Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

312
FXUS61 KLWX 171126
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
626 AM EST Sat Jan 17 2026

.WHAT HAS CHANGED...
Latest observations as of early this morning as well as latest
model guidance indicate a bit slower and stronger front that
gets hung up near the area tonight into Sunday. Meanwhile, the
wave headed up from the South is a little quicker, and this
combination may result in more lift/moisture further west. Stay
tuned for further updates later this morning.

&&

.KEY MESSAGES...
- 1) An Arctic outbreak is likely early next week, with near to
  below normal temperatures continuing through the remainder of
  the week.

- 2) Multiple disturbances will bring snow to parts of the area
  through Sunday.

&&

.DISCUSSION...
KEY MESSAGE 1...Multiple disturbances will bring snow to parts
of the area through Sunday.

System number 1 will push across the area today. WAA ahead of
this wave (anchored by low pressure over the Great Lakes)
resulted in a coating to a couple inches of snow overnight over
far western MD down along and west of the Allegheny Front into
eastern WV (highest in NW Garrett Co. MD). Another round of snow
is expected through mid to late morning, before becoming more
showery and intermittent in nature this afternoon and possibly
into this evening. Will need to continue to closely monitor
extent of snow showers later today (possible advisory extension)
and southward extent (possible advisory expansion). Although the
steadiest snow is expected this morning, some shower/squall
potential exists tonight in more favorable upslope low-level
flow with modest CAPE into the DGZ.

Farther to the east, waves of low/mid-level fgen paired with
modest jet forcing aloft looks to produce a narrow band of
precipitation mainly this morning. The greatest lift and
therefore focus looks to be over north-central Maryland.
Temperatures are colder here, with a coating to an inch or two
of snow most likely over the higher elevations near the PA line.
Have issued an SPS to cover this given the relatively small
spatial area of impactful snow potential.

Elsewhere, a few rain/snow showers are possible this morning as
the frontal system pushes through. Most members of the 00Z HREF
actually indicated a ribbon of light freezing rain between the
Blue Ridge Mountains and US-29. However, given southerly flow
and rapidly rising dew points (nothing locking cold air in and
steadily rising wet bulbs), figured this threat was low enough
to essentially leave out of the forecast. Can`t rule out some
spotty rain/sleet mix around 32 F but impacts should be little
to none, especially given the light and spotty nature of it.

System number two - a shortwave diving into the Deep South
(rounding the base of a trough to the west a bit quicker this
morning) - will begin to take aim at the Mid-Atlantic late
tonight. Model guidance overnight has come into much better
agreement with the amplitude of the upper wave, and the track
and strength of surface low pressure moving up off the coast,
tucking it a bit closer thanks to a linger low-level frontal
zone. This increases confidence in some light snow or a
rain/snow mix (depending on boundary layer temps) on Sunday,
mainly east of the Blue Ridge. The most likely scenario is for
a light coating of snow mainly on grassy and elevated/untreated
surfaces. The hourly temp forecast indicates mostly above
freezing (mid 30s), but 30-32 F is more likely in areas/brief
periods of any steadier precip. A reasonable high-end snowfall
forecast would paint a few inches near/east of US-15, but the
ceiling doesn`t appear much higher than that given the quick-
moving nature of the system and marginal surface temps.

KEY MESSAGE 2...An Arctic outbreak is likely early next week,
with near to below normal temperatures continuing through the
remainder of the week.

A reinforcing Arctic front will cross the Mid-Atlantic Monday.
This may bring a few snow showers to the Alleghenies, but the
bigger story will be the very cold weather in its wake.

Temperatures will crash into the single digits along and west of
the Blue Ridge/Catoctin Mountains by daybreak Tuesday, with low
to mid teens to the east. Combined with 10-20 mph blustery northwest
winds (20-30 mph at higher elevations), this will send wind
chills into the single digits for most south of I-70 and east of
the Blue Ridge Mountains, with single digits below zero likely
over northern MD and along/west of the Blue Ridge Mountains.
Wind chills of 15 to 30 below zero are anticipated over the
Appalachians by early Tuesday morning.

Not much of a "warm-up" is expected during the day Tuesday.
Temperatures in the lower to middle 20s Tuesday afternoon are
about 15 degrees below average for this time in January. Dry
conditions are anticipated throughout the day Tuesday through
Wednesday night. The transition to milder temperatures will be
from Tuesday into Wednesday as high pressure moves to the east
and a southerly flow develops helping to modify the air. Highs
Wednesday may still be a few degrees below average but only by
about 3 to 5 degrees.

With the high pressure shifting farther to the east Wednesday
into Thursday, this makes way for an approaching cold front from
the northwest Thursday into Friday. Models tend to show this
front aligned more east-northeast to west-southwest versus
north-northeast to south-southwest. This indicates that the
front may not have much of a fast push through our region, but
rather slide or sink across our area as reinforcing Arctic air
tries to move in from the northwest. The timing and temperatures
may mean everything Thursday into Friday with regards to wintry
precipitation or liquid precipitation and whether the front
pushes through Thursday, Thursday night, or Friday. Moisture is
obviously needed to get precipitation, which shouldn`t be an
issue given the return of southerly winds into the front. Model
consensus reveals the front does move through the area toward
the southeast, but there is uncertainty as to when. Either way,
we need to anticipate the possibility of wintry precipitation
at some point with this front later in the upcoming week or next
weekend. Temperatures should modify even more into the upper
30s to lower 40s on Thursday ahead of the frontal passage.
Friday`s temperatures appear to be colder and becoming below
average once again with the possibility of light wintry
precipitation.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
A brief period of MVFR or even IFR conditions is possible
across northern terminals (especially KBWI/KMTN) roughly 18Z
from west to east as a band of precip (-SN or -RASN) pivots
across. A few ice pellets can`t be ruled out, but it should
mainly come down to snow vs rain. S/SW winds today becoming W/NW
tonight mainly AOB 10 kts (though some 15-20 kt gusts are
likely 15Z-22Z or so; can`t rule out a couple of PK WND obs a
little over 25 kts around midday).

Low pressure passing up along the coast will likely bring a
little snow or a rain/snow mix mainly to the I-95 terminals
Sunday, though there has been a westward shift. Some light
accums and at least brief reductions are becoming increasingly
likely, though temps will be marginal and the system will be
fast-moving so it may still be a stretch to get anything
widespread "plowable". N/NW winds may briefly gust to around 15
kts Sun PM as the low pulls away.

Blustery and cold conditions are expected early next week as a
reinforcing Arctic front pushes across. Winds may gust 20-25 kts
Monday shifting from S/SW to W/NW.

VFR conditions are expected Tuesday through Wednesday night.
Winds Tuesday will be NW 5 to 10 knots, becoming SW 5 to 10
knots Wednesday.

&&

.MARINE...
South to southwest winds will gust 15-20 knots this morning,
increasing a bit late this morning into this afternoon with
gusts of 20-25 knots. By late afternoon, winds are expected to
diminish as a cold front moves through. A period of light snow
or a rain/snow mix is possible especially near the upper tidal
Potomac River and the upper Chesapeake Bay this morning into
early afternoon.

Lighter northwest winds are anticipated in the wake of the front
tonight, with a slight uptick possible for a time Sunday
afternoon and evening as low pressure passes offshore. This low
is expected to bring light snow or a rain/snow mix, which will
reduce visibility over the waters on Sunday.

Blustery and very cold conditions are expected early next week.
SCAs are likely Monday into Tuesday as SW winds turn NW. SCAs
are possible again Wednesday in southerly flow.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Winter Weather Advisory until 4 PM EST this afternoon for
     MDZ509.
VA...None.
WV...Winter Weather Advisory until 4 PM EST this afternoon for
     WVZ501.
MARINE...Small Craft Advisory until 4 PM EST this afternoon for
     ANZ530>534-537>543.
     Small Craft Advisory until 4 PM EST this afternoon for ANZ535-
     536.

&&

$$

DISCUSSION...KLW/DHOF
AVIATION...KLW/DHOF
MARINE...KLW/DHOF