Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 181105 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 605 AM EST Sat Nov 18 2017 .SYNOPSIS... A strong cold front crosses tonight. Many may see first flakes of season in the colder air Sunday. High pressure early next week. Cold front Tuesday night. High pressure again late week. && .NEAR TERM /THROUGH TONIGHT/... As of 435 AM Saturday... Warm frontal boundary will lift northeast across the CWA today as low pressure over the central U.S. moves into the Great Lakes region. Temperatures are finally starting to warm quickly across the area, particularly across western zones, as southerly flow/waa kicks off. Already seen quite the temperature jump this morning at the office, with an over 10 degree jump from earlier this evening. The winds and precipitation chances will increase as the day progresses, with very warm temperatures as area remains in the warm sector for much of the day. With the tightening pressure gradient, and strengthening llj across the region, expecting gusty winds for much of the day, particularly when the cold frontal boundary arrives later tonight, in which the potential for the stronger winds aloft to mix to the surface will be more likely. It is possible that strong wind gusts over 40 kts will be possible, particularly late tonight with any showers or storms as the front crosses the region, but threat is not expected to be widespread enough, or long enough in duration to warrant a wind advisory area wide. The one exception will be along ridge tops, where advisory criteria winds are expected for much of the night and on Sunday. Will issue a wind advisory for the higher terrain of Nicholas, Webster, and Randolph counties, along with all of Pocahontas county, as eastern slopes will be prone to downsloping effects behind front. Will leave the wind advisory in place across northeast KY and southwest VA counties. Previous shift issued this in response to coordination issues with surrounding offices, although do not expect conditions in those areas to be worse than remainder of lowlands where no advisory exists. Frontal boundary will be well to the east of the area by Sunday morning/end of the forecast period. Much cooler air will usher in behind the front, with precipitation changing over to a rain/snow mix or all snow across the higher terrain. Around an inch of snow or less is possible across the higher terrain of Randolph, Pocahontas and Webster counties Saturday morning. && .SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/... As of 435 AM Saturday... A large, intense surface low moves up the Saint Lawrence River Valley Sunday and Sunday night, its central pressure falling through the 970s /MBs/ during this time. This places the forecast area, along with the Great Lakes, Ohio Valley, middle Atlantic and northeast states in deep layer west to northwest flow, that wanes with time from the southwest, as high pressure builds in from that direction, into the southern Appalachians. This flow will lead to upslope snow showers, enhanced at times by trajectories off the Great Lakes, that also wane with time. Wind gusts near 40 kts over the higher ridges Sunday morning, will gradually wane a bit through Monday morning. Following the main upper level short wave trough lifting out behind the surface low, a second short wave trough crosses Sunday night. This leads to a secondary surge in low level flow and cold advection late Sunday afternoon and Sunday evening, which could result in a second though lesser peak in wind gusts and upslope snow showers. Another 1 to 2 inches snow accumulation across the higher windward terrain Sunday into Sunday night could bring snowfall totals there up to around 3 inches. Many lowland locations could see the first snow flakes of the season, but the boundary layer will be able to melt many of the hydrometeors in the isolated to scattered coverage there Sunday. Clearing takes place late Sunday night into Monday morning, as high pressure builds in, and that high rules the roost through Tuesday. Another cold front crosses Tuesday night, with limited moisture. Models differ on whether or not we could squeeze a few light rain showers out of it with the frontal passage, and a few light upslope snow showers behind the front. Temperatures close to central guidance, except a little lower in cold advection Sunday morning, and a little lower in the valleys under high pressure Tuesday morning. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 435 AM Saturday... High pressure, with dry weather and somewhat below normal temperatures, dominates this period, between the northern and southern branches of the jet stream. Low pressure may pass south of the area during this time, beneath the southern branch. && .AVIATION /11Z SATURDAY THROUGH WEDNESDAY/... 12Z Saturday through 12Z Sunday... As of 605 AM Saturday... A warm front will bring some showers...mainly across the north Saturday morning, with isolated MVFR conditions possible in showers, particularly across southeast Ohio, and northern West Virginia. After 14Z, gusty south-southwesterly winds will develop, with sustained winds in the teens, and gusts in the 20 kt range. After 00Z sunday, a cold frontal boundary will move through the region, with showers, and widespread MVFR and local IFR conditions developing, particularly after 02Z. In addition, there is the potential for an uptick in winds with the front with the possibility of tsra and wind gusts over 40 kts. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z SUNDAY... FORECAST CONFIDENCE: Medium ALTERNATE SCENARIOS: Timing of showers and associated restrictions could vary from 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. DATE SAT 11/18/17 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 H H 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 M EKN CONSISTENCY H H H H H H H H H H M M PKB CONSISTENCY L M M M M H H H H H M M CKB CONSISTENCY H H H H M M M H H H M M AFTER 12Z SUNDAY... IFR possible late Saturday night in rain, possibly mixing with snow across the north by dawn. IFR may linger through Sunday, even into Sunday night, across the northern mountainous counties in upslope snow showers. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Wind Advisory from 4 PM this afternoon to noon EST Sunday for WVZ520-522>524-526. OH...None. KY...Wind Advisory from 1 PM this afternoon to 4 AM EST Sunday for KYZ101>103-105. VA...Wind Advisory from 1 PM this afternoon to 4 AM EST Sunday for VAZ003-004. && $$ SYNOPSIS...TRM/SL NEAR TERM...SL SHORT TERM...TRM/AB LONG TERM...TRM/AB AVIATION...SL

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