Area Forecast Discussion
Issued by NWS Blacksburg, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KRNK 141424
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
924 AM EST Thu Dec 14 2017

.SYNOPSIS...
A low pressure system sliding by to our north will bring strong
gusty winds to the Appalachians and central mid Atlantic region,
along with upslope snow showers for the higher elevations west
of the Blue Ridge. High pressure will then build over the
eastern part of the country and bring us fair weather with a
warming trend as we head into the weekend. A low pressure system
will then move out of the lower Mississippi valley late in the
weekend and bring a chance of rain to the forecast for Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 920 AM EST Thursday...No significant changes needed to
the going forecast. Wind headlines still remain in effect until
noon from the Blue Ridge west, though in both cases the core of
the strongest winds have since passed. Since it is still quite
breezy, would rather keep the headlines going until expiration
as best pressure rises currently underway and steepening low-
level lapse rates will keep conditions gusty through the
morning. With low-level vertical wind profile weakening with
time, should see gust magnitudes get steadily lower into the
afternoon hrs.

West-northwest flow aloft helping to drag some lake-effect
moisture southeastward and radar is detecting some weak echoes,
so there may still be an opportunity for additional small
accumulations of snow in western Greenbrier County. Near-term
forecast guidance continues to dry this up moving into the
afternoon.

Overall otherwise a variably cloudy day with greatest cloud
cover west of the Blue Ridge and least in the Piedmont. Highs
have already occurred west of the Blue Ridge and will struggle
to reach any higher than present values. In the Piedmont, should
see values ranging from the mid 40s to near 50 with a more
likely chance of diurnal temperature warming trend with less
cloud cover.

Previous discussion issued at 220 AM Thursday...

Clipper type low pressure system will slide by to our north
early this morning. The low level wind field associated with
this system is quite robust and looks like it will peak just
before daybreak, about the time cold air advection becomes
established and helps force higher momentum air from the
hilltops to the lower elevations. This will result in strong
gusty winds primarily at the higher elevations along and west of
the Blue Ridge through early this morning where a wind advisory
is in effect until Noon. A high wind warning is in effect from
the mountains of NC into the Grayson highlands of VA where gusts
to 60 MPH have been common. The wind field will gradually
slacken and the high wind threat will diminish by Noontime.

The brisk wind flow will also result in upslope clouds and snow
showers west of the Ridge. Some of the higher elevations may
pick up a fresh coating of snow with a couple of inches possible
for western Greenbrier county. This will combine with the wind
to create some areas of blowing snow early this morning. Moisture
abates after daybreak with just some lingering flurries late
this morning. Much quieter east of the Ridge with generally
fair and blustery conditions for today. High temperatures today
will generally be in the middle 40s east to low/mid 30s west.

High pressure will settle over the region tonight with quiet
weather expected, though there appears to be enough moisture to
keep some cloudiness around especially west of the Ridge. This
will keep temperatures tonight from reaching their full
potential. Lows tonight will be in the middle 20s east to
teens/lower 20s west, though if cloud cover is less than
expected these temperatures may be adjusted downward.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 245 AM EST Thursday...

Split flow Friday will feature passage of northern/southern
stream energy. These features are forecast to remain out of
phase with deeper moisture remaining to the east Friday with a
surface wave developing offshore, while just ahead of the
northern shortwave trough. Guidance showing lots of mid/high
clouds from Friday but with little precip. Forecast will reflect
spotty upslope snow showers and flurries far northwest sections
Friday night, but only 20ish pop for now given lack of moisture
with this system. MOS is cooler than normal Friday given
progged clouds for much of the day which should hold the
mountains in the 30s and low 40s east.

Fast west/northwest flow to continue behind this system into the
weekend with slowly building heights by Saturday as the 850 mb cold
pool starts to lift out. This warm advection wont deepen enough to
be realized at the surface until Saturday afternoon with
sunshine helping to push highs into the 40s to perhaps around 50
southeast. Some increase in high clouds possible Saturday night
but likely thin enough to still allow lows to reach the 20s to
around 30.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 324 PM EST Wednesday...

Warming trend will continue late in the weekend into early next week
as weak southeast ridging keeps a more zonal trajectory in place
until Wednesday when a passing trough aloft digs back into the
region. However with the warm advection will see moisture return
perhaps by late Sunday but moreso Sunday night into early Monday
with a residual upper low ejecting northeast across the Gulf states.
Appears much of this precip would be light and mostly liquid given
westerly flow and well above freezing 850 mb temps. Models then
diverge on whether or not this feature helps develop a weak low
offshore, aided by yet another shortwave headed out of the
southwest states, or things remain more progressive and drier
into Tuesday. Given somewhat wetter trends will continue chance
pops Sunday afternoon into Monday while leaving in low pops
northwest Monday night/Tuesday for showers ahead of the next
front and over the south per lingering shortwave energy. Drier
and colder air should follow the front for Wednesday as deeper
northwest flow kicks in. Otherwise looking at highs rebounding
to above normal Sunday-Tuesday and well into the 50s east for
early next week.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
As of 530 AM EST Thursday...

Primary weather concern this TAF period will be strong gusty
winds. Clipper type low pressure system will slide by to our
north early this morning. The low level wind field associated
with this system is quite robust and looks like it will peak
just before daybreak, about the time cold air advection becomes
established and helps force higher momentum air from the
hilltops to the lower elevations. This will result in
west/northwest wind gusts of 30KT to 40KT for sites along and
west of the Blue Ridge before winds gradually subside through
early this afternoon.

The brisk wind flow will also result in upslope clouds and snow
showers west of the Ridge with KBLF and KLWB most likely to see
MVFR conditions before moisture abates during the morning.
Conditions east of the Ridge will be downslope and favorable for
VFR conditions. However, a weak low moving up the middle
Atlantic coast may throw enough forcing and moisture back to the
northwest to generate some sub VFR cig toward the end of the TAF
period.

Extended Discussion...

Other than an outside shot of MVFR/VFR ceilings and possible
upslope snow showers at Bluefield Friday night, VFR conditions
should prevail until Sunday night. A better shot exists for sub-
VFR conditions from a system system forecast to emanate from
the mid-Mississippi Valley Sunday night into Monday.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Wind Advisory until noon EST today for VAZ007-009>014-016>020-
     022>024.
     High Wind Warning until noon EST today for VAZ015.
NC...High Wind Warning until noon EST today for NCZ001-002-018.
WV...Wind Advisory until noon EST today for WVZ042>044-507-508.

&&

$$
SYNOPSIS...MBS
NEAR TERM...AL/MBS
SHORT TERM...JH/PM
LONG TERM...JH
AVIATION...KK/MBS


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.