Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 111123 AFDRLX AREA FORECAST DISCUSSION National Weather Service Charleston WV 723 AM EDT Tue May 11 2021 .SYNOPSIS... Weak cold front crosses today. High pressure builds in and remains in place through the end of the week, amid weak upper level systems crossing. && .NEAR TERM /THROUGH TONIGHT/... As of 710 AM Tuesday... Clearing between an exiting southern stream short wave trough, and a northern stream broad short wave trough driving a cold front into the area, has allowed dense valley fog to form quickly, mainly along and south of the I-64 corridor. Updated the forecasts and issued an SPS until 9 AM. As of 420 AM Tuesday... A cold front entering the forcast area first thing this morning will cross from northwest to southeast today. While this is a reinforcing front with no moisture feed ahead of it, it is managing to squeeze out light rain just behind it in central Ohio, and a slight chance is coded along and just behind the front, in a narrow band moving across northern portions of the forecast area. Clearing progresses from northwest to southeast in the wake of the cold front tonight, but only so far, as a southern stream low pressure wave holds it up south, and even brings a slight chance for rain showers to southwest Virginia overnight. Temperatures close to central guidance, just low enough for the freeze watch in the northern mountains overnight tonight. The potential for frost across the northern lowlands will depend upon how quickly it clears and decouples. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 339 AM Tuesday... An expansive surface high centered in the Great Lakes region will provide dry and cool conditions on Wednesday. Despite mainly sunny skies and the strong mid May sun angle, highs will be about 10 to 15 degrees below normal given the cool northerly flow in place. With clear skies, light winds, and decoupling for many locations across the forecast area, favorable radiational cooling conditions are expected on Wednesday night. As a result, frost will be possible, especially for areas north of I-64 but overnight lows across the southern parts of the forecast area may remain just warm enough to preclude any frost potential. Also can`t completely rule out freeze conditions in parts of the northern mountains, but temperatures might be on the marginal side for a freeze. Regardless, it will be a cold night so frost and possibly even freeze headlines may be needed for parts of the area. Thus, will maintain mention in the HWO to highlight this potential for now. With high pressure remaining in control for Thursday, mainly dry conditions are expected once again. However, a weak upper trough moving eastward across the TN valley may provide enough support for a few light showers, mainly across southern portions of the forecast area. While confidence is not very high in the development of any showers, will keep slight PoPs in the forecast for now across southern WV and southwest VA but the overall dry nature of the air mass should pretty much keep all areas dry. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 339 AM Tuesday... As the sprawling aforementioned high pressure system begins to gradually shift east of the area and off the mid-Atlantic coast this weekend, temperatures will gradually moderate late this week and through the weekend as return flow should bring temperatures pretty close to normal values by Sunday. Meanwhile, despite high pressure in control at the surface, a series of upper disturbances embedded in the northwest flow aloft may support several opportunities for showers and storms Friday and through the weekend. Given differences in timing/strength of these disturbances, will mainly keep low PoPs across the region late week and through the weekend. The more unsettled weather pattern is then expected to continue into early next week as deeper moisture returns to the area and additional disturbances arrive. && .AVIATION /11Z TUESDAY THROUGH SATURDAY/...
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As of 710 AM Tuesday... Clearing between an exiting southern stream short wave trough, and a northern stream broad short wave trough driving a weak cold front into the area, has allowed dense valley fog to form quickly, mainly along and south of the I-64 corridor but to a lesser extent farther north, This impacts the lowland TAF sites until 13Z-14Z, especially CRW with VLIFR ceiling and visibility. The cold front crosses today, bringing nothing more than an unimpactful light rain shower. Otherwise, high pressure building in behind the cold front today and tonight will continue to provide VFR conditions. Light and variable surface flow early this morning will become northwest behind the front today, and will be a bit gusty this afternoon, before slowly diminishing tonight. This, together with drier air arriving behind the front, may be enough to preclude fog tonight. Light north to northwest flow aloft early this morning will become light northwest today, and then light north tonight. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY... FORECAST CONFIDENCE: High, except low for fog. ALTERNATE SCENARIOS: Fog this morning, including timing of improvement, may vary. A few light rain showers may occur today.Valley fog may form tonight if the sky clears and the winds decouple. 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 H H 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 M M H H H H H H H H H H EKN CONSISTENCY M H 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 WEDNESDAY... No widespread IFR conditions are forecast.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...Freeze Watch from late tonight through Wednesday morning for WVZ523-525-526. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/RG NEAR TERM...TRM SHORT TERM...RG LONG TERM...RG AVIATION...TRM

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