Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

200
FXUS61 KLWX 181828
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
228 PM EDT Sat Apr 18 2026

.WHAT HAS CHANGED...
Upstream observations over the Ohio Valley show that shower
coverage may be a tick or two higher and an hour or two faster
than this morning`s model guidance consensus.

&&

.KEY MESSAGES...
- (1) A cold front crosses overnight into Sunday morning.

- (2) High pressure moves in early next week, with persistent
  cool temperatures and fire weather risk.

- (3) Warming temperatures late next week.

&&

.DISCUSSION...
KEY MESSAGE 1...A cold front crosses overnight into Sunday
morning.

An upper-level trough and corresponding strong surface cold front
will cross the Mid-Atlantic tonight into Sunday morning. There is
not the best overlapping synoptic setup with the surface cold
front being displaced from upper-level trough. Despite this, there
is a decent signal for strong low-level convergence and modest
moisture advection. This leads to intermittent showers through
Sunday morning, exiting east of the Chesapeake Bay by Sunday
afternoon. Cannot rule out a few thunderstorms through this
evening mainly west of the Blue Ridge/Catoctin Mountains. SPC
does have a Marginal Risk (level 1 of 5) for these areas, with a
Slight Risk (level 2 of 5) clipping far western Maryland. The
main threat is gusty winds given steep low-level lapse rates and
moderate flow a few thousand feet AGL, but the threat is
somewhat conditional on if/when convection organizes into a band
over the Ohio Valley. Areas further east are more stable given
onshore flow off nearby cooler waters, lowering thunder
chances. Guidance continues to show some elevated instability
early Sunday morning resulting in the potential for a few
downpours or a clap or two of thunder. Still favoring a gusty
line of showers with the front itself early Sunday morning with
a notable wind shift from S/SE to W/NW; gusts of 40-45 mph are
possible (with around 50 mph possible on the ridges) in a 1- to
3-hour window immediately in the wake of the front.

Once precipitation moves out, NW CAA will bring breezy
conditions Sunday afternoon into evening. High temperatures on
Sunday will be reached early in the day, and are expected to be
15 to 25 degrees cooler than Saturday - a stark contrast to the
recent spell of record heat.

Depending on how much rain falls and how quickly humidity drops,
a fire weather threat could develop mainly west of I-95 Sunday
afternoon. See the Fire Weather section below for details.


KEY MESSAGE 2...High pressure moves in early next week, with
persistent cool temperatures and fire weather risk.

Following a secondary cold front Monday, a strong upper-level
trough and shortwave will pivot overhead. Very cold air at
850-500 hPa will result in very steep lapse rates, with deep
inverted-V profiles noted in forecast soundings up to 8-12 kft.
This will result in wind gusts of 20 to 30 mph as dry low-level
air moves in. Given mid-level moisture and the shortwave, some
cloud cover and a few sprinkles or even a light/brief graupel
shower can`t be ruled out.

High pressure builds overhead Monday night into Tuesday leading
to lighter winds. The cold, dry airmass, clear skies and light
to calm winds Monday night into Tuesday morning are likely to
result in widespread frost/freezing temperatures.

As the high moves offshore Tuesday, winds turn out of the south
beginning the end of the early-week cool spell. Another cold
front will begin approaching from the north late Tuesday night
into Wednesday, but with little moisture to work with.


KEY MESSAGE 3...Warming temperatures late next week.

Temperatures begin to warm to the 70s and 80s in the later half of
next week, with a warm front on Friday pushing highs back into
the mid-80s range for much of the area. Some residual showers
may be possible on Wednesday stemming from low surface pressure
to the north. Thursday and Friday will see significant upper-
level ridging over the region, allowing for relatively light
winds and low rain chances.


&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Winds will remain S/SE into this evening with 15-20 kt gusts at
times. Winds may become a bit lighter and more E especially
further north and east for a time, and LLWS is possible as a LLJ
pivots overhead. SHRA and perhaps TS approach KMRB as early as
00Z, with lesser thunder chances east as precip moves in mainly
after midnight.

An abrupt wind shift to the northwest is expected 06Z-12Z Sun
with FROPA. Some MVFR is possible Sun AM. Gusty winds of 30 to
perhaps 40 kts are possible for a brief time right after FROPA.
Gusts of 20 to 30 kts then linger through Sun eve before lighter
winds overnight. A secondary cold front likely results in 20 to
30 kt gusts again heading into Mon with a spotty shower possible.
Otherwise, VFR Sun night through Tue. Winds shift to S by Tue.

Southerly winds shift northeast by Wednesday night as low
pressure passes to the north and a cold front drops in. Gusts
up to 15 knots are possible across terminals on Wednesday before
gradually decreasing overnight. Northerly winds are expected on
Thursday with VFR conditions across the area.

&&

.MARINE...
Southeast flow will remain gusty this evening, with a bit of a
lull for a time overnight for most waters. Winds will likely
remain elevated over the wider waters off southern MD, though.
An abrupt shift to the northwest is expected between 4 AM and 8
AM Sunday from northwest to southeast, with gusts of 30-40 kts
for a brief time likely necessitating Special Marine Warnings
even if there is little to no precipitation as a strong cold
front crosses the waters.

Showers and gusty winds (SCAs) linger behind the front, with
drying expected by Sunday afternoon. Winds become lighter Sunday
night then increase again Monday with a secondary front. Light
winds Monday night turn southerly Tuesday with additional SCAs
possible by Tuesday night.

Small Craft Advisories may be needed Wednesday morning as winds flow
southerly with gusts up to 20-25 knots before gradually decreasing
later in the day. Winds shift to northerly overnight with winds
on Thursday likely falling below SCA criteria.

&&

.FIRE WEATHER...
While some rain is expected late this evening into Sunday
morning, amounts of a tenth to two tenths on average will not be
sufficient to wet fuels significantly. It should be noted some
hi- res guidance does have localized amounts near a half an
inch, but pinpointing the exact locations of these spotty
amounts is very difficult. Strong gusty winds of 35 mph with
potential for gusts as high as 45 mph will create renewed fire
weather concerns despite marginal humidities and the overall
light rainfall Sunday into Monday. Given the short duration of
precipitation (6 hours or less for most), the 100-hour fuel
moisture values aren`t likely to rise much at all. The 10-hour
fuel moisture likely rises considerably, but drops quickly
through the day Sunday due to the drying effects of strong winds
and rapidly lowering humidity especially west of the Blue Ridge
and Catoctin Mountains.

Much cooler temperatures are expected Monday and Tuesday with a
moderating trend in temperatures expected during the middle and
second half of the week. Strongest winds look to be on Monday out
of the northwest with gusts to 25 mph (30 mph over ridges). For
the rest of the week, winds will be on light side thanks to high
pressure overhead, but humidities will be marginally low to near
critical levels. A dry pattern seems likely to continue with
little to no rainfall.

&&

.TIDES/COASTAL FLOODING...
SE flow will cause tides to rise to around or a little over one
foot above normal through early Sunday morning ahead of a strong
cold front. Minor tidal flooding is possible at several sites
especially for the waters around central to southern MD, with
near moderate flooding possible in a high-end scenario at
Annapolis (though a wind shift to the northwest right around
high tide should prevent that).

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory from 3 AM to 10 AM EDT Sunday for
     MDZ014.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for
     ANZ530>533-535-536-538>542.
     Small Craft Advisory from 6 AM to 6 PM EDT Sunday for
     ANZ530>533-535-536-538>542.
     Small Craft Advisory until 6 PM EDT Sunday for ANZ534-537-543.

&&

$$

DISCUSSION...DHOF/CPB/SRT
AVIATION...DHOF/CPB/SRT
MARINE...DHOF/CPB/SRT