Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Blacksburg Virginia
103 PM EST Monday Jan 26 2015
a deep low pressure system will pass across the area this morning...
on its way to the coast by early this afternoon. This system will
bring periods of snow and rain to much of the region today into
Monday. Strong northwest flow should follow this feature Monday
night into Tuesday before high pressure builds in for the middle
of the week.
Near term /through tonight/...
as of noon EST Monday...
Low pressure is currently passing overhead with upper trough axis
and colder air soon to follow. At 11am the center of the surface
low was over eastern WV with a cold front extending southwest into
eastern KY/TN. Temperatures ahead of the front and south of the
low were in the 30s/40s with some sun across the Piedmont of NC.
North of the low and west of the cold front temperatures were
below freezing. The front will continue to make its way east and
over the mountains this afternoon with temperatures in the
mountains falling during the afternoon. Deformation zone on the
northwest side of the low will result in a period of snow this
afternoon and evening over the mountains. Highest accumulations
are expected to be in the WV Highlands where about 4 inches of
accumulation is anticipated this evening...and in the higher
elevations of far western Virginia...and the high country of NC...from
Mount ROgers Virginia to Beech Mountain North Carolina where 2-4 inches
of snow is expected to occur. A Winter Weather Advisory has
already been issued for the WV Highlands. May need to consider one
for the NC high country too...especially for elevations at or above 4000
As the front crosses the mountains this afternoon look for winds
to increase from the northwest...temperatures then taking a
tumble. Even though snow accumulations will be on the lighter side
across the Greenbrier valley and New River valley...an inch or
less...this snow will be falling during the evening commute and in
tandem with temperatures dipping below freezing...ingredients that
could potentially make for a hazardous evening commute even with
just a little coating of snow.
For areas east of the mountains...warm temperatures today should
mitigate any evening commute concerns. Never the less temperatures
will also take a tumble with the frontal passage this evening with
a chance for any lingering rain to mix with snow during the
After the passage of the front tonight...the media focus will be
on coastal New England where this area of low pressure will wrap
up into a major winter storm. For the central Appalachians...we
get to deal with the backlash winds and mountain snow showers.
Their is some potential for wrap around moisture from the coastal
storm to penetrate as far south as our northeastern County Warning Area late
tonight...so will have to monitor this closely as their may be a
need for winter weather headlines for areas northeast of
Lynchburg...specifically Appomattox...Buckingham and points north
Even though we are not advertising much precipitation within our local
forecast...this weather system is very dynamic...lots of energy
aloft that will cause this storm to deepen quickly as it moves up
the East Coast. Have even seen a few lightning strikes within the
showers over the North Carolina Piedmont which is an indicator of
how unstable this atmosphere is becoming and the potential energy
that is building up for this thing to feed off of once it gets
east of our forecast area and certainly setting the stage for
coastal bombogenesis tonight. Models have been struggling with
quantitative precipitation forecast...and it was a bit interesting to see all the quantitative precipitation forecast the 06z GFS
model was painting over our County Warning Area this morning...yet not much was
occurring...convective feedback in the model. What really made it
humorous was the model then took the 4-6 tenths of an inch of quantitative precipitation forecast
and converted it to all snow. Anyone issuing forecasts and blindly
following guidance this morning would have then experienced a
good taste of meteorological cancer...a garbage in...garbage out
sort of forecast.
Quantitative precipitation forecast issues aside...the impact from this storm for our local area
will be minor compared to our neighbors to the north. I.E. Nothing
we havn't see before. In summary...a period of snow is likely for
our mountains this afternoon and evening with flurries and
scattered snow showers lingering into Tuesday. It will become
blustery with northwest winds of 10 to 20mph...and gusts of 25 to
30 miles per hour. A 40 miles per hour gust over the NC/VA/WV Highlands is certainly
possible. Colder air spilling into the area tonight will push
temperatures into the teens across The Highlands...to near 30 in
Short term /Tuesday through Wednesday night/...
as of 340 am EST Monday...
A coastal low tracking north along the middle Atlantic coast will
become a strong nor-Easter by days end Tuesday. The bulk of the
precipitation with this system will remain over New England. The
broad upper level low will cover a good chuck of real estate from
the Great Lakes...Ohio and Tennessee valleys...and the Carolinas and
points northeast. The middle rings of this low will send a series of
short waves across the area Tuesday. These waves will track across
the coastal Piedmont...bring light precipitation to areas east of
Highway 29 early Tuesday morning. Temperatures should be cold enough for
snow with any accumulations confided to grassy and/or elevated
surfaces. The bulk of accumulating snow will be focused on northern
slopes and higher elevations across the mountains Tuesday into
Tuesday night. Short waves on the outer bands of the low could
deposit 1-2 inches on these slopes north of i64...to about an inch
towards the North Carolina high County. These amounts are
questionable with the flow being more northerly than northwesterly
from the Great Lakes. The wettest of the snow will occur Monday
night and continue to get drier with each passing wave. The dryness
of the snow could lead to higher amounts but should not exceed 3
inches during the upslope portion of this event Tuesday into Tuesday
With the nor-Easter off the New England coast and high pressure in
the middle west...a tight pressure gradient will keep breezy and gusty
conditions in the region Tuesday and Tuesday night. Pressure rises
do not appear to be to strong especially in northerly flow and a 30-
40kt jet. These winds will relax overnight as high pressure to the
west tracks over the region starting late Tuesday night.
Temperatures likely to peak early in the day Tuesday as the cold
front slides across the region. Highs across the west will range in
the middle 20s to lower 30s. East of the Blue Ridge could warm to near
40f. If winds could decouple by sunrise...Wednesday mornings lows
will dip into the teens in the west to middle 20s east. High pressure
moves off the coast allowing a warm front to track over the area.
Unfortunately...Wednesday afternoon highs will fall shy of normal.
Long term /Thursday through Sunday/...
as of 230 PM EST Saturday...
Upper level pattern will be going back to split flow for the
extended with a cutoff low over the Baja California peninsula dominating the
southern stream...and a western ridge/eastern trough for the northern
stream. GFS is less amplified with the northern stream which gives
it a warmer look than the European model (ecmwf).
We will see a northern stream low move by to our north on Thursday
which will bring US a chance of light synoptic precipitation which
looks to be mix to rain for Thursday. This system will then swing a
cold front through the region Thursday evening which sets the stage
for upslope snow showers Thursday night into Friday. The winds
behind the cold front look quite blustery right through Friday.
High pressure then builds over the middle Atlantic region and forms a
bit of a wedge with quiet weather for for Saturday. Euro wants to
bring a surge of Arctic air into the region as we head into Sunday.
GFS is not on board with this and ensembles were not indicating a
major Arctic outbreak. Will be leaning more toward the GFS/ensemble
solution and keep temperatures Sunday into Sunday night a good 20f warmer
than the European model (ecmwf).
Aviation /18z Monday through Saturday/...
as of 100 PM EST Monday...
Low pressure over the middle Atlantic will move northeast developing
into a major coastal storm for New England. As the storm
strengthens this evening and overnight...much colder air will
advect into the central Appalachians supporting snow showers and
blustery northwest winds.
For a time this afternoon and evening...IFR ceilings will develop
east of the mountains per a shallow moist northeast wind. Once the
northwest wind develops this evening...this cloud layer should
lift. However...cloud bases over the mountains will remain low
with periods of snow showers and flurries.
High confidence for areas of MVFR and occasional IFR conditions through
this evening with high confidence for MVFR conditions lingering
over the mountains through Tuesday.
northwest flow continues on Tuesday. MVFR conditions likely
across kblf/klwb and perhaps even kbcb due to scattered upslope
snow showers. Eastern taf locations should become VFR on Tuesday.
High pressure on Wednesday will provide a quiet day with VFR
conditions across all taf locations. Another clipper system
arrives on Thursday...bringing a chance of sub-VFR ceilings and
Hinton all hazards radio...162.425mhz was off the air this
morning. Technicians are onsite.
The Roanoke transmitter...Poor Mountain 162.475 mhz...is also
experiencing problems with intermittent outages. Technicians are
onsite there also.
Virginia...Winter Weather Advisory until 10 PM EST this evening for
WV...Winter Weather Advisory until 10 PM EST this evening for