Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 250526 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1226 AM EST THU DEC 25 2014 .SYNOPSIS... COLD FRONT BRINGS GUSTY WINDS AND SHOWERS INTO THIS EVENING. CHRISTMAS DAY STARTS COLD...CLOUDY...AND WINDY...WITH A FEW RAIN AND SNOW SHOWERS. HIGH PRESSURE CHRISTMAS NIGHT INTO SATURDAY. && .NEAR TERM /THROUGH TODAY/... 630 PM UPDATE...TWEAKED GRIDS TO FOLLOW LINE OF SHRA/TSRA A LITTLE BETTER. BULK OF GUSTS ASSOCIATED WITH FRONT HAVE BEEN AROUND THE 40 MPH MARK...WITH A FEW LOCATIONS REPORTING SLIGHTLY HIGHER. AS THE FRONT CONTINUES TO PUSH EASTWARD...EXPECT TO SEE CONTINUED LIGHT SHOWER ACTIVITY...AND OCCASIONAL GUSTY WINDS. PREVIOUS DISCUSSION FOLLOWS... MODELS CONTINUE TO DRIVE A STRONG COLD FRONT EASTWARD ACROSS THE AREA THIS AFTERNOON AND EVENING...ACCOMPANIED BY A BAND OF SHOWERS AND A FEW THUNDERSTORMS. STILL SHOWING A MODERATE WESTERLY 850MB JET... PUNCHING IN BEHIND THE FRONT...AND LIFTING UP ACROSS THE LOW LANDS AND NORTHERN MOUNTAINS. THIS COUPLED WITH A TIGHT AND IMPRESSIVE COLD ADVECTION THERMAL PATTERN WILL GREATLY ENHANCE DOWNWARD MOMENTUM TRANSFER...FIRST WITH THE SHOWERS AND FOR SEVERAL HOURS BEHIND THE FRONT. THUS...WILL CONTINUE THE WIND ADVISORY FOR NORTHWESTERN TWO THIRDS OF THE AREA TIL 10 PM EST THIS EVENING. WHILE GUSTY WINDS WILL CONTINUE FOR AWHILE AFTER 10 PM...LOSS OF MIXING THRU HEATING AND LESSENING OF THE THERMAL GRADIENT WILL DECREASE THE WINDS FROM WEST TO EAST. FOR TEMPERATURES...THERE WILL BE A STRONG TEMPERATURE DROP BEHIND THE FRONT...BUT ABNORMALLY WARM TEMPERATURES AHEAD OF THE FRONT WILL BE FOLLOWED BY ONLY SEASONAL TEMPERATURES TONIGHT AND CHRISTMAS DAY. SO...POST FRONTAL RAIN SHOWERS WILL STRUGGLE TO CHANGE TO SNOW SHOWERS BEFORE ENDING FOR THE MOST PART FROM WEST TO EAST TONIGHT. THE EXCEPTION WILL BE THE HIGHER ELEVATIONS OF THE NORTHERN MOUNTAINS WHERE RAIN WILL CHANGE TO SNOW...BUT LITTLE SNOW ACCUMULATION IS EXPECTED AS DEEPER MOISTURE IS LOST BY THE TIME OF CHANGEOVER. ON CHRISTMAS DAY...LOTS OF LOW CLOUDS IN THE MORNING....BREAKING FOR SOME SUNSHINE IN THE AFTERNOON AS HIGH PRESSURE AND MUCH DRIER AIR SETTLES IN FROM THE WEST. LOOK FOR HIGHS IN THE 40S. && .SHORT TERM /TONIGHT THROUGH SATURDAY/... WITH MOISTURE IN THE MOUNTAINS SHOWN TO BECOME LESS THAN 1.5 KFT THICK IN THE NRN MOUNTAINS BY 00Z FRI...AND THE TOP OF THE CLOUD AT -5C OR WARMER...OPTED TO CUT OFF UPSLOPE RAIN/SNOW SHOWERS THERE BY THEN TO START THE PERIOD. COLD ADVECTION IS CUT OFF AS COLD CORE SHIFTS E...AND HIGH PRESSURE TAKES OVER AT THE SFC BENEATH UPPER LEVEL RIDGING. THE HIGH MAINTAINS ITS INFLUENCE ON THE WEATHER AS IT BECOMES ANCHORED OVER THE MIDDLE ATLANTIC STATES FRI AND REMAINS SO THROUGH FRI NT...BEFORE DRIFTING EWD...OFFSHORE...ON SAT. THIS SPELLS DRY WEATHER WITHOUT MUCH CLOUD...ONCE THE CLOUDS IN THE NRN MOUNTAINS GRADUALLY BREAK UP THU NT. CLOUDS...MAINLY HIGH...INCREASE SAT AFTERNOON AS A LARGE POSITIVE TILT UPPER LEVEL S/W TROUGH AND SFC COLD FRONT APPROACH. MODELS CONTINUE TO TREND SLOWER WITH THIS FEATURE...LIKELY OWING TO THE TENACIOUS UPPER LEVEL HIGH OVER THE BAHAMAS. THUS HAVE SLOWED THE CHANCE FOR PRECIPITATION INCREASING FROM THE W...LIMITING IT TO JUST A SCHC ALONG AND W OF THE OHIO RIVER BY THE END OF THE DAY SAT. BLENDED IN THE MET AND MAV FOR LOWS THU NT...A LITTLE HIGHER OVER THE MIDDLE OHIO VALLEY ON ACCOUNT OF THE GRADIENT ON THE BACK SIDE OF THE HIGH THERE...AND A LITTLE LOWER ELSEWHERE WITH GOOD RADIATIVE COOLING IN THE VALLEYS. BLENDED IN THE MET FOR LOWS A LITTLE LOWER FRI NT WITH LESS CLOUD AND HIGH PRESSURE KEEPING THE FLOW LIGHT ESPECIALLY S AND E OF THE OHIO RIVER. BLENDED IN THE MET FOR HIGHS FRI FOR LITTLE CHANGE. RAISED HIGHS SAT A LITTLE ABOVE CONSENSUS AND GENERALLY ABOVE THE STRAIGHT GUIDANCE AND BELOW THE BIAS CORRECTED GUIDANCE. WITH LESS CLOUD...SAT SHOULD NOT BE MUCH IF ANY COOLER THAN FRI. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... MAIN SYNOPTIC FEATURE FOR THE LONG TERM IS A COLD FRONT PASSING THROUGH AND THEN A SECONDARY WAVE RIDING ALONG THE FRONT. THE GFS CONTINUES TO SUPPRESS THE SECOND WAVE...KEEPING IT MAINLY SOUTH AND EAST. THE LATEST ECMWF IS TRENDING THIS WAY AS WELL. STARTED WITH WPC GUIDANCE...AND THEN BLENDED IN ANOTHER DOSE OF THE GFS. HAVE THE COLD FRONT PASSING THROUGH ON SUNDAY WITH LIKELY POPS ACROSS MUCH OF THE CWA. THEN HAVE ANOTHER AREA OF LIKELY POPS ACROSS MAINLY THE COAL FIELDS AND SOUTHERN MOUNTAINS SUNDAY NIGHT INTO EARLY MONDAY WITH THE SECONDARY WAVE. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... MVFR CIGS THIS MORNING WITH TIGHT SURFACE GRADIENTS IN PLACE AS COLD FRONT EXITS TO THE EAST. THERE STILL MAY BE LOCAL IFR EARLY THIS MORNING AS A FEW SHOWERS WILL CONTINUE TO BE GENERATED AS SWIFT JET MAXIMA PASSES WITH SOME UPPER LEVEL DYNAMICS BEHIND THE SFC FRONT. WILL CARRY SOME WIND GUSTS IN THE 20-25KT RANGE ACROSS ALL SITES INTO THE MID MORNING HOURS. GRADIENTS RELAX BY ABOUT 15Z AND WE SHOULD SEE A SLACKENING OF SFC WINDS. ATMOSPHERIC COLUMN WILL CONTINUE TO DRY THROUGH TODAY WITH A TRANSITION TO VFR BY AROUND 18Z...WORKING WEST TO EAST. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING DEVELOPMENT OF MVFR STRATUS OVERNIGHT...AND IMPROVEMENT ON THURSDAY MAY VARY FROM FORECAST. 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 THU 12/25/14 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 M M H HTS CONSISTENCY H H H H H H H H H M H H BKW CONSISTENCY H H M M M M H M H H H H EKN CONSISTENCY H H H H H L L H H H M H PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H H AFTER 06Z FRIDAY... IFR POSSIBLE IN RAIN AND MOUNTAIN RAIN AND SNOW SHOWERS SUNDAY THROUGH EARLY TUESDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/JMV/MZ NEAR TERM...JMV/SL SHORT TERM...TRM LONG TERM...MZ AVIATION...KMC

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