Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 241111 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 711 AM EDT Mon Oct 24 2016 .SYNOPSIS... A dry cold front will slide southeast across the mountains this morning before passing to the south of the area this afternoon. High pressure builds in behind the front later today into Wednesday bringing continued dry and cool weather. Another cold front looks to cross the region on Thursday with the next chance of showers. && .NEAR TERM /THROUGH TONIGHT/... As of 230 AM EDT Monday... Deepening upper trough across the northeast U.S. along with northwest flow aloft will propel a reinforcing cold front through the region by this afternoon. Main concern continues with stronger westerly winds just ahead of the boundary this morning, and perhaps with northwest trajectories for a while behind the front across the north/west with mixing this afternoon. However given the best jet aloft early this morning and weakening subsidence this afternoon as better dynamics pass north, expecting to stay below wind advisory criteria, but quite breezy/windy espcly northern sections. Moisture along the front remains quite limited with mostly upslope aided low clouds that could spill east out to the Blue Ridge this morning before enhanced post frontal drying occurs. Cant totally rule out a light shower/sprinkle far northwest mountains as a shortwave swings by within the upper trough and the better cool advection develops per latest HRRR but quite iffy. Otherwise becoming mainly sunny and still rather mild espcly south/east given lagging cool advection that looks to hang up across the mountains until later this afternoon. Since this in light of good downsloping, bumped up highs a good category or more in spots today with 72-78 east and 61-68 west. Decent surface ridge builds in behind the front from the northwest overnight which should allow any lingering upslope clouds to fade and winds to diminish this evening. However how fast winds decouple and to what degree remains in question given the parent high still back in the Ohio Valley around daybreak. Models do attempt to develop a bit of a bubble high across the mountains where likely to see the deeper valleys espcly northwest sections lose the gradient for a longer period late. Also dewpoints look rather low for much frost so given this combination, cut back frost to more patchy nature in the valleys and without any advisory headlines at this point. Otherwise mostly clear with lows ranging from the mid 30s to lower 40s excluding localized near 30 readings in deepest valleys. && .SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/... As of 215 AM EDT Monday... During the first half of this portion of the forecast, surface high pressure will dominate the weather pattern our our region. Concurrently, a broad upper level ridge will strengthen across the central portion of the United States. A persistent upper low/trough will continue to spin across the Pacific Northwest. By Wednesday night into Thursday, a piece of energy from the low/trough across the Pacific Northwest will eject eastward and push through the top of the upper ridge. By Thursday morning, the low will progress eastward from the Great Lakes region into PA/NY/NJ. Its associated cold front will cross our area during the day. The latest guidance offers a solution with a faster arrival and departure times than previously advertised. As such, have increased the coverage across the western parts of the area late Wednesday night, and adjusted the peak of coverage across the area to the forenoon hours Thursday. By late Thursday night, coverage is expected to be confined to southeast West Virginia within the upslope flow in the wake of the exiting system. Average daily temperatures will trend a little cooler through Wednesday, and then increase slightly Thursday. As a whole, readings will be near normal for this time of year. && .LONG TERM /FRIDAY THROUGH SUNDAY/... As of 300 PM EDT Sunday... An area of weak high pressure builds in behind the front from the northwest on Friday. Models are not in agreement with next weekends weather. The GFS quickly brings the next cold front across the region Saturday. The ECM has high pressure lingering into Friday night, with a warm frontal passage Saturday followed by a cold front on Monday. Temperatures will moderate toward normal on Friday. Next weekends temperatures will depend on timing of each frontal passage. For now, will carry seasonal temperatures. && .AVIATION /12Z MONDAY THROUGH FRIDAY/...
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As of 645 AM EDT Monday... Weak cold front pressing in from the north/northwest should push across the mountains this morning and elsewhere during the afternoon if not sooner. Given dry air in place, still expecting overall VFR to prevail today and tonight. Could continue to see periods of scattered to broken strato-cu near the KLWB-KBLF corridor, along and espcly behind the front as cool advection/upslope kick in through early this afternoon. However expecting most of this canopy to have bases above 3k feet before all moisture mixes out later this afternoon given mixing of very dry air behind the front. Main issue continues with the lingering low level jet early this morning and subsequent wind shear per near calm surface winds in spots to start. Guidance suggests enough weakening of the winds aloft combined with mixing to help alleviate wind shear issues by mid or late morning. Thus will keep LLWS in until mixing occurs along and just behind the front by later this morning. Behind the front winds should gust at times to 20-25kts, then weaken again by the end of the day as high pressure starts to build in from the northwest by tonight. Extended aviation discussion... Tuesday and Wednesday...Potential for river valley fog in the mountain valleys with local vsby restrictions between 08-14Z each morning, otherwise widespread VFR. Thursday...Low pressure is forecast to move across the upper midwest and into the Great lakes with a surface front crossing the Ohio Valley. Threat for showers and sub-VFR will be possible along this front which would impact the central Appalachians by Thursday. Attm, this does not appear that it will have a significant impact to our region. Biggest impact would be from Ohio Valley north into Great Lakes closer to the surface low. High pressure builds in from the northwest Friday, with potential MVFR ceilings at BLF/LWB before the high arrives.
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As of 300 AM EDT Monday... Little or no rain has fallen across the northwest North Carolina Piedmont in the last 14 days. Conditions are becoming increasingly dry for western North Carolina, espcly just east of the Blue Ridge. Drying conditions will continue for this region again today, and for much of the upcoming work week. Passage of a dry cold front by this afternoon may pose control problems for any fires in the lee of the Blue Ridge, and especially for areas which have not seen rainfall. Greatest concern would be from Mount Airy, North Carolina, and areas to the southwest, including Pilot Mountain. Wind gusts of 15 to 25 mph are possible into this afternoon, coupled with humidity minimums in the 25 to 35 percent range which will cause added drying of smaller fuels. Therefore plan to include a headline for now in the fire weather forecast as a heads up for low humidity and gusty winds today.
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&& .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/JH NEAR TERM...JH SHORT TERM...DS LONG TERM...RCS AVIATION...AMS/JH/PM/WP FIRE WEATHER...JH/PM is the U.S. government's official web portal to all federal, state and local government web resources and services.