038
FXUS61 KLWX 010801
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
401 AM EDT Thu May 1 2025

.SYNOPSIS...
A stalled frontal boundary remains situated across southern Virginia
through this morning before slowly lifting back north Thursday
evening into Friday morning. A cold front will gradually
approach from the west before moving through late in the
weekend. This frontal zone stalls nearby into the early to
middle portions of next week while multiple waves of low
pressure track along it.

&&

.NEAR TERM /THROUGH TONIGHT/...
GOES-19 nighttime microphysics satellite imagery shows some
uptick in mid-level clouds moving across central Virginia toward
the D.C. metro and southern Maryland. Otherwise, a slew of high
clouds continue to pass by overhead. A seasonably mild air mass
persists early this morning with current temperatures in the mid
50s to mid 60s. Winds have become calm in a number of spots
which has resulted in ample radiational cooling effects. As a
result, these locations that have decoupled have seen
temperatures fall into the low 50s.

Expect a dry start to the day with the stalled frontal zone over
southern Virginia. By this afternoon, this boundary will
gradually return northward as a warm front which results in a
marked increase in low-level moisture content. At the same time,
forcing aloft begins to improve as a shortwave trough
approaches from the Tennessee/Ohio Valleys. Increasing positive
vorticity advection will further augment lift as this system
pushes across the Alleghenies into northern Maryland.

High-resolution models have started to hone in on a more
organized batch of showers and thunderstorms. 6-hour rainfall
totals between 2-8 PM run around 1 to 2 inches across portions
of the eastern West Virginia panhandle into Allegany and
Washington counties. As a result, the Excessive Rainfall Outlook
has been upgraded to a Slight Risk for some isolated flash
flooding threat. Given the relatively dry antecedent conditions
and persistent drought, the focus for any hydrologic issues
should be rather isolated in nature.

Additionally, as this warm front moves across western Maryland,
an isolated severe thunderstorm or two are possible. Presently
damaging winds would be the primary threat with any of the
stronger storms. The remnants of this activity should gradually
cross the Blue Ridge into the metros by the late afternoon to
early evening. With the loss of daytime heating, convective
coverage should diminish into the overnight hours. After
spending the day in the upper 70s to mid 80s, mild weather
persists into the night with low temperatures in the low/mid 60s
(50s for mountain locations).

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
The warm front eventually clears the entire area by Friday
morning. This sets the stages for the warmest day of the year
with forecast highs in the mid/upper 80s. With daily record high
temperatures around 91 degrees, do not expect any records at
this point. A steady wind out of the southwest is expected which
is accompanied by gusts to around 15 to 20 mph. The added
moisture in the atmosphere should help bolster instability
during the peak heating of the day. At this point, activity
should be more isolated to scattered in nature. The pattern
aloft remains southwesterly with some additional perturbations
in the flow possibly further bolstering convective growth.

The timing of the upstream cold front continues to slow given
the blocking pattern over the western Atlantic. While this cold
front was to move through on Friday, the current forecast shows
a frontal passage on Sunday morning. Consequently this keeps the
Mid-Atlantic region entrenched in the warm/moist sector. As a
result, forecast lows on Friday night will be in the low/mid
60s.

Saturday looks very unsettled as a brunt of the longwave trough
moves in from the west. Increasing surface convergence coupled
with anomalous moisture content will make for a wet day across
the area. The chances for rainfall run between 70 and 90 percent
throughout the day. Although clouds will be widespread and limit
instability, the forcing from the trough should at least promote
some thunderstorm development. High temperatures are expected to
be in the upper 70s to mid 80s. However, there is a decent
amount of ensemble spread which suggests temperatures could be a
bit cooler. Shower chances persist into Saturday night with lows
dropping down into the 50s to low 60s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Blocking pattern will result in ULL stalling and spinning over the
Ohio Valley/Mid-Atlantic through much of the long term. This will
result in daily shower and thunderstorm chances, with some days
having higher chances depending on placement of ULL and associated
features. Ensemble probabilities for 1 and 2 inches of rain continue
to increase through the long term, but probabilities for 4 inches
remain low at this time. Given the ongoing drought (IAD is down
nearly 33" going back to 2021), hopefully this rain is more
beneficial than problematic. Still a bit of uncertainty on how
quickly the ULL pulls away midweek.

Temperature wise, below average daytime highs are expected with lows
a few ticks above average due to forecast cloudcover. This results
in 60s for most for highs (50s mtns), with 50s for lows (40s in
mtns).

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
VFR conditions are expected through most of the day with initial
winds mainly light and out of the east-southeast. A stationary
boundary currently over southern Virginia should slowly lift
northward as a warm front over the next 24 to 30 hours. As this
occurs, shower and thunderstorm chances increase, especially for
the western terminals (i.e., KMRB and KCHO). At this point, the
most likely area to see a thunderstorm would be KMRB where a
PROB30 group is highlighted between 20Z-00Z. Some restrictions
are possible as this activity moves through. Winds eventually
turn more southerly to perhaps south-southwesterly later this
evening into the night.

The warm front clears the area by early Friday, with mainly
south to southwesterly flow persisting on Friday into Saturday.
Mainly VFR conditions are expected on Friday before wetter
weather arrives on Saturday. Restrictions are looking likely due
to the soaking rain.

MVFR to IFR conditions at all terminals possible with showers and
thunderstorms Sunday into Monday night. Northerly winds Sunday
become more easterly by the second half of Monday. Winds generally
less than 15 kts outside of any thunderstorms.

&&

.MARINE...
A stationary boundary over southern Virginia will gradually lift
northward as a warm front later this afternoon and evening. This
eventually shifts winds from east-southeasterly to mainly
southerly. A mainly south to southwesterly wind can be expected
tonight through Friday and into the first half of the weekend.
There will be some ramp ups in the wind at times which may lead
to Small Craft Advisories at times. However, there is some
uncertainty in when the peak would be.

Showers and thunderstorms are possible each day, with the most
widespread activity coming on Saturday ahead of a slow moving
cold front.

Northerly winds expected Sunday with gusts largely below SCA
criteria. Winds become easterly Monday and remain below SCA
criteria.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...CPB
AVIATION...BRO/CPB
MARINE...BRO/CPB

NWS LWX Office Area Forecast Discussion