654
FXUS61 KLWX 202356
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
756 PM EDT Mon Apr 20 2026
.WHAT HAS CHANGED...
No significant changes to the forecast this evening. Winds will
slowly subside before midnight. Freeze Warnings go into effect for
most of the region outside of the Alleghenies early Tuesday morning.
Additional light rain chances and warming temps mid to late
week.
&&
.KEY MESSAGES...
1) Widespread freeze late tonight into Tuesday morning as high
pressure builds over the region.
2) Warming temperatures mid to late week with additional rain
chances possible this weekend.
&&
.DISCUSSION...
KEY MESSAGE 1...Widespread freeze late tonight into Tuesday morning
as high pressure builds over the region.
The upper level trough and secondary cold front responsible for the
gusty graupel showers earlier this morning/afternoon continues to
push offshore this evening. Breezy conditions remain with gusts out
of the northwest at 15 to 30 mph. Winds will slowly decrease prior
to midnight setting us up for a widespread freeze heading into early
Tuesday morning.
Canadian high pressure builds over the region late tonight into
Tuesday leading to lighter winds (less than 15 kts) across the
region. This will lend to a perfect radiational cooling set up with
clear skies and lightening winds allowing temps to fall. Widespread
freeze conditions are expected for most of the area aide from the
major urban centers and areas directly influenced by larger bodies
of water. Some frost may also be noted, but given some elevated wind
and ample dry air in place, the threat may be limited.
For context, this is ~10 days past the median date of the last
spring freeze based on 1991-2020 climatology for areas along/east of
I-81. Given the warmth early this spring, many areas are ahead of
schedule from a growth stand point, so this freeze could be
rather impactful.
There are no frost/freeze headlines for the Alleghenies as the
growing season has not started there yet.
KEY MESSAGE 2...Warming temperatures mid to late week with
additional rain chances possible this weekend.
As Canadian high pressure slides off toward the south, a quick
moving cold front will cross the region by mid-week (late Tuesday
night into Wednesday). There will not be a whole lot of moisture to
work with, so any rainfall amounts are likely to be meager in nature
(less than a 0.10"). Some instability in the atmosphere could
produce a few thunderstorms, particularly during the afternoon
hours. A lack of stronger forcing, shear, or instability should lead
to generally weak convection, though some spotty downpours, gusty
winds, and small hail can`t be ruled out.
After a chilly start to the work week, ensembles agree on a
warm up through the middle to latter portions of the week. High
temperatures could push back into the low/mid 80s by Friday
ahead of another system likely to bring a return of rain by the
second half of Friday. A threat of showers continues through
much of the weekend before the frontal system exits east of the
region by late in the weekend. On Sunday, the latest forecast
package calls for highs returning to the 60s. This eventually
all lends itself to a cooler finish to the month of April.
However, there is uncertainty in the evolution of low pressure
approaching the area by then, and just how the temperature and
precipitation forecast pans out. The good news is that rain chances
are back in the forecast given the expanding drought and elevated
fire weather concerns across the region.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
High level scattered to broken clouds continue to diminish
as the secondary front/upper trough push offshore. Some upslope
clouds remain along the Alleghenies in northwest flow with FEW-SCT
stratocumulus north and east of KIAD/KDCA. All terminals will flip
over to SKC conditions later this evening ands into tonight with
high pressure building overhead. It will be rather chilly tonight
with a widespread frost/freeze possible early Tuesday morning across
all terminals as high pressure settles overhead.
VFR conditions continue Tuesday through Friday. Some temporary
sub- VFR conditions are possible with a weak cold front
Wednesday. The front could bring brief -SHRA/-TSRA at the
terminals Wednesday morning into Wednesday afternoon. Locations
down around KCHO may see nothing at all. Winds shift to the
south Tuesday at less than 15 kts with southwest winds ahead of
the front Wednesday switching back to the northwest Wednesday
afternoon. Gusts Wednesday will remain between 10 to 20 kts.
Some LLWS also possible west of the corridor Tuesday night as
southerly flow increases ahead of the boundary.
Additional WAA showers are possible by Friday afternoon which
could be accompanied by a few restrictions. Initial winds will
be out of the NW on Thursday before becoming mainly westerly on
Friday. A shift to southeasterly is possible by Friday night.
More shower chances with temporary sub-VFR reductions are
possible this weekend.
&&
.MARINE...
High pressure builds overhead late tonight into Tuesday. Light winds
tonight turn southerly Tuesday with additional SCAs possible
late Tuesday into Wednesday due to southerly channeling. Sub-SCA
level winds are expected late Wednesday with winds out of the SW to
NW as a cold front crosses. This front may bring a few showers and
thunderstorms mainly Wednesday afternoon.
Expect sub-advisory level winds for both Thursday and Friday.
Weak gradients will favor multiple wind shifts before turning
mainly S/SE by Friday night.
SCA conditions return for portions of the waters this weekend.
&&
.FIRE WEATHER...
Much cooler temperatures are expected through Tuesday with a
moderating trend in temperatures expected during the middle and
second half of the week. Winds will be on light side starting
tonight thanks to high pressure overhead, but humidities will be
marginally low to near critical levels. The next potential for
rainfall is Wednesday into Thursday (mainly north of I-66/US-50),
but amounts look light.
Special Weather Statements may be needed for portions of the
Shenandoah Valley and central VA Piedmont Tuesday afternoon.
Elsewhere, winds should remain light enough to reduce fire weather
concerns.
&&
.TIDES/COASTAL FLOODING...
Southerly flow is expected Tuesday into Tuesday night. This will
result in rising tidal anomalies. The higher members of P-ETSS
and SFAS, as well as STOFS and CBOFS all hint at the potential
for minor flooding at Annapolis early Wednesday as a result.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Freeze Warning from 2 AM to 10 AM EDT Tuesday for DCZ001.
MD...Small Craft Advisory until 9 PM EDT this evening for MDZ008.
Freeze Warning from 2 AM to 10 AM EDT Tuesday for MDZ003>006-
008-011-013-014-016>018-503>508.
VA...Freeze Warning from 2 AM to 10 AM EDT Tuesday for VAZ025>031-
036>040-050-051-053>057-501-502-505>508-526-527.
WV...Freeze Warning from 2 AM to 10 AM EDT Tuesday for WVZ051>053.
MARINE...Small Craft Advisory until 9 PM EDT this evening for ANZ530-
531-535-536-538>540-542.
Freeze Warning from 2 AM to 10 AM EDT Tuesday for ANZ530.
Small Craft Advisory until 4 AM EDT Tuesday for ANZ532>534-537-
541-543.
&&
$$
DISCUSSION...DHOF/KJP
AVIATION...DHOF/KJP/EST
MARINE...DHOF/KJP/EST
NWS LWX Office Area Forecast Discussion