Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
941 PM EST Wednesday Feb 10 2016
an upper level trough lingers across the region through tonight.
High pressure returns later tonight through Thursday night. Weak low
pressure lifts along the southeast coast Friday and pushes off the
southeast coast Friday night. Arctic high pressure builds in for the
Near term /until 6 am Thursday morning/...
forecast updated to adjust probability of precipitation a bit based on latest radar
trends and surface observation. Up to a dusting is possible over some portions of
the lower Eastern Shore...but not expecting any accumulations over most
trough axis aloft swings through the forecast area lt this aftn/eve...then
off the CST overnight. Scattered-broken cloudiness will accompany this trough...along
west/ possible isolated snsh or flurries (esp northern half and on the lower Maryland eastern
shore). Otherwise...mainly sunny southeast...partly sunny elsewhere west/ seasonably
cold thus far this afternoon. A bit a gusty west-southwest at times adding a bit
of a chill. Temperatures ranging from the u30s-m40s.
Partly cloudy-vrb clouds through early tonight...then clearing
thereafter (linger snsh/flurries in vicinity of portions of Eastern Shore until
after mdngt). Low temperatures in the upper teens across the central Virginia Piedmont
where sky clears earlier to m20s along the coast and Eastern Shore.
Short term /6 am Thursday morning through Saturday/...
broad upper level trough aligned along the eastern Seaboard on Thursday. Dry/cold
deep layered west-northwest flow as conds average sunny-partly cloudy. Hi temperatures a touch
lower than today...ranging from the l-m30s north to the M-u30s S.
Surface hi pressure over the region Thursday night into Friday...as additional upper level
energy digs over the Midwest into the Gulf states. Models continue to
insist on development of weak surface low pressure in vicinity of southeast Continental U.S. CST Friday
morning...which tracks east out to sea Friday aftn/ngt. 12z/10 European model (ecmwf) remains
the model that keeps moisture west/ that system S of the forecast area. Will continue to
blend the NAM/GFS and current forecast...which has a period of -sn possible
across far southern and southeast portions of Virginia and across NE NC (starting between
15-18z/12). Model soundings quite dry below 5kft and expecting snow ratios
upwards of 15:1. Quantitative precipitation forecast at this time at or below .10" on average. Some scattered -sn possible elsewhere
as trough aloft sharpens into the region from the west-northwest. Probability of precipitation will range
from 40-60% southeast...to 15-25% elsewhere. Snow accums right now an forecast to be
an in or less. Due to clouds and a cold start...expect highs only
in the l-m30s most places.
Vrb clouds/possible isolated -snsh Friday evening...then strong cold front to cross the
forecast area lt Friday night/Sat morning...ushering in additional Arctic air. Ptntl
for Bay/ocn induced snsh...otherwise sky clear-partly cloudy Sat west/ gusty northwest
winds (to 25-30 mph). Hi temperatures from the u20s northwest to 30-35f elsewhere (wind
chills avgg in the teens to l20s).
Long term /Saturday night through Wednesday/...
strong cold air advection will continue Saturday night as Arctic high pressure
builds in from the northwest. 850mb temperatures plummet to around -20 to -
22c across the area. This will usher in the coldest airmass so far
this winter...and it will likely be the coldest airmass of the 2015-
16 winter locally based on the fact that it will be middle-February and
the 8-14 day CPC outlook indicates above average temperatures as we
move into the later portion of the month. Lows Saturday night drop
into the single digits for much of the area with middle teens southeast. A northwest
wind (strongest e) will drop wind chills below 0f for much of the
area and based on the current forecast wind chill advisories will
likely be necessary. The high builds across the region Sunday with
high temperatures ranging from the low 20s NE...to middle/upper 20s
elsewhere under a mostly sunny sky...although Bay streamers are
possible early in the day. High pressure shifts toward New England
Sunday night with attention turning to a developing system over the
deep south Monday. There is plenty of uncertainty with respect to
the details. However...a trough does dig across the Ohio Valley
Monday night with low pressure developing in vicinity of the
southeast coast. The cold air will shallow and retreat during this
period...but will likely be stubborn to retreat too fast. The amount
of wintry precipitation will depend on the exact track...with the 10/12z
GFS/CMC showing a colder more southern and offshore track...with th3
10/12z European model (ecmwf) depicting an inland and warmer track. Drying occurs
midweek in the wake of the departing system...with a northern stream wave
clipping the area late in the period.
Aviation /03z Thursday through Monday/...
high pressure builds into the Middle Atlantic States through Friday.
Low pressure moves through the Carolinas late Friday. Arctic spreads
into the region during the weekend.
Ceilings of around 6 to 8k feet are expected to scatter out by around
midnight. Radar returns are associated with these clouds but low dew
points will limit the potential of anything reaching the ground. A
few flurries could result...especially in the sby area. Gusty west
winds may subside overnight and increase once again Thursday with
gusts to between 20 and 24 knots.
Outlook...dry weather is expected through early Friday. There will
be a chance for light snow mainly orf/ecg area late Friday. Dry
weather with gusty northwest winds return for the weekend. High pressure
moves off the coast by Monday morning. There will be a chance for
rain or snow Monday as southeast to south winds bring a warm
advection ahead of the next weather system.
the pressure gradient tightens later tonight into Thursday
with modest cold air advection. This will help strengthen west-northwest flow overnight
through Thursday evening...with speeds averaging 20-25kt with gusts
up to 30 knots across most of the marine area with 15-20kt with gusts
up to 25kt over the rivers. Seas generally average 4-5ft with 3-4ft
waves in the Bay. High pressure builds over the middle Atlantic late
Thursday night into Friday morning before moving offshore in the
afternoon. This will bring a brief period of sub-Small Craft Advisory conditions. Low
pressure tracks off the southeast coast Friday afternoon...which
could bring some reduced visibility in snow for the southern coastal zones.
A strong Arctic cold front then crosses the coast Saturday...with
Arctic high pressure building into the area through Sunday. Strong
cold air advection is expected with the pressure gradient tightening between low
pressure departing to the NE and high pressure building in from the
northwest. Gale conditions are possible...especially across the Bay and
ocean. Freezing spray is likely as temperatures plummet Saturday
afternoon and especially Saturday night. The wind will diminish
Sunday into Sunday night as the high settles across the area.
river Flood Warning remains in effect for the Nottoway at Sebrell.
See flsakq for details.
all coastal flood advisories have been discontinued as tidal
anomailes continue to fall in westerly flow. The flow becomes more
west-northwest tonight...which will allow anomalies to further fall. Strong
northwest flow associated with an Arctic cold front could produce blow-
out tides this weekend.
Marine...Small Craft Advisory until 10 PM EST Thursday for anz630>633-
Small Craft Advisory until 1 am EST Friday for anz634-650-652-