Area Forecast Discussion
Issued by NWS Charleston, WV
Issued by NWS Charleston, WV
683 FXUS61 KRLX 282301 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 701 PM EDT Mon Sep 28 2026 .WHAT HAS CHANGED... 00Z aviation discussion has been issued. Dew points this afternoon and evening were adjusted downward across the lowlands relative to high-biased central guidance. Overnight river valley fog was highlighted in the western valleys, while daytime temperatures were nudged down across northern and eastern counties under persistent low cloud cover. && .KEY MESSAGES... 1.) River valley fog likely overnight into Tuesday morning, with greatest coverage and highest confidence across the western valleys and southern coalfields. 2.) Warming Wednesday through Thursday with lowland temperatures reaching the lower 80s amid continued dry conditions. 3.) Widespread rain chances return Friday night into the weekend, non-zero risk for some water issues, but chances remain low. && .DISCUSSION... KEY MESSAGE 1... Visible satellite and surface observations show a persistent stratocumulus deck around 3000 to 5000 ft wrapping southward across northern West Virginia and the Northeast Mountains, driven by broad cyclonic flow around the departing low pressure system off the New England coast. Regional soundings, including the 12Z PIT observation, depict moist low-level profiles with saturation banked beneath a subsidence inversion around H850. Weak orographic ascent will continue to squeeze out isolated light sprinkles or drizzle along the western windward slopes through early evening. Across the western valleys, southeast Ohio, and northeast Kentucky, skies have remained mostly sunny, allowing temperatures to rise into the lower 70s. Central guidance dew points have been adjusted downward 3 to 6 degrees for this afternoon and evening to correct for typical high bias in dry advection regimes. For tonight, light northerly winds will decouple quickly as surface ridging noses in from the northwest. In areas across the western valleys and southern coalfields that remain largely clear, efficient radiational cooling will trigger rapid river valley fog development late this evening, becoming locally dense after midnight. Farther northeast soundings suggest boundary layer RH will remain near saturation; thus, any breaks in the cloud canopy overnight will lead to almost immediate, dense surface fog and stratus development. Any fog should dissipate through 10-11 am Tuesday. KEY MESSAGE 2... Broad surface high pressure shifts across the central Appalachians on Tuesday, keeping boundary layer flow light and generally easterly. As the coastal circulation lifts northeastward toward the Canadian Maritimes, an upper-level ridge builds eastward across the Ohio and Tennessee Valleys through midweek. Low-level flow transitions southwesterly by Wednesday. Lowland high temperatures will climb from the mid 70s on Tuesday into the lower to mid 80s Wednesday and Thursday. Forecast profiles indicate deep vertical mixing tapping into very dry air between H850 and H700, which will mix afternoon surface relative humidities down into the 30 to 40 percent range. KEY MESSAGE 3... Global ensembles continue to resolve split-stream flow late in the week, with an active subtropical jet carrying deep moisture downstream from the remnants of Eastern Pacific Tropical Cyclone Polo into the southern Plains and Lower Mississippi Valley. While some deterministic guidance and central guidance show slight chances of showers edging into western zones late Thursday night into Friday. 10th percentile QPF shows negligible accumulation prior to Friday night as the surface cold front slowly settles southward. Atmospheric moisture surges over the weekend with precipitable water values climbing toward 1.7 inches in weak steering flow aloft. However, heavy rainfall and flash flood threats appear minimal across the local area. Severe storm and intense rainfall rates will be heavily mitigated by meager instability, as mid- level lapse rates remain poor (5.0 to 5.5 C/km) due to widespread upstream convection over the southern Plains intercepting the thermodynamic plume. Furthermore, vegetation is still quite active for early October given recent warm and wet conditions and we will have had nearly a week without meaningful precipitation for soils to recover. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... The western edge of a cloud bank associated with the departing nor`easter continues to meander along and east of the I-79 corridor, with a clear sky to the west. MVFR CIGs will remain socked in at KCKB and KEKN while the overcast hovers at VFR at KBKW through about 06Z before lowering into MVFR/IFR overnight. Farther west, VFR will continue at KCRW, KHTS, and KPKB for the rest of the evening, but VSBYs are expected to crater into LIFR beyond 06Z, with sub-VFR VSBYs arriving near or shortly before 06Z. IFR/LIFR CIGs continue to be forecast at KBKW, KCKB, and KEKN; however, it is possible that substantial reductions to VSBYs develop, especially at KCKB and KEKN, should breaks in the already-thin overcast occur as the nor`easter moves over New England. Regardless, all terminals are expected to observe IFR conditions or lower tonight due to CIGs and/or VSBYs. Improvements to VFR will arrive following sunrise Tuesday at all terminals, with calm winds transitioning into a gentle breeze from the north or remaining otherwise variable during the afternoon hours Tuesday. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY... FORECAST CONFIDENCE: High through 04Z, then low for fog during the overnight hours. ALTERNATE SCENARIOS: Clouds may erode overnight at KBKW, KCKB, and KEKN, which would result in rapid development of LIFR/VLIFR VSBYs from fog. Low stratus may last longer into Tuesday morning than forecast, particularly at KCKB and KEKN. The timing of fog development may vary from the current 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 TUE UTC 1HRLY 23 00 01 02 03 04 05 06 07 08 09 10 EDT 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 CRW CONSISTENCY H H H H H H M L L L M M HTS CONSISTENCY H H H H H H H M L L H H BKW CONSISTENCY H H H H H H M L L L L L EKN CONSISTENCY H H H H H H M M M M M M PKB CONSISTENCY H H H H H H M L L L M M CKB CONSISTENCY H H H M M H L L L L L M AFTER 00Z WEDNESDAY... IFR or lower from valley fog is forecast Wednesday morning. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ DISCUSSION...JP AVIATION...Sincavage