Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 270757

Area Forecast Discussion
National Weather Service Blacksburg VA
257 AM EST Thu Feb 27 2020

Strong northwest winds will ease up by Thursday night as deep
low pressure moves into Quebec and Maine. A clipper system
arrives Friday with a reinforcing shot of cold air. High
pressure builds in for the weekend.


As of 155 AM EST Thursday...

Snow showers this morning as a secondary shortwave pushes across
will start to wane after this occurs after 12z, but west-northwest
flow and trajectories off Lake Michigan may keep snow showers around
off and on across the western slopes of Greenbrier County through
this evening, though additional accumulations are expected to 2
inches or less after 7am. Will let the winter weather advisories run
as is given morning commute being impacted by sub-freezing
temps/wind and scattered to numerous snow showers.

As for the wind headlines, the area will see a secondary surge as
the next shortwave passes around 12z today, but best energy with the
low level jet passes across the Alleghanys and pressure rises are not
that impressive. Will not change the high wind warning in NC
although gusts over 58 mph are not expected except possibly gaps
between peaks like Blowing Rock and Mount Jefferson.

Winds will start to subside to a more typical late winter scenario
late this afternoon, then drop even more overnight.

Should see skies clear out this morning east of the mountains,
though wind and strong cold advection will make it feel like
January, where Wednesday felt like mid-March. By afternoon sunshine
expected everywhere except lingering low clouds west of Lewisburg,
WV. Highs will range from the upper 20s to lower 30s across much of
the mountains, to upper 30s to mid 40s across the foothills/piedmont.

A fast moving clipper system makes inroads toward the central
Appalachians late tonight, with shortwave energy sliding across the
southern Appalachians. Model solutions delay snow showers increasing
til after this period though could see an uptick in isolated to
scattered snow showers pre-dawn Friday across the southeast WV
mountains and as far south as the NC mountains, though pops will be
left at 20-30 at best.

Expect increasing clouds late tonight with jet cirrus increasing
over the Blue Ridge and east. Temperatures tonight will be closer to
normal, ranging from the lower to mid 20s across the mountains, to
upper 20s across the east, though cloud cover thickness may act to
cause temps to steady out late.

Forecast confidence this period is high.


As of 230 AM Thursday...

On Friday an area of upper level low pressure will still be making
slow progress eastward across southeast Canada. Cyclonic flow around
this system will help to continue ushering weaker shortwave troughs
into the region from points northwest of the area. On such feature
is expected to cross the region Friday morning, followed closely by
another Friday night. While the region will still be under the
influence of an upslope flow regime, and the typical cloud cover and
rain/snow shower coverage this pattern entails, the influence of the
upper level dynamics these features contribute will help carry
precipitation farther east, especially by Friday afternoon.

The result will be a mix of rain and snow showers during the day
Friday, with more snow the farther west one is in the forecast area
thanks to the availability of colder temperatures there. By Friday
night into Saturday, only snow showers are forecast, with coverage
across far western sections, and coverage gradually decreasing as
the shortwave troughs shift east of the area, and low level winds
start to back.

An upper level ridge will cross the region on Saturday night into
Sunday, bringing a return of a precipitation-free forecast for the
entire forecast area, and an increase in temperatures.

By Sunday night, the ridge axis is expected to flatten in repsonse to
a shortwave trough heading eastward through the Great Lakes region.
Light precipitation may return to the far western sections of the
area associated with this feature by daybreak Monday.

Temperatures on Friday will be around or slightly below normal. They
will trend colder heading into Saturday with values about five to
ten degrees below normal. The rebound on Sunday will yield
temperatures around or slightly above normal.

Confidence in this portion of the forecast is moderate.


As of 130 PM EST Wednesday...

As high pressure passes off the coast during Monday, a low
pressure system should develop across the central Mississippi
River Valley. Its associated warm front should stretch eastward
to the Appalachian Mountains during Monday afternoon through
Tuesday to bring increasing warm air advection and a chance of
rain showers. The main cold front with this low pressure system
along with the heaviest bulk of moisture will wait until
Wednesday to cross over the Mid Atlantic.


As of 1216 AM EST Thursday...

Strong west to northwest winds will be the main aviation issue
through most of this period, with gusts in the 25 to 40kt range,
highest in the mountains. This will lead to turbulence and
crosswinds for those terminals with north-south runways.

Snow showers/flurries across the mountains early with sub-VFR
ceilings, and at times vsbys will start to wane after 12z, with
VFR expected at all sites by midday, with BLF the last to go VFR
toward 18z. LWB should see a broken ceiling most of the day
Thursday into Thursday evening around 3500-5000 ft.

Winds will start to subside somewhat after 00z/Friday.

Forecast confidence is high for most of this period, though
lower this morning with intermittent snow showers which could
drop vsbys/cigs to IFR or lower at BLF/LWB.

Extended Aviation Discussion...

A clipper system arrives Friday with another round of snow
showers for the mountains with sub-VFR cigs with some sub-VFR
vsbys especially BLF/LWB. These sub-VFR may linger into Saturday
across the west, before high pressure builds in with VFR for
most of the weekend.

The next weather maker will bring a rain threat by early next
week with sub-VFR likely in the mountains.


VA...Wind Advisory until 7 PM EST this evening for VAZ007-009>014-
     High Wind Warning until 7 PM EST this evening for VAZ015.
     Winter Weather Advisory until noon EST today for VAZ007-015.
NC...Wind Advisory until 7 PM EST this evening for NCZ002.
     High Wind Warning until 7 PM EST this evening for NCZ001-018.
     Winter Weather Advisory until noon EST today for NCZ001-018.
WV...Winter Weather Advisory until noon EST today for WVZ042-043-


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