN OF NUMEROUS SNOW SHOWERS BY THIS AFTERNOON IN THE NEARLY AUTO CONVECTIVE LOW LEVEL ENVIRONMENT. OTHERWISE UPSLOPE FLOW WILL CONTINUE TO FAVOR SNOW SHOWERS IN AND NEAR THE MOUNTAINS THROUGH THE PERIOD. BLENDED IN A COMBINATION OF NAM...RUC AND LAMP TEMPERATURES AND DEW POINTS TODAY...AND THEN BIAS CORRECTED MET/MAV FOR LOW TEMPERATURES TONIGHT. WINDS WERE DERIVED FROM THE NAM USING THE RUC METHOD FOR GUSTS...OFF WHICH WIND SPEEDS WERE MODULATED. WITH ALL OF THIS IN MIND...THE WINTER WEATHER ADVISORY FOR SNOW IS LEFT TO EXPIRE AT 1 PM FOR THE NE KY COUNTIES...BUT EXTENDED ACROSS THE REMAINDER OF THE LOWLAND COUNTIES AND SW VA UNTIL 6 PM TONIGHT...AND IN AND NEAR THE MOUNTAINS UNTIL 6 AM THURSDAY. FURTHER...THE ADVISORY WAS EXTENDED UNTIL 6 PM THURSDAY FOR THE NORTHERN MOUNTAINOUS COUNTIES OF POCAHONTAS AND RANDOLPH COUNTIES WHERE A WIND CHILL ADVISORY WAS HOISTED FOR OVERNIGHT TONIGHT INTO THURSDAY MORNING FOR WIND CHILLS AS LOW AS -20C. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... BROAD UPPER LEVEL TROUGH WILL CONTINUE TO AFFECT THE LOCAL AREA WEDNESDAY. THE LOW STARTS TO LIFT OUT OF THE AREA WED NT AND THU. A SERIES OF VORTICITY LOBES WILL ROTATE AROUND THE PERIPHERY OF THE TROUGH TO KEEP SOME FORCING FOR SNOW SHOWERS WEDNESDAY THROUGH THURSDAY. WESTERLY FLOW WEDNESDAY VEERS FROM THE NORTHWEST THURSDAY. NORTHWEST FLOW WILL SET THE PLUME OF MOISTURE FROM LAKE MICHIGAN RIGHT TOWARDS NORTH OF OUR AREA THURSDAY. IN ADDITION...NORTHWEST FLOW WILL PRODUCE UPSLOPE SNOW SHOWERS IN AND NEAR THE MOUNTAINS WEDNESDAY NIGHT INTO THURSDAY. INCREASED SNOW AMOUNTS FROM 1 TO 4.5 INCHES ALONG THE NORTHEAST MOUNTAINS FOR THURSDAY. ANOTHER VORTICITY LOBE CROSSES THE AREA FRIDAY UNDER NORTHWEST FLOW ENHANCING SNOW OVER THE LOWLANDS...AND UPSLOPE SNOW OVER THE EASTERN MOUNTAINS FRIDAY INTO THE WEEKEND. USED THE SUPERBLEND FOR TEMPERATURES THROUGH THE PERIOD. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... ARCTIC FRONT THIS WEEKEND...WILL BRING IN A REINFORCING SHOT OF COLD AIR...ALONG WITH LIGHT SNOW SHOWERS BACK INTO THE FORECAST. OVERALL...ONLY LIGHT ACCUMULATIONS FIGURED FOR SATURDAY...AND MAINLY ACROSS THE MOUNTAINS IN FAVORED UPSLOPE REGIONS. WITH THE VERY COLD AIR...EXPECT A RATHER LIGHT FLUFFY SNOW OVER THE WEEKEND. BASED ON TIMING OF THE FRONT...COULD BE FALLING TEMPERATURES EARLY ON SATURDAY...BEFORE BECOMING SOMEWHAT STEADY DURING THE DAY. SATURDAY NIGHT LOOKS TO BE QUITE COLD ACROSS THE REGION...WITH A GRADUALLY CLEARING SKY...AND -24 AIR AT 850MB IN PLACE. WENT BELOW GUIDANCE ACROSS THE CWA...PARTICULARLY ACROSS MOUNTAINOUS VALLEYS SUCH AS AT KEKN. BRIEF HIGH PRESSURE SUNDAY THROUGH MONDAY...BEFORE ANOTHER CLIPPER SYSTEM MOVES INTO THE OHIO VALLEY REGION BY EARLY TO MID NEXT WEEK. THIS LOOKS TO BE A MOSTLY SNOW EVENT...ALTHOUGH THERE COULD BE A BRIEF PERIOD OF A RAIN SNOW MIX ACROSS PARTS OF THE LOWLANDS. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... LARGE UPPER LEVEL TROUGH REMAINS OVER THE AREA NEXT 18 HOURS...KEEPING MVFR CONDITIONS COMMON IN SNOW SHOWERS. IFR CONDITIONS AT TIMES IN HEAVIER SNOW SHOWERS WHICH ARE MOST LIKELY IN THE MOUNTAINS THIS PERIOD...BUT ALSO ACROSS NRN WV AND ERN OHIO THIS AFTERNOON...AS A SHORT WAVE TROUGH MOVES THROUGH WITHIN THE LARGER SYSTEM. CONFIDENCE REMAINS LOW ON ACCOUNT OF THE TIMING OF THE SNOW SHOWERS AND THE HIGHLY VARIABLE CONDITIONS AS A RESULT. TEMPO GROUPS FOR IFR CONDITIONS WERE ADDED MIDDAY INTO THIS AFTERNOON WHEN SNOW SHOWERS ARE EXPECTED TO BE MOST NUMEROUS. SFC FLOW WILL BE W TO SW AND A BIT GUSTY AT TIMES BENEATH LIGHT TO MODERATE W FLOW ALOFT TODAY THAT BECOMES NW TONIGHT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z THURSDAY... FORECAST CONFIDENCE...LOW ALTERNATE SCENARIOS: TIMING AND EXTENT OF IFR WILL VARY IN SNOW SHOWERS. TAF VSBY MORE VARIABLE THAN INDICATED IN DETERMINISTIC TAF FORECAST. IN PARTICULAR...SHOW SHOWERS UNDER THE UPPER LEVEL TROUGH ARE LIKELY TO DOT THE RADAR LIKE POPCORN THIS AFTERNOON. IFR CONDITIONS CAN EASILY OCCUR BENEATH ANY OF THESE SNOW SHOWERS. 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 WED 02/10/16 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 M M M M M M M M M M M M HTS CONSISTENCY M M M M M M M H H H H H BKW CONSISTENCY M M M M M M M M M M M M EKN CONSISTENCY M M M M M M M M M L L L PKB CONSISTENCY M M M M M M M M M M M M CKB CONSISTENCY M M M M M M M M M M M H AFTER 12Z THURSDAY... SOME IFR CONDITIONS IN SNOW SHOWERS LINGER OVER WV MOUNTAINS INTO THURSDAY. IFR CONDITIONS IN SNOW SHOWERS POSSIBLE AT TIMES FRIDAY NIGHT THROUGH SATURDAY NIGHT...ESPECIALLY IN THE MOUNTAINS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR WVZ005>011-013>020-024>036. WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR WVZ037>040. WINTER WEATHER ADVISORY UNTIL 6 PM EST THURSDAY FOR WVZ046-047. WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST THURSDAY FOR WVZ046-047. OH...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR OHZ066- 067-075-076-083>087. KY...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR KYZ101>103-105. VA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR VAZ003- 004. && $$ SYNOPSIS...ARJ/TRM/SL NEAR TERM...TRM SHORT TERM...ARJ LONG TERM...SL AVIATION...TRM

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