Area Forecast Discussion
Issued by NWS Blacksburg, VA

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077 FXUS61 KRNK 111756 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1256 PM EST Mon Dec 11 2017 .SYNOPSIS... High pressure will bring a brief period of fair weather to the Appalachians and central mid Atlantic region to start the work week. However, low pressure moving through the Great Lakes region will push another surge of very cold air into the region on Tuesday with blustery conditions and snow showers in the mountains. && .NEAR TERM /THROUGH TONIGHT/... As of 1256 PM EST Monday...Overall forecast holding up well, and have made no significant changes to the forecast attm. Previous discussion issued at 245 AM follows... Not too much change from previous forecast for this period with upslope cloudiness expected to erode by dawn or shortly thereafter. Today will likely be the warmest day this week with temperatures rising into the 40s, maybe close to 50 in the southeast CWA. Clouds increase tonight ahead of shortwave/clipper front seen on water vapor this morning over the northern Plains. Most model solutions show light precip arriving by dawn in the far west along the front, with main sfc low and better lift staying north over the Ohio Valley. With clouds tonight will see low temperatures close to normal with upper 20s to lower 30s. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 255 AM EST Monday... Looking at strong cold air advection behind front Tuesday with temperatures starting out steady or slightly warming in the west in the lower to mid 30s, with mid 40s east, then temperatures should crash into the 20s by late afternoon. There will be a burst of winds behind this front with gusts to advisory levels likely in the higher terrain of the Blue Ridge and Alleghanys, but coverage at the moment is borderline in terms of issuing headlines. Since its 3rd period will let next shift re-evaluate it. Will mention in the HWO. Will see snow shower machine kick in shortly thereafter in the mountains with best upslope and upper support occurring late Tue afternoon into late Tue night. Could see 4-6 inches on the western slopes of Greenbrier by Wed morning with 1-3 inches to southern WV near Bluefield, and possibly the NC/TN border mountains into Mt Rogers, with a dusting as far east as the Alleghanys to New River Valley. As this trough deepens should another period of stronger wind Tuesday night and Wednesday. In addition, temperatures falling into the lower teens in the mountains, combined with wind speeds should send wind chills below zero in the mountains, and single digits to around zero in the foothills/piedmont Wednesday morning. Will see axis of trough accelerate east Wednesday with snow showers ending early. Still cold with highs in the 20s west to lower to mid 30s east. By Wed night, next clipper enters the TN valley with increasing clouds with maybe a few snow showers reaching the mountains by dawn. With flow turning more west and some warm advection ahead of clipper lows should will be in the mid teens to around 20 west, to lower 20s east, with potential for some rise in temperature late. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 340 PM EST Sunday... Upper air pattern is forecast to remain amplified with a cold upper level trough over eastern North America through Friday. Embedded short waves passing through the general flow pattern will result in clouds and potential for mountain snow showers and flurries. Temperatures will favor the colder side of normal until Friday...trending back closer to normal for the weekend as the upper flow becomes more zonal. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... As of 1256 PM EST Monday... VFR through at least 06z, though ceilings will steadily lower from west to east, especially into the evening/overnight hrs. Winds southwest 4-8 kts. We`ll then expect deterioration in flight categories as approaching Alberta Clipper and shot of modified Arctic air introduces periods of MVFR to LIFR snow showers, along with gusty northwest winds. These conditions are more likely west of Roanoke along the southern Blue Ridge in NC up into southeastern West Virginia. May see a period of short-duration snow squalls associated with the Arctic frontal passage between 11-14z at Bluefield, Lewisburg and perhaps Blacksburg. Ceilings expected to drop to sub-VFR levels by early morning along and west of the Blue Ridge. VFR conditions expected away from the mountains, with gusty post-frontal northwest winds developing. Sustained winds between 10-15 kts with gusts up to 30 kts, highest at Roanoke. Extended Discussion... A continuation of MVFR to IFR snow showers are expected west of the Blue Ridge through Tuesday night. Weak high pressure builds in Wednesday followed by another weaker clipper Thursday that passes to our north. Into Friday, potential for a stronger clipper system to re- energize off the Atlantic coast, inducing a period of sub-VFR with light to moderate snow. Conditions then trend VFR for Saturday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...MBS/WP NEAR TERM...AL/WP SHORT TERM...WP LONG TERM...PM AVIATION...AL/WP

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