Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

078
FXUS61 KLWX 211503
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1003 AM EST Wed Jan 21 2026

.WHAT HAS CHANGED...
Snow totals increased slightly for the Alleghenies this
afternoon and through Thursday morning. No other changes were
made to the forecast with the threat for a significant winter
storm remaining for the weekend.

&&

.KEY MESSAGES...
- 1) Confidence of a significant winter storm across the region
  remains high Saturday into Sunday, but confidence in exact
  amounts of snow versus ice is lower especially south and east.

- 2) Frigid temperatures are looking like a virtual certainty
  this weekend into early next week.

- 3) Accumulating snow over portions of the Alleghenies late
  this afternoon through Thursday morning.

&&

.DISCUSSION...
KEY MESSAGE 1...Confidence of a significant winter storm across
the region remains high Saturday into Sunday, but confidence in
exact amounts of snow versus ice is lower especially south and
east.

Ingredients are coming together to produce a significant winter
storm across the region this weekend. Based on the latest
guidance, wintry precipitation (snow) may arrive as early as
Saturday morning for west-central VA before spreading east and
northeast slowly through the day. Snow then continues Saturday
night into Sunday morning, then could mix with sleet and
freezing rain for some areas Sunday into Sunday night. While
deterministic guidance continue to show some run-to-run
variability, the overall trend has been bringing the higher
QPF amounts toward central Virginia, with a potential for mix
wintry precipitation Sunday afternoon and night. In a multi-
day sense, global ensemble probabilities remain very high for
seeing 6+ inches of snow. This comes with the presumed snow-
to-liquid ratio of 10:1 which this system will not be given the
Arctic nature of the air mass. Ratios could be considerably
higher yielding a fluffier snow. With the parent features still
across the more barren high latitudes, models may take another
day or two to resolve such features with better precision (note:
recon flights are expected to take place near the Southwest
CONUS later today - that`s where models have been most sensitive
to changes, so hopefully this additional data will help hone in
on details). The details will be important in determining any
precipitation type transitions. However, given the very cold air
locked in at and near the surface with strong Arctic high
pressure anchored firmly to our north, plain rain is highly
unlikely anywhere in the region. It will therefore come down to
snow versus ice, both of which could be significant and highly
impactful across a widespread area.

On the synoptic pattern side of things, many ingredients are in
place to produce the mentioned winter storm. On Saturday, Arctic
high pressure (1045-1050 mb) across the Midwest eventually
reaches New England by the evening as a still robust 1040 mb
anticyclone. This yields the familiar cold air damming wedge
setup which stretches down into the southeastern U.S.

Looking aloft, a split jet structure is evident with deep cyclonic
flow in the northern stream and a progressive feature ejecting out
of the Four Corners (this is the feature that introduces the
most uncertainty/model variability). The downstream confluent
flow will aid in ample forcing in the form of overrunning across
vast portions of the central/eastern U.S. While the main
surface low sweeps across the Gulf Coast states, a broad area of
isentropically driven precipitation spreads over the frigid air
mass to the north. Based on the latest guidance and trends,
precipitation type issues could arise Sunday/Sunday night. An
energy transfer eventually unfolds Sunday afternoon/evening
which focuses to deepening low pressure off the Outer Banks
of NC. Eventually, this features pulls away from the coast late
Sunday night which gradually brings the brunt of the
precipitation to an end, though some light precipitation
(perhaps freezing drizzle east/upslope snow showers west) could
linger into Monday morning.

With the system not arriving until Saturday evening sometime, now is
the time to prepare for this winter storm. Check back at the office
website (weather.gov/lwx) as well as the winter page as the system
moves into the Day 1-3 period (weather.gov/lwx/winter).


KEY MESSAGE 2...Frigid temperatures are looking like a virtual certainty
this weekend into early next week.

As mentioned in the winter storm section, Arctic high pressure takes
charge over the weekend which yields frigid temperatures across the
area. On Saturday, forecast 850-mb temperatures range from -15 to
as low as -20C which even dry adiabatic mixing would keep
surface temperatures below freezing. However, given the time of
year and the fact 1000-850 mb winds are northerly, mixing
largely tops out around 900 mb. With that said, Saturday`s high
temperatures should struggle to escape the teens in most spots,
with a few low 20s possible across far southern Maryland. Along
the Allegheny Front, single digits are likely all that can be
mustered. As snow comes in Saturday night, this will fall amidst
temperatures in the single digits to lower teens.

While a small increase in temperatures is expected on Sunday, it
will likely not be noticeable with area-wide highs in the mid-teens
to low/mid 20s. As precipitation tapers Sunday night, the
forecast calls for overnight lows in the single digits to lower
teens. Looking ahead into the next work week, frigid conditions
should persist. Depending on the degree of snowpack, the
forecast may even be too optimistic in terms of "warmth". While
daily highs next week are to push into the 20s, all could see
low temperatures in the low/mid single digits on certain nights.
Given elevated winds overnight, some locations along the
Allegheny Front could see wind chills fall into the negative
teens, with wind chills falling into the single digits on either
side of 0F across much of the rest of the area.


- 3) Accumulating snow over portions of the Alleghenies late
  this afternoon through Thursday morning.

A warm front will lift into the area through Thursday with a
cold front to follow Thursday night. This series of fronts will
deliver a period of accumulating upslope snow showers/squalls
across the Alleghenies late this afternoon into early Thursday
morning. Elsewhere, dry conditions are expected with moderating
temperatures and breezy conditions. Highs today will push back
into the mid 30s and low 40s after starting in the upper single
digits and low to mid teens. Temperatures warm even more
Thursday with widespread highs in the mid 40s and low 50s east
of the Alleghenies under increased south/southwest flow.

As for snow in the Alleghenies, totals are a bit in flux with
marginal temperature profiles. The 12Z guidance increased from
guidance overnight with 3-5 inches of snow expected along the
highest elevations in western Garrett County. With the threat of
freezing rain, a Winter Weather Advisory will likely be issued
later this morning to accommodate the threat. Precip should mix
with rain below 2500 feet at the onset into this evening with
all snow expected during the overnight period into Thursday
morning. Snow to liquid ratios look to remain at 6-10:1
increasing to 10-12:1 during the peak of the event. The bulk of
the snow looks to fall during the warm frontal passage with
upslope snow showers and perhaps a few squalls lingering into
Thursday morning as a weak cold front swings through. Some
instability has also been noted in the DGZ leading to the
potential for near advisory- level snow in far western portions
of Garrett Co. (west of the Eastern Continental Divide) and down
into portions of western Grant Co. These locations could see
localized 2-4" of snow along western favored slopes above 2800
feet (i.e Keysers Ridge, Piney Mountain, Hoyes Crest/Backbone
Mountain), with a bit lesser amounts at lower elevations due to
marginal temperatures. Confidence is too low for an advisory at
this time. Expect slick travel and delays along I-68/US-40 west
of Frostburg, MD and US-219 from the MD/PA line to WV line late
this evening through Thursday morning. Further east downsloping
will eat away at any precipitation chances outside of a rogue
snow shower pushing toward the Catoctins/northeast MD and
eastern WV panhandle as the front lifts through this evening. No
accumulation is expected at this time east of the Alleghenies
as plenty of dry air will be hard to overcome east of the
mountains (plus again, marginal temperatures). With the series
of fronts pushing, through expect wind gusts around 25-35 mph
with gusts up to 40 mph along the ridges. Winds will gradually
decrease Thursday night into Friday. There is a small chance
some of the higher peaks of the Alleghenies near Wind Advisory
criteria tonight into Thursday (i.e. 45-50 mph gusts).

The next chance of wintry precipitation arrives Friday,
especially in locations south of I-66/US-50. This is due largely
in part to strong isentropic lift/warm air advection ahead of
the southern stream upper-level low. This could lead to
overrunning precipitation in the form of light snow or even a
light wintry mix (rain/snow/sleet) across the central VA
piedmont and Northern Neck. Confidence in this remains low at
this time given recent model trends. Even with that said, it is
something to watch given the dynamical setup in place before the
main event this weekend. Highs Friday range from the teens over
the mountains to mid 30s and low 40s east.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will continue through Friday morning as surface high
pressure shifts offshore and a series of moisture-starved
fronts push through. The biggest concern for aviators will be
the wind, especially heading into the midweek period. Expect
southerly winds to gust 20 to 30 kts outside the mountains as a
warm front lifts through this afternoon. These winds will
slacken a bit tonight with LLWS likely this evening given 30-50
degree directional shear and 40-50 kts at 2kft ALG. Winds will
increase again Thursday ahead of an approaching Arctic cold
frontal boundary. Expect 15 to 25 kt gusts Thursday out of the
west and southwest. Winds will turn back to the northwest
Thursday night into Friday with gusts less than 15 kts expected.

A light rain/snow mix could impact terminals across central and
southern VA Friday although confidence is low at this time.
Skies begin overcast on Saturday morning, but any snow should
not commence until around Saturday evening. As ceilings lower
through the day, expect restrictions to kick in ahead of this
swath of snowfall. At that point, expect a lengthy period of IFR
caliber conditions Saturday evening/night and into all of
Sunday. Given the degree of cold air in place, this should be
all snow to start, though there are hints of an icy mix by later
Sunday, especially south and east.

Initial winds will be out of the northwest on Saturday morning
before shifting to the north to northeast through the day as Arctic
high pressure builds across New England. For Sunday, winds largely
remain northerly as low pressure eventually develops off the North
Carolina coast later in the day. Gusts each day over the weekend
should top out around 10 to 15 knots, perhaps slightly higher in
the metros.

&&

.MARINE...
SCA conditions return this afternoon and night under southerly
channeling. Gusts of 20 to 25 kts are expected at this time.
Highest gusts look to be over the open waters of the Chesapeake
Bay/lower tidal Potomac River. Winds will fall back below SCA
levels for most of the waters Thursday into Thursday night under
westerly flow. This will continue Thursday night into Friday.
Additional SCAs will likely be needed Friday night, and near
gale-force can`t be ruled out in strong northerly channeling.

With Arctic high pressure pushing from the Midwest toward New
England on Saturday, northerly winds will remain elevated
across the waters. Channeling effects look to continue which
may require Small Craft Advisories, especially across the wider
waters on Saturday morning.

After a brief lull as winds shift to northeasterly, gradients
increase again on Saturday evening/night yielding additional 20 to
25 knot gust potential. These blustery winds continue into Sunday as
winds turn northerly. Widespread snow impacts the waters Saturday
evening through most of Sunday, an icy mix possible Sunday
afternoon and night. There could even be freezing spray given
the frigid nature of the air mass and elevated wind fields.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 5 AM EST Thursday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 5 AM EST Thursday for ANZ530>543.

&&

$$

DISCUSSION...AVS/BRO/DHOF/EST
AVIATION...BRO/DHOF/EST
MARINE...BRO/DHOF/EST