Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 220027 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 827 PM EDT Sun Aug 21 2016 .SYNOPSIS... A cold front will move east of the region this evening. Cooler and drier high pressure will enter our forecast picture tomorrow, and be the controlling influence on our weather pattern through at least mid-week. The next decent chance of precipitation, for at least areas west of the Blue Ridge, will be Friday when a cold front moves into the area. && .NEAR TERM /THROUGH MONDAY/...
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As of 825 PM EDT Sunday... Transition is underway from a maritime airmass to a dry continental airmass. Surface cold front has now cleared the forecast area and we should now see dewpoints clicking downward with every passing hour. A large area of high pressure was centered over the central US. This feature will gradually build east over the next few days promoting dry weather and cloud free skies. Aside for some lingering cloudiness in the mountains tonight (and potential for river valley fog), overall trend will be for clearing with sunny skies anticipated across the entire CWA on Monday. With the arrival of the lower dew point airmass, overnight low temperatures will begin to dip considerably lower than what we have experienced over the last month. Tonight will be 5 to 10 degrees cooler than last night with some of the coolest readings in over a month anticipated for Monday night into Tuesday morning when lows dip into the 50s areawide. Daytime temperatures will still climb to within 5 degrees of normal, with highs in the 70s mountains to the 80s piedmont, but with the dry airmass it should feel much more pleasant than the maritime mugginess. Time to open up the windows and turn off the AC for a few days.
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&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 300 PM EDT Sunday... A large area of dry high pressure will drift slowly from west to east across the region during this period. PWATS will drop below 1 inch through the period and 850mb temps will drop back to near or just below +15C. The cold front of today will stall well to our south for a change, likely across north GA into central SC. Broad weak high pressure will dominate the pattern aloft. Will not advertise any showers/thunderstorms Monday or Tuesday with zero pops...quite a change from most of the past three months. By Wednesday, the surface high drifts far enough to the east to allow some return moisture into the southwestern mountains, especially northwest NC. This, combined with strong insolation and the resultant differential heating, may allow for isolated showers/thunderstorms to creep into the Watauga/Wilkes county area late in the day, enough to warrant a 15% pop in those areas. The most notable change through the period, other than the absence of the incessant diurnal shower/thunderstorm activity of recent weeks, will be the much lower dewpoints/relative humidity values. This will in turn allow nights to finally cool back to more normal values in the 50s mountains to lower and mid 60s Piedmont. Daytime high will be closer to normal, but creep to just above normal by Wednesday. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 300 PM EDT Sunday... Expect a return to more typical and more familiar summerlike conditions through the period. Surface high pressure will continue to drift east allowing a steady stream of increasingly warm/moist Gulf air to advect northeast into the region. Although high pressure aloft with heights hovering near 594dm will be common through the period, a weak trough in the westerlies will skirt by to our north Thu-Fri. This will drag a weak front into the region late Thu which will enhance the chance for showers/thunderstorms. Expect the activity to be more concentrated across the mountains aided by differential heating, but some will drift into the Piedmont by Thursday evening. Instability looks more than sufficient for thunder, but dynamics are weak at best. Have capped pops at the 30- 40 percent level for now, but later forecasts may be able to refine areas that will see slightly higher pops, most likely Greenbrier down toward Tazewell/Bland. The remnants of the front will drift into North Carolina by Friday afternoon and wash out. Isolated to scattered showers/thunderstorms still possible as a result, with the best emphasis across the northwest NC mountains at this point. With high pressure aloft through the period, not much temperature change expected. In fact, 850mb temps are progged by most long range models to return into the +20C range or better, especially across the lower elevation areas. Thus we will likely see a return of at least lower 90s east of the Blue Ridge by Friday and Saturday. Minimum temps will also be on the increase again and trend toward well above normal by the end of the week with dewpoints creeping well back into the 60s. The warm, above normal temperature trend also occurred about this time last year when many Piedmont sites saw several consecutive days in the lower to mid 90s. Looking into the future regarding the tropics, the long range models have multiple variable solutions regarding the tropics. At least through the end of August, it appears the RNK CWA will not be impacted by any tropical systems as high pressure aloft dominates the region over the next 7-10 days. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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As of 800 PM EDT Sunday... A cold front has passed through the central appalachians. As such expect clearing skies and a taste of shower free weather for at least the next 3 days. Aside for some MVFR upslope cloudiness along the western slopes of the Appalachians tonight, widespread VFR will prevail. As high pressure builds into the forecast area from the Ohio Valley winds will be out of the northwest averaging 5 to 10 kts with a some gusts to 15 to 20 kts vcnty of the ridges. Extended aviation discussion... High pressure will provide for mainly VFR conditions Monday through Wednesday across the region. The exception will be isolated pockets of late night/early morning river and mountain valley fog. Thursday a bit more moisture will work its way north into western parts of the area on the west side of a departing high pressure. Isolated showers 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.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...DS NEAR TERM...PM SHORT TERM...RAB LONG TERM...RAB AVIATION...PM is the U.S. government's official web portal to all federal, state and local government web resources and services.