Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
867 FXUS61 KRNK 192340 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 640 PM EST Sun Feb 19 2017 .SYNOPSIS... High pressure will build over the region tonight and control our weather pattern through at least Tuesday. A weak cold front will cross the area Tuesday night and exit the region on Wednesday. A warm front will move north through the region Thursday into Friday. && .NEAR TERM /THROUGH MONDAY/... As of 245 PM EST Sunday... Satellite imagery continues to show cloud cover across the western portions of the region slowly eroding. While not all cloud cover is expected to have dissipated by sunset, the trend towards less should continue. A few locations across the Piedmont experienced a few diurnally based cumulus development this afternoon, specifically over and near Buckingham County, VA. Anticipate all of this cloud cover to dissipate at or just before sunset. This evening, we are expecting what limited moisture remains in the lowest couple of thousand feet off the surface to redevelop into stratus clouds again, across approximately same region of the mountains experiencing them currently. However, as the drier air aloft continues to build downward as the night progresses, most, if not all, of these clouds are expected to dissipate between roughly 200 AM and 500 AM. Winds will die off quickly at sunset, yielding calm or light and variable conditions for the entire region. Low temperatures will range from the mid 30s to near 40 across the mountains with around 40 to lower 40s across the Piedmont. The highest ridge tops will be a little milder than their surrounding valleys thanks to warmer air working its way into the area aloft above the nocturnal inversion. On Washington`s Birthday, an upper ridge of high pressure will move eastward from the Tennessee Valley to over the western portion of the forecast area. At the surface, the southern axis of a ridge of high pressure will nose south along the lee of the Appalachians by the afternoon. With building heights, and at worse filtered sunshine through advancing thin cirrus clouds, temperatures will trend milder than those realized today, especially in the west where cloud cover will be significantly less. High temperatures will range from the mid 60 to near 70 across the mountains with lower 70s across the Piedmont. A couple locations may reach or be very close to setting record high temperature records tomorrow. Please see the CLIMATE portion of this discussion for details. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... As of 235 PM EST Sunday... Models continue to advertise long wave upper ridge moving east and offshore with a weak short wave in the northern stream arriving in the eastern United States by Tuesday night. Jet support is not very impressive Tuesday and Tuesday night with much of the upper diffluence remaining over the Ohio Valley and north. Monday evening western valleys along with the foothills and piedmont will decouple early. Then as the surface and 850MB high moves of the coast wind pick up from the west-southwest so expecting temperatures to rise on the western ridges overnight. Axis of deeper moisture crosses the from West Virginia into North Carolina between 00Z/7pm Tuesday night and 12Z/7AM Wednesday morning. Will be slowing down arrival of precipitation based on this timing. Have also trimmed probability of precipitation behind the front on Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 235 PM EST Saturday... Per WPC, not much weight put on the GFS, especially Friday through Sunday, as it is faster with most of the synoptic scale features than much of the other guidance. Timing of the cold frontal passage still similar with the front coming through Saturday morning. 00Z ECMWF had colder air behind the front just brushing through the Mid Atlantic region, which was not nearly as cold and as far a push south as previous runs. High temperatures will still drop about 10 degrees but coldest air will start moderating after Sunday morning. A low level jet and cold air advection will result in strong gusty winds behind the front into Sunday morning. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
As of 640 PM EST Sunday... VFR conditions will prevail east of the crest of the Blue Ridge mountains through the taf period, as high pressure build into the region. Winds will become light and variable winds overnight through Monday. In the west, drying from aloft diminished clouds cover this afternoon into this evening. However, as the night progresses, moisture that becomes trapped under the nocturnal inversion will allow ceilings to redevelop and spread eastward. SCT to BKN MVFR to IFR clouds will develop late tonight into Monday morning. Drier air will eventually win with clouds decreasing in coverage Monday morning. VFR conditions are expected across the mountains by Monday afternoon. Winds overnight into Monday, will be light and variable winds. VFR visibilities are expected for much of the region. Some late night valley MVFR fog is possible in areas near and south of KBLF. There is a small window from 09z-13z that there could be some fog at KLWB and KBCB. No low level wind shear is expected during the TAF period. No precipitation is expected during the TAF period. Moderate Confidence in Visibility...Ceiling...and winds during the taf period. Extended Aviation Discussion... High confidence of VFR conditions Monday afternoon through Tuesday morning. Moderate to high confidence of patchy MVFR conditions across the mountains Tuesday afternoon into Wednesday with the passage of a cold front. East of the Blue Ridge, mainly VFR conditions will prevail. Thursday into Thursday night, moderate confidence of patchy light rain returning to the area, with ceiling and visibilities remaining mainly VFR. Some patchy MVFR is possible. Friday, moderate to high confidence of precipitation trending more showery, as low level jet increases in advance of a strong cold front. Expect a mix of MVFR and low end VFR ceilings and mainly VFR visibilities with isolated, brief sub-VFR visibilities under heavier showers. Surface wind gusts of 20 to 30 kts possible across the higher terrain. Showers may linger in the western mountains Saturday morning. Drier weather will prevail for much of the weekend.
-- End Changed Discussion --
&& .CLIMATE... As of 315 PM EST Sunday... Record High Temperatures and Year of Occurrence Feb 20 Blacksburg, VA..68 in 1984 Bluefield, WV...67 in 1986 Danville, VA....74 in 1971 Lynchburg, VA...76 in 1930 Roanoke, VA.....75 in 1939 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...DS NEAR TERM...DS SHORT TERM...AMS LONG TERM...AMS AVIATION...DS/KK CLIMATE...DS is the U.S. government's official web portal to all federal, state and local government web resources and services.