Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 221736

Area Forecast Discussion
National Weather Service Blacksburg VA
136 PM EDT Sat Oct 22 2016

Low Pressure over New England will move north into eastern Canada
today, while dry high pressure works its way across the
southeastern United States and into the Mid Atlantic region. A
fast moving clipper sort of front will move east through the upper
Midwest on Sunday, passing through our region late Sunday night
or early Monday as a dry cold front. High pressure will then
build southeast from the upper midwest and across the Ohio Valley
and Mid-Atlantic states from Monday through Wednesday. Little or
no precipitation is expected today and No precipitation is
expected from Sunday through Wednesday.


As of 1225 PM EDT Saturday...

Wind Advisory over the southern Blue Ridge has expired. 12Z
soundings from RNK and GSO this morning showed winds through the
lowest 8000 feet up to 35KTS. Strongest gusts once mixing started
this morning were in the 30 to 40 mph range. Do not expect
anything higher than this for the rest of the day.

Models maintain some low level cloudiness across the mountains impacting
areas primarily west of the Blue Ridge. Have increased coverage
and duration of cloud cover over the mountains. Short term models
hold clouds in well into the evening. With the little if any
heating, lowered maximum temperatures, mainly west of the Blue

Favorable conditions for potential frost will occur tonight for
areas west of the Appalachian divide. High pressure will move from
the mid MS valley and become centered over the Tennessee Valley
tonight. This will result in near calm winds for the Tennessee
Valley which includes Smyth and Tazewell counties and areas to the
southwest toward Bristol. A near calm wind and clear sky will
allow temperatures to dip into the lower to mid 30s for these
areas supporting frost.

East of the Appalachian divide, temperatures will also fall into
the 30s to lower 40s, but turbulent mixing from the wind will be
unfavorable for widespread frost. Certainly can`t rule out some
patchy frost in the sheltered valleys, but not enough coverage
forecast at-time to warrant an advisory. If future forecast models
indicate less wind, then we may need to extend the advisories
farther to the north and east.


As of 230 AM EDT Saturday...

During this portion of the forecast, an upper low will continue to
make slow progression eastward through southeast Canada. A surface
high pressure will build over the southeast U.S., while an upper
ridge strengthens across the central U.S. The resultant synoptic
pattern across our region will be one of zonal to northwest flow.
Within this flow, and shortwave trough is expected to cross over, or
just north of the region, Sunday night into Monday.

For the vast majority of the region, and for the vast majority of
this portion of the forecast, no precipitation is expected. There
may be some isolated showers across parts of southeast West Virginia
late Sunday night into early Monday morning in association with the
shortwave trough.

Temperatures will trend milder through Monday, then decline again
Monday night into Tuesday in the wake of the shortwave trough and
its associated weak cold front. High pressure will again build into
the region by Monday night into Tuesday. Temperatures will likely dip
into the mid 30s across a generous potion of southeast West Virginia
and neighboring counties of southwest Virginia. Patchy frost is
probable given the expected light winds and limited cloud cover.

While winds are expected to be weaker on Sunday as compared to those
of yesterday and today, speeds and gusts ramp up once again with the
passage of the shortwave trough Sunday night into Monday. Another
case of gusts approaching wind advisory criteria is likely at the
highest elevations.


As of 330 PM EDT Friday...

High pressure will move in from the upper midwest and bring fair
weather with slightly below normal temperatures to the region for
Tuesday and Wednesday. The high will then take up a wedge position east
of the Appalachians as a vigorous short wave amplifies and drops out of
the upper midwest. This looks to bring a chance of precipitation back
to our forecast for Thursday with some additional upslope precipitation
west of the Blue Ridge lingering into Friday.

Temperatures will generally be near seasonal norms through the


As of 135 PM EDT Saturday...

MVFR ceilings will continue in the mountains for the rest of the
day with ceilings gradually lifting and then becoming scattered.
Isolated light showers may occasionally bring ceilings down to
2500 feet at KLWB this afternoon. Based on short term models,
medium confidence that clouds will clear out of KBLF and KLWB by
03Z/11PM. VFR conditions are expected east of the Blue Ridge.

Pressure gradient will continue to result in gusty northwest winds
today with surface gusts of 15-30 kts. Winds will subside

Extended aviation discussion...

Sunday through Monday...Widespread VFR. No flight restrictions.
High pressure building in over the Tennessee Valley then southeast
United States will result in lighter wind speeds.

Tuesday and Wednesday...Potential for river valley fog in the
mountain valleys with local vsby restrictions between 08-14Z each
morning, otherwise widespread VFR.


VA...Frost Advisory from 2 AM to 9 AM EDT Sunday for VAZ007-009.


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