Area Forecast Discussion
Issued by NWS Blacksburg, VA

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179 FXUS61 KRNK 241733 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 133 PM EDT Wed Aug 24 2016 .SYNOPSIS... High pressure over the mid Atlantic slowly shifts east into Thursday. The upper ridge will remain overhead through the end of the workweek. && .NEAR TERM /THROUGH TONIGHT/... As of 1030 AM EDT Wednesday... High pressure will slowly move east through tonight. Mid and high clouds associated with a weak wave aloft will spread east across the region through midday. Moisture will increase this afternoon with flow from the southwest at 8h. The combination of low level convergence, solar heating and orographic lift may produce an isolated shower or thunderstorm this afternoon across the western mountains. The best chances will occur across the southwest mountains. High temperatures this afternoon will range from the mid 70s in the mountains to the mid 80s in the Piedmont. Decreased pops for the tonight and added mention of patchy valley fog overnight under clear to partly cloudy skies. Low temperatures will vary from the around 60 degrees in the west to the mid 60s in the east. && .SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/... As of 400 AM EDT Wednesday... The underlying theme through the period will be a strong subtropical ridge anchored over the region. However, a weak front will drift into the region Thursday and drift very slowly south into the Carolinas over the weekend. Moisture and warmth will definitely be on the increase under the upper high. With the front lingering through the region, there will be some focus for increased convection, although dynamics aloft are weak at the very best. Convection that develops will be largely a result of differential heating, but will tend to focus either near the frontal boundary or across the mountains. For Thursday, this should be mainly west of the Blue Ridge, with the focus drifting further south/southeast with time into Friday and Saturday. Given the pattern and very weak forcing, cannot support more than 20-30% pops at this time, with areas east of the Blue Ridge overall seeing the least likely chance for showers and thunderstorms. Thunderstorms should be non- severe, quite spotty in nature, and limited in duration. With respect to temperatures, 850mb temps will continue to hover in the +15C range for Thursday, but jump into the +20C to +21C range for the remainder of the period. This will result in surface temps reaching the lower 90s again across the Piedmont and well into the 80s west of the Blue Ridge Friday and Saturday. These readings are well above normal. && .LONG TERM /SUNDAY THROUGH TUESDAY/... As of 430 AM EDT Wednesday... Will certainly need to keep an eye on the tropics as we head into next week with the Atlantic Basin/Gulf becoming quite active as several disturbances in the ITCZ drift west from African across the tropical Atlantic and into the Caribbean and Gulf. Models are at considerable odds with respect to tracks and intensity and with yet no consistency from run-to-run, so have not introduced any indication of tropical weather in this period at this time. However, several models suggest that eventually one or more tropical systems will drift into or develop in the western Atlantic or the Gulf of Mexico. At any rate, it would appear that if a tropical system were to impact the RNK CWA, it would be beyond this period anyway. For much of the period strong high pressure aloft is progged to remain over the region. Another weak cold front will drift into the region from the north late in the weekend, with the original front washing out across the Carolinas. The proximity of the fronts and strong insolation along with abundant low-level moisture will continue to support widely scattered diurnal convection, either focused near the frontal boundary or across the mountains. Really no significant change in sensible weather during this period with temperatures well above normal, especially low temperatures. Expect minimum temperatures to average 10-15 degrees above normal with maximum temperatures about 5-7 degrees above normal. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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As of 130 PM EDT Wednesday... VFR conditions will prevail through most of the TAF valid period as high pressure drifts slowly east across the region and high pressure aloft builds over the area. The only exception will be patchy early morning fog, which so far has only really been an issue at KLWB, but could occur at BCB/LYH as low level airmass moistens back up. Any fog will be gone between 12-14z Thursday. Any showers this afternoon are expected to stay over the NC mountains and foothills. 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. Monday high pressure bubbles in but still a very humid airmass to keep isolated storms around in the afternoon, but mainly VFR.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK/WP NEAR TERM...KK/WP SHORT TERM...RAB LONG TERM...DS/RAB AVIATION...RAB/WP is the U.S. government's official web portal to all federal, state and local government web resources and services.