SYNOPSIS
A stationary boundary will linger over the area through tomorrow
afternoon. A strong cold front will move through tomorrow night.
Thereafter, an upper low will circulate overhead through the
weekend.
NEAR TERM /THROUGH TONIGHT/
Current radar imagery shows a few light showers scattered about
the area. On and off light showers will continue through the
evening and first half of the overnight as a weak push of warm
advection moves through aloft. With thick cloud cover in place
temperatures will remain mild overnight, with overnight lows in
the upper 40s and lower 50s for most.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
Low clouds should hold strong through much of the day tomorrow,
but it will remain mild, with high temperatures in the 60s for
most.
Later tomorrow through the remainder of the week, attention will
turn to a potent system approaching from the North and West. A
broad, deepening upper low will dive SouthEastward from the
Northern Plains toward the Great Lakes during the day tomorrow.
A prominent shortwave on the leading edge of the much broader
upper low will move overhead tomorrow evening, driving a strong
cold front through the area during the late afternoon and
evening hours. Showers should develop to the West of the Blue
Ridge during the afternoon, and may strengthen into a squall
line to the East of the Blue Ridge tomorrow evening. Any
convection would be rather low topped in nature, but a few
rumbles of thunder could be possible tomorrow evening. The wind
field ahead of the line isn`t strong at all, so any gusts
produced by the line would likely be sub-severe. However, there
is a strong surge of wind within cold advection behind the
front. Winds may briefly approach Wind Advisory criteria for a
few hours behind the front, especially along the ridgetops. Some
showers may linger for a few hours behind the front, but should
rapidly come to an end as conditions dry out during the second
half of the night.
There will be a lull in the precipitation Thursday morning as
the first shortwave and its associated synoptic scale forcing
for ascent lifts off to our NorthEast. Daytime heating will
allow limited instability to develop within the boundary layer.
As a result, snow showers will start to develop in the mountains
within upslope flow during the afternoon hours and continue on
and off through the night. The snow showers could be quite
squally in nature during the afternoon and early evening hours,
with instability extending up into the dendritic growth zone.
Several inches of snow may be possible with this first round of
snow. Winter Storm Watches go into effect along the Allegheny
Front starting at 1 PM Thursday and continue through Saturday
afternoon. To the East of the mountains, much of the day will
remain dry, but a few mixed rain/snow/graupel showers may be
possible during the afternoon. Temperatures will hold in the
30s in the mountains, with high temperatures in the 40s to near
50 further East.
LONG TERM /FRIDAY THROUGH TUESDAY/
A large upper trough remains in place across the NorthEast to Mid-
Atlantic Friday into the start of the weekend. The two main pieces
of vorticity embedded within the upper trough pivot around each
other, and bring several times of enhanced upslope snow showers to
the mountains. Additionally, expect periods of enhanced shower
activity East of the mountains, some of which could contain a mix of
snow and/or graupel. No accumulation is likely East of the
Alleghenies given the above freezing ground temperatures.
The steadiest and heaviest upslope mountain snow shower activity
looks to occur Friday afternoon into Saturday morning. Snow shower
activity likely lingers through much of Saturday as NorthWest flow
continues. Overall the coverage and intensity will slowly decrease
with time as drier air filters in.
Outside of the significant snow accumulation, blowing and drifting
will become a problem. Gusts up to 50 mph along the higher ridges
are possible, with 30-40 mph gusts elsewhere. The strongest winds
East of the mountains will occur late Friday night into Saturday
morning before decreasing into Sunday. The combination of winds and
cold temperatures produce wind chills in the teens and 20s Friday
into Saturday in the mountains.
Chilly conditions Friday as highs only reach the 40s, with low 60s
possible in a few spots in Central VA. In the mountains, high range
in the low to mid 30s. A steady warming trend quickly ensues this
weekend into the start of next week, as highs go from 40s to 50s on
Saturday to upper 50s to 60s Monday.
High pressure briefly builds in from the South Sunday into Monday
before another warm front lifts into the region. A cold front
approaches Monday night, bringing the next chance for rain.
AVIATION /20Z TUESDAY THROUGH SUNDAY/
VFR conditions and light East to SouthEasterly winds are
expected this afternoon. A few showers will move through the
area during the first half of the overnight. As this occurs, ceilings
will drop to MVFR tonight, and may reach IFR by tomorrow
morning. IFR conditions should linger through much of the day
tomorrow, before a strong cold front moves through tomorrow
evening. A brief line of heavier showers or storms may accompany
the front tomorrow evening, with showers potentially lingering
for a few hours behind the front. Conditions should improve back
to VFR behind the front, but winds will become gusty out of the
West through the remainder of the night. VFR conditions and
Westerly winds are expected on Thursday. A passing rain or mixed
rain/graupel/snow shower can`t be ruled out Thursday afternoon,
but the vast majority of the day should remain dry.
Gusty West to NorthWest winds Friday into Saturday are going to be
the main impact to aviation in the area. Winds generally sustained
at 15-20 knots each afternoon, and around 10-15 knots at night.
Frequent gusts to 25-30 knots likely each day. There could be
occasional periods of MVFR clouds at times, mainly at MRB, but
should predominantly remain VFR. Some shower activity could contain
snow and/or graupel Friday morning, though confidence is currently
low. Winds decrease Sunday.
MARINE
Light SouthEast winds are expected over the waters through the
day today, with light Easterly winds through much of the day
tomorrow. A strong cold front will move over the waters
tomorrow evening, leading to an abrupt wind shift to Westerly,
with strong winds immediately behind the front. Gale gusts may
be possible for a few hours behind the front tomorrow evening
into the first half of the overnight. A Special Marine Warning
may also be needed due to the sudden onset of the Gale gusts.
SCA conditions are expected in Westerly flow Thursday through
Thursday night.
High end SCAs are likely to continue through Saturday afternoon with
frequent gusts of 25-30 knots across the waters. Gale force gusts
are possible over the open waters of the bay and lower tidal Potomac
late Friday night into Saturday. Winds decrease Saturday night, but
still remain in Small Craft Advisory range.
TIDES/COASTAL FLOODING
Minor coastal flooding is possible at the more sensitive tidal
sites like Annapolis and DC SW Waterfront over the next couple
tide cycles. Water levels will decrease Wednesday night through
the upcoming weekend as winds turn Westerly.
LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Gale Watch from Wednesday evening through late Wednesday night
for MDZ008.
Winter Storm Watch from Thursday afternoon through Saturday
evening for MDZ001.
Coastal Flood Advisory from 6 PM this evening to midnight EST
tonight for MDZ014.
VA...Winter Storm Watch from Thursday afternoon through Saturday
evening for VAZ503.
WV...Winter Storm Watch from Thursday afternoon through Saturday
evening for WVZ501-503-505.
MARINE...Gale Watch from Wednesday evening through late Wednesday night
for ANZ530>543.
