Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 200947 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 547 AM EDT Thu Oct 20 2016 .SYNOPSIS... A front extended from New England through the Ohio Valley to a low over the Southern Plains. This low will track across the Tennessee and Ohio Valleys by Friday morning and will push a strong cold front across much of the eastern United States Thursday night and Friday. High pressure build in behind the low on Sunday and Monday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 500 AM EDT Thursday... A strong upper level trough mid-conus will move east across the MS Valley today. At the surface, low pressure will move northeast through the Ohio Valley and into the eastern Great Lakes by tonight. A strong cold front will trail the surface low and will move east, crossing the Appalachian mountains tonight, then east across the foothills and piedmont Friday. An extensive area of showers with embedded thunderstorms will move east with the front, this activity overspreading our CWA from west to east beginning this evening (5-10PM time frame) west of Interstate 77, then spreading across the New River, Greenbrier, and Shenandoah Valleys between 10PM-2AM...before spilling east of the Blue Ridge late. Per late arrival of any thunderstorm activity, do not anticipate anything severe. The storm prediction center does highlight areas mainly west of our CWA for fast-moving storm cells and line segments capable of marginally severe wind or hail...this threat focused on the eastern Oh/TN Valleys. Today will be the last day of near record warmth with temperature readings 10-20 degrees above normal. The unseasonable warmth will come to an end with tonights frontal passage, temperatures taking a noticeable tumble Friday.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 350 AM EDT Thursday... An upper trough will deepen and move into the East over the next couple of days. A wave of low pressure will lift northward into New England and push a strong cold front east across our region. The cold front will push off the coast by Friday evening and move further out into the Atlantic ocean on Saturday. Scattered showers and a few thunderstorms will develop ahead and along the front. The Day 2 convective outlook places general thunderstorms over eastern portions of our Forecast area. However, Surface instability looks quite limited given the morning timing of the fropa. Generally it seems like a band of showers with front. Used an non-diurnal temperature curve for Friday with falling temperatures expected west of the Ridge throughout Friday, and falling across the Piedmont by the afternoon. High temperatures Friday will range from the lower 50s in the mountains to the mid 60s in the Piedmont. As a large area of high pressure over the Mississippi valley ushers in significantly colder air behind the front, the low level flow will become energized and make for blustery conditions for Friday afternoon into Saturday. Expect about 40 kt of 850 mb flow during the peak of the cold advection Friday afternoon to Saturday morning. However, winds are expected to remain below wind advisory levels. It is time for you to find your cold weather gear Friday night with temperature readings dropping to lows from the mid 30s in the west to the mid 40s in the east. There will also be the prospect for the first snowflakes of the season Friday night into Saturday morning at the higher elevations (above 3500 feet msl) west of the Blue Ridge but no significant snow accumulations expected with warm ground. But, low temperatures at or below freezing may well end the growing season for some higher elevations west of the Blue Ridge Friday night. Light upslope showers will continue Saturday with cold advection combined with lingering low level moisture in the Northwest flow. High temperatures on Saturday will vary from the lower 40s in the northwest mountains to the lower 60s in the Piedmont, with the blustery wind making it feel even colder. Clear to partly cloudy conditions will prevail Saturday night into Sunday morning. Low temperatures will drop into the mid 30s in the mountains to the lower 40s in the Piedmont. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 320 PM EDT Wednesday... The upper pattern will be trending toward reestablishment of an upper ridge over the eastern US through the middle of next week. This will generally keep our weather quiet and dry through the period. Return flow around high pressure to our south will push some warmer temperatures into the region for Sunday and Monday. A fast moving short wave will zip through the Great Lakes region and drive a low through New England. This will swing a weak cold front through the region later on Monday afternoon with any precipitation expected to remain off to our north. Cooler high pressure will then build in on Tuesday and take up a wedge position east of the Appalachians by Wednesday. && .AVIATION /10Z THURSDAY THROUGH MONDAY/...
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As of 600 AM EDT Thursday... High pressure aloft will provide one last day of near record warmth for the Mid-Atlantic. A deepening upper trough and associated strong cold front sweep through the region tonight and Friday. Generally VFR conditions are expected today after a brief period of fog this morning. Local ifr/lifr due to dense fog will be found in some of the river valleys early this morning. Fog is expected to be shallow, and will burn off quickly after sunrise. Once the fog has dissipated, expect VFR for the remainder of the day. As for precipitation threat, all models suggest that associated frontal convection/precipitation will remain west of the RNK CWA (west of BLF/LWB) through sunset today. The air mass in advance of the front is very stable with unseasonably warm temperatures aloft providing a strong cap on convection as well as clouds. Precipitation associated with the front will largely be post- frontal, not pre- frontal. Thus, will not introduce any precipitation until closer to midnight for BLF and LWB and well after midnight for areas east of the Blue Ridge. With respect to clouds, model soundings indicate a strong inversion around the 850mb-800 mb layer, resulting in continued SCT cloud development in the 5-7kft layer. This should be the case throughout the day, becoming BKN late in the day western areas as the frontal system approaches from the west. Cloud bases are expected to remain mostly VFR until midnight. After midnight cloud bases and vsbys will deteriorate with the arrival of the frontal showers. Winds to remain mostly calm or light SSW-SSE through 14z/10am this morning, becoming SW 7-10kts after 14Z, with low end gusts,up to 15 kts, possible KBLF, KBCB, and KROA by mid afternoon. Medium to high confidence in cigs/vsbys through the TAF valid period. Medium to high confidence in wind direction/speed through the TAF valid period. Extended aviation discussion... Showers, perhaps an isolated thunderstorm will develop over the mountains toward midnight Thursday/Friday, with showers spreading east of the mountains as the front moves east Friday morning. The best chance of precipitation will be from midnight Thursday night through noon on Friday. This will be the most likely period of widespread MVFR to IFR ceilings and visibilities. The strong cold front will move through the region from west to east, mainly in the 06Z Fri to 15Z Friday time frame. A southwest to northwest wind shift is expected to occur late Thursday night across the region with gusty northwest winds behind the front continuing into Friday night and possibly Saturday. Areas of sub- VFR conditions will likely accompany the front and precipitation. A return to VFR conditions is expected for most areas Friday night into Saturday. The exception will be western parts of the region where a healthy northwest upslope flow, and lingering low level moisture, will prolong an IFR/MVFR ceiling during this time period. Even the mountain areas will become VFR again for Sunday and Monday.
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&& .CLIMATE... As of 515 AM EDT Thursday... Record maximum temperatures... New record max temperatures were set at Blacksburg and Danville Wednesday with 83 and 86 degrees, respectively. Record temperatures are possible again today. Oct 20 Location Record Max Bluefield.....79 in 1993 Danville......88 in 1984 Lynchburg.....85 in 1993 Roanoke.......84 in 2005 Blacksburg....82 in 1985 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...PM SHORT TERM...KK LONG TERM...DS/MBS AVIATION...PM/RAB CLIMATE...AMS is the U.S. government's official web portal to all federal, state and local government web resources and services.