Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Blacksburg Virginia
303 PM EST Mon Nov 11 2019
a strong cold front will sweep southeast through the area
tonight into early Tuesday, bringing a surge of very cold air
along with strong gusty winds. Rain showers will move in ahead
of the font tonight, then gradually mix with and change to snow
showers in the mountains overnight. Upslope snow showers are
expected to continue west of the Blue Ridge on Tuesday, while
locations east of the ridge will see showers gradually ending,
followed by clearing skies for the afternoon.
Near term /through Tuesday/...
as of 130 PM EST Monday...
A good amount of sunshine this afternoon across the Appalachians
and central mid Atlantic region, but clouds are not far off as
the strong cold front approaching from the west remains on
schedule. There will be rain showers out ahead of the front, but
as the front crosses the region and much colder air surges in,
precipitation will mix with/change to snow overnight. Locations
west of the Blue Ridge will see some flakes and possibly a light
coating but appreciable accumulations will be limited to the
higher elevations where an inch or two of accumulation is
expected, with amounts possibly up to 3 inches for western
Greenbrier County WV. The cold air will be chasing the departing
rain showers east of the Blue Ridge so some wet flakes can also
be expected just before the precipitation ends Tuesday
morning/early afternoon. Snow showers will very gradually wind
down west of the ridge throughout the day on Tuesday with only a
light additional accumulation at the higher elevations.
Winds will really start to howl behind the front with gusts of
45mph to 50mph expected at the higher elevations, especially
from the southern Blue Ridge into the mountains of NC. Combined
with the surging cold air wind chill values will be quite low,
especially at the higher elevations, through Tuesday night.
As noted, the surge of cold air behind the front is substantial
and temperatures are expected to generally be falling throughout
the day on Tuesday. Look for an early high in the mid/upper 40s
east of the ridge, 30s to the west.
Short term /Tuesday night through Thursday night/...
as of 208 PM EST Monday...
Some snow showers and flurries will linger in western mountains
especially in western Greenbrier. Used a blend of hires arw-
east and NAM for pops Tuesday night. It is going to windy with 6
hour pressure rises around 6-9mb and strong cold advection
Tuesday evening into Tuesday night. The combination of wind and
temperatures will drop winds chills to single digits to single
digits below zero, with the coldest at the highest terrain. Wind
chills could be as cold as minus 5 to minus 10 in western
Greenbrier. Record low temperatures will be challenge Tuesday
night with readings from the single digits to around 20 degrees.
See climate section below for records.
High pressure centered over West Virginia Wednesday morning will
slowly slide east into Wednesday night. High temperatures Wednesday
will range from the upper 20s in the mountains to around 40 degrees
in the Piedmont under plenty of sunshine. Record coldest high
temperatures are possible, despite the sunshine. The high center
will slide eastward Wednesday night. Another cold night is on tap
Wednesday night with good radiational cooling, though higher ridges
out west may get some mixing. Low temperatures Wednesday night
into Thursday morning will vary from the mid teens in the mountains
to the mid 20s in the Piedmont. High pressure will move into
the Atlantic Ocean Thursday. Meanwhile, upper trough will dig
across the lower Mississippi Valley. Clouds will increase on
Thursday with approach of next shortwave. High temperatures
Thursday will range from the lower 30s in the mountains to the
upper 40s in the Piedmont. Some light over-running precipitation
may be possible across southeastern portions of the forecast
area Thursday night. Low temperatures will vary from the lower
20s in the mountain valleys to the lower 30s in the Piedmont.
Medium confidence in short term forecast.
Long term /Friday through Monday/...
as of 208 PM EST Monday...
Forecast becomes more complicated with differing model solutions
leading to lower confidence in the long range period. The challenge
is how far west the over-running precipitation GOES with coastal
frontal boundary and wave of low pressure.
The European model (ecmwf) and its ensemble mean continue to be slower and more
amplified with the shortwave and eventual closed low that will
affect the southeast by the end of the week and into the weekend.
This results in the European model (ecmwf) being farthest west and closest to the
coast with the developing surface low, while the UKMET and CMC are
With uncertainty, decided to follow wpcguide with pops for Thursday
night into Friday morning. As for ptype, temperatures will be
running close to freezing out east, and could see some
freezing/frozen precipitation Friday morning. Kept it simple for now
with light rain or snow.
Beyond Friday models start to diverge, low pressure slowly lifts
north along the coast into early nest week. The northern and western
edge of precipitation varies depending on model choice. Hard to
believe that there will be a secondary low which forms in the
Atlantic Ocean like GFS was showing.
Majority model consensus shows high pressure at the surface winning
out over our area, while most precip stays toward the coast.
Temperatures still staying below normal, but not well below normal
like early week.
Aviation /20z Monday through Saturday/...
as of 130 PM EST Monday...
VFR flight conditions expected into this evening.
West of the Blue Ridge, conditions will rapidly deteriorate
after dark as a cold front approaches and pushes rain showers
into the region with MVFR cigs. Much colder air will surge in
behind the front and change the precipitation to snow showers
and pushing cigs/vsbys to IFR at times, especially at the higher
elevations such as kblf. Poor flight conditions will persist
into Tuesday morning before some gradual improvement toward the
end of the valid period.
East of the Blue Ridge, rain showers will arrive late tonight
with a mix/change to snow just before the precipitation pulls
out to the east. Cigs will generally go to MVFR by daybreak,
then improve to VFR for the latter portion of the valid period.
Winds will become quite strong and gusty behind the front,
though taf sites are expected to remain below 40kts.
Extended aviation discussion...
Conditions gradually improve back to VFR on/by daybreak
Wednesday west of the Blue Ridge as high pressure and drier air
finally builds in from the west. The high will maintain VFR
conditions with no flight restrictions Wednesday into Thursday
and for the mountains Friday. Models showing potential southeast
coastal system moving moisture toward Dan Thu night- Fri which
could bring ceilings toward low end VFR.
as of 315 am EST Monday...
Temperatures will get close to some records for Nov 12 and 13
due to the Arctic air coming in behind the cold front. Listed
below are current records.
Sitecoldest highs/year coldest low/year
Bluefield 30/1983 15/1950
Danville 36/1987 21/1941
Roanoke 39/1983 17/1926
Blacksburg 29/1987 17/1973
Sitecoldest highs/year coldest lows/year
Bluefield 28/1976 10/1911
Danville 41/1968 20/2016
Lynchburg 36/1911 20/1996
Roanoke 38/1976 19/1920
Blacksburg 34/1968 15/1983
Virginia...Winter Weather Advisory from 4 am Tuesday to 7 am EST
Wednesday for vaz015>017.
Winter Weather Advisory from 4 am to 1 PM EST Tuesday for
NC...Winter Weather Advisory from 4 am Tuesday to 7 am EST
Wednesday for ncz001-002-018.
WV...Winter Weather Advisory from 4 am to 1 PM EST Tuesday for
Winter Weather Advisory from 4 am to 7 PM EST Tuesday for
Wind Chill Advisory from 7 PM Tuesday to 7 am EST Wednesday