Area Forecast Discussion
Issued by NWS Charleston, WV
Issued by NWS Charleston, WV
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311 FXUS61 KRLX 010821 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 421 AM EDT Wed May 1 2024 .SYNOPSIS... Dense fog this morning as a cold front exits. High pressure brings dry weather with a warming trend today into Friday. A cold front brings showers and storms this weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 420 AM Wednesday... GOES-R microphysics imagery, surface observations and area cameras evince enough dense fog to warrant a Dense Fog Advisory throughout the area. Coded one up until 10 AM this morning. As of 200 AM Wednesday... A cold front has moved off to our northeast and a surface trough sits east of the Appalachian Mountains. Skies will continue to clear and winds will calm as a result. These factors, paired with lingering low-level moisture from recent rainfall, will allow the perfect setup for widespread dense fog with low visibilities this morning. Sheltered river valleys and mountain valleys with poor drainage winds will see the lowest visibilities, which could be below a quarter of a mile at times. A statement has been issued across the entire forecast area for visibilities of a quarter of a mile or less that will likely be observed within thicker fog columns. Caution should be used traveling this morning. Fog will lift and clear after sunrise this morning and a dome of high pressure over the Deep South will move up over the area. This feature will reinforce dry weather and invoke the start of another warming trend under southwesterly flow. Temperatures today look to be fairly warm with highs in the low to mid 80s across the lowlands; 60s to high 70s in the mountains. Another round of fog looks possible again tonight into Thursday morning, though will not be as widespread and intense with low- level moisture drying out this afternoon. Overnight lows will be in the 50s again as we decouple under the high pressure. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... 335 AM Wednesday... Thursday morning is likely to find a nearly stationary front draped west to east just north of the area. This front will lift north as a warm front, Thursday through Friday, ahead of a cold front approaching from the west. There may be showers and thunderstorms along and north of the front back in central Ohio Thursday morning, where the front is already beginning its northward move. This activity should move northeast, remaining north of the forecast area, as the northward movement of the front progresses east. This leaves the area in very warm, dry air, with plenty of sunshine on Thursday once any morning fog burns off. As the cold front and its associated southern stream short wave trough move into the area Friday, clouds will start to increase ahead of it Thursday night in the form of cirrus and stratocumulus, and then any sunshine Friday morning will give way to lowering and thickening cloudiness, with showers and thunderstorms becoming a possibility by the end of the day. The forerunner increase in cloud, and modest dew points in the lower 60s, likely contribute to modest instability Friday afternoon, with CAPE less than a KJ/kg. Given modest low to mid level flow.shear, thunderstorms are not expected to be especially strong, but they can produce heavy downpours and gusty winds in the middle Ohio Valley by late in the day. Deterministic central guidance highs are now in line with the 50th percentile guidance is rather high for daytime highs both days, and are comfortably below record highs. Thursday night will be mild, although decoupling could allow lows lower than central guidance. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 420 AM Tuesday... A southern stream short wave trough that moves into the area Friday exits Friday night, but the cold front washes out. With the air mass actually a bit more moist by Saturday, and an additional southern stream short wave trough crossing the area, showers and thunderstorms are likely Friday night through Saturday, and even into Sunday. The nearly saturated atmosphere will not be that unstable, but PW values could climb to 1.5 inches or higher, so heavy downpours are a good possibility. The vegetation and recent dry weather should minimize the potential for high water. By later in the day Sunday, the short wave trough exits, giving way to ridging, lessening shower and thunderstorm coverage Sunday afternoon, compared with Saturday afternoon, at least across the middle Ohio Valley. This should also lead to a lull in the active weather Sunday night into Monday. The chance for showers and thunderstorms then ramps back up during the day on Monday, and continues Tuesday, as a warm front and mid-upper level flat waves cross, out ahead of a large mid- upper level low over the plains. This could all culminate in a better chance for strong, heavy thunderstorms on Wednesday, as the plains mid-upper level low pushes into the Great Lakes, pushing a strong cold front into the area. Gradient winds will also increase and become gusty ahead of this front Tuesday and especially Wednesday. After a rain-cooled Saturday, perhaps not too unlike Tuesday, central guidances reflects a slow moderation in temperatures next week, ahead of the upcoming, potential strong midweek system. Nights will also cool off a bit, and then warm back up a bit. Above normal temperatures prevail throughout the period, but we should remain well shy of record territory. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... As of 108 AM Wednesday... Widespread dense fog will allow for IFR/LIFR restrictions or lower across the forecast area this morning as skies begin to clear from west to east and winds decrease. Shortly after sunrise, dense fog will start to lift and dissipate between ~12-13Z, subsequently giving way to VFR under mostly clear skies. This will last through the day until another round of river valley fog arrives overnight into Thursday. Winds calm to light and variable this morning, becoming light and SW`rly during the day. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z THURSDAY... FORECAST CONFIDENCE: Medium. ALTERNATE SCENARIOS: Timing and intensity of dense fog this morning could vary. Low stratus could form across the higher portions of the mountains instead of dense fog. 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 WED 05/01/24 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15 CRW CONSISTENCY M M H H H M H H H H H H HTS CONSISTENCY H H H H H L L H H H H H BKW CONSISTENCY M H H H L L H H H H H H EKN CONSISTENCY M M M M M L H H H H H H PKB CONSISTENCY H H H H M L H H H H H H CKB CONSISTENCY M H H H M M H H H H H H AFTER 06Z THURSDAY... IFR conditions possible due to fog Thursday morning. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Dense Fog Advisory until 10 AM EDT this morning for WVZ005>011- 013>020-024>034-039-040-515>526. OH...Dense Fog Advisory until 10 AM EDT this morning for OHZ066-067- 075-076-083>087. KY...Dense Fog Advisory until 10 AM EDT this morning for KYZ101>103- 105. VA...Dense Fog Advisory until 10 AM EDT this morning for VAZ003-004. && $$ SYNOPSIS...TRM/LTC NEAR TERM...LTC SHORT TERM...TRM LONG TERM...TRM AVIATION...LTC