Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 160500 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1200 AM EST Thu Nov 16 2017 .SYNOPSIS... A cold front will move east across our region tonight followed by dry weather under high pressure Thursday into Friday. A strong cold front will then bring more showers and windy conditions to the region this weekend. Cold high pressure will build in behind the front for early next week. && .NEAR TERM /THROUGH THURSDAY/... As of 1010 PM EST Wednesday... 3km NAM nest and other HiRes guidance showed light showers crossing the foothills and piedmont late this evening. Based on theses models and the latest radar trends have updated probability of precipitation...with the showers exiting east of Buckingham and Charlotte Counties by 2AM. Only minor changes to temperatures overnight. The cold front with some showers will travel east across the Appalachians tonight into Thursday. For Thursday morning expected some lingering upslope morning showers or drizzle in West Virginia. By Thursday, high pressure over the midwest moves toward our area with drier air. There is enough pressure gradient between the high center and the low over New England to result in a breezy afternoon. Some wind gusts over 30 mph are possible in the higher ridges of the Blue Ridge. In a familiar cold advection pattern, temperatures will stay cool in the mountains and warmer with downslope flow in the east. High temperatures will vary from the upper 40s in the west to the lower 60s in the east. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 200 PM EST Wednesday... Quiet weather under more seasonal temperatures will return Thursday night and last into Friday night as surface high pressure builds in under shortwave ridging aloft. May still see some gusty northwest winds Thursday evening before the gradient relaxes under building heights overnight. Lingering upslope clouds may also persist over the far northwest ridges, otherwise expecting clearing skies Thursday night with dry weather lasting into Friday night. Decent late night radiational cooling should allow lows to fall below freezing Thursday night including some 20s mountains. High pressure overhead should ensure a very nice Friday with steady warm advection aloft resulting in highs in the 50s and 60s under light winds. Moisture pushes east in advance of the next strong upstream trough later Friday night with mixing on the ridges also increasing under tightening of the 850 mb jet aloft. Slower timing again suggests that any showers will primarily remain to the west overnight. Thus only expecting some increase in clouds including a possible wide range in lows from the 40s/near 50 ridgetops, to the 30s across the valleys and eastern low spots. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 130 PM EST Wednesday... Timing of the next upper trough and subsequent surface cold front still remains somewhat in question over the weekend as overall models continue to trend slower and closer to the earlier ECMWF. This scenario looks about 6 hours slower than yesterday with the surface front outrunning a secondary shortwave that looks to lag back to the northwest until later in the weekend. This now holds the leading edge of the frontal showers back into the western mountains until early Saturday afternoon with only isolated showers within the warm sector elsewhere ahead of the boundary until late in the day. Increasing southwest jet aloft ahead of the lead shortwave axis trailing the front likely to make for a breezy/windy Saturday but warm with highs 50s to mid 60s. Surface front including the 850 mb boundary finally looks to surge through Saturday evening/night with most showers in the early evening to the early morning hours of Sunday timeframe. Appears will be an associated shot of stronger winds as the front and/or embedded band of shallow convection slides through during the evening followed by gusty northwest winds overnight as the initial shot of cold advection arrives. Models have again trended weaker with the jet aloft but do show a band of impressive pressure rises as subsidence works in while inversion levels lower due to cold advection. This would still support wind advisory criteria in spots along the Blue Ridge overnight so keeping mention in the HWO. Otherwise should be enough showers to warrant a period of likely or higher pops espcly western half, with thickness cold enough to support a brief change to snow showers far west overnight as temps cool toward freezing. Front quickly exits Sunday allowing high pressure to nose in from the southwest which now looks to limit upslope given drying but still enough for snow showers/flurries northwest into Sunday afternoon. Otherwise continued breezy/windy and quite chilly under increasing sunshine ahead of a secondary shortwave approaching from the northwest. This feature may again ramp winds up to advisory levels Sunday afternoon/evening via aided mixing and arrival of colder air aloft. Highs mostly 30s/40s mountains to low 50s east. Lows mostly 20s under continued cold advection within an increasingly dry airmass. Winds should slowly diminish Monday as the upper trough lifts out and high pressure builds in from the southwest into Tuesday. Another weak mid level feature likely to pass across Tuesday night into Wednesday before the high weakens and the split flow begins to tap return flow moisture resulting in more clouds Day7 but dry at this point. However will stay below seasonal normals with only a slight boost in highs on Tuesday at this point. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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As of 1155 PM EST Wednesday... A cold front will track over the region tonight. This front will bring rain showers to the foothills before 08Z/2AM. Expect the showers to the be east of KDAN and KLYH at the start of the TAF forecast period. The best chance for MVFR visibilities and IFR ceilings will be along western slopes to include KBLF and possibly KLWB into Thursday morning. By Thursday afternoon, all sites will see sunny skies (VFR). Medium confidence on the timing of the improvement, especially over the mountains. Winds will become breezy and gusty (15-25kts) behind the front tonight across the mountains, then for the entire area tomorrow. After sunset the wind will diminish. Extended Discussion... VFR conditions anticipated through Friday. A cold front is expected to cross through the Mid Atlantic region Saturday with precipitation and strong winds both ahead of and behind the front. Gusty winds may continue into Sunday but there is large spread in the guidance at that time frame. Dry weather expected Monday into Tuesday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK NEAR TERM...AMS/KK/RCS SHORT TERM...JH LONG TERM...JH AVIATION...AMS/RCS

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