Severe Thunderstorm Warning 1, NWS Blacksburg, VA

Area Forecast Discussion
National Weather Service Blacksburg VA
241 PM EST Thu Jan 12 2023

.SYNOPSIS...
A strong cold front sweeps through the region tonight with
shower and storm this evening. In its wake, colder air, brisk
winds and accumulating mountain snow showers are expected into
Saturday morning. High pressure returns to Saturday afternoon
into early Monday, before the next cold front brings rain on
Monday night into Tuesday morning.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 230 PM EST Thursday...

A dynamic upper level storm system across southwest TN early
this afternoon with strong UVM on the left front upper level jet
nosing into N GA/TN has spawned showers and thunderstorms in
this region approaching our area.

While instability values are weaker in our region, increasing
bulk shear will allow locally damaging winds to occur with this
line that is expected to exit our area between 02-04Z. A narrow
ribbon of 100+ j/kg CAPE pushes into the NC Piedmont and VA
Southside this evening, so kept isolated chances of thunder in
place for this area.

With the slower movement of this2 system, increased low
temperatures in the eastern portion of the forecast area.

After the departure of this system, a northern stream shortwave
across MN dives southeast into the southeast U.S. by Friday
evening. This will enhance the ongoing upslope snow, and expect
heaviest snow rates to occur late in the near term period. Snow
fall totals changed little from the previous forecast, with a
slight uptick in amounts in western Greenbrier county which is
close to warning criteria, but the winter weather advisory will
remain without any changes.

Strong northwest winds tomorrow will create blowing snow in the
higher elevations, but expect winds (based on forecast
soundings) to remain just below advisory criteria.
&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 105 PM EST Thursday...

Models are showing a closed low over the Carolinas and Virginia
Friday night. This system will generate a surface low off their
respective coasts. A pressure gradient between this surface low
and incoming high pressure will tighten over the mountains
Friday night into Sunday morning. Breezy and gusty conditions
can be expected through the period and moreso along the Blue
Ridge Friday night into Saturday evening when pressure rises and
a cross-barrier jet is at their peak.

Northwest flow with a trajectory from the Great Lakes will keep
western upslope snow showers and mountain flurries ongoing into
Saturday morning. High pressure moving into the Ohio Valley will cut
off moisture feed by the afternoon. Additional snow accumulations of
two inches is possible in western Greenbrier and an inch in the
northwestern North Carolina mountains.

Temperatures will run 5F to 10F cooler than normal Saturday. On
Sunday, temperature rebound quickly with highs at or slightly warmer
than normal.
&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 114 PM EST Thursday...

High pressure will keep the region dry Sunday into Monday. A cold
front will bring rain into the area Monday night, then exit Tuesday
morning with a frontal passage. Cool high pressure will slowly build
into the area Wednesday. By Thursday, this surface high drifts off
the coast creating an insitu wedge over the area. An approaching
cold front will then send moisture over this wedge on Thursday.
Areas outside of the wedge will likely see light rain showers while
areas inside most likely will have light rain, drizzle and/or fog.

Temperatures will continue to run warmer than normal during this
period.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
As of 1235 PM EST Thursday...

At Midday, MVFR ceilings were noted across much of northern NC
and the Virginia Piedmont and expect MVFR conditions, with the
potential for IFR ceilings at KLYH and KDAN through this evening
until a cold front sweeps through this region tonight.
Confidence is lower that these MVFR conditions reach KROA.

A band of showers with gusty winds will impact KBLF 21-00Z,
LWB/BCB 22Z-01Z, KROA 22Z-02Z and KDAN/KLYH 23Z-03Z. During this
time, winds could gust over 30 knots with temporary MVFR/IFR
cigs.

After midnight, winds will shift to the west/northwest and gust
to 15-25 knots with higher gusts expected during the day on
Friday.

While precipitation will end for most sites by 06z, lingering
snow showers will keep MVFR cigs and vsbys at KBLF through the
TAF period. Gradual clearing is expected at all other TAF sites
on Friday.

Average confidence for ceiling, visibility, wind and timing of
precipitation.

EXTENDED OUTLOOK...

Gusty winds and upslope snow showers continue Friday
night/Saturday morning with sub-VFR in the mountains. Snow
showers should end by midday Saturday but may take til late
Saturday afternoon for ceilings to scatter out/improver over
BLF/LWB.

A building upper ridge will provide for VFR conditions Saturday
night into Sunday. Although, there could be pockets of late
night/early morning river and valley fog. Monday looks dry and
VFR, but moisture and showers arrive Monday night into Tuesday.

&&

.EQUIPMENT...
As of 1210 PM EST Saturday...

A communication hardware outage at the Lewisburg, WV airport,
KLWB, will prevent automated observation from being distributed
between 7PM and 9AM every night. The restoration time is
unknown.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Winter Weather Advisory from 4 AM Friday to 7 AM EST Saturday
     for VAZ007-009-015.
NC...Winter Weather Advisory from 4 AM Friday to 7 AM EST Saturday
     for NCZ001-018.
WV...Winter Weather Advisory from 4 AM Friday to 7 AM EST Saturday
     for WVZ042-043-508.

&&

SYNOPSIS...RCS
NEAR TERM...PH
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...PH
EQUIPMENT...RCS

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