Area Forecast Discussion
Issued by NWS Charleston, WV

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409 FXUS61 KRLX 261738 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 138 PM EDT Fri May 26 2017 .SYNOPSIS... High pressure will bring a brief reprieve of dry, warmer weather today. Disturbances along a wavering front will bring showers and thunderstorms over the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 940 AM Friday... No changes this morning. As of 210 AM Friday... Finally a break in the weather expected today. Upper low continuing to move off to the east, as high pressure nudges into the region. Much of the area will still be under quite a bit of cloud cover this morning, but expect a general improvement as the day progresses. Gusty west-northwesterly winds will continue through much of the afternoon behind departing low. Clouds will gradually increase later this evening and overnight. A warm frontal boundary and upper disturbance will move into the region late tonight/early Saturday, kicking off showers and isolated thunderstorms again, becoming more numerous later in the day Saturday. && .SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/... As of 5 AM Friday... A roughly west-northwest to east-southeast oriented front, roughly parallel to the upper level flow, will oscillate about the area Saturday into Sunday, modulated on the mesoscale by thunderstorm complexes that are likely to form along or near it. This begins with a modest 25 kts h85 LLJ Saturday morning along a theta e axis in which h85 dew points climb from 12 to 15C. Deep layer bulk shear as high as 50 kts Saturday morning decreases to 40 kts south and only 20 kts north Saturday afternoon, while CAPE increase to near 3 kj/kg south and central portions of the area Saturday afternoon, so southern to perhaps central portions of the area appear favored for the strongest thunderstorm development Saturday afternoon and evening. Depending upon how the convection evolves Saturday into Saturday night, cool pooling could effectively push the boundary south Saturday night, setting up another warm advection feed Sunday morning. The h85 is progged to peak near 35 kts overnight Saturday night, before decreasing again, but bulk shear is forecast to increase to over 50 kts again overnight Saturday night and continue through Sunday, while CAPE forecast values vary among models but are forecast to be highest west. Upper level ridging crosses Saturday night, switching the upper level flow from west-northwest Saturday to west-southwest on Sunday, with embedded short wave troughs tied to convective mesoscale complexes, but with a general tendency to push the front northeastward into Sunday night. Will maintain heavy rain and strong thunderstorm wording in HWO and state briefing, but, in collaboration with neighboring offices, will wait until we get a little closer to convective development to begin timing and placement of any needed flash flood watches. A cold front crosses overnight Sunday night, leading to a drier weather pattern to start the new work week. The mesoscale dominated pattern is likely to result in variation from central guidance temperatures with time, which show small diurnal ranges not far from normal on average. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 5 AM Friday... A weak cold front crosses Tuesday beneath upper level northwest flow, with surface high pressure and upper level ridging remaining well out to the west. The high does pass south of the area on Wednesday, and another upper level short wave trough is progged to drive a new surface cold front into the area Wednesday night and Thursday. It may taken the better part of Friday to push that front through the area. Central guidance temperatures accepted, largely near normal. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 125 PM Friday... VFR through the afternoon with wind gusts 20-25kts and cumulus above 4kft. Complex of storms moves in from the west northwest after 05Z Saturday, and will likely be on the slow wane. However, TSRA and IFR visibilities are likely at PKB and CKB, but carry only SHRA into EKN by the time it reaches that terminal. The southern sites of HTS, CRW, and BKW will likely be on the fringe of this activity, so some restrictions may have to be added here with a track that goes a bit further to the south. All models are holding strong on decreasing ceiling heights into the late morning hours, so carry MVFR during this time. Cold front drops south, so the bulk of the afternoon convection should be relegated south of PKB-CKB-EKN. That said, leaving low chances for convection across the north. Forecast Confidence: High through 06Z. Medium after. ALTERNATE SCENARIOS: Convection timing tonight could vary by an hour or two. Thunder chances may need to be added or eliminated across northern terminals.. EXPERIMENTAL TABLE OF FLIGHT CATEGORY NOT AVAILABLE 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. Table unavailable at this time. AFTER 18Z SATURDAY... IFR likely in showers and storms Saturday night and Sunday. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...SL/26 SHORT TERM...TRM LONG TERM...TRM AVIATION...26

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