Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 171711 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 111 PM EDT Tue Oct 17 2017 .SYNOPSIS... High pressure will remain across the area through Friday. && .NEAR TERM /THROUGH TONIGHT/... As of 925 AM EDT Tuesday... Mountain valley/river valley fog will be gone by 10-1030am. 12z RNK sounding showing a steep but shallow inversion with very dry airmass in place. Frost advisory expired at 9am with another one set for tonight in the mountains. May have to ponder one further east as some of the rural/outlying areas got into the mid 30s this morning and center of high will be overhead tonight. Otherwise, sunny skies and seasonal highs in the lower to mid 60s expected this afternoon. Previous discussion from early morning... Temperatures at 850 MB rise from around +4 this morning to near +10 Wednesday morning. Long wave trof moves offshore this morning. Expecting subsidence with little to no cloud cover today and tonight. Cold air over the warmer lakes and rivers has produced fog along the Bluestone, Clinch, and Greenbrier River this morning. This fog will dissipate quickly after sunrise as will the frost. Will leave the Frost Advisory in place through 9AM. Dry air mass will result in a large spread between morning lows and afternoon highs. Blend of MET/MAV guidance is reasonable for maxes today. More frost and potentially freezing temperatures are expected tonight. The surface high will be centered over western Virginia with little change in this pattern through morning. This will lead to calm to light and variable wind. Coldest air will be out of the region but conditions are ideal for radiational cooling. Have gone toward the cooler MET/National Blend guidance for overnight lows. Will issue a Frost Advisory for areas west of the Blue Ridge for tonight. Advisory may need to be expanded east based on a final look at the 12Z model cycle today. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 240 AM EDT TUESDAY... High pressure will be centered over the mid-Atlantic region Wednesday and Thursday promoting dry weather, light winds and mainly clear skies. Large nocturnal/diurnal temperature swings are anticipated with lows in the 30s/40s and highs in the 60s/70s. Persistent subsidence will allow some very dry air to work its way to the surface from aloft, especially across the highest elevations where dewpoints may dip into the single digits and teens for elevations above 3500 feet by 12Z/8AM Thursday. This will likely promote minimum humidity readings in the 15-25% range, 5-10% below MOS guidance. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 217 PM EDT Monday... Amplified upper ridge over the southeast will keep us on the warmer side of normal and dry heading into the weekend. By Saturday night, the ridge axis begins to get kicked east of our area by a deepening trough pushing into the middle of the country. Models are disagreeing on the depth of the trough with GFS weaker than the Euro, as it closes off a southern low over southern TX. The Euro on the other hand closes to low off further north closer to the northern TX. Since both show low closing off, and upper flow turning more southwest, influx of moisture should bring increasing chances of showers by early next week. Should be a dry weekend followed by a good chance of showers Monday. Temperatures staying above normal during this period. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... As of 105 PM EDT Tuesday... Beautiful day for flying with clear skies and no restriction to vsbys. A little bit of a northeast wind at ROA around 10kts but should lighten up by late afternoon. High pressure is going to keep us VFR through the valid taf period. Exceptions could be fog at LWB/BCB again late tonight pending frost, but with another day of drying fog should be more limited to over the rivers/lakes. Extended Aviation Discussion... High pressure will remain over the region for the week with VFR weather through Saturday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...Frost Advisory from 2 AM to 9 AM EDT Wednesday for VAZ007- 009>020. NC...Frost Advisory from 2 AM to 9 AM EDT Wednesday for NCZ001-002- 018. WV...Frost Advisory from 2 AM to 9 AM EDT Wednesday for WVZ042>044- 507-508. && $$ SYNOPSIS...AMS NEAR TERM...AMS/WP SHORT TERM...PM LONG TERM...PW/RAB/WP AVIATION...AMS/WP is the U.S. government's official web portal to all federal, state and local government web resources and services.