Area Forecast Discussion
Issued by NWS Blacksburg, VA

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780 FXUS61 KRNK 291402 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 1002 AM EDT Mon May 29 2017 .SYNOPSIS...
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Two cold fronts will cross through the region from the northwest,the first this afternoon and the next late on Tuesday. High pressure will follow for late in the week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 950 AM EDT Monday... Weak echoes on radar in the western CWA this morning with front, so not much to speak of in terms of rainfall, just isolated showers. Will see good insolation early on, while front slides over the area into the NC piedmont by later afternoon. 12z RNK/GSO modified sounding showing some instability but meager lapse rates. High-res models painting a picture for afternoon convection across the NC mountains, more along the Smokys, moving east northeast to the NW piedmont of NC by 23z. Forecast soundings showing 1000-1500 MLCAPEs along/south of the VA/NC border this afternoon after 3pm. The modified 12z GSO sounding was somewhat lower on CAPE, but close to 1000 J/Kg. Given how the parameters set up and model solutions depict, will keep low chance pops in the southern CWA this afternoon, but we will see some potential for isolated severe convection south of the VA border by 4-7pm, but does appear best concentration will stay of our forecast area. High temps still on track with mid to upper 70s mountains, to lower to mid 80s foothills/piedmont. Decent upper jet over KY/WV with stream of high clouds may shift eastward along with any convective blowoff this afternoon to bring increasing clouds, as shown by the 06z NAM, so increased cloud cover a little. Previous discussion from early morning... Upper low moves east across the Great Lakes today and tonight with little change in 500MB heights over the Mid Atlantic region. 500MB temperatures drop today which should eliminate the mid level cap. Surface low off the southeast Virginia coast will move northeast today. This will push the warm front out of the Virginia piedmont with winds coming around to the west. Low clouds and fog over Lynchburg and to the north and east will move out as the front retreats. The west surface through 850MB wind will keep low level and moisture against the west slopes of the Appalachians. By afternoon winds back enough to the southwest to bring deeper moisture into the foothills and piedmont of North Carolina and southern Virgina. Models now bringing the boundary through the region this morning. A wave of low pressure tracking along the front will slow down its southward progress tonight. Will have highest probability of precipitation in northern North Carolina this afternoon, but GFS, RAP and NAM all showing differences in location of the northern edge of the deeper moisture.
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&& .SHORT TERM /TUESDAY THROUGH THURSDAY/... As of 250 AM EDT Monday... A broad area of low pressure will cover southern Canada south into the southern plains to the Carolinas Tuesday. This upper level trough will push a surface trough over the area Tuesday afternoon and evening. This trough with lowering heights will be enough to generate thunderstorms in the afternoon with a few becoming strong. Majority of the stronger convection should stay south across the Carolinas where a mid level disturbance is forecast to track. Tuesday night this surface trough will slide south with little to no overnight convection. The passing of the surface trough Tuesday will mainly bring a wind shift. Outside of a shower, temperatures should warm into the upper 70s to mid 80s. A weak cold front will bring another day of scattered convection to the area Wednesday. This front will have better jet dynamics than Tuesday`s trough. However, low level winds will primarily be out of the west and possibly strong enough to disrupt organized convection in the afternoon. Still can not rule out some strong to severe thunderstorms during the late afternoon and into the evening. Depending on the timing of the front and associated showers, temperatures will range in the 70s west of the Blue Ridge and low to mid 80s east. The upper level trough will begin to lose its influence on the region Thursday. Surface high pressure and zonal flow will keep the region dry. Temperatures will warm to near normal with mid 70s west and lower 80s east. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... As of 1111 AM EDT Sunday... Heavily used a blend of guidance for this forecast period. Clearing of the front Wednesday night with increasing subsidence follows for overnight into Thursday. Thursday appears to be the next day with fully dry and mostly sunny conditions for the forecast area along with seasonable temperatures. Unfortunately, it appears that is short-lived, as a trough digs into the southwestern CONUS and sends weak vorticity maxima pivoting eastward across the central Plains, Ohio/TN valleys and into the Appalachians. Difficult to time any specific disturbances at this range but it does appear we return to a more unsettled weather pattern for late week into the weekend. Temperatures start out near normal, then begin to trend near to slightly above along with rising dewpoints heading into the weekend. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... As of 735 AM EDT Monday... Warm front has moved northeast and surface winds in the piedmont of Virginia and North Carolina were light out of the southwest. The west edge of the LIFR/IFR stratus and fog was near KFVX. MVFR clouds were along the west slopes of the Appalachians. Isolated showers are expected in southeast West Virginia this morning. Visibilities will remain VFR. Medium confidence that ceilings at KBLF will improve to VFR by 14Z/10AM. A cold front moves into the area from the northwest this afternoon. Winds will back to the southwest ahead of the front, bringing increasing moisture and a chance of showers and thunderstorms into northern North Carolina and extreme southern Virginia. 00Z NAM had the northern edge of the precipitation as far north as KROA and KLYH but many of the other models held a bulk of the precipitation chance in North Carolina. Scattered thunderstorms may approach KDAN around 00Z but low confidence of occurrence so kept it out of the TAF. Extended Aviation Discussion... Mainly VFR through the week except for early morning river valley fog. There is the potential for scattered afternoon and evening storms Wednesday, Friday and the weekend. Tuesday and Thursday are expected to be dry. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/WP NEAR TERM...AMS/WP SHORT TERM...RCS LONG TERM...AL AVIATION...AMS/PM

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