Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 210539 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 139 AM EDT Wed Oct 21 2020 .SYNOPSIS... Upper level ridging will increase across the Southeast and mid- Atlantic tonight and tomorrow, contributing to a warming trend that will push temperatures well above normal through the remainder of the work week. A cold front is expected to arrive on Saturday, bringing a modest cool down to the region and a chance of rain. && .NEAR TERM /THROUGH TODAY/... As of 1250 AM EDT Wednesday... No big changes are planned for the forecast during the remainder of the overnight period. We are still expected the development of patchy fog towards daybreak, that will not last very long after sunrise. Have tweaked hourly temperatures, dew points, wind/gusts, sky cover grids over the next few hours based upon the latest observations and expected trends. As of 1030 PM EDT Tuesday... High pressure still in control today as a weak wedge continues to remain in place east of the mountains. Stalled cold front over the Ohio River Valley will retreat back north as ridging along the southeast United States builds in for Wednesday. A weak east/southeast flow keeping enough shallow Atlantic moisture in place to see fog development again tonight. At the moment, mountain river valleys along with the Piedmont of Virginia and North Carolina have the best chance for patchy dense fog through sunrise. Higher elevations and areas to the west should remain mixed well enough to limit fog to the river valleys late tonight. Temperatures will remain a couple to several degrees above normal today and tomorrow as a 588dm upper-level ridge remains in place over the southeast coast. Warmer tomorrow with some locations reaching the low 80s. Tonight should remain rather mild east of the Blue Ridge as fog and high clouds could hinder some cooling. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... As of 130 PM EDT Tuesday... The big story of the short range portion of the forecast will be above average temperatures as high pressure underneath a broad ridge allows for ample warming to take place. As of now, Thursday looks to be the warmest day of the week, with areas out east nearing the 80 degree mark. Later in the period, Friday, an advancing front from a low tracking from the central Plains, toward the Great Lakes region, approaches the Mid-Atlantic. As this nears, high pressure over the region weakens and shifts eastward. As high pressure shifts, frontal advancement is expected to slow, holding any real rain chances off until Saturday. Any earlier rain chances would be dependent on return flow interacting with the southern Blue Ridge/NC mountains to spark isolated showers Friday afternoon. Greatest rain chances and amounts Saturday with the front will be for the west, as the front dries out in the Piedmont. Forecast confidence is moderate. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 130 PM EDT Tuesday... Guidance since yesterday in the long range has come into better alignment, with GFS coming into better agreement with the ECMWF and Canadian: the trough over the Great Lakes/Canada shifts northward. This prevents waves within the flow from really impacting our area. Instead, a bulk of the precipitation will fall to our west, though at this time range it is too early to rule out at least some rainfall for the western slopes. The rest of the area will remain under a mix of clouds. Tuesday into Wednesday, the trough is expected to dig slightly south, pushing a front into the area, increasing rain chances. At the same time, a LLJ is projected to set up over the Mid-Atlantic, bringing windy conditions for the area. Overall, temperatures during this period will be cooler than the short range`s, but still remain above average. Increased cloud cover should especially help keep nighttime temperatures mild. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... As of 130 AM EDT Wednesday... Weak southeast flow will keep a shallow layer of moisture near the surface overnight with sub-VFR conditions entering the region and lingering until daybreak. For now have in MVFR fog across much of the foothills and piedmont of Virginia and North Carolina. LIFR fog is possible again at KLYH and at KBCB. Much of the low clouds and fog will begin to mix out around 15Z/11AM but it may take longer in central and eastern Virginia. VFR conditions are expected in the mountains and foothills for the afternoon. A return to some patchy MVFR fog is possible by late in the valid TAF forecast period concluding at 06Z/2AM Thursday. Confidence in the above aviation scenario is moderate to high. The biggest question mark is the coverage of the sub-VFR conditions in the east through daybreak. .Extended Aviation Discussion... Some sub-VFR conditions early Thursday will give way to VFR conditions throughout the remainder of Thursday, with possibly more fog Thursday night/Friday morning. Isolated MVFR showers are possible mainly in the mountains Friday night. These conditions look to spread east by Saturday as our next front crosses through the area. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...NF NEAR TERM...AMS/BMG/DS SHORT TERM...RR LONG TERM...RR AVIATION...AMS/BMG/DS

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