847
FXUS61 KLWX 311931
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
231 PM EST Wed Dec 31 2025
.SYNOPSIS...
A reinforcing shot of cold air, wind, and mountain snow look to
accompany an area of low pressure and it`s associated cold front
tonight into tomorrow morning. High pressure briefly returns
from the west Friday before another area of low pressure passes
to the south Saturday into Sunday. High pressure returns
briefly Sunday with another clipper type system set to push
across the area early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
The biggest change to the forecast package was to start the
winter headlines in the Alleghenies earlier (~1830Z) given
reports of freezing drizzle from spotters along with cameras
being iced over that were previously not. Any untreated surface
could be icy through the afternoon before the precipitation
changes back over to snow.
The main upper level disturbance and it`s reinforcing cold
front swing through tonight into Thursday morning. This system
will be much stronger bringing with it renewed cold
temperatures, wind, and impactful mountain snow. A strong west
to northwest wind will lead to better upslope enhancement over
the mountains with perhaps some spillover in the form of snow
squalls, showers, and flurries east of the mountains late
tonight into early Thursday morning.
Winter Storm Warnings remain in effect for areas west of the
Allegheny Front, with western Highland and extreme western Allegany
Counties both in Winter Weather Advisories. The combination of the
upslope flow, strong mid-level forcing and saturation within the DGZ
along with instability and high SLRs (15-17:1 increasing to 20 to
22:1) suggest that significant accumulation is possible (around 6-
10"+ along and west of the Allegheny Front). Strong winds gusting to
around 40 to 50 mph will also create poor visibility at times, with
near-blizzard conditions possible. Of particular concern is the
timing, with the onset of the worst conditions likely occurring
right around, or just before, midnight on New Year`s Eve/New Year`s
Day. When all is said and done, areas in the warnings could see
anywhere from 6 to 10 inches +, with the areas in advisories between
2 and 5 inches.
Most hi-res guidance continues to hint at the potential for snow
showers or squalls with some impacts north of I-66/US-50.
Greatest potential in true snow squall warning criteria (winds >
25 mph, VSBY < 1/4 mile, and road temps below freezing) are
favored in the Cumberland to Frederick, MD area. Will continue
to monitor. Further south, a dry boundary layer is in place that
gets drier overnight with FROPA. This is partially observed in
the difference between the composite reflectivity in hi-res
model guidance and the 1km AGL reflectivity. SFC Td depressions
in most hi-res guidance >10F pre-frontal, and in the 15-20F
range with FROPA. What this is getting at is it likely snows
east of the mountains, but may not be true snow squall criteria.
The confidence for accumulation east of the mountains still
remains in question.
Highs today will range from the mid 20s over the Alleghenies to mid
30s and low 40s further east. Wind chills will make it feel like the
single digits over the mountains with upper 20s and low 30s east.
Gusts of 20 to 25 mph can be expected later this morning and into
the afternoon. Lows tonight will fall back into the low teens over
the mountains with low to mid 20s elsewhere across the region. Wind
chills will fall back below zero over the mountains with low teens
further east.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Accumulating upslope mountain snow showers will likely linger along
and west of the Alleghenies through Thursday midday. Northwest flow
will gradually diminish as the moisture source is choked off
given brief high pressure building in from the Ohio River
Valley. The high will gradually settle overhead Thursday night
into Friday bringing drier and colder conditions. Winds will
also decrease during this time as the gradient finally relaxes
heading into late week.
Expect highs Thursday in the teens over the mountains with upper 20s
and low 30s, along and north of I-66/US-50. Locations south will be
a touch warmer with highs in the mid 30s. Northwest winds will gusts
20 to 30 mph with (35 to 45 mph gusts mtns.) Thursday morning
into Thursday evening. This will yield single digit to below
zero wind chills over the mountains with teens and 20s for feels
like numbers east. The northwest winds will also bring down
drier air to the surface, so cut Tds tomorrow afternoon to
account for this. Lows Thursday night will fall back into the
teens and 20s under clearing skies and decreasing winds.
High pressure will shift off the southern Delmarva coast Friday
morning into Friday afternoon. Meanwhile, stalled front to the
south will try to lift back to the north Friday afternoon into
early Saturday. This system will lead to extra cloud cover,
mainly south of I-66/US-50 and down around I-64. Any
precipitation chances will remain south of US-460 in VA. The
front flops back to the south Saturday morning. Highs Friday
will range from the upper 20s and low 30s over the mountains to
upper 30s and low to mid 40s east. Lows Friday night will fall
back into the upper teens over the mountains with low to mid 20s
east.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A strong upper level low over eastern Canada will continue to pull
in cooler and drier air into the northern mid-Atlantic region this
weekend. Zonal to a slightly troughy pattern will be in place over
our region with models and ensembles suggesting a southern stream
shortwave will bring precipitation to parts of the Carolinas and
Virginia during the early parts of this weekend. Model guidance over
the past few days have trended slightly northward with precipitation
this weekend, but models continue to keep most precipitation mainly
south of our forecast area. If the northern trend in precipitation
continues, parts of our region could observe some wintry
precipitation especially with a cold air mass in place.
The southern clipper low is forecast to be off-shore by Sunday with
high pressure favored to build over the region through early Monday.
Multiple clipper systems next week may bring additional chances for
precipitation to the region.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Wind gusts remain 15 to 25 kts through the afternoon. Skies
will be SCT-BKN as strato/alto cumulus roll off the mountains.
An additional wave of low pressure and reinforcing cold front look
to track across the region late tonight into Thursday morning. This
may bring an additional period of light flurries or snow showers to
the corridor between 07z-12z/2am-7am Thursday. MVFR/IFR vsbys are
possible during this time and any light accumulation may have impact
due to the cold conditions. Confidence here is low given the limited
moisture east of the mountains. Something that will have to monitor
given hi-res guidance suggesting the potential for light snow at
BWI, MTN, IAD, MRB, HGR, and DCA during the time window above.
Did add snow to MRB, just not enough confidence at any of the
other terminals at this time. Any accumulation would be light
and likely to occur within a 1-2 hour time window. With this
band of snow and the front coming through early Thursday morning
will come another round of wind. Expect gusts of 20 to 25 kts
Thursday morning into Thursday evening out of the WNW. Winds
will gradually diminish Thursday night as high pressure builds
back into the region.
VFR conditions return Thursday afternoon through Friday as high
pressure builds back into the region. Winds will shift from the
northwest Thursday to the west Friday. Gusts of 10 to 15 kts
Thursday evening and night will decrease to less than 10 kts
Friday.
Low ceilings will be possible on Saturday, but VFR conditions are
likely to return Sunday. Additional restrictions are possible early
next week.
&&
.MARINE...
Winds in large remain near SCA criteria through the afternoon
before picking up this evening ahead of a cold front. SCAs continue
through Thursday with gusts of 25 to 30 kts expected across the
waters in the wake of the departing cold frontal boundary. A
brief period of gales can`t be ruled out right with frontal
passage early Thursday morning.
High pressure will lead to diminishing winds late Thursday night
into Friday. Sub-SCA level conditions are expected at this time.
Sub-Small Craft Advisory level winds are favored in the long term at
this time.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 4 PM EST Thursday for MDZ008.
Winter Weather Advisory until 10 AM EST Thursday for MDZ501.
Winter Storm Warning until 10 AM EST Thursday for MDZ509-510.
VA...Winter Weather Advisory until 10 AM EST Thursday for VAZ503.
WV...Winter Storm Warning until 10 AM EST Thursday for WVZ501-503-
505.
MARINE...Small Craft Advisory until 4 PM EST Thursday for ANZ530>534-
537>543.
Small Craft Advisory until 6 PM EST this evening for ANZ535-
536.
Small Craft Advisory from 2 AM to 4 PM EST Thursday for ANZ535-
536.
&&
$$
SYNOPSIS...CPB/EST
NEAR TERM...CPB/EST
SHORT TERM...CPB/EST
LONG TERM...JMG
AVIATION...JMG/CPB
MARINE...JMG/CPB
NWS LWX Office Area Forecast Discussion