Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 070243 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 943 PM EST Wed Dec 6 2017 .SYNOPSIS... A cold front will stall off the coast tonight. Colder and drier weather continues into Thursday. Friday, low pressure will shift along the front bringing some snow the piedmont/foothills. This system pulls east by Saturday morning. && .NEAR TERM /THROUGH THURSDAY/...
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As of 930 PM EST Wednesday... The late evening update will continue to reflect little change in the overall forecast. Have made some minor adjustments to the exiting scattered sprinkles across the the far southeastern sections of the region as that activity continues to edge eastward. Sky cover has remained on the cloud side across the entire area. A decrease in coverage across the northwestern sections looks more probable later tonight. Temperatures are within a couple of degrees of the forecast values, so not notable adjustments there. As of 610 PM EST Wednesday... The forecast update for early this evening will reflect little change from the afternoon issuance. However, one adjustment will be the inclusion of some patchy sprinkles across parts of Southside Virginia and neighboring sections of north central North Carolina. Radar returns are indicating dBZ values in the 20s to lower 30s values over parts of this area. Given cloud heights are still around 10,000 ft AGL, suspect that at best some sprinkles are reaching the ground in a few spots. Currently, there is an enhanced band of these 20-30s dBZs along a line from near Reidsville, NC to Danville, VA to Phenix, VA. Have also adjusted hourly temperature, dew point, wind, gusts, and sky cover to better reflect the latest observations and expected trends through the late evening hours. As of 145 PM EST Wednesday... Upper flow remains southwest this evening with jet induced cirrus/cirrostratus overhead, so sky cover will stay mainly cloudy this evening. Stronger shortwave dives into the Lower Great Lakes late tonight with several embedded vorts ahead of it moving across the southern Appalachians into Virginia. 8h flow will be northwest with models favoring some upslope lower clouds overnight in the west but precip threat will be very low with deeper moisture along baroclinic zone along the coast. Some low/mid level cloudiness early on this evening in southside VA and may see a sprinkle. Lows tonight will be actually closer to normal, with mid to upper 20s in the mountains, to lower to mid 30s east. Thursday, more of the same with mid/high clouds keeping the area cloudier, with main moisture axis of precip well to our southeast, as main shortwave shifts toward the eastern Ohio Valley to mid Mississippi Valley. Highs should range from the mid 30s higher ridges, with upper 30s to around 40 rest of the mountains/west of Blue Ridge, with mid to upper 40s east.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM EST Wednesday... The region will remain in the RR quad of energetic upper jet with broad synoptic ascent through Friday night, while waves of low pressure ripple along a baroclinic zone along the coast. As the baroclinic zone buckles a bit, additional forcing associated with deformation on the northwest side of a wave will push precipitation into the piedmont Friday/Friday night. As the precipitation nudges into the region Friday, precipitation type will favor all snow up to the Blue Ridge where QPF will be lightest and result in just some flurries. In the piedmont where a bit more QPF is expected it is looking like a mix of rain/snow and with the ground still warm any accumulations will be limited to a slushy coating. Latest model runs are trending the back edge of the precipitation a bit further to the northwest. If this continues QPF may increase with a corresponding change to any snow accumulations, so this will be watched closely. Any lingering precipitation will be pulling off to the east late Friday night/Saturday morning. After a brief lull Saturday afternoon, a vigorous short wave will drive a low through the Great Lakes and into New England with a trailing cold front moving through the Appalachians. This will bring a good chance of upslope snow showers to locations west of the Blue Ridge Saturday night/early Sunday morning, along with very blustery winds ushering another shot of cold air. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 300 PM EST Wednesday... CONUS remains locked in an amplified pattern featuring a western ridge and an eastern trof, keeping the Appalachians and central mid Atlantic region in temperatures well below normal through the middle of next week. Short wave energy moving through the upper trof will fuel blustery northwest winds as they drive periodic reinforcing surges of cold air into the region. There will also be a chance for upslope snow showers west of the Blue Ridge mainly through the first part of next week, possibly mixed with rain. There are also hints of some synoptic forcing developing along a baroclinic zone just off to our southeast which may brush close enough to bring some rain and/or snow showers to Southside and portions of the piedmont Tuesday, though the bulk of precipitation will remain closer to the coast. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... As of 605 PM EST Wednesday... VFR conditions are expected during the extent of the TAF forecast period concluding at 00Z Friday/7PM Thursday. Winds will generally be light and variable or light from the west overnight. During the course of the daylight hours Thursday, most areas will see a slightly stronger west or southwest wind. Extended Discussion... Should see continued VFR Thursday night into early Friday with light north to northwest winds, as a disturbance rides along a frontal zone well south of our region. The front to our southeast will have a low pressure wave along it while the upstream trough digs a little. Could see some snow and sub-VFR cigs/vsbys toward DAN/LYH in the Friday afternoon through Saturday time frame. An arctic cold front this weekend, could also bring snow showers to the mountains with potential sub- VFR ceilings and intervals of sub- VFR vsby mainly at BLF/LWB, with post- frontal strong northwest winds Saturday night into early Sunday. VFR conditions then return Sunday evening. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AL/WP NEAR TERM...DS/WP SHORT TERM...MBS LONG TERM...MBS AVIATION...AL/DS/WP

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