Area Forecast Discussion
Issued by NWS Charleston, WV

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901 FXUS61 KRLX 211130 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 630 AM EST Tue Nov 21 2017 .SYNOPSIS... Southwest flow today brings milder afternoon. Cold front crosses tonight. High pressure Wednesday through Thanksgiving and Friday. Cold front crosses Saturday. High pressure Monday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 630 AM Tuesday... The atmosphere has become mixed, with increasing winds and rising temperatures over the middle Ohio valley, while the valleys in and near the central Appalachians remained decoupled. As of 300 AM Tuesday... After a chilly start, a south to southwest flow around the back side of high pressure moving off the east coast, brings about a milder afternoon today. It also brings low level moisture northward into the central appalachians, resulting in an increase in cloud cover there late this afternoon and evening. A northern stream short wave trough drives a surface cold front through the area late tonight. This brings an increase in clouds throughout the area tonight, along with the chance for rain showers across northern portions of the area, where mid level forcing associated with the front is strongest. Southern portions of the area are left on the anticyclonic shear side of the jet stream, and remain mainly dry. The rain showers will transition to snow showers in the northern WV mountains early Wednesday morning, as the colder air moves in behind the front, although the -8 to -9 C at the top of the moist layer near h85 is marginal for the presence of ice crystals in cloud. Either way, little if any accumulation is expected through 12Z Wednesday, as temperatures will be just getting below freezing over the very highest ridges by then. Stayed away from the high MAV on highs today, the previous forecast close to the latest MET and short term consensus guidance, which was also used for hourly temperatures tonight, with the crossing cold front.
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&& .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... As of 300 AM Tuesday... Light rain and snow showers will taper off as the morning progresses on Wednesday, with no additional accumulations expected. High pressure, with cooler, but dry weather will take hold for Thanksgiving Day and Friday, with temperatures topping out in the 40s to 50s. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... As of 300 AM Tuesday... Another progressive system will affect the region late Friday night into the weekend. Rain and snow showers are expected to develop, particularly across the north, as a cold front sweeps across the region. After a brief lull in the precipitation later in the day Saturday, outside of upslope rain and snow showers across the mountains, a reinforcing short wave will bring another round of precipitation for Sunday, along with an additional shot of cooler air. Light accumulations are expected across the mountainous counties. && .AVIATION /11Z TUESDAY THROUGH SATURDAY/...
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As of 630 AM Tuesday... VFR today with cirrus the dominant cloud type, with additional FEW030 morning cu developing during mixing of the boundary layer. Low level moisture will be drawn up across the central Appalachians from the south, out ahead of a cold front approaching from the northwest. This could bring MVFR ceilings to the mountains tonight, starting around 00Z BKW and then around 06Z EKN. Elsewhere, higher SCT-BKN stratocu is expected tonight, as the cold front moves into the middle Ohio Valley. A light rain shower is possible in east central Ohio, and into northern WV, late tonight. As the front crosses overnight, a period of MVFR stratocu is likely most if not all sites. Timing of the front ranges from around 08Z along the Ohio River to around 11Z in the WV mountains. Light south to southeast surface flow early this morning, will increase and become south to southwest on today, with wind gusts to around 20 kts possible during mixing from afternoon heating. These southwest winds will diminish this evening, and then turn light northwest behind the cold front late overnight tonight. Flow aloft will be moderate southwest, switching to moderate west to northwest behind the front late overnight tonight. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: Timing and extent of MVFR stratocu could vary late today and tonight. BKW and EKN ceilings could drop to near IFR overnight. 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 TUE 11/21/17 UTC 1HRLY 10 11 12 13 14 15 16 17 18 19 20 21 EST 1HRLY 05 06 07 08 09 10 11 12 13 14 15 16 CRW CONSISTENCY H H H H H H H H M M M M HTS CONSISTENCY H H H H H H H H H H M M BKW CONSISTENCY H H H H H H H H H H M L EKN CONSISTENCY H H H H H H H H H H M M PKB CONSISTENCY H H H H H H H H H H M M CKB CONSISTENCY H H H H H H H H H H M M AFTER 12Z WEDNESDAY... No widespread IFR conditions expected.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...TRM SHORT TERM...SL LONG TERM...SL AVIATION...TRM

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