Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 070552 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 1252 AM EST Thu Dec 7 2017 .SYNOPSIS... Cold. Cold front crosses Thursday night. Low pressure and cold front likely to bring snow showers Saturday afternoon and night, and early next weak. Brief, modest, intervening warm up Monday. && .NEAR TERM /THROUGH TODAY/... As of 700 PM Wednesday... Adjusted evening temperatures up a bit over the middle Ohio Valley per current trends. Forecast otherwise on track. As of 140 PM Wednesday... Challenging forecast despite the lack of sensible weather element overall. Cirrus embedded within the jet stream still prevalent over the Appalachians this afternoon and will continue over the mountains tonight. For the lower levels of the atmosphere, 850hPa thermal trough with an increase in dewpoints at that level will bring stratocumulus to the northern lowlands and most of the mountains after 03Z tonight. The increase in the sky cover is fairly dramatic from the previous forecast on the overnight. Given the temperatures at 850hPA within the thermal trough, flurries are a possibility, and have this represented in the higher elevations tonight. Will be tough to get any precipitation so will keep this a trace event tonight. Heading into Thursday, a weak cold front reinforces the cold airmass for the area, and keeps the threat of a few flakes flying over the northern zones. So carry slights and low end chance briefly, but this is a non accumulating event with temperatures expected to be above freezing during the daytime hours. And speaking of those temperatures, have gone with the colder MET given the advection taking place...just do not think lowland 40s will be possible as suggested by the MAV guidance, so threw those out for this forecast issuance. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... As of 230 PM Wednesday... Isolated snow showers and flurries will continue Thursday night as cold air advection continues. The 850mb thermal trough looks to cross in the predawn hours Friday morning, so end any lingering flurries by 12Z. A coastal system passes by to our south and east Friday and Friday night. The precipitation shield should remain on the other side of the Appalachians and have continued with the dry weather. Do have some clouds across the mountains and eastern slopes. A surface low moves into the Great Lakes Saturday, and will drive a cold front through the forecast area. Combined with a 500mb trough, we should see an area of snow showers and gusty winds move into the middle Ohio River Valley late morning or early afternoon...and continue drifting eastward into Saturday night. NAM is the slow outlier on the arrival of this system, and stayed on the GFS/ECMWF quicker side. Light snow accumulations are expected, with 1-2 inches in the northern mountainous counties of WV possible. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 230 PM Wednesday... Snow showers will linger into Sunday afternoon across the northern mountainous counties as upslope flow and cold air advection continue. We should see a brief quiet period Sunday night and Monday with a slightly warmer afternoon on Monday. Models look to have backed off a bit on the intensity of the next system Monday night into Tuesday, as they now feed the the energy into a developing coastal system. Both GFS and ECMWF swing a cold front through fairly quickly Monday night, bringing another shot of cold. This will lead to another period of good upslope flow and snow showers with 850mb temps dropping into the -16C to -18C range Tuesday into Wednesday. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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As of 1240 AM Thursday... Some disturbances combined with an upslope wind flow will produce some clouds at times early this morning. A moisture starved cold front will then move across the area today. Some light snow or flurries can not be ruled out over northern WV, remaining possible in the northern mountains through the evening hours. Outside of any precipitation, clouds west of the mountains will be predominately VFR, while the mountains could see MVFR clouds at times. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: Periods of MVFR in the mountains could vary. Can not rule out some restrictions in light snow in northeastern WV this afternoon and 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. DATE THU 12/07/17 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 H H M HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H H H H H H H H H H H L EKN CONSISTENCY H H H H H H M M M M M L PKB CONSISTENCY H H H H H H H H H H H L CKB CONSISTENCY H H H H H H H H H M M L AFTER 06Z FRIDAY... IFR possible in snow showers Saturday and Saturday night.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/MZ/26 NEAR TERM...TRM/26 SHORT TERM...MZ LONG TERM...MZ AVIATION...RPY

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