Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 140544 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1244 AM EST Tue Nov 14 2017 .SYNOPSIS... High pressure will bring abundant clouds and some fog to the Appalachians and central mid Atlantic region as it moves into New England and wedges down east of the mountains. After fair weather Wednesday, a weak cold front will bring a chance of showers west of the Blue Ridge Wednesday night and Thursday. Then after a quiet end to the workweek, a strong cold front will bring showers along with very windy conditions to the area for the weekend. && .NEAR TERM /THROUGH TODAY/...
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As of 1240 AM EST Tuesday... For the remainder of the overnight hours, we are still expecting a generous coverage of clouds across the region as low level moisture is trapped under a nocturnal inversion. This brings a bit of concern for forecast low temperatures, especially in the east. Have increased values by a degree or two across Southside Virginia and neighboring sections of north central North Carolina where dew points are still in the mid 40s. As of 215 PM EST Monday... High pressure moving into New England will wedge down east of the mountains and remain in control of our weather through Tuesday. Abundant low level moisture is locked in under the subsidence inversion and is only slowly able to mix out east of the Blue Ridge where self-destructive sunshine is redeveloping clouds. Clouds remain solidly in place west of the Ridge and are expected to remain entrenched through late Tuesday morning. Some light upslope sprinkles are still possible west of the Blue Ridge. After dark expect cooling in the boundary layer to reinforce/redevelop clouds, along with some patchy fog developing. West of the Blue Ridge where best moisture is running up the mountains believe there will be some patchy drizzle as well, along with the possibility of some icing in freezing drizzle or freezing fog. Confidence in any icing is low and if it were to occur would likely be so light as to avoid any significant impacts. Thus, will include some patchy freezing drizzle mainly at the higher elevations of western Greenbrier but will not issue any advisory or statement due to uncertainty/very light amounts. Will reassess the situation as it evolves overnight. Shallow moisture looks to be waning tomorrow so expect clouds to slowly mix out in time to see some late day rays of sun. Expect lows tonight around 40 degrees east of the Blue Ridge with low/mid 30s to the west. Highs Tuesday will be in the middle 50s east to mid/upper 40s west.
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&& .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... As of 126 PM EST Monday... An upper level trough axis center over our area Tuesday afternoon will move east into the Atlantic ocean Tuesday night. Low temperatures Tuesday night into Wednesday morning will range from the upper 20s in the mountains to the mid 30s along the southern Blue Ridge Mountains. A cold front in the Ohio Valley will approach our area Wednesday and push into the western mountains by Wednesday evening. The timing of the front and its associated precipitation is a little slower on 12z model run. High temperatures Wednesday will vary from the mid 40s in the west to the mid 50s in the east. As the upper trough moves by to our north Wednesday night in Thursday morning, the front will stall to our south near the North Carolina and South Carolina border. Low temperatures will generally be from the upper 30s in the northwest mountains of Greenbrier county to the lower 40s in the piedmont. On Thursday, the forecast area will be sandwiched between the midweek upper trough with stalled weak front expected to our south and weak high pressure evident across the East. Under partly to mostly sunny conditions, temperatures will be seasonable with high readings from the lower 40s in the mountains to the mid 60s in the piedmont. Thursday night will be colder than Wednesday night with values from the upper 20s in the coldest northwest valleys to the mid 30s in the piedmont. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 126 PM EST Monday... As a shortwave exits towards Nova Scotia early Friday,a powerful cyclone will develop and emerge out of the Mississippi Valley by Friday afternoon. Rapid intensification of this system is expected while moving into the Great Lakes region this weekend with a secondary area of low pressure developing off the New England coast by late Saturday. A warm front will lift north across our area Friday evening into Friday night, than a strong cold front will sweep east across our region Friday night into Saturday. The timing of the front remains faster on the GFS compared to ECMWF. Utilized an ensemble blend for timing of the boundary. The cold front could arrive in the form of a narrow strongly forced line of showers or thunderstorms. The actual evolution will determine how much instability we will have to work with. The GFS/Canadian/ECMWF are depicting a deep upper trough across the east/northeast U.S. into the first half of next week. This will lead to below to well below normal temperatures in the extended periods with lows in the 20s and highs in the 30s and 40s west to around 50 in the Piedmont. Precipitation will be below normal with a predominate drier northwest flow aloft. Gusty northwest winds are expected behind the front with strong CAA/significant pressure rises, and deep low pressure developing across the Northeast. For areas along and west of the Blue Ridge, appears solidly in the Wind Advisory category, with the potential for a High Wind Warning at the higher elevations in northwest NC into southwest VA. Will highlight the wind potential in the HWO. There remains plenty of time to work out the details with this strong cold front. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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As of 1230 AM EST Tuesday... The center of surface high pressure will continue to progress eastward overnight and into Tuesday. Anticipate an axis of this high to advect southward along the lee of the Appalachians through the night, with lingering low level moisture trapped under an inversion. Most ceilings will be mainly VFR east of the crest of the Blue Ridge with a mix of IFR/MVFR across the mountains through the overnight hours. Some patchy fog will also be possible, but overspreading mid to mid level cloud cover will limit that. Also, an earlier forecast hinted at the potential for some patchy dz/fzra at some of the higher elevations in the west from roughly now through daybreak Tuesday. This potential still exists and will continue to be reflected in the gridded forecast, but likely to impact the airfields. During the course of Tuesday into Tuesday night, drier air will continue to work its way into the region yielding a trend toward VFR conditions for most area by the afternoon. Some patchy fog will return late Tuesday evening. Extended Discussion... VFR conditions then continue until Wednesday evening, with a cold frontal passage. A period of sub-VFR conditions, brief showers and a west-northwest wind shift appear possible for the overnight period. Possible post-frontal sub-VFR ceilings into Thursday in the western Appalachians, otherwise VFR conditions. VFR then anticipated through Thursday evening. A cold front is expected to cross through the Mid Atlantic region Friday and Saturday with precipitation and strong winds both ahead of and behind the front.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...MBS NEAR TERM...DS/MBS SHORT TERM...KK LONG TERM...KK AVIATION...AMS/DS/MBS

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