Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 102053 AFDRNK Area Forecast Discussion National Weather Service Blacksburg VA 353 PM EST Sat Dec 10 2016 .SYNOPSIS... High pressure will bring fair but chilly weather to the region through Sunday. A cold front will then move across the area and bring a good amount of rain to the Appalachians and central mid Atlantic region Sunday night into Monday, with the possibility for some wintry weather early Sunday night mainly from Greenbrier county West Virginia through the Alleghany Highlands. A series of weak disturbances will then skirt the region through midweek with low precipitation chances through Wednesday. && .NEAR TERM /THROUGH SUNDAY/... As of 330 PM EST Saturday... Visible satellite imagery shows that shallow upslope clouds earlier this morning have mixed out, leaving skies generally clear with a few streaks of cirrus. However as warm air advection develops mid/high clouds will stream from the northwest overnight with a good amount of cloudiness from about the Route 460 corridor northward. The potential cloud cover will make for a tough temperature forecast as conditions are good for radiational cooling with a cold airmass still in place. Believe temperatures will fall at a good clip early before clouds become thick/solid enough to significantly inhibit cooling. Will go with a low temperature forecast that is on the cool side of guidance but a bit warmer than readings we saw this morning. Expect readings around 20 east of the Blue Ridge with teens to the west. Sunday looks to feature a good deal of clouds early north and late south, with a mix of sun/clouds in between. Temperatures will be warmer, through still below normal, with highs in the low/mid 40s east to upper 30s/around 40 west. By late in the day moisture will be streaming up east of the Ridge but any chance for precipitation looks to hold off until after dark. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 300 PM EST Saturday... Strong southwest low level jet and warm air advection develop Sunday night ahead of the next cold front. This will raise surface temperatures overnight. Much of the ensemble guidance meteograms have temperatures above freezing across the region by 7AM. So any potential for winter precipitation types will depend on how fast moisture increases and when the air mass will be saturated enough to support precipitation Sunday night. The GFS was slower with the arrival of the precipitation late Sunday and early Monday morning than the NAM. AT this time temperatures support rain for much of the area with the exception of some mix of freezing rain at the onset in Greenbrier and Bath counties. Ice amounts are very light and very isolated. The surface front will cross through the Mid Atlantic states on Monday. Guidance was keeping the highest rainfall amounts in the mountains but still a high probability of precipitation east of the Blue Ridge but with lower amounts. Clouds and precipitation will limit rise in temperatures so have trimmed maxes on Monday. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 300 PM EST Saturday... On Tuesday night and Wednesday a deep arctic upper low moves across eastern Canada, keeping low heights over much of the northeast United States. Thursday, Friday and Saturday the 500MB pattern amplifies with deep troffing over the western half of the United States. Base on WPC guidance including the 00Z Ecmwf, Wednesday is the next time frame for a chance of precipitation. Isentropic lift over a large, cold high will result in a low possibility for winter precipitation, most likely light snow, especially Wednesday night. The next arctic front will approach the region next weekend. There is a potential for a Miller B storm system to develop by that time with a large region of overrunning and mixed winter precipitation across the region sometime between Friday and Saturday night. However, timing has been variable in the models for the past few runs and a big surge of warm air advection will greatly influence precipitation type. && .AVIATION /21Z SATURDAY THROUGH THURSDAY/... As of 145PM EST Friday... Expecting high pressure to bring quiet weather through the TAF period with VFR conditions and light winds. Visible satellite imagery shows that shallow upslope clouds earlier this morning have mixed out, leaving skies generally clear with a few streaks of cirrus at all TAF sites. Overnight, high pressure will slide by to our east and allow warm air advection to begin. The main consequence of this through the TAF period will be a high cig of mid/high clouds streaming in from the northwest overnight. Any significant increase in low level moisture is not expected until after this TAF period late in the day on Sunday. Extended aviation discussion... Some light precipitation and sub-VFR cigs are possible Sunday evening as moisture streams north from the Blue Ridge eastward. Then, a cold front will arrive later Sunday Night which will likely produce sub- VFR conditions at times, and possibly a wintry mix in the mountains. The cold front crosses the area Monday with continued threat of showers and sub- VFR at times, then somewhat of a break Monday night and maybe Tuesday, with another system arriving midweek with more precip, and more than likely sub-VFR at times. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...MBS NEAR TERM...MBS SHORT TERM...AMS LONG TERM...AMS AVIATION...JH/MBS

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