Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 190211 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 911 PM EST Thu Jan 18 2018 .SYNOPSIS... High pressure shifts from the Gulf Coast states this evening to the southeast coast by Saturday. This high pressure system will then linger over the southeast states into Monday before a cold front enters from the west Monday night into Tuesday. && .NEAR TERM /THROUGH FRIDAY/...
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As of 900 PM EST Thursday... Low temperatures the main concern overnight as winds remain gusty on the ridges while have decoupled in spots across the valleys and out east. This continues to make for a wide range in values from the mid teens in spots to the mid 30s at elevation. Evening soundings show a 35-40 kt westerly 85h jet that continues to mix down given such dry air and a very low inversion. Models show this jet slowly weakening overnight as the high to the south slips east but enough with possible waves breaking to keep speeds up past midnight. This should also hold lows in the 20s along the ridges overnight with some teens elsewhere, as would only take a short period of lighter winds over snow cover and low dewpoints for readings to plummet. Therefore only making small changes to the earlier update of gridded temperatures with the ongoing advisory/sps for black ice continuing into Friday. Previous discussion as of 210 PM EST Thursday... Winter weather advisory for refreeze of snowmelt in NC through Friday morning, per policy agreement with NC EM officials. Rest of CWA will likely be under a Special Weather Statement to cover refreeze. Otherwise, looking at high pressure building in with winds subsiding this evening but not quite going calm. Still a chilly night with lows in the teens, but at least wind chills will not be as low given less wind. One possible concern tonight besides the slick roads would be fog. With warm advection and somewhat lighter winds over snow, fog can sometimes form. However, given limited melting the low levels stay a little dry and winds may stay up enough overall to restrict fog formation, but still possible, especially in the piedmont. We continue to stay in a split flow pattern into Friday with heights rising and 8h temps rising per warm advection. Under sunny skies, temperatures should reach into the 40s. We should start to see better snowmelt Friday.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... As of 115 PM EST Thursday... This period of the forecast will be highlighted by a warming trend across the area. An upper level ridge will build across the southeast U.S., all while the synoptic flow across our region turns zonal. By the end of this time period, low level trajectories that clip far western parts of the area will have their origin from across the western Gulf of Mexico. The result will be moderating temperatures with eventually increasing clouds by the end of the weekend, especially across the west, with also the potential for some isolated showers across the far west by Sunday. By Sunday, high temperatures will range from the low to mid 50s across the mountains, and mid 50s to around 60 across the Piedmont. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 130 PM EST Thursday... The mild weather will continue Sunday night into Monday in advance of an approaching cold front. Also, isolated to scattered showers will start to increase across the area during the day in advance of this same front. Look for showers to become more numerous Monday night into early Tuesday morning as the front passes through the region. While temperatures will decrease behind the front, readings will still remain above normal for this time of year heading through the middle part of the week. After Monday night, our next chance for precipitation will be a small one Wednesday night into Thursday as a weak disturbance passes through FL/GA/SC. Otherwise, dry weather is expected as another area of high pressure builds into the region. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... As of 610 PM EST Thursday... VFR to prevail under clear skies through the period. Could see some deep valley patchy fog late as warming aloft continues over the snow, but appears too uncertain given dry air to include. In addition, winds should stay up slightly to prevent this so wont include mention at this point. West-northwest winds will continue in the 10-15 kt range over the mountains into this evening, including gusts up to 30 kts across the higher elevations. Winds should diminish and become light over the east. Winds will subside more by mid/late evening, but some stronger winds above the developing surface inversion will result in low level wind shear along the KLWB- KROA-KBCB corridor for a few hours overnight. As the surface high to the south slides east should see lighter westerly winds on Friday with speeds generally 10 kts or less with perhaps a few gusts to 15-20 kts along the ridges during the afternoon. Extended Discussion... High pressure will cover the region Saturday through Sunday night. VFR conditions are expected as well as warming temperatures. Moisture will return to the west Monday into Monday night with sub- VFR conditions possible in rain showers ahead of another cold front. VFR conditions return during Tuesday as weak high pressure follows the front in from the west. && .EQUIPMENT... As of 245 PM EST Thursday... NOAA Weather Radio, WXL60 (Roanoke Transmitter) which broadcasts at 162.475 MHz remains off the air. The phone company continues to investigate and no estimated time has been given for restoring this. We apologize for the outage. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...Winter Weather Advisory until noon EST Friday for NCZ001>006- 018>020. WV...None. && $$ SYNOPSIS...AMS/WP NEAR TERM...JH/WP SHORT TERM...DS LONG TERM...DS AVIATION...AMS/JH/WP EQUIPMENT...WP is the U.S. government's official web portal to all federal, state and local government web resources and services.