Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Blacksburg Virginia
1005 am EST Wednesday Feb 10 2016
a strong upper low centered over the Ohio Valley will remain
nearly stationary today before slowly moving east tonight into
Thursday. Weak upper shortwaves will move across the mountains
through tonight resulting in scattered snow showers and snow
flurries.Temperatures will remain below normal for the remainder
of the week. Another clipper system will cross our region on
Friday with some light snow accumulations...especially in the
mountains. Arctic high pressure builds in for the weekend. Another
winter storm may impact the middle-Atlantic region Monday into
Near term /through tonight/...
as of 1000 am EST Tuesday...
A broad and cold upper level low will keep accumulating snow on
western slopes with scattered flurries across the the rest of the
mountains...possibly spilling over to the foothills. Some banding
is evident this morning...but none appear to be to intense.
Some clearing taking place this morning which will help keep
breezy and gusty conditions into this afternoon. Winds will
increase tonight as more cold air pushes into the region. This
will create dangerous winds chill values overnight.
As of 445 am EST Tuesday...
Posted a wind chill advisories for along and west of the Blue Ridge
mountains to capture wind chills colder than 5 below for tonight
into Thursday morning.
Winter weather warnings and advisories remain in effect through 7 am
Broad upper low will remain across the Ohio Valley today and lift
northeast tonight. Several embedded shortwaves will pivot around the
upper low across our region. Northwest flow of cold air combined
with the shortwaves will result in periods of snow showers and snow
flurries mainly for the mountains. Snow showers should taper off
this morning after the first robust shortwave pushes east into the
Atlantic Ocean. The upslope lift may hold into tonight in the
western mountains. Additional snowfall will range from a coating to
as much as 3 to 7 inches in the western Greenbrier County in
southeast West Virginia. Winds through this evening will remain
breezy and gusty. Moderate pressure rises over the North Carolina
high County could bring gusts up to 40 miles per hour this afternoon. After
morning wind chill values as cold as the single digits across the
mountains and lower teens east of the Blue Ridge....this afternoon
highs will range from the teens in the mountains to the upper 30s in
the Piedmont. Low temperatures tonight will vary from the single
digits in the northwest mountains to the middle teens. The combination
of wind and temperatures will produce wind chills as cold as 5 to 20
Short term /Thursday through Saturday night/...
as of 430 am EST Wednesday...
Multiple winter concerns through the period in the form of
For Thursday...tail end of long standing upslope event finally
winding down. Feel that additional snowfall should generally be 1
inch or less and mostly ending by afternoon...except for a few
flurries...as the flow aloft briefly becomes more westerly and the
trough axis temporarily shifts east of the region. This allows the
upslope trajectory to become less favorable and cold advection to
subside. 850mb temperatures bottom out in the morning around -17c in the
north to -12c in the south...warming slightly be afternoon to -16c
in the north to -10c in the south. Still a very cold air mass and
will leave all areas west of the Blue Ridge well below freezing
throughout the day...barely above to the east.
For Friday...a strong Alberta clipper is embedded within the deep
eastern U.S. Polar trough quickly tracking from the northern
plains/upper Midwest toward the central/southern Appalachians. As
this system translates into the Piedmont...a coastal low begins to
form and rapidly intensify along the SC/NC coast. This system has
strong dynamics...and although moisture is very limited...light
precipitation looks likely. Nearly all of the models paint a solid
swath of light quantitative precipitation forecast tracking mainly from SW Virginia toward the mtv/Dan
area by early afternoon. With a very cold...dry air mass in
place...the snow ratios will be high...and a quick 1-2 inches of
snow appears likely. No problem with it sticking to the ground
either as temperatures will be in the single digits and 20s during
this time frame. This system will exit to the east by afternoon
and precipitation will likely diminish quickly as the main focus
relocates to the coastal areas. However...this clipper precedes
the next surge of significant Arctic air that will settle in for
the region over the weekend. Therefore...upslope snow will begin
again in earnest along the western slopes.
By Saturday...a strong 1047mb Arctic high will be settling down
through the upper Midwest into the Ohio/Tennessee Valley. This air mass
will clearly be the coldest air mass we have seen since February
2015. While the extreme cold/core of this air mass will track
toward New England and the northern middle-Atlantic where 850mb temperatures
are prognosticated to be near -36c...we will see -22c or so here...which
exceeds are coldest air mass in January by about 5c or so. Below
zero temperatures appear likely in the western mountains and wind
chills appear quite significant both Saturday and Sunday morning
with potential for -20 to -25c in western high elevations
areas...and wind chills to near -5c as far as as the Piedmont.
Wind chill advisories and warnings will most likely be needed.
Upslope snow will be diminishing by Saturday night as the surface
high drifts overhead. Sunday morning will be the coldest of this
Long term /Sunday through Tuesday/...
as of 515 am EST Wednesday...
Sunday will be mostly dry and very cold with temperatures starting
out below zero in the west to single digits in the east.
Monday into Tuesday brings the potential for perhaps a
significant winter storm...especially per European model (ecmwf)...as a deep trough
rotates through the region on the heels of the bitter cold Arctic
air mass that will reside across the region over the weekend. Among
the models...the GFS is a southern outlier...while the European model (ecmwf) has a
bullseye of precipitation across our region. There are also
concerns about the ptype as warmer air encroaches...at least
aloft...into the Piedmont. Winter precipitation appears likely
for the entire County Warning Area at this point...with snow the mostly likely
ptype west of the Blue Ridge...and snow transitioning to a mix of
snow/sleet/perhaps even some freezing rain per model
soundings...across the eastern/southeastern portion of the
Piedmont. The antecedent air mass will be very cold and at this
point the models seem to have a poor degree on the intensity or
depth of this cold air...which will ultimately figure into the
equation. Needless to say...all interests within this time frame
will want to remain abreast of later forecasts regarding this
potential winter storm. Projected quantitative precipitation forecast greater than 1 inch for
parts of the County Warning Area and possible at least weak coastal low
development does suggest that several inches of snow could be
possible...or perhaps even sleet in some Piedmont areas.
With respect to temperatures...the bitter cold of the weekend will
abate...but temperatures...outside the Piedmont...will likely
remain at or below freezing through much of the period.
Aviation /15z Wednesday through Sunday/...
as of 643 PM EST Tuesday...
Snow showers...cold and winds will hinder aviation operations
today into tonight.
Scattered to broken MVFR clouds with IFR conditions possible in snow
showers. Kblf has the best chance of going IFR in heavier snow
showers. Seems klwb/kbcb may stay MVFR...with kbcb going VFR
later this morning. Snow showers will be mainly confined to the
western slopes...but light snow showers or flurries could breach
the New River valley and Roanoke valleys through middle morning.
Winds will stay gusty with sustained winds out of the west
northwest at 10 to 18 kts with gusts expected over 25 kts at
kblf/klwb/kbcb/kroa today. Winds may gust as high as 45 miles per hour across
the higher terrain this afternoon. Winds should weaken at times
this evening into tonight.
In the east at kroa/klyh and kdan...VFR conditions will
prevail today into Thursday. Sub-VFR should become more confined
to the mountains and western slopes into Thursday with primary
area of MVFR/IFR conditions confined to the west...upslope...side
of the Appalachian Mountains. This will primarily impact kblf/klwb
with mainly VFR conditions east of the higher mountain ridges into
central and eastern VA/NC.
Medium confidence in ceilings...visibilities and winds during
the taf period.
Conditions should briefly return to mainly VFR Thursday night as
weak high pressure builds in and moisture decreases.
Another clipper system poses to move across the area
Friday...bringing the potential for sub-VFR conditions to the west.
VFR conditions should return for much of the weekend...prior to the
arrival of an additional weather system...bringing the threat for
sub VFR conditions again Monday and Tuesday.
Virginia...Wind Chill Advisory from midnight tonight to 10 am EST
Thursday for vaz007-009>020-022>024.
Winter Weather Advisory until 7 am EST Thursday for vaz007-
NC...Wind Chill Advisory from midnight tonight to 10 am EST
Thursday for ncz001-002-018.
Winter Weather Advisory until 7 am EST Thursday for ncz001-018.
WV...Wind Chill Advisory from midnight tonight to 10 am EST
Thursday for wvz042>044-507-508.
Winter Weather Advisory until 7 am EST Thursday for wvz042>044-
Winter Storm Warning until 7 am EST Thursday for wvz043-508.