Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 220237 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 1037 PM EDT SAT MAY 21 2016 .SYNOPSIS... Surface low pressure exits tonight. Upper level low drifts across on Sunday. High pressure over Ohio/Tennessee Valleys Monday into Tuesday. && .NEAR TERM /THROUGH SUNDAY/...
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1030 PM UPDATE... Made some tweaks to the overnight sky grids given current trends. Thinking some clearing will work into SE OH/NE KY/SW WV overnight. Tough to figure fog potential in areas that clear...but given a 20 kt wind just off the deck...think fog would be confined to more protected valleys. 745 PM UPDATE... Cold front pushing east thru the mountains as of 00z. This should take the bulk of the shra with it. However cannot rule out a stray shra or two this evening until the final s/w trof axis crosses after midnight. Still thinking low stratus will be the rule overnight...generally from CRW/CKB on east. Some clearing may try to work into SE OH/NE KY/W WV late with more of a fog threat in the valleys. The low level flow may prevent dense fog formation on the hills. PREVIOUS DISCUSSION BELOW... 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 NIGHT THROUGH TUESDAY/... Influence of upper level low will continue through the first 24 to 36 hours of the short term period. Showers can be expected across the Eastern Mountains in West Virginia and with cold temps aloft and weak isolated thunderstorm or two will also be possible monday afternoon in the Northern Mountains. Upper level low finally drifts northeast on Tuesday and upper ridge moves overhead making for a great weather day. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... The dry weather we get on Tuesday will be short-lived as upper ridge breaks down and is replaced with zonal flow aloft. This pattern is looking very summer-like as we end up on the edge of the Bermuda High. Southwesterly flow will push warm and moist air from the Gulf of Mexico into the region...and dew points may approach 70F by the end of the work week. There will be a threat for showers and thunderstorms each day from mid week to the weekend in the moist airmass as we maximize daytime heating in the afternoon hours. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/...
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The cold front as of 00z is pushing thru the mountains along with the mid level wave. As this shifts east this evening...much of the shra activity will wane. Post frontal stratus is expected to linger this evening across most terminals primarily staying in the MVFR range early. However...this stratus is expected to hold true thru the overnight from KPKB to KCRW and east while lowering into IFR or perhaps lower...especially for the mountain terminals. Some clearing may be realized over SE OH/NE KY and SW WV overnight with some dense valley fog possible. Current thinking is low level flow will be strong enough to keep KHTS from dropping blo IFR in fog overnight. 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 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 00Z MONDAY... FORECAST CONFIDENCE: Low. ALTERNATE SCENARIOS: Trade off of fog versus stratus and timing lowering of 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. DATE SUN 05/22/16 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY M M M M M M M M M M M L HTS CONSISTENCY H H H M H H M M M M M M BKW CONSISTENCY M M M M M L L L L L L L EKN CONSISTENCY L L L L L L L L L L L L PKB CONSISTENCY M M M L M M M M M L M L CKB CONSISTENCY L L L L L L L L L L L L AFTER 00Z MONDAY... 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...TRM/MPK NEAR TERM...TRM/30 SHORT TERM...MPK LONG TERM...MPK AVIATION...30 is the U.S. government's official web portal to all federal, state and local government web resources and services.