Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 250525 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1225 AM EST TUE NOV 25 2014 .SYNOPSIS... WINDS DIMINISH TONIGHT AS STRONG LOW PRESSURE MOVES AWAY. HIGH PRESSURE TUESDAY. LOW PRESSURE MOVING UP THE EAST COAST WEDNESDAY BRINGS SNOW TO THE APPALACHIANS. WEAKER SYSTEMS UNTIL EARLY FRIDAY. && .NEAR TERM /THROUGH TODAY/... SFC OBS SUGGEST WINDS CONTINUE TO DECREASE...AT THE SAME TIME THE ATMOSPHERE DECOUPLES. ADJUSTED WIND AND WIND GUSTS DOWN ACCORDINGLY. REST OF FORECAST REMAINS REPRESENTATIVE. PREVIOUS DISCUSSION BELOW... 6PM UPDATE...DROPPED THE WIND ADVISORY FOR THE LOWLANDS AS WINDS HAVE DECREASED BELOW CRITERIA. DID ELECT TO LET THE NORTHERN MOUNTAIN ZONES RIDE A LITTLE LONGER...AS A FEW GUSTS AT OR BORDERING CRITERIA CONTINUE TO BE OBSERVED. OTHERWISE...MADE NO MAJOR CHANGES. PREVIOUS DISCUSSION FOLLOWS... CORE OF LLJ CURRENTLY SLIDING THRU NE OH. SURFACE FRONT MAKING ITS WAY THRU E OH AND N KY AS OF 18Z. STILL LOOKING AT ABOUT A 3 HR WINDOW...BEGINNING NOW /18Z/...FOR ADV CRITERIA GUSTS ACROSS CWA AHEAD OF AND ALONG THE FRONT. THIS IS SUPPORTED BY VARIOUS MODEL SOUNDINGS WHICH SHOW GOOD MOMENTUM TRANSFER AIDED BY DRY LOW LEVELS. NUMEROUS ASOS AND AWOS SITES ACROSS THE AREA HAVE REPORTED 50 TO 55 MPH GUSTS IN THE PAST HR. THE GUSTS SHOULD DIMINISH AFTER 21Z AND PROBABLY WILL BE ABLE TO NIX THE ADV SOONER THAN CURRENT EXPIRATION OF 00Z. LOWERED POPS THIS AFTERNOON PER RADAR TRENDS. ATMOSPHERE IS JUST TOO DRY IN THE LOW LEVELS. REGION NEVER GETS INTO MUCH OF WIND SHIFT ALOFT AS TROF LIFTS OUT OF OH VALLEY. SO A GLANCING BLOW OF GOOD CAA. AS SUCH...THINK ANY POST FRONTAL STRATUS WILL BE CONFINED TO SE OH AND N WV. WINDS WILL SLACKEN A GOOD BIT OVERNIGHT...BUT STILL WILL HAVE A BL PUFF TO KEEP LOWS UP A BIT. TUESDAY WILL FEATURE SOME SUNSHINE WITH SOME INCREASING CLOUDS OVER THE MOUNTAIN IN THE AFTERNOON. TEMPS WILL BE SEASONABLY COOL. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... MODELS ARE IN BETTER AGREEMENT ON EAST COAST STORM ON WEDNESDAY. PER COORD WITH WWD AND NEIGHBORS...ISSUED WINTER STORM WATCH FOR POCAHONTAS AND RANDOLPH COUNTIES FOR THE POSSIBILITY OF SIX INCHES ACCUMULATION. THIS IS AN ELEVATION BASED EVENT...SO THE LARGEST ACCUMULATIONS WILL BE OVER THE HIGHER TERRAIN. THE STORM DEVELOPS AS TRANSITORY L/W TROUGHING SETS UP OVER THE ERN CONUS. WITHIN THE LARGER TROUGH...THE INDIVIDUAL S/W/S NEVER PHASE. HOWEVER...LIKE A PATIENT HITTER...THE SECOND S/W TROUGH STAYS BACK LONG ENOUGH FOR THE LEAD SYSTEM TO IMPACT AREAS AS FAR W AS THE CENTRAL APPALACHIANS. THE LOW CENTER TAKES THE CLASSIC TRACK NEWD UP THE CAROLINA COAST TUE NT...AND THEN FROM JUST S OF HATTERAS WED MORNING TO S OF CAPE CODE WED EVENING...SO THE MAIN EVEN IS WED STARTING EARLY IN THE MORNING. MODEL SOUNDINGS AND MOS GUIDANCE SUGGEST A FREEZING LEVEL OF 1500-2000 FT MSL...SO THE LOWLANDS AND THE LOWER MOUNTAIN VALLEYS WILL HAVE TEMPERATURES JUST ABOVE FREEZING. THE HIGHEST TERRAIN WILL HAVE TEMPERATURES AS LOW AS THE MID 20S...LOW ENOUGH FOR IMPACTFUL SNOW ACCUMULATIONS ON UNTREATED SURFACES. WITH DECENT MODEL CONSENSUS...USED A BLEND OF THE NAM...GFS...CMC AND ECMWF...AS WELL AS WPC...FOR QPF...CROSS-CHECKED WITH THE POPS. GIVEN WE ARE NOT DEALING WITH A WARM LAYER ALOFT...AND BOTH CRYSTAL PRESENCE AND GROWTH LOOK GOOD...SNOWFALL IS A FUNCTION MAINLY OF SFC TEMPERATURE AND QPF. HAVE COUNTY AVERAGES OF THREE INCHES WITH PEAK AMOUNTS JUST OVER 5 INCHES IN THE WATCH AREA. THE WINTER STORM WATCH IS BASED ON A 50% CONFIDENCE OF SIX INCHES FOR THE HIGHER TERRAIN WITHIN THE WATCH AREA AND COVERING AT LEAST HALF THE COUNTY ON THE BUSIEST TRAVEL DAY OF THE YEAR. THE WATCH IS ALSO ON THE UPSTREAM END OF WATCHES EXTENDING ALL THE WAY UP THROUGH NEW ENGLAND FOR THIS EVENT...MAKING AN EARLY DECISION ALL THE MORE PRUDENT. BLENDED IN NAM MODEL AND MOS FOR TEMPERATURES WHICH DID NOT ENTAIL MUCH CHANGE FROM THE PREVIOUS FCST FOR THE ALL-IMPORTANT EVENT TUE NT AND WED. HAVE WED NT A LITTLE COLDER THAN PREVIOUS GIVEN GUIDANCE CONSENSUS IN THAT DIRECTION...BLENDED IN THE BIAS CORRECTED MET. AVERAGED IN A CONSENSUS BLEND FOR HIGHS THU FOR LITTLE CHANGE FROM THE PREVIOUS FCST. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... USED A BLEND OF THE ECMWF AND NAEFS MEAN FOR THE FORECAST. THIS ALLOWS FOR SOME UPSLOPE SNOW THURSDAY NIGHT...SO WILL INCREASE POPS THURSDAY EVENING. WARM ADVECTION THEN TAKES OVER FOR FRIDAY AND SATURDAY. NEXT FRONTAL BOUNDARY PUSHES INTO THE REGION ON SUNDAY. CONFIDENCE REMAINS LOW ON WHAT HAPPENS WITH THIS BOUNDARY ON MONDAY...SO FOR NOW WILL KEEP SOME LOW POPS AS IT COULD HANG OVER THE AREA. && .AVIATION /05Z TUESDAY THROUGH SATURDAY/... SATELLITE IMAGES INDICATE THIN HIGH LEVEL CLOUDS SCREAMING NORTH ACROSS THE AREA. SFC OBS SUGGEST THESE CLOUDS ARE ABOVE 12000 FEET. SOME MID LEVEL CLOUDS ARE EVIDENT ACROSS OH...SOME TRYING TO MOVE INTO SOUTHEAST OH AND WV OVERNIGHT. HOWEVER...CHANCES FOR THESE MID LEVEL CLOUD DECKS ARE LOW. THEREFORE...WILL KEEP VFR CONDITIONS AT ALL SITES...UNDER LIGHT WEST SOUTHWEST FLOW. WIDESPREAD VFR CONDITIONS EXPECTED TUESDAY. MVFR CEILINGS UNDER SNOW SHOWERS ARE POSSIBLE BY WEDNESDAY. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY... FORECAST CONFIDENCE: HIGH. ALTERNATE SCENARIOS: MVFR CEILINGS COULD FORM OVER HIGH ELEVATION SITES. 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 TUE 11/25/14 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12 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 M M H H H H H H H H H H EKN CONSISTENCY M M 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 06Z WEDNESDAY... IFR CONDITIONS IN SNOW IS POSSIBLE OVER THE MOUNTAINS ON WEDNESDAY...AND AGAIN WEDNESDAY NIGHT AND THURSDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR WVZ046-047. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...ARJ/TRM NEAR TERM...ARJ/SL/30 SHORT TERM...TRM LONG TERM...RPY AVIATION...ARJ

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