Area Forecast Discussion
Issued by NWS Blacksburg, VA

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511 FXUS61 KRNK 240537 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 137 AM EDT Wed Aug 24 2016 .SYNOPSIS... High pressure over the mid Atlantic shifts further east into midweek allowing a return of more humid weather by the 2nd half of the week. Outside of some mountain thunderstorms, it will be mainly dry with the upper ridge overhead through Friday. && .NEAR TERM /THROUGH TODAY/... As of 900 PM EDT Tuesday... Another quiet night with high pressure sliding across and dry air aloft in place per evening soundings. However dewpoints have crept up quite a bit since last night making for a bit more humid and warmer overnight. In addition likely to have some mid/high clouds crossing the region from the west through daybreak while spotty strato-cu lingers in spots. Thus may tweak the west toward partly cloudy overnight while keeping the east mainly clear under the center of the surface ridge. With current temps running about 5-8 degrees warmer than this time last night, would expect lows to be mostly in the 60s, similar to current dewpoints, with only the valleys seeing a few 50s by daybreak pending spotty fog coverage. Previous discussion as of 324 PM EDT Tuesday... High pressure is situated over the mid Atlantic but mesoanalysis loop suggesting that moisture is already back on the increase across the Tennessee Valley into the Southern Appalachians. Still influence of drier air aloft per WV will keep it dry over us tonight. Seems the main issue will be if this current sc/cu field dissipates this evening or stratifies as weak subsidence inversion sets up. Will lean toward partly cloudy near and east of the Blue Ridge overnight with mostly clear elsewhere. Fog will be limited to river valleys if at all. Wednesday shows increasing flow from the southwest at 8h with wedge eroding. Models are starting to fire up some convection toward the Southern Appalachians north into WV by the afternoon. Forecast sounding showing some moisture but shallow so will only included slight chance in the west tomorrow. Warmer tonight than this morning but still cooler than several days ago, and actually close to normal for Aug 24th. Lows will range from around 60 in the mountains to lower to mid 60s east. Should see more cumulus develop in the mountains Wednesday with more sunshine east. Highs will be warmer ranging from the upper 70s to lower 80s mountains to mid 80s east. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... As of 330 pm EDT Tuesday... High pressure aloft will start to center over our area Thursday while main belt of westerlies stays across the upper midwest into the Northeast. Showers and storms will be mainly orographically and diurnally driven with coverage scattered in the mountains to little or no coverage east. Friday looks even drier as the center of the high is directly overhead capping much of the region. A few stray showers or storms may fire across the ridges. Temps and dewpoints begin returning to what we had a week ago with highs Thursday in the lower to mid 80s mountains, to upper 80s piedmont, running higher Friday from the mid to upper 80s mountains to mid 90s piedmont. Lows will return back into the mid 60s west to upper 60s to around 70 east. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 130 PM EDT Tuesday... During this portion of the forecast, surface high pressure will remain centered over the Carolinas. The prevailing synoptic flow will trend zonal to slightly northwest. The location of the high places southerly flow across the region, especially across western sections. Also, a number of weak disturbances are forecast to progress into or through the region within the northwest flow aloft. The result will be a pattern that will favor daily chances of showers and storms, especially across the western portions of the area. Most of these will be isolated to scattered in coverage. However, on days when the heating of the day coincides with the passage of one of the weak shortwaves, a brief period of enhance coverage is possible. The coverage will also have a greater potential to progress east of the crest of the Blue Ridge. Low temperatures will be around five to ten degrees above normal during this time frame, with highs around 5 degree above normal. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... As of 136 AM EDT Wednesday... Mid and high clouds associated with a weak wave aloft will spread east across the region this morning. VFR conditions will prevail this morning as high pressure drifts slowly east across the region. The only exception likely to be early morning fog mainly at western TAF sites, especially KLWB and possibly KBCB where MVFR/IFR will be possible around daybreak pending on clouds. Surface high slips east to the Mid-Atlantic coast today with weak southerly flow helping moisture increase in advance of a cold front well to the west. This should allow for a more widespread bkn cumulus/strato-cumulus layer by this afternoon with some lingering mid deck cigs above. Better low level moisture may also lead to widely scattered showers across the far western mountains but too isolated to mention near any western taf site. Otherwise still appears bases, after patchy early morning fog/stratus, should remain VFR today with a possible period of MVFR at KBLF/KLWB late afternoon. Any showers should fade with loss of heating this evening given lack of much support, making for mostly VFR again overnight outside of late night fog/stratus in the valleys. Morning low clouds and fog will lift by late Thursday morning. Medium confidences in ceiling, visibilities and winds during the taf period. Extended aviation discussion... Richer moisture will work its way north Thursday into western parts of the area on the west side of a departing high pressure. Isolated showers and storms will be possible across the mountains, but for the most part, VFR conditions will still prevail. On Friday, there is a greater chance of showers, and possibly some storms, with the approach of our next cold front. Pockets of MVFR conditions will again occur briefly under the stronger showers or storms. The front lingers in the area during the weekend keeping enough moisture for diurnal mountain showers and storms when periods of MVFR could occur. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...WP NEAR TERM...JH/WP SHORT TERM...WP LONG TERM...DS AVIATION...JH/KK is the U.S. government's official web portal to all federal, state and local government web resources and services.