Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 231959 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 214 PM EST TUE DEC 23 2014 .SYNOPSIS... LOW PRESSURE MOVES WEST OF THE AREA BUT BRINGS RAIN TUESDAY NIGHT AND WEDNESDAY. COLD FRONT WEDNESDAY WILL BRING GUSTY WINDS. CHRISTMAS DAY STARTS COLD...CLOUDY...AND WINDY. && .NEAR TERM /THROUGH WEDNESDAY/... MODELS HAVE DEEPENING SURFACE LOW TRACKING NORTHWARD THRU CENTRAL KENTUCKY AND WESTERN OHIO LATER TONIGHT AND WEDNESDAY. ONCE THE SURFACE LOW GETS INTO NORTHERN OHIO LATER WEDNESDAY MORNING...IT WILL SWEEP A STRONG COLD FRONT EASTWARD ACROSS MUCH OF THE AREA WEDNESDAY AFTERNOON...REACHING THE MOUNTAINS LATE IN THE DAY. WE LIKE THE SLIGHTLY FASTER GFS WITH THE FRONT...GIVEN THE STRENGTHENING PRESSURE GRADIENT AROUND THE LOW. BUT FIRST...MODELS HAVE A BROAD AND DEEP MOIST SOUTHERLY FLOW AHEAD OF THE LOW...WITH NUMEROUS UPPER DISTURBANCES TRACKING OVER THE AREA. LOOKS LIKE WIDESPREAD SHOWERS WILL MOVE IN EARLY TONIGHT AND QUICKLY OVER OVERSPREAD THE AREA. THERE IS SOME QUESTION AS TO IF AND WHEN THIS BROAD SHIELD OF SHOWERS WILL END BEFORE THE COLD FRONT STARTS TO TRACK EASTWARD WEDNESDAY AFTERNOON...AS TRACKING OF EMBEDDED DISTURBANCES IN THE SOUTHERLY FLOW WILL BE VERY DIFFICULT. PAST EXPERIENCE HAS SHOWN WITH THESE SYSTEMS THAT THERE WILL BE A TAPERING OFF OF THE SHOWERS BEFORE THE ORGANIZED BAND OF SHOWERS AND A FEW THUNDERSTORMS MOVE IN FROM THE WEST. THUS...WILL BRING IN CAT POPS TONIGHT...EXCEPT LIKELY IN THE SHADOW ZONE BETWEEN THE OHIO RIVER AND THE MOUNTAINS DUE TO SOUTHEAST DOWNSLOPING WINDS...AND THEN GO CHANCE POPS FROM SOUTH TO NORTH WEDNESDAY MORNING. EXPECT WELL ABOVE NORMAL TEMPS TONIGHT WITH SOUTHERLY FLOW AND CLOUDS. FOR WEDNESDAY...WILL TRACK THE STRONG COLD AND ORGANIZED BAND OF SHOWERS AND STORMS ACROSS THE AREA...REACHING THE OHIO RIVER AROUND 19Z...CENTRAL WV AROUND 21Z...AND ON INTO THE MOUNTAINS BY 00Z. WHILE THE WESTERLY 850MB WINDS ARE NOT PARTICULARLY IMPRESSIVE COMING IN BEHIND THE FRONT...THERE IS A REAL STRONG POTENTIAL FOR DOWNWARD MOMENTUM WITH A VERY IMPRESSIVE COLD ADVECTION SURGE. THIS IN COMBINATION WITH THE SHOWERS AND STORMS...POSE REAL THREAT FOR DAMAGING WINDS UP TO 50 MPH ALONG AND JUST BEHIND THE FRONT...SO THAT A WIND ADVISORY HAS BEEN POSTED FOR EXTREME SOUTHEAST OHIO...EXTREME NORTHEAST KENTUCKY AND EASTWARD INTO CENTRAL WEST VIRGINIA WEDNESDAY AFTERNOON. TEMPERATURES WILL BE WELL ABOVE NORMAL TONIGHT AND WEDNESDAY AHEAD OF THE FRONT...BEFORE FALLING OFF. SINCE THE COLD ADVECTION BEGINS LATER WEDNESDAY AFTERNOON...HAVE CHOSEN NOT TO GO WITH A NON DIURNAL TEMPERATURE CURVE. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... STRONG GRADIENT AFTER COLD FRONT EXITS CHRISTMAS EVE AND COULD SEE SOME WIND GUSTS IN THE ADVISORY CRITERIA CONTINUING INTO THE EVENING HOURS BEFORE DYING DOWN TOWARDS MIDNIGHT. MODELS IN AGREEMENT WITH UPPER TROF SWINGING THROUGH CHRISTMAS DAY. COLD AIR WILL BE WORKING IN WITH H850 TEMPS FALLING BETWEEN -3 TO -6 BY 12Z. COULD SEE ANY RAIN...MIX AND CHANGE TO SNOW BRIEFLY IN SE OH TOWARDS DAYBREAK WITH A MIX ELSEWHERE. RAIN AND SNOW MIX WILL CHANGE TO ALL RAIN TOWARDS LATE MORNING AS TEMPS RISE. UPSLOPE MIX TO ALL SNOW IN THE HIGHER ELEVATIONS OF THE MOUNTAIN COUNTIES WILL CONTINUE INTO THE AFTERNOON. LITTLE OR NO SNOW ACCUMULATION IS EXPECTED. HIGH PRESSURE WILL START TO BUILD INTO THE AREA CHRISTMAS NIGHT AND INTO FRIDAY. DRY WEATHER AND CLEARING SKIES ARE ON TAP. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... HIGH PRESSURE EXITING TO THE EAST EARLY IN THE LONG TERM. MODELS THEN HAVE SOME DISCREPANCIES GOING FORWARD. ECMWF HAS HAD A STRETCH OF RATHER LACKLUSTER PERFORMANCE IN THE LONG TERM RECENTLY...SO WHILE NOT DISCOUNTING IT COMPLETELY...DID PUT MORE WEIGHT ON THE GFS WHILE BLENDING. THIS BRINGS A MOISTURE STARVED COLD FRONT THROUGH SATURDAY...AND THEN A SECOND SURFACE WAVE RIDES UP THE FRONT SUNDAY INTO MONDAY. GFS HAS THIS WELL SOUTH AND EAST OF CWA...WITH THE EASTERN THIRD OF THE CWA BEING CLIPPED BY THE NW FRINGE OF THE QPF FIELD. FOR COMPARISON...THE ECMWF IS MUCH FARTHER WEST WITH THE SECOND WAVE. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... 18Z TUESDAY THRU 18Z WEDNESDAY... FORECAST AREA UNDER WARM SECTOR AND WAA...AS SFC LOW FORMS TO OUR SOUTHWEST OVER THE TENNESSEE VALLEY. CIG AND VSBY VALUES SHOULD REMAIN AOA VFR THIS AFTERNOON...EXCEPT MVFR CEILINGS FOR PORTION OF SOUTHEAST OHIO WHERE SCATTERED SHOWERS WILL FALL. SYSTEM BECOMES BETTER ORGANIZED TONIGHT AND PUSHES A BROAD SWATH OF MOISTURE AND RAIN NORTHWARD ACROSS THE OH VALLEY AND THE SOUTHERN COALFIELDS... SPREADING INTO THE NORTHEASTERN AREAS BY 06Z. MVFR CONDITIONS STARTING IN THE FAR SOUTH AND WEST AROUND 00Z...SPREADING RAPIDLY NORTH TO COVER ENTIRE AREA BY 08Z. SOME MOUNTAIN SITES WILL LOWER TO IFR CONDITIONS AFTER 06Z. AFTER 12Z WEDNESDAY...RAIN TAPERS OFF AND BECOMING VFR CEILINGS FROM SOUTH TO NORTH AS DISTURBANCE EXITS. COLD FRONT AND MVFR CEILINGS IN SHOWERS AND THUNDERSTORMS ENTER FAR WESTERN SECTION OF SOUTHEAST OHIO BY 18Z...WITH VERY GUSTY SOUTHWEST WINDS WITH PASSAGE OF FRONT. S TO SE FLOW WILL CONTINUE...WITH HIGHER ELEVATIONS GUSTING TO NEAR 20 KTS AT TIMES MAINLY LATER IN PERIOD. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: MVFR CEILINGS AND LIGHT RAIN CHANCES MAY BE MORE WIDESPREAD LATE THIS AFTERNOON IF DISTURBANCE IS FASTER. IFR CONDITIONS MAY BE MORE WIDESPREAD TONIGHT IN AREAS OF HEAVIER RAIN AND FOG. 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 20 21 22 23 00 01 02 03 04 05 06 07 EST 1HRLY 15 16 17 18 19 20 21 22 23 00 01 02 CRW CONSISTENCY H H H H H H H H H M M M HTS CONSISTENCY H H H H H H M M M M M H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H M H H PKB CONSISTENCY H H H H H H M M M M M H CKB CONSISTENCY H H H H H H H H H M H M AFTER 18Z WEDNESDAY... IFR POSSIBLE IN RAIN TUE NT INTO WED. IFR IN CLOUDS POSSIBLE IN THE HIGHER ELEVATIONS OF THE MOUNTAINS WEDNESDAY NIGHT INTO THURSDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...WIND ADVISORY FROM NOON TO 10 PM EST WEDNESDAY FOR WVZ005>011- 013>019-024>026. OH...WIND ADVISORY FROM NOON TO 10 PM EST WEDNESDAY FOR OHZ066-067- 075-076-083>087. KY...WIND ADVISORY FROM NOON TO 10 PM EST WEDNESDAY FOR KYZ101>103- 105. VA...NONE. && $$ SYNOPSIS...JS/JMV/MZ NEAR TERM...JMV SHORT TERM...JS LONG TERM...MZ AVIATION...JMV

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