Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 031914 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 214 PM EST Sat Dec 3 2016 .SYNOPSIS...
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Weak upper trough Sunday into Sunday night. Low pressure Monday night Tuesday. Briefly milder in its wake mid week, then much colder late week.
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&& .NEAR TERM /THROUGH SUNDAY/...
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As of 145 PM Saturday... As expected the stratus has held firm today as cirrus overspreads the area ahead of the next system. Even though some of this stratus will lift as the low level flow turns more SE, this will keep temps from dropping much tonight so another day of going above guidance for lows. A southern stream system will approach Sunday in the form of a surface wave with induced isentropic lift overspread the TN Valley into SW VA. Given how dry the low levels are, this will fall as virga initially before reaching the ground around sunrise. Thermal profiles suggest some wet snow may fall on the highest ridges in SW VA early Sunday morning but with little if any accumulation. Most of the lift will slide into VA as the day progresses with a S/W trof tracking thru the OH Valley. This combined with some downsloping SE flow should leave much of the area dry as the shadow and dry air keep any precip as virga until late in the day. Across the mountains, in particular Pocahontas County, light precip will fall as a mixture with all snow on the ridges. Temps on Sunday should manage to warm well into the 40s across the Lowlands with 30s in the mountains.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 430 PM Saturday... Precipitation overspreads the area from southwest to northeast on Sunday, as a weak short wave trough crosses. This will be a split system, with the best forcing associated with the short wave passing north of the forecast area. However, channeled vorticity and southern stream moisture will make for another precipitation maxima to the south. With this maxima coming close to the forecast area from the south, precipitation is most likely late Sunday far southern portions of the forecast area, mainly the southern mountains. Precipitation may begin as a wintry mix far south first thing Sunday morning, but low level warming will bring about a quick change over to rain, without much accumulation or hazard. As the system moves off to the east on Sunday night, there may be enough cold air aloft for a wintry mix in the northern mountains. However, since the moisture layer will be becoming shallow, lack of ice crystals may lead to just drizzle / freezing drizzle but, again, not much hazard. Weak Pacific high pressure crosses Monday, as upper level ridging crosses late Monday. This will be quickly followed by the next system, an upper level closed low over northwest Mexico early this morning, that ejects out into TX early Monday morning, and then dampens out as it moves up the Ohio Valley Tuesday morning. This, and its attendant surface low pressure system and associated warm advection and dynamics, will result in rain overspreading the forcast area quickly as dawn Tuesday approaches. The rain will diminish from southwest to northeast Tuesday as the system lifts on through. Little in the way of cold air initially follows the system Tuesday night, so an overcast, damp night appears in store, but any lingering precipitation will be light, and primarily of the liquid variety. Temperature close to a raw and MOS based blend. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 430 PM Saturday... Much colder air arrives this period, but with lingering questions as to when the colder air arrives. Models disagree on the degree of cold air eventually coming in Wednesday and Wednesday night in the wake of the Tuesday system, and on the timing of a cold front on Thursday. The two factors combined result in a 15 F degree or more spread between temperature outcomes Thursday. The forecast represents a blend, but a little toward the colder solution, per WPC preference and coordination with neighboring offices. Rain showers in the wake of the cold front Thursday are thus most likely to mix with and change to snow showers in the west, and over the higher terrain. Cold canadian air takes over by Thursday night, and dominates through the balance of the forecast, with highs below freezing for the first time this early winter season Friday, and maybe getting back above freezing over the lowlands on Saturday, as upslope snow showers diminish. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/...
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As of 200 PM Saturday... Widespread MVFR cigs mainly across the mountains of WV, and north central WV through the late afternoon. Otherwise, a general improvement to low VFR much of the area this evening, although MVFR cigs may continue to linger across parts of the higher terrain including at site KEKN. A system approaches from the SW on Sunday with cigs gradually lowering into MVFR across KBKW. Light rain will try to overspread the area but dry air in the low levels will keep much of this across SW VA and the E Slopes, where a light wintry mix is expected, especially in the high terrain where IFR conditions will develop. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing of category changes in clouds may vary this evening. 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 H H H H H H H H H H H M HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY M H H H H H H H H H H M EKN CONSISTENCY M M M M M M M M M M M L PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY M M M H M M M M H H H M AFTER 18Z SUNDAY... IFR possible in rain and snow, particularly in the mountains Sunday night into Monday. Additional IFR possible in rain and snow towards mid week.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...30/26 NEAR TERM...30 SHORT TERM...TRM LONG TERM...TRM AVIATION...30

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