Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 102324

Area Forecast Discussion
National Weather Service Blacksburg VA
624 PM EST Sat Dec 10 2016

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


As of 610 PM EST Saturday...

Appears forecast on track with increasing mid/high level clouds
arriving around midnight or thereafter. No major changes with this
early evening update.

Previous afternoon discussion...

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.


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

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.


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

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.


As of 615 PM EST Friday...

Area of high pressure overhead will shift east overnight and
offshore Sunday. Will see increasing mid and high clouds late
tonight into Sunday with some lower clouds still VFR starting to
impact the NC/VA border area late Sunday afternoon. So expect
light/calm winds to go to the southeast to south Sunday but stay
around 5-10kts, but could very well get stronger toward the end
of the this taf period in BLF.

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. High pressure arrives Thursday although a northwest flow
with the center of the high over the midwest will keep some
stratocu around in the BLF area possibly MVFR. Winds will also be
gusty and strong Thursday.




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