Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 201428 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1028 AM EDT Mon Mar 20 2017 .SYNOPSIS... High pressure over the eastern United States will move southeast off the coast by this evening. Low pressure over the Central Plains will move east today and tonight, which will push a warm front across the Mid Atlantic region tonight and by Tuesday the low will be over Virginia with a front trailing back across the Tennessee Valley. This front will drift slowly south as a large high builds over the eastern United States Wednesday and Thursday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 1015 AM EDT Monday... Still keeping an eye on a decaying thunderstorm complex moving southeast into eastern Kentucky/western West Virginia from Ohio. Rapid update models indicate a few residual showers from this complex approaching our southeast West Virginia/far western Virginia counties during early afternoon, and associated clouds entering the area before noon. Have lowered daytime temperatures across southeast West Virginia 2 to 3 degrees in anticipation of increased debris clouds from this system entering our area, though have not yet increased rain chances. Will wait to see how quickly the system decays through noon before considering adjustments to rain chances today. Precipitable water values are up in the 0.75 to 1.0 inch range after 00Z/8PM. High pressure over Virginia this morning will move off the southeast coast by this evening. A cold front with waves of low pressure along the boundary approaches the region tonight and by late tonight will extend from Virginia through Kentucky into Oklahoma. As a broad east- west oriented baroclinic zone develops, this front will provide some of the lift needed for precipitation. Have increased probability of precipitation after midnight.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 300 AM EDT Monday... The upper ridge flattens Tuesday as surface high pressure shifts to the southeast. This will allow a weak disturbance and its associated cold front to travel east across our region. The cold front will progress into the region on Tuesday afternoon and evening, then push south Wednesday as the wave of low pressure pushes into the Atlantic ocean. Increased dynamics and instability Tuesday afternoon will yield greater coverage of showers, along with the potential for some isolated thunderstorms across roughly the southern half of the region. The day 2 convection outlook placed a marginal severe threat to our south and west. High temperatures on Tuesday will be mild about ten to fifteen degrees above normal, with readings from around 50 degrees in the northwest to the mid 70s in the southeast. The showers will continue into the Tuesday night, until the reinforcing cold front exits the southern half of the region early Wednesday morning. Any lingering moisture may change to snow showers in the northwest mountains. Any snow accumulations will be light and generally less than an inch. Low temperatures Tuesday night will vary from the mid 20s in northwest Greenbrier county to the mid 40s along the southern Blue Ridge. Both the ECMWF and GFS showed high pressure builds into the area Wednesday into Wednesday night. High temperatures on Wednesday will range from the lower 30s in the northern mountains to the mid 50s in the Piedmont. It will be dry and cold Wednesday night will low temperatures from around 20 degrees in the north to around 30 in the south. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 300 AM EDT Monday... High pressure will build southeast across our region Thursday and slide off the coast Thursday night. With the GFS keeping the moisture to our north for Thursday night into Friday morning, removed the mention of rain and freezing rain for northern portions of the forecast area. Dry weather will continue on Friday as shortwave passes to our north. As the center of the high creeps east, clockwise flow around the high will draw increasing moisture back into the area Friday night into Saturday, in the form of patchy light rain. Saturday night into Sunday, a cold front is expected to cross the area. Look for increasing chance of showers during this time frame, with a slight chance of thunderstorms Sunday afternoon across most of the region. The unsettled weather will continue on Monday. Temperatures during this portion of the forecast will be around ten degrees below normal on Thursday, but trend to readings about ten degrees above normal by Sunday. Temperatures will trend cooler on Monday. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... As of 735 AM EDT Monday... High pressure was centered over the Carolinas this morning. Just high, thin clouds from upstream thunderstorms expected through noon. Winds were light and variable. Mid/high clouds will be increasing by the afternoon ahead of an approaching frontal system with sub VFR cigs toward the end of the valid period in the mountains, though any precipitation looks to hold off until after 03Z/11PM tonight. Models were showing some differences with the southern extent of the precipitation tonight. Most confident of showers north of a KBLF to KCHO line, including at KLWB overnight. MVFR visibilities are expected with the showers and ceilings will gradually lower late tonight in the mountains to MVFR. Extended Aviation Discussion... Precipitation and MVFR or lower ceilings will cover much of southwest Virginia, southeast West Virginia and northwest North Carolina on Tuesday into Tuesday night due to the cold front moving slowly south through the region. High pressure builds in for Wednesday which should improve ceilings back to VFR. By Thursday the high will wedge in from the northeast so will stay VFR though some residual lower cigs may get trapped espcly along and east of the Blue Ridge Wednesday night into Thursday resulting in possible MVFR cigs. Dry and warmer weather is expected on Friday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...AMS/NF SHORT TERM...KK LONG TERM...DS/KK AVIATION...AMS

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