Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 210604 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 204 AM EDT Thu Sep 21 2017 .SYNOPSIS... A weak short wave will move southeast across our region this evening, then high pressure follows for tonight through Saturday. A cold front will approach the Mid Atlantic region the middle of next week. && .NEAR TERM /THROUGH TODAY/... As of 700 PM EDT Wednesday... Showers and storms will continue to decrease in coverage across the area with the loss of heating. Upper level support will not be zero, so still anticipate some isolated showers lingering a couple of hours after sunset. No major changes were made to the ongoing forecast. Tweaked hourly temperature, dew point, sky cover, and wind grids based upon the latest observations and expected trends heading into the early overnight hours. As of 300 PM EDT Wednesday... The upper level pattern continues with ridging dominating the East and troffing in the West. A shortwave trough with several lobes of vorticity will travel southeast tonight into Thursday. Scattered showers and thunderstorms have developed this afternoon in the deep moisture convergence and surface LIs around minus 3. However, convection should remain shallow as it will be fighting the northwest wind especially out east. HRRR, HiResW-ARW-east, RUC, NAM and GFS showed convection traveling eastward this afternoon into this evening, then storms taper off on most solutions by 06z. In general, scattered showers and thunderstorms will diminish this evening into tonight with the loss of solar heating. The combinations of light winds and low level moisture will result in patches of fog late tonight into early Thursday morning. Low temperatures tonight will range from the upper 40s in the colder mountains valleys to the mid 60s in the Piedmont. Differential heating, surface convergence and orographic lift Thursday along the Appalachians may produce isolated to scattered showers and thunderstorms. Convective depth will remain rather shallow given dry mid-level air in place and surface-based CAPES at/below 1000 J/kg. Any showers or thunderstorms should follow a diurnal trend and dissipate with sunset. High temperatures Thursday will vary from around 70 degrees in the mountains to the mid 80s in the Piedmont. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... As of 310 PM EDT Wednesday... Will stay rather quiet in our area this period, with showers/few thunderstorms Thursday evening waning fairly quickly once sunset occurs. Will see a weak convergent area set up over the southern Appalachians Friday which should lead to isolated coverage of showers or storms then drying out Friday night, with potential for a stray shower into Saturday, though better upper support stays south of our area, while upper ridge builds across the Ohio Valley into WV. Temperatures to stay above normal by several degrees, but not seeing any records threatened. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 310 PM EDT Wednesday... We will remain in an amplified pattern across the country with two storms in the western Atlantic to watch. Will see Jose weaken into a post-tropical system in the short term and continue to weaken this period. Will see Hurricane Maria head north to off the NC coast, with question remaining on how close and if it Maria comes ashore. Model ensembles and consensus from NHC keep it east of the mainland. Meanwhile, the central U.S. will be active with deep upper trough and slow moving front. Will see this translate to upper ridge across our area but expect potential for some clouds and possible showers to flirt with our piedmont counties Tuesday per leftovers of Jose interacting with coastal front/trough. However, threat of any appreciable rain looks low for the next 7 days and even beyond the front washes out as it moves into the eastern U.S. by Thu-Fri next week. Temps remain above normal during this time frame with lows in the upper 50s to around 60 west, to lower to mid 60s east. Highs ranging from the mid 70s to around 80 west, to lower to mid 80s east, with some upper 80s not out of the question, especially if Maria stays strong and we get on the western subsidence side of the system without any mid/high clouds Tuesday. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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As of 200 AM EDT Thursday... At 05Z/1AM GOES-16 Fog images were showing fog in the river valleys in West Virgina, including the Greenbrier River. Precipitation has ended and the sky had cleared over much of southwest Virginia, southeast West Virginia and northwest North Carolina. Dew points depressions were already near zero in many locations, and with the rain earlier on Wednesday afternoon, there is low level moisture available for areas of fog. River valleys through the southwest Virginia and southeast West Virginia mountains will have IFR or lower ceilings and visibilities developing before 10Z/6AM. Sub-VFR conditions will improve to VFR around 13Z-14Z/9AM-10AM this morning. VFR ceiling and visibility then expected for the rest of the day. Extended Aviation Discussion... Overall persistence forecast to prevail for the rest of the week. Strengthening high pressure remaining in place between exiting Jose offshore and a weak cold front approaching from the west. This should maintain good flying weather outside of isolated diurnal showers and thunderstorms. Dry weather is expected Friday through Monday.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/KK NEAR TERM...DS/KK SHORT TERM...WP LONG TERM...WP AVIATION...AMS/DS is the U.S. government's official web portal to all federal, state and local government web resources and services.