Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 180441 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1141 PM EST Wed Jan 17 2018 .SYNOPSIS... A complex low pressure system just east of the region will continue to move slowly northeast and away from the area overnight. High pressure over the Central and Southern Plains will move into the Gulf Coast region by late Thursday bringing a milder westerly flow across the region. Temperatures will moderate over the weekend ahead of the next cold front approaching the eastern United States on Monday. && .NEAR TERM /THROUGH THURSDAY NIGHT/... As of 854 PM EST Wednesday... Light snow persists over the far southeast this evening associated with complex surface low pressure offshore and the residual upper low that remains about overhead. However starting to see the snow fade as drier air works in from the north so will let the winter storm warning expire at 9 pm with deeper moisture exiting per the latest HRRR. This to be replaced by an advisory for black ice across the remainder of our North Carolina counties and a SPS elsewhere for the overnight. Expect subsidence to finally win out across the east with skies clearing after midnight while lingering low clouds over the northwest likely persist under northwest flow but should gradually fade as well late as the column dries. Moisture appears too shallow for much added snow other than flurries far northwest so basically going dry with clearing overnight. However the clearing over expansive snow cover will allow temperatures to fall more than expected with some spots likely at or below zero espcly valleys despite continued mixing. Appears winds will stay up enough to even support expanding the wind chill advisory east to include Roanoke and points along the eastern slopes where thresholds are higher than the western zones. May be close to wind chill warning criteria as well over the western higher elevations but not enough coverage to upgrade at this point. Otherwise bumped down lows a good category or two since already near forecast lows in spots attm. Previous discussion aS of 318 PM EST Wednesday... Winter Weather Advisories were posted for Black Ice in western North Carolina until noon on Thursday. Winter Weather Warnings remain in effect for Eastern portions of forecast area until 9 pm. Wind Chills Advisories are in effect for the western mountains into Thursday morning. The upper trough will drift east across the region this evening and off the coast later tonight into Thursday morning. The associated surface front will track east into the Atlantic ocean. Good low level moisture convergence and lift will continue bands of snow in the east this afternoon into tonight. Snow will taper off this evening into tonight from west to east. Used a blend of the HRRR, Conshort and Nam for pops and weather this afternoon into tonight. Low temperatures will range from the single digits in the mountains to the mid teens in the Piedmont. Minimum temperatures tonight may need to be lowered to account for the fresh snow cover. The combination of winds and temperatures will produce low wind chills values overnight into Thursday morning in the mountains. The melting and freezing of snow will result in black ice across potion of western North Carolina. The rest of the state of North Carolina may need a black ice advisories also tonight into Thursday morning where such advisories are issued. The upper low will continue to travel east Thursday into Thursday night. Very cold Arctic high pressure across the Southern Plains will build east Thursday into Thursday night. Winds will diminish fairly quickly during the day Thursday as high pressure builds in from the southwest. With the warming at 850mb and near full sunshine, High temperatures will vary from the mid 20s in Northwest Greenbrier county to the lower 40s along the southern Blue Ridge. Under mostly clear skies with a snow pack, Low temperatures Thursday night will be cold with readings from the single digits in the mountains to the lower 20s in the Piedmont. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... As of 318 PM EST Wednesday... High pressure will travel east across the Southeast States Friday into Friday night. This will result in a warming trend as flow become southwest. 850mb temperatures will be in the 0C to +5C range. With bright sunshine and west winds, high temperatures will warm into the lower 409s in the west to the lower 50s in the east. Low temperatures Friday night will generally be in the lower 20s to near 30 degrees. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 235 PM EST Wednesday... Little change this period with high pressure heading east late in the weekend. An upper trough over the Gulf Coast states and return flow may bring a few showers Sunday morning to the mountains of WV/Far SW Va. We stay warmer than normal ahead of a deep trough/closed low moving across the central U.S. Monday which then sends a front across us Tuesday with a threat of showers. Colder air behind it may bring a few snow showers to the mountains of WV, but temps behind this system are not as cold as the pattern we are in now. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... As of 1140 PM EST Wednesday... Flying conditions will slowly improve across eastern sections overnight as the final band of light snow heads southeast over the next couple of hours before exiting. In the wake of this band, will see conditions quickly transition to VFR with only scattered to broken strato- cu including areas of mid clouds. Only exception will be across the far western ridges where sub- VFR may linger around KBLF and perhaps redevelop at KLWB overnight. However expect cigs at both locations to gradually mix out to scattered VFR clouds toward daybreak Thursday as very dry air advects in. There may also be a brief period of upslope snow showers or flurries across the southeast West Virginia sites over the next few hours before shallow moisture fades. Winds will also be gusty in the mountains from the northwest with gusts of 20 to 30 knots. High pressure finally builds in late tonight. High pressure will result in VFR conditions for all taf sites on Thursday. However west winds will remain rather strong across the ridges with gusts to 20-25 knots possible. Extended Discussion... Dry air will and high pressure will cover the region Thursday night through Sunday. VFR conditions are expected as well as warming temperatures. Moisture will return to west Sunday night into Monday with sub-VFR conditions possible ahead of another cold front. VFR conditions should return on Tuesday. && .EQUIPMENT... As of 245 PM EST Wednesday... NOAA Weather Radio, WXL60 (Roanoke Transmitter) which broadcasts at 162.475 MHz remains off the air. Telephone company will be working on this and hope to have it back up by Thursday afternoon. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Wind Chill Advisory until 10 AM EST Thursday for VAZ007- 009>020-022>024-032>035. NC...Wind Chill Advisory until 10 AM EST Thursday for NCZ001-002- 018. Winter Weather Advisory until noon EST Thursday for NCZ001>006- 018>020. WV...Wind Chill Advisory until 10 AM EST Thursday for WVZ042>044- 507-508. && $$ SYNOPSIS...AMS/JH/KK NEAR TERM...JH/KK SHORT TERM...KK/WP LONG TERM...WP AVIATION...AMS/JH/KK EQUIPMENT...PM

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