Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 261137 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 737 AM EDT Tue Sep 26 2017 .SYNOPSIS... High pressure over the eastern United States will continue to bring warm and dry weather to the region through midweek, while Hurricane Maria stays just off the east coast. A dry cold front will move through the Appalachians and mid Atlantic region on Thursday, with much cooler weather for the end of the workweek into the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 725 AM EDT Tuesday... Cirrus has thinned out across the mountains this morning and more patchy fog has formed in the mountain valleys but this should dissipate very quickly within an hour or so after sunrise. Low stratus can also been seen on nighttime satellite microphysics curves barely sneaking into the far eastern corners of Halifax and Charlotte Counties, and may try to get into parts of Caswell, but westward trend seems to have slowed and once heating of the day gets going and based on model guidance, expect this to retreat and mix out during the mid morning hours. Otherwise no other changes to today`s forecast. Previous discusison as of 412 AM EDT Tuesday... While generally dry and warm high pressure remains over the Appalachian region sandwiched in between a cold front across the Midwest and Hurricane Maria off the Carolina coast, there has been a slight increase in low level moisture with some areas of stratocumulus over parts of the mountains, as well as moving in across the Piedmont with the gradient west of Maria. Patchy fog has begun developing early this morning where breaks in the clouds are. Lower stratus just to the east of our area may sneak in across parts of the Piedmont today, but does not look like it will make much progress before the heating of the day helps to mix it and it breaks up or drifts back east. Meanwhile, cirrus over the mountains should remain thin enough to allow daytime cumulus to form with dew points in the 60s and afternoon temperatures reaching into the 80s again except on higher ridges. This is about 10 degrees or so above average for this time of year. With some weak convergence along Blue Ridge and over higher peaks on the west side of Appalachians, would not be totally surprised if an isolated shower were to form in one or two spots, most likely along southern Blue Ridge or in SE WV from Flat Top to wrn Greenbrier Co. Certainly not expecting any thunder, and most likely no showers will form at all given dry air aloft. Did add a couple small areas of slight chc pops however for a few hours this afternoon however. Otherwise weak Hurricane Maria will remain far enough offshore to have minimal effects on our area as it continues to move slowly north through today, other than keeping a northeast wind direction with speeds in the 10-15 mph for Piedmont areas and maybe a gust or two approaching 20 mph. Not all that unusually for late September in any case. Does not look like any peripheral showers will even reach into our Piedmont areas. By tonight despite the fact that Maria still will not quite be ready to shift eastward and away from the coast, low-level clouds on the far western periphery are expected to pull east and dissipate per most model guidance and some weakening of the system, and thus do not expect any low-level cloudiness to persist over the Piedmont, but more likely to develop in spots again in mountain valleys, along with patchy fog. This an almost routine occurrence for this time of year. Mild low temperatures expected once again. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... As of 300 AM EDT Tuesday... During this portion of the forecast, a ridge of mild and dry high pressure will be situated across the area on Wednesday, all while Hurricane/Tropical Storm Maria moves north through the western Atlantic east of the North Carolina coast. By Thursday, Maria will be jogging northeast and increasing in speed as a tropical storm, while a cold front heads southeast across the region. The front will be very moisture starved, and currently, at best we are anticipating increased cloud cover across the mountains with little if any associated precipitation. The biggest impact the front will have will be a notable change in airmass. We will quickly transition from above normal and more humid than normal conditions, to a pattern that is only slightly above normal on Friday and Friday night, along with lower humidity readings. Somewhat windy conditions are anticipated behind the front Friday into Friday night. Gusts of 25 to 30 mph will be possible at the higher ridge tops, with weaker gusts across the mountain valleys and Piedmont region. && .LONG TERM /SATURDAY THROUGH MONDAY/... As of 203 PM EDT Monday... 500 MB trough digs across the Great Lakes into our area Friday into Saturday with high pressure starting to shift southward from the Great Lakes into Sunday. Will be a dry/cooler with temps close to or below normal. Later Sunday into Monday the flow turns more northeast as the high wedges southward. Should start to see clouds increasing Monday especially as the flow turns more east off the ocean. At the moment confidence in any showers is low, so keeping pops below 15 percent. && .AVIATION /11Z TUESDAY THROUGH SATURDAY/... As of 735 AM EDT Tuesday... Early morning IFR conditions at KLWB as well as MVFR at KBCB are expected to lift by 13 or 14Z. Otherwise VFR conditions expected at all TAF sites today with high pressure over the NE U.S. bringing light northeast winds to the region, except a little gusty this afternoon at KLYH and KDAN with Hurrican Maria off the Carolina coast. IFR stratus will be on the doorstep of KDAN but should remain to the east today. A few high cirrus clouds across the entire region, with some cumulus by this afternoon in the mountains. Very slight chance for an isolated afternoon shower on ridges to the west of KLWB and maybe near KBLF but if these can even form will unlikely move into vicinity of these airports so certainly not worth including in TAFs. Lower cigs may develop again in the Piedmont late tonight into early Wednesday as Maria makes it closest approach offshore of the Carolinas. Latest guidance suggests a swath of VFR to MVFR cigs may advect inland again on increasing northeast flow with at least a period of sub-VFR possible early Wednesday but most likely this will again remain east of KDAN and KLYH. Patchy mountain valley IFR fog likely again by late tonight and early Wednesday. Extended Aviation Discussion... Maria should exit farther offshore Wednesday night into Thursday ahead of a cold front that looks to cross the region from the west during the day. Front appears mainly dry with just a band of upslope aided low clouds possible behind the front Thursday before much drier post frontal air swings in on northwest winds later Thursday into early Friday. Strong high pressure then follows the boundary with continued VFR outside of added upslope clouds far west Friday through Saturday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...MBS/SK NEAR TERM...SK SHORT TERM...DS LONG TERM...WP AVIATION...JH/MBS/SK

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