Area Forecast Discussion
Issued by NWS Blacksburg, VA

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646 FXUS61 KRNK 140501 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1201 AM EST Sun Jan 14 2018 .SYNOPSIS... High pressure will build in from the northwest tonight through Sunday and remain north of the region into Monday. A second surge of Arctic air comes in behind a cold front that passes through the area Monday night and Tuesday. && .NEAR TERM /THROUGH SUNDAY/... As of 700 PM EST Saturday... Still some upslope bands of light snow/flurries affecting portions of the region west of the Blue Ridge this evening, but no more than a local dusting of snow is expected before moisture wanes and clouds/flurries decrease overnight. Temperature trends a bit ahead of schedule so have lowered mins just a tad to compensate. Previous discussion... Wind chill advisory has been posted for western Greenbrier county until 10 am Sunday where the combination of wind and temperatures will create very cold wind chills. The NAM, GFS and HiresW-arw-East were slower to diminish moisture and taper off snow showers. A lingering fetch of low level moisture from Lakes Huron and Erie may keep light snow going into tonight. As a result decided to increase pops in the west and extend the chance for snow showers and snow flurries in the west longer into this evening. Any accumulating snow will be less than an inch and will remain confined over the far west with the limited upslope. High pressure to our northwest will build eastward tonight into Sunday. The upper trough will pivot across from the west overnight with another shortwave travel east. This may result in additional upslope clouds in the west. Low temperatures tonight will range from the single digits in the mountains to the lower 20s in the Piedmont. High pressure moves into Pennsylvania on Sunday, providing mostly sunny and dry conditions. High temperatures Sunday will vary from the upper teens in northwest Greenbrier county in West Virginia to the mid 30s in the piedmont. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 200 PM EST Saturday... A ridge of surface high pressure will still be centered across the eastern sections of the region heading into Sunday night. As we progress through Monday evening, the center of this high will be displaced eastward in response to the approach of a cold front from the west. Precipitation-free conditions are forecast during this time period, with temperatures continuing to average about ten to fifteen degrees below normal. By late Monday night, the leading snow showers in association with the cold front are expected to reach a few parts of southeast West Virginia. During the day Tuesday, model guidance varies as to the degree and speed the front and associated precipitation make their way into the region. The bulk of the guidance suggest Tuesday night is a more likely candidate for the actual frontal passage. Isolated to scattered snow showers will be forecast to reach as far east as the crest of the Blue Ridge by Tuesday afternoon, with the best concentration across southeast West Virginia. Snowfall totals, even for most of this higher concentration area, are expected to be less than one inch. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 1100 AM EST Saturday... The Tuesday night and Wednesday time frame of this part of the forecast will be highlighted by a sharply amplified longwave trough that will pass into and across the region. Guidance varies to the degree which moisture will accompany this systems associated surface cold front as it crosses the area. However, was is consistent is that some degree of moisture will. This should lead to at least isolated to scattered snow showers across the forecast area during this time frame. In the wake of the front, northwest flow across western sections of the area should allow for a continuation of isolated to scattered snow showers across parts of southeast West Virginia Wednesday night. We will need to keep an eye on the trend of the forecast wind chills. The latest numbers suggest the region may be close to reaching Wind Chill Advisory thresholds. Heading into Thursday and Thursday night, an already tight pressure gradient may trend even tighter, than thus yield even gustier winds across the area. A lot will depend upon how much offshore development there is a of a coastal low on the tail end of the departing upper trough. Guidance still varies on this potential as well. Late Thursday night into Friday, and continuing in Saturday, look for the synoptic pattern to trend zonal across the area with some upper level ridging across the Gulf Coast states. Anticipate a warming trend heading into the weekend, with little if any precipitation. The only very small chance currently offered would be on Saturday just along the eastward side of the crest of Appalachians. Guidance suggests that slightly higher moisture content air may get lifted upslope in a narrow region, especially the area of the North Carolina Foothills. Temperatures may be cold enough at the onset for an hour or two of very light freezing rain before temperatures rise above freezing for the remainder of the day. Temperatures during this portion of the forecast will start about ten to fifteen degrees below normal Tuesday night into Wednesday. From Thursday into the start of next weekend, anticipate a warming trend that will bring readings to values around five degrees above normal by Saturday. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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As of 1159 PM EST Saturday... Lingering MVFR clouds and flurries in upslope NW flow west of the Blue Ridge will continue to gradually decrease overnight. Expect VFR conditions Sunday as cold and dry high pressure moves out of the Ohio valley and into New england, bringing the Appalachians and central mid Atlantic region fair weather and good flight conditions through Sunday. Winds will also gradually diminish. Extended Discussion... VFR expected across the region Sunday night and Monday under high pressure. MVFR snow showers are possible Tuesday and Wednesday from a clipper system. This will lead to another surge of Arctic air. Drier weather is anticipated for Thursday and Friday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...Wind Chill Advisory until 10 AM EST Sunday for WVZ508. && $$ SYNOPSIS...KK NEAR TERM...KK/MBS SHORT TERM...DS LONG TERM...DS AVIATION...PM

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