Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 250601 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 201 AM EDT Sun Jun 25 2017 .SYNOPSIS... A cold front will drop southeast of the region overnight allowing drier air to filter in through Sunday. Other than a quick moving disturbance passing through the region on Tuesday, the bulk of the upcoming week will be controlled by dry, cooler high pressure. Showers, storms, and warmer conditions return to the forecast Friday into the upcoming weekend. && .NEAR TERM /THROUGH TODAY/... As of 900 PM EDT Saturday... MSAS showing drier air gradually working southeast across the area this evening with somewhat lower dewpoints now out to the Blue Ridge. However still have to wait for one final wave across southern sections to pass before getting into overall better dry advection overnight. Given weak flow, will take some time to push low level moisture out of the southeast sections where tropical dewpoints in the 70s persist. This could still lead to an isolated shower or two as the dewpoint boundary approaches so keeping in a mention far southeast another hour or two. Also bumped up lows a little across the piedmont where guidance only shows a slow drop in dewpoints after midnight with lows mid/upper 60s. Otherwise should see skies clear overnight given drying/subsidence behind the front/wave with only some patchy dense fog in spots along with perhaps areas of stratus far west. Lows should be quite comfortable by morning over the mountains with widespread 50s likely, while staying in the 60-65 range along and just east of the Blue Ridge. Previous discussion as of 315 PM EDT Saturday... A cold front was situated just south of the NC/VA border this afternoon. Daytime heating along the feature has triggered some scattered showers and storms. These are expected to continue into early this evening through approximately sunset before dissipating. The front will progress southeast through the overnight hours as drier higher pressure works its way into the region. Skies will initially trend mostly clear to clear once the precipitation ends. However, later tonight, residual low level moisture, and weak upslope conditions in the west are expected to prompt the formation of some stratus across portions of southeast West Virginia and neighboring counties of southwest Virginia. This moisture will be shallow, expect the layer to dissipate not long after sunrise Sunday as the boundary layer mixes. Skies will be mostly sunny by mid-day with at most high level cirrus clouds dimming the sunshine from time to time. Temperatures will start trending cooler. Anticipate lows tonight in the mid to upper 50s across the mountains and the low to mid 60s across the Piedmont. On Sunday, high temperatures will range from the low to mid 70s across the mountains to the low to mid 80s across the Piedmont. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... As of 310 PM EDT Saturday... Trough in place and should be noticeably less humid. Appears shortwave diving across the central Appalachians/mid Atlantic late Monday night into Tuesday will have enough lift/moisture to bring a few showers to the area, mainly along/west of the Blue Ridge. Still not a widespread big event. Lows Sunday night-Tuesday night will run about 10 to 15 degrees cooler than normal over most of the area, ranging from the mid 40s to around 50 west, to lower to mid 50s across foothills/piedmont. Highs Monday and Tuesday will be 5 to 15 degrees below normal, cooler in the mountains, ranging from mid 60s to around 70, with mid to upper 70s east. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 230 PM EDT Saturday... Trough lifts out midweek with height building across the southern U.S. Surface high will slide east of the region Wednesday night. Digging trough over the upper midwest to start to build a little more of heat ridge in the southeast with 591 heights. Will stay mainly dry but heating up with threat of typical summertime convection as early as Thursday over the WV mountains, with better threat Friday-Saturday. Southwest flow aloft increases by Saturday with a frontal boundary slowly moving toward the Ohio Valley. Should see an uptick in coverage in the mountains over the weekend in convection. After highs in the 60s/70s Tuesday will see it a little warmer Wednesday with mid 70s west to lower 80s east. Dewpoints will still be in the 50s, with some 40s mountains but Thursday will see moisture increase with highs bumping up another 5 degrees with upper 70s/lower 80s west, mid to upper 80s east. These warmer temperatures which are close to normal for the end of June will stick around into July 1st, but the humidity will be more noticable as well. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... As of 155 AM EDT Sunday... Moving into an extended period of mostly VFR conditions across the region over the next few days. The weak front has pushed southeast of the area down toward the I-40 corridor taking the showers and thunderstorms with it. Flow aloft is still broad west-northwest under the influence of a broad upper trough deepening across the Great Lakes. This will continue until Tuesday when a short wave rounds the base of the upper trough and following its passage, the flow begins to relax, become more zonal and eventually southwest as the trough weakens and lifts out. The only potential through the period for any non-VFR conditions would be during the late night/early morning hours when any spots that decouple and radiate effectively will see fog development. Given the moist ground from recent rainfall and the cooler/drier air mass moving into the region for the first half of the week, this seems like a reasonable possibility at sites such as KLWB AND KBCB. Not overly confident about such tonight because air mass has not fully transitioned yet and there are some high clouds skirting the area. Have advertised MVFR-IFR conditions briefly in fog at these two sites in the 09Z-13Z time frame, otherwise will monitor. Potential would seem less Monday morning due to drier air. Winds will be WNW-NW at speeds of 3-6kts before 13Z, then increasing to 6-11kts with low end gusts at most locations during the 14Z-22Z time frame, diminishing or becoming calm after 00Z. Medium to high confidence in ceilings through the TAF valid period. Medium to high confidence in visibilities through the TAF valid period. Medium to high confidence in wind speed/direction through the TAF valid period. Extended Aviation Discussion... A weak disturbance dropping in from the northwest may bring a period of MVFR cigs along with a few showers to the mountains late Monday night into Tuesday. Otherwise expecting overall VFR for Monday through Thursday with some brief late night/early morning mountain and river valley fog possible. On Friday, the potential will increase for some brief, localized sub-VFR conditions as showers and thunderstorm chances increase. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...DS/JH NEAR TERM...DS/JH SHORT TERM...WP LONG TERM...WP AVIATION...DS/JH/RAB is the U.S. government's official web portal to all federal, state and local government web resources and services.