Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 211823 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 223 PM EDT SAT MAY 21 2016 .SYNOPSIS...
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Surface low pressure exits tonight. Upper level low drifts across on Sunday. High pressure over Ohio/Tennessee Valleys Monday into Tuesday.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Numerous showers and isolated thunderstorms have popped up this afternoon in response to an upper level short wave trough digging inn from the northwest, and low level cyclonic convergent flow with the remnants of a surface low pressure system over the area. Beneath the upper level trough, a surface front was pushing southward into the middle ohio valley, with gusty winds and a more solid stratus deck in its wake. The surface low and cold front will collapse southeastward through the area through this evening, as the upper level short wave trough continues slowly digging in. It will close off into an upper level low Sunday that will then drift southward through the central appalachians. The showers were producing heavy downpours but were also on the move, and will dissipate tonight with the loss of heating; they are most likely to persist in the mountains. Otherwise the stratus will fill back in, especially as the front passes. Sunday will bring mixing, which will break up much of the fog and stratus in the morning, but result in a repeat of pop up showers and thunderstorms, especially over the mountains under the upper level low. With lower freezing and -20c levels, instead small hail for Sunday afternoon thunderstorms, with gusty winds also possible. We should also be able to mix 20 kt gusts to the surface outside showers and storms. No major changes to temperatures in light of the latest guidance.
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&& .SHORT TERM /SUNDAY THROUGH TUESDAY/... The overall trend across the short term forecast is one of a clearing/drying pattern as an upper level low cuts off and settles over the Outer Banks area of North Carolina. This will be a fairly slow process as it does so...with the synoptic scale pattern getting backed up a bit as a result. Upper level ridging over the central part of the CONUS will be slow to reach the middle Ohio Valley...but it will get there...eventually. From a sensible weather point of view...weak disturbances on the back side of the upper low could keep isolated convection going over the northern mountains of WV. Downplaying the aggressiveness of this in the models just a bit...and will use only slight chance for the mountains Monday. Meanwhile...the bulk of the lowlands and southern mountains will be clearing...with a slow warming trend in the forecast as low level temperatures creep back upwards...as do the heights aloft. By the end of the short term/Tuesday...the forecast is completely dry...approaching 80F in the lowland areas. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... SFC high pressure will be overhead for the start of the period but the fair weather will be short lived. After Wednesday the Guidance shows that a stationary boundary will settle over the area and this will keep unsettled conditions into the weekend with several short waves moving across the area in zonal flow. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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An upper level low slowly drifting into the area from the north this this period will make for changeable weather conditions and a low confidence forecast. In the lower levels, moist air wrapping around the surface low center already over the area has led to a lot of stratus, but this was breaking up this afternoon. Limited sunshine was providing just enough heating to get scattered showers and even isolated thunderstorms going. Any shower or thunderstorm can bring brief IFR vsby but may initially break up any status in place. The showers are likely to diminish in area coverage tonight once the sun goes down, but the stratus will become more widespread, with areas of fog forming especially on ridge and hilltops. Clearing may edge into the middle Ohio Valley by dawn Sunday. This would result in a more widespread fog. The stratus and any fog will mix out and burn off Sunday morning, but showers are likely to start popping up by afternoon, especially in and near the mountains, where a thunderstorm is also possible. Light west to southwest surface flow will become light northwest tonight, and then become a bit gusty toward Sunday afternoon. Light west to northwest flow aloft will become light to moderate north tonight and continue on Sunday. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SUNDAY... FORECAST CONFIDENCE: Low. ALTERNATE SCENARIOS: Timing of highly changeable conditions will vary with numerous afternoon showers around. Trade off of fog versus stratus. Stratus may break up over the middle Ohio Valley toward dawn Sunday. This would allow a more widespread dense fog to form. 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 15 16 17 18 19 20 21 22 23 00 01 02 EDT 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22 CRW CONSISTENCY M M M M M M M M M M M M HTS CONSISTENCY M M M M M M M M M M M M BKW CONSISTENCY M M M M M M M M M M M M EKN CONSISTENCY M M M M M M M M M M M L PKB CONSISTENCY M M M M M M M M M M M M CKB CONSISTENCY M M M M M M M M M M M L AFTER 18Z SUNDAY... IFR in fog possible late Monday night into Tuesday morning.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...KTB/TRM/26 NEAR TERM...TRM SHORT TERM...26 LONG TERM...MPK AVIATION...TRM

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