Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 170529 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 1229 AM EST WED DEC 17 2014 .SYNOPSIS... IN WAKE OF COLD FRONT...ABUNDANT LOW LEVEL MOISTURE THROUGH THURSDAY NIGHT. HIGH PRESSURE FRIDAY. LOW PRESSURE APPROACHES FOR THE WEEKEND. && .NEAR TERM /THROUGH TODAY/...
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WV LOOPER ALONG WITH SAT IR IMAGERY SHOWED A NICE LOOKING LOW TO MID LEVEL VORT MAX WORKING OUT OF CENTRAL OH AND INTO WV EARLIER THIS EVENING...WITH IT EVENTUALLY REACHING THE WV PANHANDLE BY 02Z. MOST OF THE STRONGER SHOWER ACTIVITY ASSOCIATED WITH THIS FEATURE DISSIPATED BEFORE REACHING THE OH RIVER. CAN EFFECTIVELY SAY THAT THE COLD FRONT IS NOW THROUGH THE CWA BUT CAA CLOUDS AND PLENTY OF LOW LEVEL MOISTURE REMAIN IN ITS WAKE. THE ATMOSPHERE IS STILL UNSETTLED IN THIS REGIME. WEAK LIFT AND SLIGHT INSTABILITY WILL ALLOW FOR PRECIPITATION TO FORM ON AND OFF TONIGHT...MAINLY IN WARMER LOWER LEVELS IN THE FORM OF DRIZZLE. ISSUED SPS TO COVER THE POSSIBILITY OF FZRA OVER THE HIGHEST RIDGE TOPS OF OUR MOUNTAIN COUNTIES AS THESE AREAS ARE FORECAST TO DIPPED BELOW FREEZING BY MORNING. OTHERWISE...DO NOT PLAN SIGNIFICANT CHANGES TO THE FORECAST. PREVIOUS DISCUSSION BELOW... 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 CENTRAL 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.
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&& .SHORT TERM /TONIGHT THROUGH FRIDAY/... MODELS SHOWING SOME LOW LEVEL MOISTURE REMAINING WEDNESDAY NIGHT INTO THURSDAY MORNING WITH COLD ADVECTION AND UPSLOPE NORTHWEST FLOW. MOISTURE IS SHALLOW...BUT BELIEVE THAT SOME FLURRIES ARE POSSIBLE IN THE NORTHERN AND CENTRAL MOUNTAINS. A WEAK DISTURBANCE MOVES ACROSS ON THURSDAY. WITH DRY AIR IN THE LOW LEVELS...NOT SURE THAT THE PRECIPITATION WILL MAKE IT TO THE GROUND. WILL LEAVE DRY FOR NOW...BUT MAY NEED TO ADD SOME SMALL CHANCES IF THE MODELS CONTINUE TO TREND WETTER WITH THIS DISTURBANCE. SOME COLD AIR ADVECTION SETS BACK IN BEHIND THE DISTURBANCE THURSDAY NIGHT. WITH LIGHT UPSLOPE FLOW CONTINUING AND SOME LOW LEVEL MOISTURE...WILL ADD SOME FLURRIES IN THE NORTHERN AND CENTRAL WEST VIRGINIA MOUNTAINS. HIGH PRESSURE BUILDS IN FOR FRIDAY. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ACTIVE WEATHER IN THE LONG TERM PERIOD. PERIOD STARTS OUT WITH A SPLIT UPPER FLOW PATTERN ACROSS THE U.S...WITH A LOW PRESSURE SYSTEM IN THE SOUTHERN STREAM MOVING EAST ACROSS THE SOUTHEASTERN UNITED STATES FRIDAY NIGHT INTO SATURDAY...WITH A SHORTWAVE TROUGH IN THE NORTHERN STREAM PUSHING EAST ACROSS THE OHIO VALLEY...BRINGING A REINFORCING SHOT OF COLD AIR INTO THE REGION. MODELS ARE STARTING TO COME INTO BETTER AGREEMENT WITH THE TRACK OF THE LOW...BUT ECMWF IS DEEPER...AND MORE PROGRESSIVE WITH NORTHERN STREAM SHORTWAVE...THUS RESULTING IN A COLDER SOLUTION. DEPENDING ON WHICH SOLUN PANS OUT...COULD SEE MORE OF A WINTRY MIX...AS WITH THE GFS SOLUN...OR A MAINLY SNOW...WITH POSSIBLY BRIEF RAIN/SNOW MIX ACROSS LOWLANDS...WITH THE ECMWF SOLUN. HAVE TRENDED THE FORECAST TOWARDS HPC...WHICH TENDS TO FAVOR WARMER SOLUN. THUS...EXPECTING A WINTRY MIX TO DEVELOP ACROSS THE AREA FRIDAY NIGHT/SATURDAY...BEFORE TRANSITIONING TO MAINLY RAIN ACROSS THE LOWLANDS SATURDAY...THEN BACK TO SNOW OR A MIX SATURDAY NIGHT. ITS POSSIBLE WINTER WEATHER HEADLINES MAY BE NEEDED DURING THIS PERIOD. HIGH PRESSURE WILL BUILD IN BEHIND THE SYSTEM FOR EARLY NEXT WEEK...FOR A BRIEF BREAK IN THE PRECIPITATION...BEFORE ANOTHER SYSTEM MOVES IN TOWARDS MID WEEK. && .AVIATION /05Z WEDNESDAY THROUGH SUNDAY/...
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LOOKING AT PERSISTENT MVFR CEILINGS/IFR IN BKW THROUGH THE BULK OF THE PERIOD WITH BRIEF IFR INTO THE DAWN HOURS OVER THE LOWLANDS. THIS IS THANKS TO ANOTHER DIRTY HIGH PRESSURE SYSTEM WHICH WILL TRAP MOISTURE IN THE BOUNDARY LAYER LIKE WAS SEEN A FEW DAYS AGO AND SHOULD YIELD OVERCAST SKIES THROUGH 06Z THURSDAY. USED THE MET MOS GUIDANCE AND NAM FORECAST SOUNDINGS FOR THIS FORECAST...NOTING THAT THE LAST 9 HOURS OF THE LAMP GUIDANCE BRINGS CEILINGS UP. WILL NOT GO WITH THIS FOR THIS ISSUANCE. NO VISIBILITY RESTRICTIONS EXPECTED WITH 8-12KT WINDS IN PLACE. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z THURSDAY... FORECAST CONFIDENCE: MEDIUM TO HIGH. ALTERNATE SCENARIOS: IFR MAY NOT DEVELOP AROUND DAWN. WILL NEED TO WATCH GUIDANCE FOR CHANGES SUPPORTING VFR AFTER 00Z THURSDAY. 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 12/17/14 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 M M H H HTS CONSISTENCY H H H H H H H H H M H H BKW CONSISTENCY L L L M M M M H H H H H EKN CONSISTENCY L L L M L L 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 M M H H AFTER 06Z THURSDAY... IFR POSSIBLE IN WINTRY MIX SATURDAY INTO SUNDAY.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KTB/RPY/SL NEAR TERM...KMC/KTB SHORT TERM...RPY LONG TERM...SL AVIATION...26

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