Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 300155 CCA AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 945 PM EDT WED OCT 29 2014 .SYNOPSIS... HIGH PRESSURE TONIGHT INTO THURSDAY. A LOW PRESSURE SYSTEM WILL BRING RAIN FRIDAY EVENING...AND ACCUMULATING SNOW IN THE MOUNTAIN COUNTIES OVERNIGHT FRIDAY NIGHT INTO SATURDAY. && .NEAR TERM /THROUGH THURSDAY/... IN THE LATE EVENING UPDATE...NOT MUCH CHANGE FROM THE UPDATE WE MADE DURING THE EARLY EVENING HOURS. WE RESTRICTED...AND WERE SLOWER...IN THE RETURN OF STRATOCUMULUS IN THE COLDER 850 TEMPERATURE POOL. STILL THINK THESE CLOUDS WILL BE FORMING OVER NORTHERN COUNTIES 06Z TO 12Z THURSDAY. WILL ADD A BIT MORE PATCHY FROST ACROSS SOUTHEAST OHIO AND SOUTHWESTERN WV WITH THE CLEARER SKY. WILL HAVE THE MOST VALLEY FOG IN SOUTHERN WV SOUTH OF CRW...08Z TO 12Z. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... ...FIRST MEANINGFUL SNOW OF THE SEASON ANTICIPATED FOR THE WV MOUNTAIN COUNTIES INTO SOUTHWEST VIRGINIA...AND PERHAPS HILLTOPS IN SOUTHERN WV COAL FIELDS FRI NIGHT AND SATURDAY MORNING... THE UPPER TROF AMPLIFIES FRIDAY IN A BIG WAY...WITH QUITE THE COLD SHOT TO ARRIVE FRIDAY NIGHT AND SATURDAY. THE MODELS HAVE CONVERGED ON TRACK OF THE CLOSED UPPER LOW...TAKING IT THRU W OH...E KY...E TN AND W NC FRI NIGHT. GOOD LIFT AND DYNAMICS TO SUPPORT QUITE A BIT OF SHOWER ACTIVITY WITH ARRIVAL OF THE UPPER TROF AND LOW BY FRI AFTERNOON. HAVE CATEGORICAL POPS MOST PLACES FRI NIGHT. WITH CAA SENDING H85 TEMPS DOWN TO JUST BELOW 0C ACROSS THE HIGH TERRAIN AND GOOD LIFT AND MOISTURE IN THE DENDRITIC GROWTH ZONE...HAVE TRANSITIONED ELEVATIONS ABOVE 3 KFT TO SNOW BY 03Z IN THE WV MOUNTAINS AND SW VA. THIS TRANSITION GRADUALLY WORKS INTO THE LOWER ELEVATIONS OF THE MOUNTAINS AND HIGHER RIDGETOPS IN NE KY...C AND S WV AFTER 06Z. DID ALLOW FOR AT LEAST A MIX FOR HTS AND CRW METRO AREAS TOWARD DAWN. ACROSS THE N LOWLANDS...A CONSENSUS OF THE MODEL SOUNDINGS KEEP THINGS MAINLY RAIN FOR AREAS LIKE PKB...CKB...AND PERHAPS EKN...AS THE CORE OF COLD POOL STAYS TUCKED IN WITH THE UPPER LOW TO THE SW. SAT MORNING...NAM/ECMWF AND TO AN EXTENT THE CMC DIFFER FROM GFS WITH PLACEMENT OF A POTENTIAL DEFORMATION BAND. THE GFS SUGGESTS AXIS IS MORE FOCUSED IN THE C AND N WV MOUNTAINS WHERE AS THE OTHER MODELS HAVE IT FARTHER SW...ACROSS SW VA/SE WV AND UP INTO THE C LOWLANDS. THIS IS KEY AS TO WHO RECEIVES BEST SHOT OF A COMPLETE CHANGEOVER BLO 1000 FT IN THE LOWLANDS. THIS AXIS WILL HAVE GOOD LIFT AND RH WELL INTO THE DENDRITIC GROWTH ZONE. AS SUCH...THIS WILL HAVE TO BE MONITORED FOR A POTENTIAL COATING IN SOME OF THESE LOWER ELEVATIONS IN THE LOWLANDS EARLY SATURDAY MORNING /PRE DAWN/ SHOULD A COMPLETE CHANGEOVER OCCUR IN THE DEFORMATION BAND. ACCUMULATIONS ON THE RIDGETOPS IN THE COAL FIELDS LOOK TO RANGE FROM A COATING TO AN INCH. ONCE INTO SW VA AND SE WV...THESE AREAS MAY SEE THE BULK OF ACCUMULATIONS WITH CONSENSUS RANGING 1 TO 4 INCHES DEPENDING ON ELEVATION. HAVE A COUPLE INCHES IN ABOVE 2500 FEET IN THE C AND N WV MOUNTAINS BY 12Z. USED HPC WWD GRIDS AS A BASE FOR ACCUMULATIONS AND THEN TWEAKING DOWN BASED ON OUR FORECASTED SURFACE TEMPS...INCORPORATING SOME RAW NAM/GFS NUMBERS. THIS ALLOWED FOR BETTER RESOLUTION BETWEEN VALLEY AND HILLTOPS. EVERYTHING TRANSITIONS TO AN UPSLOPE EVENT DURING THE DAY SATURDAY WITH ANY MIXED PRECIP OVER THE LOWLANDS ENDING AS SOME RAIN SHOWERS. KEPT LIKELY POPS IN THE FAVORED MOUNTAIN AREAS ABOVE 3000 FT WITH ANOTHER 1 TO 3 INCHES OF SNOW IN THE AFTERNOON. WILL UPDATE HWO TO REFLECT CURRENT THINKING REGARDING POTENTIAL FOR ADVISORIES IN THE MOUNTAINS AND SW VA. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... MODELS RAPIDLY LIFT THE UPPER LOW OFF THE ATLANTIC COAST SATURDAY NIGHT...WHICH WILL END THE LINGERING MOUNTAIN SNOW SHOWERS...WITH ONLY ADDITIONAL MINOR HIGH ELEVATION ACCUMULATIONS BEFORE DAWN SUNDAY. STRONG DRY CANADIAN HIGH PRESSURE WILL THEN BE THE DOMINANT FEATURE THROUGH MONDAY. THE HIGH PRESSURE CENTER WILL SETTLE OVER THE AREA SUNDAY NIGHT...THEN SHIFT OFF THE ATLANTIC COAST EARLY NEXT WEEK. THIS WILL BRING A DRAMATIC TURNAROUND IN TEMPERATURES THIS PERIOD. WELL BELOW NORMAL TEMPERATURES THIS WEEKEND WITH WIDESPREAD SUB FREEZING TEMPERATURES SUNDAY NIGHT UNDER THE CENTER OF HIGH PRESSURE...WILL WARM UP TO NEAR NORMAL VALUES BY TUESDAY AS THE HIGH SHIFTS OFF THE ATLANTIC COAST. WHILE ALL THIS ABOVE IS HAPPENING...MODELS SHOW ANOTHER UPPER TROUGH DIGGING INTO THE MISSISSIPPI VALLEY AND DRIVING IT EAST TO AFFECT OUR AREA LATER TUESDAY AND WEDNESDAY. BY THIS TIME...TEMPERATURES WILL BE WELL ABOVE FREEZING FOR A RAIN EVENT. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... CONFIDENCE STILL SET AT MEDIUM...DUE TO QUESTIONS OF FORMATION AND COVERAGE OF THE RIVER VALLEY FOG IN SOUTHERN WEST VIRGINIA 06Z TO 12Z. THINKING PATCHES OF CLOUDS WILL PREVENT THICK FOG FOR CRW...BUT WILL INCLUDE SOME MVFR SINCE CLOUDS COULD EASILY BECOME JUST SCATTERED TO BROKEN. OTHERWISE...JUST 3 TO 5 THSD FT STRATOCUMULUS CLOUDS THROUGH PERIOD...EXCEPT 2 THSD FT AGL OVER HIGHER RIDGES. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z FRIDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND DENSITY OF MORNING 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. DATE THU 10/30/14 UTC 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 EDT 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09 CRW CONSISTENCY H H H H H H H M M M H H HTS CONSISTENCY H H H H H H H H H H H 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 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 H H H H AFTER 00Z FRIDAY... IFR DEVELOPING FRIDAY EVENING IN RAIN...CHANGING TO MOSTLY SNOW OVER SOUTHERN MOUNTAIN COUNTIES INCLUDING BKW 06Z TO 12Z SATURDAY...WITH A RAIN AND SNOW MIXTURE IN THE LOWLANDS SATURDAY. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JMV/30/LS NEAR TERM...KTB SHORT TERM...30 LONG TERM...JMV AVIATION...KTB

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