Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 271124 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 724 AM EDT Wed Jul 27 2016 .SYNOPSIS... A wavy front will be nearly stationary from the Mid Atlantic region to the mid Mississippi Valley through the end of the week. Weak impulses tracking along the front will combine with deep moisture to produce periodic rounds of showers and thunderstorms. The front will finally move well south of the area on Tuesday or Wednesday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 720 AM EDT Wednesday... Much of the mid and high level clouds have moves east out of the forecast area this morning. Areas of fog have developed in locations that had rain Tuesday afternoon and evening. Thunderstorms were developing along the Kentucky/Tennessee border at 5AM. Some of the short term models, including the HRRR and HiResnmm and HiResarw, bring this precipitation into the southwest county warning area before 7AM. Models showed axis of lift and moisture from southern Indiana to northern Virginia today. Expect showers and thunderstorms to develop along this corridor this afternoon. Location and coverage of showers and thunderstorms south of this axis is less well defined. Have the highest probability of precipitation across the north today. Will have enough sun this morning to push most locations back into the 80s in the mountains and the 90s east of the Blue Ridge by this afternoon. Guidance was too cool with maximum temperatures on Tuesday so have gone closer to persistence. Precipitable water values range from 1.8 inches in the western county warning area to 2.0 inches in the extreme east. Storm motion will be southeast about 20 knots. Areas that had heavy rain on Tuesday will be more susceptible to flooding problems if there are storms again in the same locations today.
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&& .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... As of 400 AM EDT Wednesday... We are in for a continuation of unsettled weather as a shallow upper trof becomes established over the eastern part of the country through the weekend. This will allow a steady stream of short wave energy to move into the region from the southwest, while the upper jet provides diffluence to aid synoptic ascent. These factors will be combining with warm/humid/unstable air along a diffuse old frontal boundary lingering across the region. This all spells a good chance for showers and thunderstorms for the latter portion of the week and into the weekend. The variability among guidance solutions is still creating a good degree of uncertainty in timing/location, but the general consensus is for increasing shear to bring a severe threat to the area for Thursday afternoon into Friday, with a possibility for an organized MCS. High precipitable water values will also make excessive rainfall a threat, so hydro issues are a concern during this period as well. There is still much to be determined with this scenario so it warrants close attention in later model runs. Coverage of showers/storms looks considerable again for Saturday but with less shear and dynamic support so a more limited severe threat. Temperatures will continue to run a bit above normal with highs going from the mid 90s to lower 90s east of the Blue Ridge, and generally low/mid 80s to the west. && .LONG TERM /SUNDAY THROUGH TUESDAY/... As of 130 PM EDT Tuesday... Overall pattern situation favors storminess every day but especially in the afternoon/evening. A frontal boundary situated from the Ohio Valley over to the Central Plains will slowly shift southeast into the Virginias and North Carolina over the weekend. Airmass will remain unstable and moist. Some issue with how far this front makes it as 5h ridge may be hard to break, but still looks like belt of westerlies will shift at least into our northern forecast area over the weekend. Highs will be seasonal with lows slightly above normal through most of the period. Highs will range from the lower to mid 80s mountains, to upper 80s to around 90 east. Lows will be in the lower to mid 60s mountains, to upper 60s to around 70 east. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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As of 140 AM EDT Wednesday... Locations that had rain Tuesday afternoon and evening have MVFR to LIFR fog this morning.LIFR visibilities at KLWB will improve to VFR by 14Z/10AM. Threat for storms again this afternoon but for now will keep it VCTS. 00Z models were showing the mountains as the preferred location for storm development. Showers and thunderstorms will also develop along a wavy stationary front from the mid Mississippi Valley into the Mid Atlantic region. KLWB is close enough to this axis to have thunderstorms this afternoon. Extended aviation discussion... The upper ridge will remain just south of the area and a residual front nearby through Sunday. This should allow for periodic daily convective coverage until the boundary either fades or sinks farther south. Appears more widespread sub-VFR possible with thunderstorms later Thursday with a stronger wave along the front with perhaps some decrease in coverage by the weekend as this feature passes. At least diurnal MVFR/IFR possible each afternoon/evening through Sunday for now. Late night and early morning fog will likely occur at the usual valley locations, and those chances increase across the entire region if any rain occurs during the afternoon or evening at any site.
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&& .CLIMATE... Record high temperatures for Wednesday (7/27) Roanoke.....103 in 1936 Lynchburg...103 in 1936 Danville....102 in 1952 Blacksburg...94 in 1993 Bluefield....89 in 1966 Record highs for July 28 Roanoke......104 in 1930 Lynchburg....103 in 1936 Danville.....102 in 1952 Blacksburg....95 in 1966 Bluefield.....90 in 2011 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...MBS LONG TERM...WP AVIATION...AMS/WP CLIMATE...PM is the U.S. government's official web portal to all federal, state and local government web resources and services.