666
FXUS61 KLWX 090900
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EST Tue Dec 9 2025

.SYNOPSIS...
Canadian high pressure will remain over the region through this
afternoon. A quick moving clipper system will pass through the
Great Lakes Wednesday, while a secondary cold front follows
suit on Thursday. Yet another fast moving frontal system may
reach the area by late Friday night. Arctic high pressure
approaches from the west late in the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
The latest surface analysis places a broad area of high pressure
across the lower Great Lakes into the Mid-Atlantic region.
Behind the earlier cold front, the air mass is considerably
drier with 24-hour dew point falls on the order of 20 to 30
degrees. As such, a number of locations are reporting dew points
down in the single digits. While a number of spots have seen
temperatures tank overnight, residual northerly winds and some
cloud cover have kept temperatures up a bit. Despite some of
those limitations, readings are generally in the teens right now
(08Z/3 AM), with spotty low 20s in the urban corridor. For
those right along the Chesapeake Bay, conditions are a tad
milder with temperatures in the mid/upper 20s. Given the degree
of dry air, some upper single digits are possible in the chilly
spots.

After the cold start, expect temperatures to rebound through the
day as radiation inversions erode. The axis of Canadian high
pressure eventually pulls away toward the Atlantic coast this
afternoon. This allows for a wind shift to southerly which aids
in a small uptick in temperatures. Most can expect highs in the
mid 30s, with some upper 30s across the Allegheny mountain
valleys. Readings closer to the freezing mark are likely near
the Mason-Dixon Line, across the I-64 corridor where a small
snowpack lies, and in the mountains. This all comes with a mix
of clouds and sun as a shortwave through passes by to the north.

Late day southerly breezes pick up in strength and continue that
way through the evening and early overnight period. While most
can expect southerly wind gusts to around 15 to 20 mph, higher
elevations should see 25 to 35 mph gusts. The combination of
increasing clouds and southerly advection will raise low
temperatures back into the mid 20s to near freezing.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
The upper-level pattern maintains northwesterly flow which is
comprised by a series of embedded disturbances. One such impulse
begins to intensify tonight across the Mid-Mississippi Valley.
This is accompanied by a deep surface low around 988-mb which
tracks from Lake Michigan toward the interior northeastern U.S.
on Wednesday. As this entire trough races eastward, the
mentioned impulse/trough sweeps across the Mid-Atlantic states
by this evening. This system will aid in a brief mild day, but
with increasing winds, and eventually a wintry setup along the
Allegheny Front.

Initially focusing on the Alleghenies, the leading edge of the
trough will bring an initial rain/snow mix to start the day on
Wednesday. However, thermal profiles quickly shift over to all
snow along the western slopes of the Alleghenies. Omega fields
are fairly impressive which supports the potential for bursts of
snow showers as this trough axis passes through. The high-
resolution solutions (06Z/00Z NAM nest and 00Z FV3) support
warning-level snow totals across western Pendleton/Grant
counties. Given this signal and rising SLR`s as colder air
arrives, Winter Storm Watches have been issued for 10 AM
Wednesday through 1 PM Thursday. The blustery winds will favor
areas of blowing snow which could lead to significant reductions
in visibility. Ensure to check the forecast at weather.gov/lwx
and weather.gov/lwx/winter before heading out to the Allegheny
Mountains.

Elsewhere, some light precipitation is possible along and north
of U.S. 50, particularly closer to the Mason-Dixon Line,
However, Froude numbers are on the low side (0.50 to 0.75) which
significantly limits the spillover potential. For activity that
does make it out northern Maryland, early morning thermal
profiles would favor a light wintry mix. Any accumulations would
be minimal and focus over the Catoctins. Despite ample clouds,
temperatures warm through the day aided by the breezy southerly
winds around 20 to 25 mph (30 to 40 mph across the mountains).
Highs are forecast to reach the mid/upper 40s, with some low 50s
possible along I-81 and off to the west.

Winds begin to shift to westerly by Wednesday evening as the
cold front tied to the clipper-type system passes through. While
clouds decrease through the night, upslope-aided snow showers
continue along and west of the Alleghenies into Wednesday night
and much of Thursday. Overnight temperatures will be in the mid
20s to low 30s (teens to mid 20s for the mountains). The
blustery conditions should lower wind chills into the single
digits over the higher terrain.

Temperatures return to below average on Thursday behind the
strong cold front. The broad deep upper low across the
northeastern U.S. will also keep some clouds around. As
mentioned earlier, snow showers continue for the Alleghenies
which will further pile up at a number of spots. Conditions over
the Alleghenies should be cold and blustery as Thursday`s highs
remain in the upper teens to 20s. The gusty west-northwesterlies
drop wind chills into the single digits again. Weak high
pressure builds in for Thursday night as lows fall into the
upper teens to 20s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The weather pattern looks to remain cold and active through this
weekend as several fast moving clipper systems cross the region. The
first one on Friday continues to trend weaker and the shortwave
aloft passes just north of the area. As a result, there is only a 20-
40 pct chance for snow showers east of the Alleghenies. However, for
the Alleghenies there is going is likely to be a period of steady
upslope snow showers Friday into Saturday. Several inches of snow
are likely from this event, and Winter Weather Advisories will be
needed if the forecast continues in its current state.

The rest of the area is forecast to be dry on Saturday. Still, it
looks to be blustery and cold as highs only reach the upper 30s to
low 40s, with winds gusting around 20-25 mph.

The next clipper moves through early Sunday morning and looks to
have a better chance for accumulating snow areawide. It is going to
be cold enough for precip to be all snow, and likely stay that way
through the event. Some of the ensembles indicate the possibility of
some mix near/east of I-95 as the system exits (if it lingers into
the afternoon hours).

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
Mainly VFR conditions are expected through Thursday across the
area. Canadian high pressure initially centered over the region
will gradually push offshore today which yields a shift to
southerly winds for the second half of the day. Some elevated
breezes continue into the evening/night with an accompanying
area of southwesterly low-level wind shear (see TAFs).

By Wednesday, southerly winds further increase ahead of a quick
moving clipper-type system. Some brief restrictions are possible
early Wednesday at KMRB as light precipitation tracks through.
Otherwise, most stay dry through the day with southerly gusts to
around 20 to 25 knots. The accompanying cold front races across
the region by Wednesday evening which ushers in a gusty west-
northwesterly wind in the wake. Northwesterly breezes remain
elevated into Thursday as an upper low passes to the north.

Snow showers could produce sub-VFR conditions at times Friday into
Friday night, though coverage of these showers is forecast to be
low. Still, low CIGs may also be a factor that impacts all the
terminals. After that, VFR conditions are expected through Saturday,
though northwest winds could gust around 20-25 knots Saturday
afternoon.

&&

.MARINE...
Small Craft Advisories remain in effect until 6 AM this morning
across the more southern waters. However, there will be a lull
in the action with Canadian high pressure over the area. This
anticyclone center does push offshore later today which aids in
southerly channeling effects by this evening. The uptick in
southerly winds continue into tonight and much of Wednesday
ahead of the cold front. While some gale-force winds are noted
in the column, the combination of cold air on top of cold water
should limit the degree of turbulent mixing.

By Wednesday evening/night, winds shift to westerly behind the
cold front with continued advisory-caliber winds overspreading
the waters. Hazardous marine conditions continue into Thursday
as northwesterlies gust to around 20 to 25 knots.

SCA winds are possible at times Friday afternoon into Friday
night, then strong winds are likely behind a cold front that
moves through by early Saturday. Gale conditions are possible
over most of the waters Saturday afternoon, with high-end SCA
conditions otherwise.

&&

.TIDES/COASTAL FLOODING...
While currrent tidal anomalies are around 0.25 to 0.50 feet,
expect these to rise later today into Wednesday in response to
the shift to southerly flow. This does bring Havre de Grace and
Annapolis into Action stage. However, this is rather brief
before water levels quickly fall behind the strong clipper-type
system during subsequent days.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...Winter Storm Watch from Wednesday morning through Thursday
     afternoon for WVZ501-505.
MARINE...Small Craft Advisory until 6 AM EST early this morning for
     ANZ534-537-543.

&&

$$

SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...KRR
AVIATION...BRO/KRR
MARINE...BRO/KRR
TIDES/COASTAL FLOODING...BRO

NWS LWX Office Area Forecast Discussion