Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 251412 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 1012 AM EDT Sun Aug 25 2019 .SYNOPSIS... High pressure with dry and cooler weather through Sunday. Upper level system Monday night. Cold front Tuesday night. High pressure through Friday. && .NEAR TERM /THROUGH TONIGHT/... As of 1007 AM Sunday... No meaningful changes needed to the forecast this morning, other than to tweak afternoon dewpoints down a bit and raise highs a tick in the Kanawha Valley and Tygart Valley. Inverted surface trof across the mountains will focus much of the the stratocumuls and cumulus today amid low level southeast flow. Atmosphere remains capped and too dry for any mountain shower. Otherwise, looking at just some patchy cirrus with a few flat cumulus today. As of 650 AM Sunday... Made a minor tweak to temperatures as locations in the northern and central mountains are currently slightly cooler than original forecast as much of this area is in the mid/upper 40s. Thus, made an update based off latest observations and trends, but other than that, no additional changes were needed at this time. As of 248 AM Sunday... Latest satellite imagery and observations reveals that river valley fog has once again formed this morning across parts of the area, with the greatest coverage so far across the Tug Fork region and much of central WV. Some lingering stratus across the northern FA has delayed fog development so far, but should still be possible, especially near EKN. Upper level ridge in eastern Canada remains in control today, supporting a very dry atmosphere with PWATs around a modest 0.50 inches throughout the region. Forecast soundings reveal that the subsidence today will lead to a stable layer around 5-7 kft AGL, yielding the development of a cumulus deck this afternoon as diurnal heating increases. Weak warm air advection will occur as the upper ridge axis north of the region continues to shift further eastward. Thus, temperatures will be a degree or two warmer today than yesterday, with the majority of the area around or just above 80F. Cloud cover is expected to increase from west to east this evening as a shortwave trough is progged to track across the mid Mississippi Valley. Increasing southwest flow ahead of this feature will bring an increase of moisture into the area by the end of the period, but the majority of precipitation is expected to hold off until the short term period. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... As of 240 AM Sunday... Pattern becomes active again with in southwest flow aloft, low amplitude trough axes, and lower level moisture advection back into the region. Despite the change in the column to more favorable conditions for upward motion, the thunder chances are rather modest going into Monday night/Tuesday. The better dynamics will remain to the west, closer to the frontal boundary that will work its way through later in the short term. The speed of the cold front will be governed by a surface low north of the Canadian border, in a system that is occluded/stacking and eventually filling. This could play a little bit of havoc with the timing, but the front should be through the mountains Wednesday. A tropical system moving northeastward away from the coast could also hamper forward speed, but the main interactions should be well east of us. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... As of 240 AM Sunday... A return to drier/cooler/quieter conditions returns for the end of the week, but the next trough axis aloft and frontal boundary will sink southward into the area for Saturday. Dewpoints in the mid 50s to lower 60s will dictate a slightly greater diurnal temperature trend as we get later into summer. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... As of 630 AM Sunday... Despite satellite imagery showing river valley fog across much of WV this morning, the only terminal impacted from the fog has been CRW. This has resulted in IFR/LIFR conditions with both restrictions in vsbys and cigs, but fog should mainly dissipate by around 13Z this morning. VFR conditions will then be in place through the entire day as surface high pressure north of the area promotes dry conditions. An inversion around 5-7 kft AGL should allow a cumulus deck to develop this afternoon, but no flight restrictions are expected from this. By this evening, surface high pressure north of the area slides further east with low level ESE flow in place throughout the area. This should result in low stratus tonight along the mountains where MVFR conditions could occur, particularly at EKN. Elsewhere, it will likely remain VFR through the end of the TAF period as high level cloud cover is progged to increase from west to east overnight ahead of a upper disturbance moving through the mid Mississippi valley. This increase in cloud cover, as well as an increase in flow, could complicate the fog potential for tonight. If fog does manage to develop though, expect that vsby and/or cig restrictions will occur. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z MONDAY... FORECAST CONFIDENCE: High. ALTERNATE SCENARIOS: Timing and location of fog development tonight 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. UTC 1HRLY 12 13 14 15 16 17 18 19 20 21 22 23 EDT 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 CRW CONSISTENCY L L H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY L L H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 12Z MONDAY... IFR is possible in showers and thunderstorms on Monday. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...26/RG NEAR TERM...30/RG SHORT TERM...26 LONG TERM...26 AVIATION...RG

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