Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 170847 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 447 AM EDT Wed May 17 2017 .SYNOPSIS...
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High pressure centered just off the southeast Atlantic Coast will provide mainly fair dry weather through Thursday. Southwest winds will bring an increase in both heat and humidity. A weak cold front will approach from the northwest Friday, shower and thunderstorm chances increasing for the weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 430 AM EDT Wednesday... Another day of subsidence will result in mainly dry conditions. Surface high pressure is centered just off the southeast Atlantic Coast, clockwise flow around the high resulting in a southwest wind across our region promoting warming temperatures and increasing dewpoints. Temperatures today should climb into the 80s areawide and will test 90 in Roanoke, Lynchburg, Martinsville, Danville and across the piedmont. These sort of temperatures will be really close to the records for the date (see climate section of this AFD for details). Increasing low level moisture should allow for some scattered CU across the mountains. The LCL is forecast between 5-8kft, so whatever forms will be high based. Similar to yesterday, model soundings suggest we will remain capped, so little or no threat for deep convection today. Debris cloudiness from a storm system in the central part of the country will move downstream toward the area for tonight. Aside for some high thin cirrus, we are not anticipating any precip. Lows tonight should remain AOA 60 per gradual increasing dewpoints.
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&& .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
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As of 330 AM EDT Wednesday... By Thursday, the upper ridge axis will be to our east with surface high pressure over the Atlantic ocean. This will keep us in a deep flow of warm, moist, unstable air ahead of a cold front slowly approaching from the northwest. Expect the main forcing mechanism on Thursday to be orographic so the better chances for showers and thunderstorms from the southern Blue Ridge in Virginia down through the mountains of North Carolina. The frontal boundary will then work through the region on Friday before high pressure moving through the upper midwest can wedge down east of the Appalachians and push the boundary through as a backdoor front Friday night. This will give the region a good chance for showers and thunderstorms through Friday before the wedge sets up late Friday night. Saturday will feature some light precipitation in upslope flow along the Blue Ridge while far southern and western locations outside of the wedge remain in the warm and unstable air and maintain a chance for thunderstorms. The overall convective environment is lacking in good dynamics but steep mid/upper lapse rates on Thursday and modest or better instability ahead of the front should be enough to support some healthy pulse cells Thursday and Friday, but outside of a few storm clusters or line segments large scale organization does not appear likely and the overall severe threat is low. Temperatures will continue to run well above normal ahead of the front with highs Thursday and Friday in the mid/upper 80s east of the Blue Ridge, low/mid 80s west. Behind the front we will start to see some cooler conditions with highs Saturday around 80 east to mid/upper 70s west.
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&& .LONG TERM /SUNDAY THROUGH TUESDAY/...
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As of 205 PM EDT Tuesday... GFS/ECMWF are in better agreement in lifting the frontal boundary back to the north as a warm front on Sunday. Cold front approaches the western Mountains Sunday night and travels east across our region Monday into Tuesday. Low pressure off the North Carolina coast Tuesday morning will lift northeast along the coast Tuesday night into Wednesday. The ECMWF was a little closer to the coast compared to the GFS. Expect a cooling trend in temperatures into Tuesday. Overnight lows will be generally in the mid 50s to the mid 60s into Monday, then lower to the upper 50s into Wednesday.
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&& .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
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As of 400 AM EDT Wednesday... VFR conditions are expected across the region through Thursday. The only exception may be some MVFR fog for a few hours just before daybreak, and even then the fog is expected to be shallow. Forecast confidence is high. Extended Aviation Discussion... Can`t rule out a late afternoon thundershower across the mountains Thursday...coverage isolated. Better threat for afternoon showers/thunderstorms by Friday and into the weekend as a frontal boundary moves southeast toward the central Appalachians. The front is forecast to stall across the region this weekend, so shower/storm chances will increase.
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&& .CLIMATE... As of 1040 PM EDT Tuesday.... List of record highs for Wednesday 5/17 for our five climate sites. Wednesday 05/17/2017 Site MaxT Year Bluefield 84 1977 Danville 92 1990 Lynchburg 93 1911 Roanoke 92 1977 Blacksburg 85 1962 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM NEAR TERM...PM SHORT TERM...MBS LONG TERM...KK AVIATION...PM CLIMATE...DS/WP

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