Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 161834 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 125 PM EST TUE DEC 16 2014 .SYNOPSIS... IN WAKE OF COLD FRONT...ABUNDANT LOW LEVEL MOISTURE THROUGH WEDNESDAY. HIGH PRESSURE THURSDAY INTO FRIDAY. LOW PRESSURE APPROACHES FOR THE WEEKEND. && .NEAR TERM /THROUGH WEDNESDAY/... AT 18Z FRONT APPROACHING CKB TO BKW LINE. STRONG MID LEVEL DISTURBANCE LOCATED NEAR DAY AT 18Z...HEADING EAST..TIMING IT TO PASS THROUGH NORTH CNTRL WV ABOUT 00Z WEDNESDAY. INTERESTING THAT HERE IN MID DECEMBER...WE CAN NOT GET A GOOD TEMPERATURE DROP...EVEN IN THE WAKE OF A COLD FRONT. WE KEPT TEMPERATURE ABOVE FREEZING OVERNIGHT TONIGHT...EXCEPT IN ELEVATIONS ABOVE 3000 FEET. WITH THE LOW LEVEL FLOW MOSTLY WESTERLY...HARD TO FIGURE HOW LOW THE CLOUDS GO FOR THE SOUTHERN MOUNTAINS...AND THUS...HOW HARD TO FIGURE AMOUNT OF DRIZZLE LATE OVERNIGHT...BUT MORE LIKELY FURTHER NORTH. ALONG WITH A MIXTURE OF LIGHT RAIN AND SNOW SHOWERS IN THE HIGH ELEVATIONS OF THE CENTRAL MOUNTAINS...WILL INCLUDE THE POSSIBILITY OF SOME FREEZING DRIZZLE...SINCE SATURATED MOISTURE DEPTH MOSTLY AOB 5 THSD FT MSL. AREA IS VERY LIMITED FOR THAT FREEZING DRIZZLE. COLDEST 850 MB AIR 12Z TO 15Z ON WEDNESDAY. WILL HOLD ONTO OVERCAST INTO AFTERNOON...WITH SOME CLEARING IN THE WESTERN COUNTIES. THE TEMP TRACE ON WEDNESDAY MAY STILL GO DOWN A BIT 12Z TO 15Z THEN TRY TO CREEP UP A FEW DEGREES DURING THE AFTERNOON. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... COMPLICATED SPLIT FLOW PATTERN ALOFT CONTINUES...WITH AN ACTIVE SOUTHERN STREAM TO THE SOUTH OF A BLOCKING PATTERN ACROSS CANADA. LINGERING MOUNTAIN SNOW SHOWERS END BY WEDNESDAY AFTERNOON AS ONE SYSTEM EXITS AND CANADIAN HIGH PRESSURE BUILDS IN. THIS HIGH PRESSURE SYSTEM WILL BRING MOSTLY DRY WEATHER AND NEAR SEASONABLE TEMPERATURES THURSDAY AND FRIDAY. ALTHOUGH CLOUDS MAY INCREASE THURSDAY FROM THE NEXT SOUTHERN STREAM SYSTEM...THE MODELS CONTINUE TO KEEP THIS SYSTEM RATHER FLAT AND ITS PRECIPITATION SHIELD TO OUR SOUTH. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... BY THE END OF THE WORK WEEK...ALL THE MODELS HAVE A MAJOR SOUTHERN STREAM SYSTEM COMING OUT OF THE SOUTHERN PLAINS. WHILE ALL AGREE THIS WILL BE A HIGHER AMPLITUDE SYSTEM THAN THE PREVIOUS AND BEGIN TO AFFECT US FRIDAY NIGHT...THERE ARE MODEL DIFFERENCES IN HOW THIS SYSTEM EVOLVES AND THE TRACK IT TAKES OVER THE WEEKEND. ALL THIS HAS TO DO WITH THE BLOCKY PATTERN ACROSS CANADA. CONSIDERING THE OPERATIONAL MODELS...THE EURO IS THE OUTLIER MODEL IN KEEPING THE CANADIAN BLOCK SUCH THAT THIS APPROACHING SYSTEM TAKES A MORE SOUTHERN ROUTE...WITH THE PARENT LOW PRESSURE SYSTEM TRACKING WELL SOUTH AND EAST OF US. THIS KEEPS ENOUGH COLD AIR FOR THE PRECIPITATION TO BE AT LEAST A WINTRY MIX. THE UKMET...CMC AND GFS MODELS ARE RATHER SIMILAR IN BREAKING DOWN THE CANADIAN BLOCK ENOUGH TO ALLOW A WEAKENING PARENT LOW TO TRACK UP JUST WEST OF THE MOUNTAINS SATURDAY BEFORE REGENERATING ALONG THE EAST COAST...BUT WITH THE GFS LOOKING TO BE A BIT TOO WARM. THE PREFERRED MODEL CONSENSUS...WITH A SLIGHTLY COOLER VERSION OF THE GFS...WILL ALLOW A WINTRY MIX AT THE BEGINNING FOR FRIDAY NIGHT. THE PRECIPITATION WILL TREND TO MOSTLY RAIN OVER MUCH OF THE LOW LANDS SATURDAY...BEFORE CHANGING BACK TO A WINTRY MIX AND THEN SNOW SATURDAY NIGHT INTO SUNDAY MORNING AS COLDER AIR RUSHES BACK IN. AT THIS DISTANT TIME FRAME...AND GIVEN THE CHANGES THAT CAN OCCUR IN THIS COMPLICATED SPLIT FLOW PATTERN...WILL ONLY MENTION THE POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK FOR THE WEEKEND STORM. IN ANY CASE...LOOK FOR TEMPERATURES TO BE NEAR SEASONABLE LEVELS. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... CONFIDENCE AT MEDIUM...UNSURE HOW QUICKLY AND HOW LOW THE CEILINGS DROP OVERNIGHT...ESPECIALLY FOR SOUTHERN WEST VIRGINIA AND SOUTHWEST VIRGINIA. WITH LOW LEVEL FLOW MOSTLY WESTERLY...FIGURING THE BEST PROBABILITY OF LINGERING DRIZZLE AND LIGHT RAIN SHOWERS IS ACROSS EASTERN OHIO AND NORTHERN WEST VIRGINIA. DID MENTION SOME FREEZING DRIZZLE 04Z TO 14Z WEDNESDAY...BUT FOR ELEVATIONS ABOVE THE EKN AND BKW TAF SITES. THE OTHER REASON ON MEDIUM CONFIDENCE...UNSURE HOW QUICKLY CEILINGS IMPROVE DURING THE DAYLIGHT HOURS ON WEDNESDAY. ALL IN ALL...WIDESPREAD CEILINGS AROUND 2 THSD FT THIS AFTERNOON WITH VSBY 3 TO 5 MILES IN ANY RAIN SHOWERS. CEILINGS BECOMING 1 TO 2 THSD FT TONIGHT WITH AOB 1 THSD FT ACROSS MOUNTAIN COUNTIES. WIDESPREAD VSBY NEAR 5 MILES IN LIGHT RAIN SHOWERS OR PATCHY DRIZZLE OVERNIGHT TONIGHT. VSBY AOB 3 MILES ACROSS HIGH MOUNTAIN TERRAIN 04Z TO 14Z WEDNESDAY IN LIGHT MIXED RAIN/SNOW SHOWERS OR DRIZZLE/FREEZING DRIZZLE. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: CEILINGS MAY TAKE LONGER TO DETEORIATE IN SOUTHERN WV MOUNTAINS INCLUDING BKW LATE TODAY AND THIS EVENING. ALSO...THINNING CEILINGS MAY LIFT...OR BREAK UP...SOONER IN THE OHO VALLEY COUNTIES DURING THE DAY ON WEDNESDAY. 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 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY M H H H H H H H H H H H HTS CONSISTENCY M H H H H H H H H H H H BKW CONSISTENCY H H H H H H M M M L H H EKN CONSISTENCY H H H M M M M M L L L L 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 M H H AFTER 18Z WEDNESDAY... HIGHER MOUNTAIN RIDGES MAY IFR IN CEILINGS LATE WEDNESDAY NIGHT AND EARLY THURSDAY AND AGAIN LATE THURSDAY NIGHT AND EARLY FRIDAY. IFR POSSIBLE IN WINTRY MIX SATURDAY INTO SUNDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/RPY/SL NEAR TERM...KTB SHORT TERM...JMV LONG TERM...MZ AVIATION...KTB

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