Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 181046 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 546 AM EST THU DEC 18 2014 .SYNOPSIS... HIGH PRESSURE BUILDS DESPITE CLOUD COVER. LOW PRESSURE SYSTEM FOR THE WEEKEND CLIPS THE MOUNTAINS. && .NEAR TERM /THROUGH TONIGHT/...
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UPDATE... ADDED SOME SLIGHT CHANCE POPS FOR A DEFORMATION ZONE TRAVERSING THE NORTHERN ZONES AFTER 21Z THIS EVENING BASED ON THE HRRR. PREVIOUS DISCUSSION... SYSTEM TO THE WEST WILL CONTINUE TO RAPIDLY SHEAR OUT PRIOR TO ENTERING THE OHIO VALLEY...HOWEVER CLOUD COVER WILL PLAY A ROLE IN THE FORECAST TODAY. AS WE FINALLY MIX OUT THE BOUNDARY LAYER...MID AND HIGH LEVEL MOISTURE PUSHES IN FROM THE WEST. ALLOWED FOR A FEW BREAKS IN THE CLOUD COVER THROUGH THE DAY BY NOT PEGGING THE GRIDS AT 100 PERCENT COVERAGE...BUT IT BKN-OVC. NAM BRINGS IN NORTHWEST FLOW IN THE LOW LEVELS FROM THE SOUTHERN GREAT LAKES IN OVER THE NORTHERN TIER OF COUNTIES LATE TONIGHT. THERMAL TROUGH IS NOT ALL THAT IMPRESSIVE...BUT OUTPUT FROM THE SREF PROBABILITIES FOR MEASURING PRECIPITATION AND THE AFOREMENTIONED NAM WARRANTS LOW END POPS COMING BACK INTO THE NORTHEAST MOUNTAINS. WILL NOT SEE MUCH OF REBOUND IN THE TEMPERATURES FROM THE MORNING LOW TODAY. USED A BLEND OF THE CONSENSUS MOS AND MET MOS NUMBERS TODAY WHICH WERE GENERALLY THE COLDER SOLUTIONS. DROPPING BELOW FREEZING CWA WIDE TONIGHT.
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&& .SHORT TERM /FRIDAY THROUGH SUNDAY/... WEAK SFC HIGH PRESSURE OVER THE GREAT LAKES WITH AN OPEN WAVE TRACKING ACROSS TN-KY-NC THROUGH THE FORECAST PERIOD. LATEST 00Z MODELS HAVE CONTINUED TO TREND A LITTLE FURTHER TO THE SOUTH WITH TRACK OF MAIN DYNAMICS OF THE WAVE...WITH NAM12 BACKING OFF THE MOST. FOR POPS...FOLLOWED LATEST SREF TRENDS WITH AN ADJUSTMENT TOWARD THE GFS AND ECMWF. MODELS HAVE TRENDED BEST FORCING MECHANISMS AND MOISTURE FURTHER TO THE SOUTH...KEPT BEST CHANCES FOR PRECIP FURTHER SOUTH OF KCRW...AND OVER THE EASTERN MOUNTAINS. BACKED OFF A LITTLE FOR THE ONSET OF PRECIP FRI NIGHT AND SAT. OVERALL THIS LEADS TO CUTTING POPS ACROSS CENTRAL WV...AND KEEPING BEST CHANCES ALONG THE SOUTHERN AND EASTERN PERIPHERY OF THE CWA. WENT WITH BC BLEND FOR TEMPS WITH A NOD TOWARD INHERITED VALUES RESULTING IN SLIGHT CHANGES IN MAX MIN TEMPS. PRECIP TYPE WILL BE A MIXED BAG AT NIGHT BASED ON SOUNDING PROFILES...WITH MAINLY RAIN DURING THE DAYTIME HOURS. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... GRADUAL DRYING TREND SUNDAY AS LOW PRESSURE SYSTEM AND UPPER SHORTWAVE TROUGH PUSHES OFF TO THE EAST. WARMER WEATHER WILL THEN TAKE HOLD SUNDAY INTO MONDAY AS HEIGHTS BUILD OUT AHEAD OF NEXT APPROACHING SYSTEM. ALTHOUGH MAINLY DRY MONDAY...COULD SEE SOME LIGHT PRECIPITATION ACROSS PARTS OF THE MOUNTAINS AS ANOTHER LOW MOVES NORTHEAST ALONG THE COAST. ECMWF AND GFS TAKE COMPLETELY DIFFERENT PATHS WITH THIS LOW...BUT AT THIS POINT...LOOKS LIKE ANY MAJOR EFFECTS WITH THIS LOW WILL REMAIN OUTSIDE OF THE AREA. FOCUS THEN SHIFTS TO A STRONG SYSTEM ACROSS THE UPPER MID WEST...THAT WILL SPREAD PRECIPITATION...AND A COLD FRONT BACK INTO THE AREA LONG ABOUT TUESDAY/TUESDAY NIGHT...AND LAST INTO AT LEAST THURSDAY...WHEN THE LOW WILL FINALLY PULL OFF TO THE NORTHEAST. PRECIPITATION SHOULD START OUT AS MOSTLY RAIN...EXCEPT ACROSS HIGHER TERRAIN...ON TUESDAY...BEFORE TRANSITIONING TO MOSTLY SNOW TUESDAY NIGHT...THEN AGAIN WEDNESDAY NIGHT. ALONG WITH THE WINTRY PRECIPITATION...GUSTY WINDS ARE EXPECTED ON WEDNESDAY INTO THURSDAY. WINTER WEATHER HEADLINES MAY BE NECESSARY DURING THIS PERIOD. && .AVIATION /12Z THURSDAY THROUGH MONDAY/...
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MIXING AFTER DAWN TODAY FINALLY BRINGS TERMINALS OUT OF THE MVFR CEILINGS...AND SHOULD HAVE THE BULK OF THE DAY VFR AFTER 16Z. HAVE MID AND UPPER LEVEL MOISTURE BRINGING CEILINGS ABOVE 7KFT AFTER THE LOW LEVEL MOISTURE DISSIPATES FROM THE SHEARING SYSTEM TO THE WEST. THERE IS A POTENTIAL FOR ANOTHER INVERSION TRAPPING MOISTURE AGAIN ACROSS THE NORTHERN TERMINALS LATER TONIGHT AFTER 06Z FRIDAY. THE START TIME FOR THIS IN THE TAFS HAS BEEN PUSHED BACK A FEW HOURS FROM THE PREVIOUS ISSUANCE. THE GUIDANCE IS NOT CLEAR ON THIS FORMATION AND LARGELY USED THE NAM FORECAST SOUNDINGS IN IDENTIFICATION OF THIS MOIST LAYER. VISIBILITIES VFR THROUGH THE PERIOD. HIGH CONFIDENCE IN THIS ASPECT OF THE FORECAST. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: TIMING OF CEILINGS LIFTING TO VFR IN THE MIXING HOURS TODAY COULD VARY. MVFR CEILINGS TONIGHT MAY NOT MATERIALIZE. 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 11 12 13 14 15 16 17 18 19 20 21 22 EST 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 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 H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H M M M M H H H PKB CONSISTENCY H H H H H H M M M M M M CKB CONSISTENCY H H H H H H M M M M M M AFTER 12Z FRIDAY... IFR POSSIBLE IN WINTRY MIX SATURDAY INTO SUNDAY.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KMC/26 NEAR TERM...26 SHORT TERM...KMC LONG TERM...SL AVIATION...26

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