Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 142348 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 748 PM EDT Sat Oct 14 2017 .SYNOPSIS... High pressure will remain over the region tonight through Sunday morning. Low pressure developing in the central Rockies tonight will track northeast and push a strong cold front through the area Sunday night. High pressure follows the front for the rest of the week. && .NEAR TERM /THROUGH SUNDAY/...
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As of 700 PM EDT Saturday... Limited changes will be made to the forecast heading through the early tonight period of the forecast. Other than some scattered cloud cover along and near the crest of the Blue Ridge from roughly Roanoke, VA southwest into the Northern Mountains of North Carolina, most locations were experiencing clear skies. This is still expected to change as we progress through the night, especially after midnight, with the development of some stratus cloud cover mainly in areas near and east of the crest of the Blue Ridge. As of 300 PM EDT Saturday... Low clouds eroded across most of the forecast area this afternoon as high pressure built across the region. The light northwest 850 MB winds should clear out the remain low clouds along the southern Blue Ridge. The combination of light winds and low level moisture will result in the development of low clouds and fog. NAMNest and ensemble guidance suggest a layer of status will likely develop in the foothills and piedmont late tonight into Sunday morning. Valley fog will form once again especially in the west. Low temperatures will vary from the lower 50s in the mountains to around 60 degrees in the Piedmont. Upper trough over the central Rockies will travel northeast across the Great Lakes region and southeast Canada Sunday. A cold front trailing south from the low will push into the area late Sunday, and move across the region Sunday night. Slowed downed the timing of the convection along the Frontal boundary Sunday morning. High temperatures Sunday afternoon will range from around 70 degrees in the northwest mountains to the lower 80s in the piedmont.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 330 PM EDT Saturday... Cold front and upper trough will move through the forecast area overnight into early Monday. As expected, with downsloping and diminishing upper support, precipitation will decrease as it crosses the Alleghanys. Some brief redevelopment of precipitation may occur may occur across the Piedmont during the evening/overnight areas, but likely pops do not appear warranted much beyond the Alleghany Front, so will just go with chance pops. QPF will range from 1/4 inch west to less than 1/10 inch east of the Blue Ridge. So, in essence, while everyone should get a little rain, amounts are expected to be negligible and mostly confined to the western areas, where 1/4 inch is possible. Will not include any thunder as all instability is expended well west of our area during the evening. Once the front moves east of the area, high pressure, both at the surface and aloft, will build over the area for the remainder of the week ensuring a dry forecast. The cool down will be the big story during this period, especially considering the belated summer weather in recent weeks. 850mb temperatures will bottom out near 0C in the northern areas Monday to around +5C in the south, then begin to slowly moderate back toward +10C mid week. Monday morning clouds and precipitation will still be in the area, so the main cold advection will arrive Monday night/early Tuesday. Have included frost in the colder valleys, but some concern about how much wind there may be yet at that point. However, the surface high center will be near CRW, so feel that frost in the decoupled valleys along with moist ground from recent rainfall, should support frost. Later shifts may need to consider adding a Frost Advisory as we get closer to that time frame. Frost will also be possible in the sheltered, protected valleys again Tuesday night/Wednesday morning, but overall coverage will be less than what is expected Tuesday morning. Some gusty winds will be noted behind the front, but at this point it appears to fall well below wind advisory criteria. Temperatures will average 5-10 degrees below normal at the beginning of the period to near normal by the end, but certainly the coolest so far of the fall season. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 350 PM EDT Friday... High pressure at the surface and aloft will remain in place and amplify over the Mid-Atlantic region through the extended period. A very dry airmass will reside over the area through the entire period providing clear/sunny skies. 850mb temperatures will slowly moderate as a 590dm ridge builds over the area aloft. Temperatures will moderate well back into the 70s by then end of the extended period, even approaching 80 degrees in the Piedmont. No rain is expected at all during this period, so have left all pops for all areas at zero! && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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As of 730 PM EDT Saturday... VFR conditions prevail across the area as high pressure works its way into the area. Lingering low level moisture will develop into IFR/MVFR stratus ceiling later tonight, especially areas near and east of the crest of the Blue Ridge, along with the development of patchy, or areas of, IFR/MVFR fog across all of the region. Some of the sheltered mountain and river valleys may see a brief period of LIFR visibilities around sunrise Sunday. Any sub-VFR conditions will quickly improve to VFR after sunrise. A cold front will approach the area Sunday afternoon. The trend of the guidance has been slower with each run. Isolated to scattered showers will be possible along and west of a KBLF-KLWB line after approximately 21Z/5PM. Extended Aviation Discussion... A cold front will arrive Sunday night to bring a chance of showers with accompanying MVFR/IFR ceilings and visibilities into Monday. The cold front should head offshore on Monday night, which will allow conditions to improve to VFR by Tuesday. High pressure will return to provide good flying weather through Friday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/KK NEAR TERM...DS/KK SHORT TERM...RAB LONG TERM...RAB AVIATION...DS/KK is the U.S. government's official web portal to all federal, state and local government web resources and services.