Area Forecast Discussion
Issued by NWS Blacksburg, VA

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984 FXUS61 KRNK 231433 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1033 AM EDT Sun Jul 23 2017 .SYNOPSIS... A slow-moving cold front will drift southward over the Mid Atlantic during today and Monday. High pressure should build to the north by Tuesday and Wednesday. The aforementioned front should stall to the south and begin heading back north as a warm front later in the week. && .NEAR TERM /THROUGH TONIGHT/... As of 1030 AM EDT Sunday... Upstream mesoscale convective systems are weakening as they reach the Appalachian Mountains at this time. Scattered showers are making it through Lewisburg to Amherst. Today will be rather active with a slow-moving cold front sagging southward, but our region has started with a fairly large amount of residual cloud cover. There will be some breaks in the clouds for sunshine to push temperatures into the 80s and 90s for highs although not as hot compared to yesterday. Mesoscale models reveal convection developing in the afternoon along the southern Blue Ridge. The Storm Prediction Center has most of our region in a slight risk for severe thunderstorms due to damaging wind gusts. Given the environmental conditions, it appears the best bet for any severe weather to develop will be along the Blue Ridge toward the Piedmont south of Route 460. For tonight, surface front still to our north and seems most models are favoring some lull in storm coverage behind the afternoons activity. However, there is enough agreement to keep a better threat of storms in the west closer to higher theta-e ridging and moisture transport. Will side with drier wx overnight, with muggy temps continuing with lows in the mid to upper 60s west, to lower 70s east. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 325 AM EDT Sunday... Front looks like it stalls/slows over the forecast area Monday but deeper moisture slides further south. Going to see a little drier wx per most model solutions with a few showers/storms over the mountains, and across the southern CWA, though isolated convection seems plausible anywhere Monday. Staying very warm with a westerly flow increasing, but dewpoints start to drop some. Highs should range from the lower to mid 80s mountains, to lower to mid 90s east. By Monday night into Tuesday the axis of the upper trough slides east and shifts the frontal boundary further south. As this occurs, high pressure over the Great Lakes shifts east Tuesday afternoon into New York. Should see a shift in the winds from west/northwest to northeast. Some drying to take place but with southeast flow arriving on the backside of the front into the southern Appalachians, showers/storms may stick around in a scattered fashion over the High Country of NC into far Southwest Virginia, and possibly east toward Martinsville/Reidsville. Some noticeable change in dewpoints, but overall temperatures should run at or just above normal. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 1230 PM EDT Saturday... Passage of high pressure off the coast on Wednesday will bring cooler easterly windflow to the mid-Atlantic, resulting in likely the coolest afternoon temperatures of the week. Upslope wind flow will make for the best chances of shower/thunderstorm activity across the mountains. Winds will shift more southerly by Thursday, resulting in a return of warmer temperatures and higher humidity, and greater coverage of afternoon showers/storms, more so across the mountains. A cold front will slowly make its way across the mid Atlantic on Friday and Saturday, again resulting in scattered showers and thunderstorms both days, a few of which may become severe for brief periods of time. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... As of 725 AM EDT Sunday... Have showers affecting LWB/BLF and BCB between 12-14z, but instability has weakened so thunder threat has diminished except west of BLF, so left VCTS here. Should be a lull after 15-16z, before more storms fire up in the afternoon. Latest high-res models are mainly developing storms east of the Blue Ridge but models also are developing more organized convection over KY after 21z which could impact the mountains afterwards. Confidence is medium that showers and storms will be around the region this afternoon/evening but low on which airports if any get affected. So for now will keep VCTS in all tafs in the mid afternoon to early evening period. Thereafter, after 03z, models showing less coverage so no mention in the tafs. Will have to see if we clear out enough late tonight for fog, but for now am leaning against it. So in summary look for VFR outside of storms, with some MVFR or IFR in storms. Winds will pick up in the 6-12kt range after 16z from the west or southwest, then drop off after dusk. Winds near or in storms will be gusty and erratic, some storms could bring damaging winds, so those with aviation interests should monitor latest radar and forecasts. Aviation Extended Discussion... The cold front currently to our north should be near the NC/VA border by Monday evening. This leaves a baroclinic zone in or near the area through much of the extended period. Additional upper- level disturbances are progged in northwest flow to impact the area, leaving an unsettled weather pattern in place. The most likely areas to see convection, at least during the first part of the week would be near the NC/VA border, mainly affecting KDAN. Late/night early morning fog can be expected in the usual locations, otherwise outside these concerns and scattered convection, mainly in the south, look for mostly VFR cigs/vsbys. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PW NEAR TERM...PW/WP SHORT TERM...WP LONG TERM...NF AVIATION...RAB/WP

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