Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 271020 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 620 AM EDT TUE SEP 27 2016 .SYNOPSIS... Weak high pressure crosses today. A large upper level low drops into the area Wednesday and Wednesday night, and then swirls about the area Thursday through Saturday, before pulling away Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 430 AM Tuesday... Bulk of near term period should be dry. Cold front to the east of the CWA...with drier air...dew points in the lower to mid 50s...filtering into the region. Gradual clearing occurring behind the front...with low cigs lingering across the higher terrain in the nwly flow...should scatter out by late morning. Otherwise...mostly sunny...and cooler today...with some breezy conditions developing...particularly across southeast Ohio...as an upper low across the Great Lakes region gradually drops south into the midwest...and as mixing of stronger winds aloft occurs during peak heating hours. Could see some patchy fog late tonight...mainly in deeper sheltered mountain river valleys...with the cooler air over warmer waters. Upper low will continue to dig south into the midwest late tonight and on Wednesday...with the possibility of a slight chance for showers developing just to our west towards Wednesday morning. For now...left the near term period dry. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... As of 430 AM Tuesday... The weather this period will be governed by a large upper level low, which begins the period, 12Z Wednesday, near Chicago, and ends the period, 12Z Saturday, in nearly the same area, maybe closer to Toledo or Indianapolis. The system is progged to dig southeastward into eastern Kentucky Wednesday and Wednesday night, and then rotate through the forecast area Thursday and Thursday night, before retreating northwestward, back through Ohio, Friday and Friday night. The closed low cuts off from the main westerlies as it digs southeastward early in the period and prior, and then basically meanders beneath a rex block thereafter. After depicting more progressive solutions, models have increasingly converged on this solution over the past several runs. The system drives a cold front through the area Wednesday into Wednesday night, as it digs southeastward toward the area, and then surface low pressure whirls about the area thereafter. After a dry start, a line of showers and thunderstorms is likely to cross the middle Ohio Valley ahead of the approaching cold front on Wednesday, before lifting northward late Wednesday beneath the upper level south to southwest flow. Some of the showers should be able to push into the central Appalachians late Wednesday into Wednesday night. Additional embedded upper level short wave troughs rotating around the upper level low late Wednesday night through Friday night will be increasingly tough to time with increasing forecast projection, but diurnal heating below the low upper level heights and temperatures will result in greater coverage of showers during the afternoon and early evening hours, when thunderstorms will also be possible. Not coded, small hail may not be out of the question given freezing levels dropping to 7-8 kft. For now, it appears the system, whirling about the Ohio Valley, will be far enough east so that an anomalous inflow of moisture ahead of it will set up east of the forecast area, and so will the more persistent, heavy, and potentially excessive, rainfall. Lowered highs into the middle Ohio valley Wednesday given the timing of the cold front, and associated showers and thunderstorms. Once the cold front is through, temperatures will be below normal, especially on highs, with small temperature ranges given lots of cloudiness spiraling about the upper level low. Only minor changes were needed in light of the latest guidance, leaning toward bias corrected guidance at night. && .LONG TERM /SATURDAY THROUGH MONDAY/... As of 320 PM Monday... Operational and ensemble guidance is in pretty good agreement with large upper level low remaining overhead well into the weekend. With the cool temperatures aloft...any daytime heating we receive will quickly yield showers and possible isolated thunderstorms. The good news is that this should bring some much needed rainfall to the region and amounts will remain light enough so we are not expecting any hydro issues. The upper low meanders northward Sunday into Monday with ridging moving in behind it. This will bring warm air back into the region with upper 70s to near 80 degrees for the start of the next work week. && .AVIATION /10Z TUESDAY THROUGH SATURDAY/... As of 620 AM Tuesday... Some patchy LIFR/VLIFR fog has developed...particularly in favored river valleys. This will generally burn off by 14Z. MVFR/IFR cigs continue to linger across the higher terrain...affecting sites such as KBKW. This will generally scatter out to a VFR deck around 14-16Z. West-southwesterly winds today. Some gusts in the teens are possible during peak heating hours...dying off around sunset. IFR fog is possible again tonight...particularly at TAF sites adjacent to rivers. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Development and extent of any fog overnight may 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 10 11 12 13 14 15 16 17 18 19 20 21 EDT 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 CRW CONSISTENCY L L L L H H H H H H H H HTS CONSISTENCY L L L M H H H H H H H H BKW CONSISTENCY L L L L H H H H H H H H EKN CONSISTENCY L L L L L H H H H H H H PKB CONSISTENCY M M L M M H H H H H H H CKB CONSISTENCY L L L L H H H H H H H H AFTER 12Z WEDNESDAY... Morning valley fog possible through Friday morning. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...SL SHORT TERM...TRM LONG TERM...MPK AVIATION...SL

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