Area Forecast Discussion
Issued by NWS Charleston, WV

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229 FXUS61 KRLX 041800 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 100 PM EST Sun Dec 4 2016 .SYNOPSIS... Weak upper trough crosses this afternoon and tonight. A low pressure system crosses Monday night and Tuesday. Briefly milder in its wake mid week, then much colder late week. && .NEAR TERM /THROUGH TONIGHT/... As of 910 AM Sunday...Forecast remains mostly on track. Just made minor tweaks to PoP based on current observations, radar, and HRRR ensemble. As of 420 AM Sunday... Active weather pattern returns to the CWA. Isentropic lift kicks off this morning with light precipitation forming mainly in far southern and eastern zones, as moisture streams out of Gulf region towards the CWA. Still could be a brief wintry mix at the onset this morning in southwest VA zones, but this will quickly change over to rain as waa takes hold. Most of the activity today will be confined to these areas, before a shortwave trough moves through the Great Lakes region later today and tonight, spreading moisture across the CWA. Out ahead of this feature, southeasterly flow will take hold across the CWA, with moisture lifting across mountain zones, with drier conditions across much of the lowlands for most of the day. Due to southeast upslope flow, mountainous counties will remain cool compared to remainder of CWA. Forecast soundings suggest the potential for a wintry mix, including periods of sleet and freezing rain, this afternoon and evening across favored areas of Randolph and Pocahontas counties in the se upslope flow. Elected to go ahead and issue a winter weather advisory for these areas, starting this afternoon, through Monday morning. Generally figuring only a few hundredths of an inch of ice accumulation at this point. As the aforementioned system moves east of the region late tonight/early Monday, will likely see a transition over to drizzle for many areas as mid and upper levels dry out. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... As of 420 AM Sunday... System pulls out first thing Monday morning. Low level westerly flow quickly takes out the CAD and, with a lack of cold air arriving in the wake of this system, temperatures climb quickly above freezing, and any lingering light precipitation Monday morning should be of the liquid variety. The next system, a closed upper level low over northwest Mexico this morning that loiters around there today before lifting out into TX tonight and Monday, opens up and dampens out as it lifts through the Ohio Valley Tuesday. This causes rain to rapidly overspread the area overnight Monday night, and then move through the area on Tuesday. With a stronger surface low pressure system compared with its predecessor, a stronger CAD wedge develops as the system approaches Monday night, and freezing rain is again possible on the higher eastern slopes and ridge lines of Pocahontas and Randolph counties. Warm advection should erode the CAD wedge on Tuesday. A bit of snow is possible over the higher terrain of the northern WV mountains on west to northwest upslope flow in the wake of the system Wednesday morning, but only slightly colder air moves in, as weak high pressure of Pacific origin approaches on Wednesday. Models continue to differ on weather the next cold front, a much stronger one, arrives Wednesday night. Temperatures close to guidance blends, which reflect a compromise that leans toward the lower side when models diverge Wednesday night. && .LONG TERM /THURSDAY THROUGH SATURDAY/... As of 420 AM Sunday... A strong cold front crosses the area sometime Thursday. Models continue to differ on this, one factor being whether a wave forms along the front and slows it down. Per WPC and coordination with neighboring offices, the forecast continues to represent a compromise that leans toward the faster and colder side. This would have rain showers that mix with and change to snow showers in the west and over the higher terrain Thursday, followed by a transition to all snow showers as Thursday evening approaches. The cold air takes charge Thursday night, and remains in firm control into Saturday. This sets up the potential for frozen precipitation as the next weather system approaches Saturday night, which would then likely change to rain at least across much of the lowlands on Sunday given a track west of the area, at least initially. Temperatures close to a guidance blend, except leaning toward the lower side on Thursday. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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As of 1245 PM Sunday.... Mid to upper level clouds will lower this afternoon and evening as a weak system approaches from the west. Generally, VFR conditions should hold through about 00Z. Then more widespread rainfall arrives as well as MVFR conditions, with IFR conditions mostly in the mountains with southeasterly upslope flow. High pressure will start to build into the area Monday morning, but low level moisture could linger until Monday afternoon, especially in the mountains. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY... FORECAST CONFIDENCE: Medium to High. ALTERNATE SCENARIOS: Timing of precipitation and MVFR/IFR conditions tonight may vary. Ceilings may lift faster tomorrow morning than currently 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. 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 L L L L M M M L HTS CONSISTENCY H H H H H M L H H H H L BKW CONSISTENCY H H M M M M H H L M M L EKN CONSISTENCY H H H H H H H H M L L L PKB CONSISTENCY H H H H H H L H H H H L CKB CONSISTENCY H H H H H H H H H M M L AFTER 18Z MONDAY... IFR possible in rain on Tuesday.
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&& .RLX WATCHES/WARNINGS/ADVISORIES...
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WV...Winter Weather Advisory until 6 AM EST Monday for WVZ523-524- 526. OH...None. KY...None. VA...None.
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&& $$ SYNOPSIS...TRM/SL NEAR TERM...MPK/SL SHORT TERM...TRM LONG TERM...TRM AVIATION...MPK

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