Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 092002

Area Forecast Discussion
National Weather Service Blacksburg VA
302 PM EST Fri Dec 9 2016

High pressure will build across the Mid-Atlantic region tonight
through Saturday. The associated cold airmass will remain over the
area through early Sunday before beginning to moderate. A cold front
will approach the area late Sunday night and Monday.


As of 302 PM EST Friday...

In the wake of this morning shortwave, drier air will push in across
the region this afternoon into tonight and taper off light snow
showers and snow flurries across the western mountains.

High pressure over the Midwest will build southeast tonight into
Saturday.  Blustery northwest winds this afternoon will gradually
subside tonight. This in combination with mostly clear skies will
allow for ideal radiational cooling conditions, promoting low
temperatures from the upper single digits for the highest
elevations, such as Mount Rogers to the lower 20s in the Piedmont.

With pressure centered over the Appalachians on Saturday, it will
be cold with high temperatures averaging 10 to 15 below normal with
readings from the mid 20s in the northwest mountains of Greenbrier
county to the lower 40s along the eastern slopes of the southern
Blue Ridge mountains.


As of 300 PM EST Friday...

High pressure over the region Saturday night will push off to our east
and allow significant isentropic lift to develop in the return flow as
a low moves through the Great Lakes region and pushes a cold front in
our direction. The upper flow is low amplitude and progressive will not
add much in the way of dynamic lift, but a plume of moisture surging up
through the piedmont late Sunday/Sunday night may help generate some
showers ahead of the main body of precipitation associated with the
approaching cold front. While temperatures will be steady to rising
Sunday night, temperature profiles support the possibility of some
freezing rain at the higher elevations from western Greenbrier through
the Alleghany Highlands with a light glaze possible before going over
to all rain Monday morning. Winds may also become gusty along the
ridges Sunday night into Monday but the warm air advection pattern will
inhibit downward momentum transfer of higher winds to lower elevations.

The bulk of precipitation will arrive in the west toward daybreak
Monday and move across the region from west to east into Monday
afternoon. Lingering upslope precipitation west of the Ridge will
transition to some wet snow across western Greenbrier with no
accumulation expected.

With the progressive pattern and transitory nature of weather systems
into early next week, expect temperatures to be variable. Readings will
be below normal Sunday followed by a warming trend as the high shifts
to our east and winds become southerly with above normal readings on
Monday. However, temperatures Monday will be falling behind the cold
front as it moves through from west to east.


As of 300 PM EST Friday...

The upper pattern will remain progressive as a large closed low digs
into eastern Canada and keeps the Appalachians and central mid Atlantic
region in essentially zonal flow. So after a brief period of relatively
quiet weather under high pressure on Tuesday, the next weather system
will begin to affect our area very late Tuesday night.

Strong isentropic lift will develop over an in-situ wedge as a complex
low approaches from the southwest. There may be some p-type issues at
the higher elevations with the initial surge of warm air advection late
Tuesday night through the first part of Wednesday. However, a
significant surge of cold air will start moving in during the day
Wednesday behind the departing low and transition precipitation to
snow, especially in upslope areas west of the Blue Ridge. There may
also be some freezing issues as the cold air arrives on blustery winds
and interacts with wet surfaces Wednesday night. Lingering snow showers
west of the Ridge will dissipate as cold high pressure builds in
through the end of the workweek.

Temperatures will generally exhibit a cooling trend for most of next
week with highs on Tuesday well above normal, falling to well below
normal by Thursday.


As of 1242 PM EST Friday...

MVFR SCT to BKN clouds will continue with the northwest
flow into the mountains this afternoon into tonight. This will
continue MVFR ceilings at KLWB and KBLF for this afternoon into
tonight with scattered flurries. The heaviest snow showers will
be tapering off during the next couple of hours.

Cold temperatures will persist through the forecast period,
remaining below freezing west of the Blue Ridge. Winds will
gradually subside over the next 24 hours as high pressure finally
builds overhead for Saturday. High pressure will pass overhead
Saturday promoting light winds and clear skies. VFR conditions
will prevail Saturday into Saturday night.

High confidence in ceilings, visibilities and winds during the
taf period.

Extended aviation discussion...

Next weather system to follow will be a cold front, models
suggesting a Sunday Night arrival which will likely produce sub-
VFR conditions at times, and possibly 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, with possibly more precip Tuesday, a pattern that will
promote sub-VFR conditions attms.




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