Area Forecast Discussion
Issued by NWS Charleston, WV

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KRLX 240018 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 717 PM EST TUE DEC 23 2014 .SYNOPSIS... LOW PRESSURE MOVES WEST OF THE AREA BUT BRINGS RAIN TONIGHT AND WEDNESDAY. COLD FRONT LATE WEDNESDAY WILL BRING GUSTY WINDS. CHRISTMAS DAY STARTS COLD...CLOUDY...AND WINDY...WITH SNOW SHOWERS. && .NEAR TERM /THROUGH WEDNESDAY/... 715 PM UPDATE... ADJUSTED TO FASTER TIMING OF THE RAIN OVER THE MIDDLE OHIO VALLEY THIS EVENING. ADDED THUNDER TO HTS TRI-STATE AREA WED MORNING...WITH DEEPENING LOW PRESSURE PASSING TO THE W...AND STRONG EARLY MORNING LLJ. MADE SOME ADJUSTMENTS TO WIND GUSTS DURING THE ADVISORY WED...KEEPING THE GIST AND REASONING OF THE PREVIOUS FCST WHICH KEYS IN MAINLY ON THE STRONG COLD ADVECTION DIRECTLY BEHIND THE COLD FRONT... BUT WITH TIMING AND DETAIL ADJUSTMENTS. PREV DISCN... 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 /00Z WEDNESDAY THROUGH SUNDAY/... MILD S TO SE FLOW DOMINATES MOST OF THE PERIOD...THE STRENGTH OF THE FLOW INCREASING AS A STRONG COLD FRONT CROSSES FROM THE W. RAIN WAS ALREADY AFFECTING THE MIDDLE OHIO VALLEY AND THE EASTERN SLOPES OF THE CENTRAL APPALACHIANS...IN RESPONSE TO LOW PRESSURE STILL DOWN OVER THE CENTRAL GULF STATES. THAT LOW WILL INTENSIFY RAPIDLY WHILE MOVING N RAPIDLY...REACHING THE TN VALLEY BY DAWN WED...AND CENTRAL MICHIGAN BY 00Z THU...CHRISTMAS EVE. RAIN WILL CONTINUE TO EXPAND ACROSS THE AREA OVERNIGHT...BRINGING WIDESPREAD MVFR CIGS AND VSBYS...STARTING FROM THE OHIO VALLEY AND THE SOUTHERN COALFIELDS EARLY ON...SPREADING RAPIDLY N TO COVER THE ENTIRE AREA BY 08Z. IFR VSBY IS MOST LIKELY IN THE WV MOUNTAINS...AND ALONG AND W OF THE OHIO RIVER OVERNIGHT...WHILE IFR CIGS ARE MOST LIKELY IN THE WV MOUNTAINS...MAINLY THE EASTERN SLOPES...BY 06Z. A DRY SLOT WILL CAUSE THE RAIN TO BREAK UP INTO SCATTERED SHOWERS DURING THE DAYLIGHT MORNING HOURS WED...WITH CONDITIONS IMPROVING TO VFR FROM S TO N...EXCEPT FOR MVFR CIGS LIKELY HOLDING ON ALONG THE EASTERN SLOPES OF THE WV MOUNTAINS. A NEW BAND OF SHOWERS AND POSSIBLE THUNDERSTORMS WILL MOVE W TO E ACROSS THE AREA WED AFTERNOON...AS THE STRONG COLD FRONT PUSHES INTO THE AREA. THIS WILL BRING A RETURN OF MVFR CONDITIONS...WITH LOCAL IFR POSSIBLE IN HEAVIER RAIN. CIG CONDITIONS WILL LIKELY LAG VSBY WED AFTERNOON...WITH MVFR VSBY MOST LIKELY WITH THE RAIN...AND THEN MVFR CIGS MOST LIKELY FOLLOWING THE PASSAGE OF THE COLD FRONT...ALTHOUGH ALSO STILL HANGING ON ALONG THE EASTERN SLOPES OF THE WV MOUNTAINS. LIGHT E TO NE SFC FLOW THIS EVENING WILL BECOME LIGHT E TO SE OVERNIGHT...AND THEN STRENGTHEN FROM THE S TO SE ON WED...WITH GUSTS INCREASING TO 20 KTS BY WED AFTERNOON...EVEN NEAR 30 KTS ON THE HIGHER RIDGES. THE STRONGEST WIND GUSTS ARE EXPECTED AS THE FRONT CROSSES. THE FRONT WILL REACH ABOUT A CRW-PKB LINE BY 00Z THU...WITH GUSTS OF 30 KTS OR MORE MOST LIKELY IN THE STRONG COLD ADVECTION RIGHT BEHIND THE COLD FRONT...CODED UP FOR HTS AT THE END OF THE TAF PERIOD. MODERATE S FLOW ALOFT OVERNIGHT WILL BECOME STRONG S FIRST THING WED MORNING...AND THEN SHIFT TO SW BEHIND THE FRONT ALOFT...WHICH WILL BE ABOUT CO-LOCATED WITH THE SFC COLD FRONT...LATE WED. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z THURSDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: IFR CONDITIONS MAY BE MORE WIDESPREAD OVERNIGHT IN AREAS OF HEAVIER RAIN AND FOG. TIMING OF CHANGING CONDITIONS WITH THE DRY SLOT AND THEN THE COLD FRONT MAY VARY ON WED. 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 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 CRW CONSISTENCY H H H H H M H H H H M M HTS CONSISTENCY H M M M M L M H H H H H BKW CONSISTENCY H H H H H M H H H H L L EKN CONSISTENCY H H H H H M H H H L H H PKB CONSISTENCY H H H M M M M M M H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 00Z THURSDAY... IFR IN CLOUDS POSSIBLE IN THE HIGHER ELEVATIONS OF THE MOUNTAINS WED NT INTO THU. && .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/TRM NEAR TERM...TRM/JMV SHORT TERM...JS LONG TERM...MZ AVIATION...TRM

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.