Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 250128 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 928 PM EDT Sat Oct 24 2020 .SYNOPSIS... A cold front moves south across the Carolinas tonight into Sunday, with high pressure wedging south into our area into early next week. Another front moves in midweek. Temperatures for Sunday will back below normal and rain is expected tonight into early Sunday night. Temperatures moderate early next week. && .NEAR TERM /THROUGH SUNDAY/... As of 900 PM EDT Saturday... Strong short wave lifting northeast to east-northeast out of Georgia, centered near ATL this evening. Vigorous, highly kinematic system that will bring a good dousing of rain to the southeastern parts of the CWA, far less to the northwest part of the CWA. The main emphasis will be across central/eastern NC, SC, and eastern GA overnight. The system will track east of the area by late Sunday, but leaving behind a wedge of cool air, low clouds, and drizzle/fog overnight into Monday morning before the situation improves. WPC concerned about rainfall over the next few hours across the NC Piedmont especially as well as back into western NC and points south. MPD was issued and included our southern tier of mainly NC counties for 1-2 inches of rainfall over the next couple of hours. This precipitation is riding along the remnant/wedge developing frontal boundary. As of 155 PM EDT Saturday... Frontal boundary stretching from the mid-Atlantic to the west of the Blue Ridge in NC slides southeast tonight slowly and will take on a west-east orientation as it becomes parallel to the upper flow. A shortwave works northeast through the Carolinas late tonight into Sunday pushing offshore by late in the day Sunday. As for the weather, will see showers form along/ahead of the front heading into mid to late afternoon from the NC mountains into the foothills of VA, but appears showers will be weak early on. Better instability where more sunshine occurred lies east of the Blue Ridge and south of the Roanoke River/U.S. 460 corridor. Allow for isolated thunder in the piedmont, and as far west as the NC mtns late this afternoon. Expect rain to increase in coverage ahead of the shortwave later this evening and overnight, as best isentropic lift becomes coincident with upper forcing. Went with likely pops along/east of the Blue Ridge, with lower threat west. Rainfall amounts are actually sliding upward per latest models along and east of the southern Blue Ridge with up to three-quarters of inch possible tonight into early Sunday, with a quarter inch or less west. High pressure to the north wedges southward into the area Sunday and will lean toward cooler temps and non-diurnal temperature curve, with clouds likely to hinder temps from rising much during the day. Exception may be southwest of a Bluefield to Marion line. Temperatures Sunday may not get out of the 40s north of U.S. 60, in the higher elevations, and even Lynchburg. Most will stay in the 50s, with 60s southwest a line from Bluefield to Wilkesboro, except the Blue Ridge. Forecast confidence is good for rain threat at least tonight-Sunday, lower on thunder threat and highs Sunday. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 210 PM EDT Saturday... Deeper moisture heads out Sunday night into Monday but wedge remains and look for patchy light rain/drizzle and fog for most Sunday night- Monday morning. Should see flow turn more south Monday afternoon but models are still showing residual low level moisture hanging tough most of the day east of the Blue Ridge. Forecast confidence is lower for sky cover and temperatures Monday but lowered highs in the piedmont a few degrees, but will still be milder Monday compared to Sunday with highs in the 60s. Upper ridge across the southeast remains in place with trough axis across the Great Lakes/Midwest. A fast flow aloft will exist over us Tuesday and frontal boundary works in but with west flow will likely see limited shower threat. Temperatures continue to warm above normal, with mid to upper 60s west on Tuesday to mid 70s east. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 1245 PM EDT Saturday... The models continue to advertise a closed upper level low crossing over the southern Plains on Wednesday with a tropical area of low pressure coming northward from the Gulf of Mexico. Any tropical moisture would get wrapped into a low pressure system over the Mississippi River Valley by Wednesday night and head toward the Mid Atlantic. Thus, confidence continues to rise for a rather wet Thursday. Periods of moderate to heavy rain are possible, but it is way too early to tell what if any hydro impacts may occur due to most of this month being quite dry and also the considerable model discrepancies with the track of the low pressure system. While there are some notable timing differences among the models regarding when the bulk of the moisture should exit off the East Coast, it seems that lingering showers could persist through Thursday night and Friday. The closed upper level low could pass overhead by Friday afternoon as well to keep the shower chances ongoing. Eventually, high pressure will build over the Appalachian Mountains during Friday night into Saturday morning. Drier and cooler conditions should take hold for the start of the weekend. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... As of 800 PM EDT Saturday... Poor aviation conditions expected through the TAF valid period as a wedge develops north of a stalled frontal boundary to our south and a vigorous short wave aloft tracks across the region from GA and SC overnight into Sunday. Showers and isolated thunderstorms this evening will give way to more widespread light rain and eventually drizzle/fog through the day Sunday. Mostly IFR-LIFR ceilings are expected through the TAF valid period once they settle in overnight and early Sunday, going nowhere after that until the wedge breaks Monday morning. Visibilities mainly MVFR through the day Sunday with pockets of IFR-LIFR in DZ/FG overnight Sunday into Monday morning. Rain will be most prevalent with periodic heavier showers east-south of the Blue Ridge mainly after 04Z Sunday. Lighter rain or drizzle expected to the northwest. Winds will become northeast to east 5-10kts late tonight/early Sunday with low end gusts expected mainly east of the Blue Ridge. /Confidence in Forecast Parameters/ -Moderate to High Confidence in MVFR-IFR or worse ceilings through the TAF valid period, -Moderate Confidence in MVFR or worse visibilities mainly after 04Z Sunday in -RA, -DZ, and BR/FG through the TAF valid period. -High Confidence in winds becoming NE-E 6-12kts with low end gusts overnight/early Sunday. -Low Confidence in isolated thunderstorms this evening. .Extended Aviation Discussion... A cool air wedge will remain in place until Monday morning when it is expected to erode. Sub-VFR conditions are likely continue until at least early Monday and when the wedge breaks. Aviation conditions will finally improve Monday afternoon as the wedge breaks. A period of mostly VFR to MVFR conditions is expected Tuesday- Wednesday before a stronger front arrives from the west possibly combined with the moisture from what is currently T.D. #28 and expected to become T.S. Zeta in the next day or so. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/WP NEAR TERM...RAB/WP SHORT TERM...WP LONG TERM...PW AVIATION...AMS/RAB/WP

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