Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 202031 AFDRLX Area Forecast Discussion National Weather Service Charleston WV 431 PM EDT Sun May 20 2018 .SYNOPSIS...
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Weak cold front sags into the area tonight, only to return northward, as a warm front, Monday and Monday night. New cold front crosses Tuesday night. High pressure mid-late week.
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&& .NEAR TERM /THROUGH MONDAY/... As of 115 PM Sunday... Did elect to reduce pops quite a bit this afternoon. Not seeing much in the way of development yet on radar or satellite, and recent model runs seem to indicate conditions too stable for much to form. Went ahead and elected to maintain a slight chance during peak heating, but not overly confident in that. The frontal boundary continues to linger across southeast Ohio this afternoon, but should continue to slowly sag south a little more today, before generally stalling out just south of or close to the Ohio River. The front will return north on Monday, as low pressure moves northeast into Ohio, with warm and humid conditions on Monday. More convection expected on Monday in warm sector, with most convection expected across southeast Ohio and the mountains, with less expected across lowlands of WV. We are still in a marginal risk for severe on Monday, but thinking overall threat looks low, as lacking significant shear/dynamics. Heavy downpours will accompany any convection. As with last night, any areas that are able to clear, will see fog development, particularly in favored river valleys. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
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As of 430 PM Sunday... Period starts with a warm front / outflow boundary over the middle Ohio Valley, out ahead of a low pressure system to the west. Showers and thunderstorms are likely near and north of this front Monday night. Storms can be a bit strong near the front early on with modest bulk shear, but decreasing CAPE after sunset should limit the strength of storms going into the overnight. Locally heavy downpours are also possible Monday night, as pw values remain up around 1.5 in. The boundary pushes back north overnight Monday night into Tuesday, but showers and thunderstorms become likely throughout the area Tuesday morning, as a cold front approaches from the west. The mid stream short wave trough driving the cold front also draws a piece of energy from a southern stream low northward ahead of it. This subtle forcing will have dew points in the upper 60s and pw values up to 1.5 inches to work with. Thunderstorms can be locally heavy Tuesday, but bulk shear greater than 30 kts staying mostly north of the cold front advancing into the Ohio Valley should limit the strength of the thunderstorms. Models are in better, but not total, agreement on the passage of the cold front by Wednesday morning, Thus, a slight chance for showers and thunderstorms was maintained for southern portions of the area Wednesday, The weather will settle down promptly Wednesday evening, with a clear, calm radiation night, as high pressure builds into the area from the north. Central guidance temperatures accepted, except lowered closer to the MEX in the valleys Wednesday night. The cooler air is balanced by increased sunshine for highs Wednesday, compared with highs Tuesday. The nights get cooler, especially in the valleys by Thursday morning.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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As of 430 PM Sunday... High pressure over the area Thursday, moves east of the area Friday and Saturday, allowing a return southerly flow of increasingly warm and humid air. After a pair of dry days Thursday and Friday, the chance for mainly diurnally driven showers and thunderstorms returns on Saturday, to start the Memorial Day weekend. Models diverge on the track of a tropical system and progress of the next cold front Sunday and beyond, arising from differences in the southward extent of the next upper level short wave trough. One camp has a deeper trough, which pulls the tropical storm northward faster and farther east ahead of it, along or just east of the Appalachians, while the other camp leaves the tropical system loitering over the deep south, left behind by a less amplified northern stream trough. Central guidance temperatures looked good, with a warming trend through Saturday.
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&& .AVIATION /20Z SUNDAY THROUGH FRIDAY/...
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As of 125 PM Sunday... VFR conditions for much of the area through 04Z, when LIFR/VLIFR valley fog is expected to develop. Any fog will generally dissipate after 13Z for a return of VFR conditions area wide. However, convection will increase again particularly after 15Z, especially across southeast Ohio and mountains. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z MONDAY... FORECAST CONFIDENCE: Medium ALTERNATE SCENARIOS: Development and extent 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 18 19 20 21 22 23 00 01 02 03 04 05 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 CRW CONSISTENCY H H H H H H H H H H M L HTS CONSISTENCY H H H H H H H H H H M L BKW CONSISTENCY H H H H H H H H H H H L EKN CONSISTENCY H H H H H H H H H H L L PKB CONSISTENCY H H H H H H H H H H M L CKB CONSISTENCY H H H H H H H H H H M L AFTER 18Z MONDAY... Brief periods of IFR possible in showers and storms into the beginning of the work week.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM/SL NEAR TERM...SL SHORT TERM...TRM LONG TERM...TRM AVIATION...SL

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