448
FXUS61 KLWX 240129
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
929 PM EDT Sat May 23 2026

.WHAT HAS CHANGED...
While there may still be a round of heavier showers and perhaps
an isolated thunderstorm along and east of the Blue Ridge
tonight, recent QPF trends suggest any amounts over a half inch
should be isolated at best. Ramped up the fog wording in the
forecast through Sunday morning, especially across western
areas where the low clouds will be intercepting the terrain.
Portions of the Small Craft Advisory will likely be cancelled by
the end of the evening.

&&

.KEY MESSAGES...
- 1) Wet, cool Holiday Weekend continues.

- 2) Chances for showers and thunderstorms persist through much
  of next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Wet, cool Holiday Weekend continues.

The eastern U.S. remains within a pronounced cold air damming
(CAD) wedge signature. The latest surface analysis depicts
robust high pressure (1035 mb) across Maritime Canada while a
frontal zone arcs along the Carolina coast up along the
Appalachians back into the Ohio Valley. This familiar setup has
supported continued east to northeasterly onshore flow across
the region. Given it is late May, the ocean waters remain on the
cooler side which has supported these well below average
temperatures.

The southwesterly flow aloft continues to steer a series of
shortwaves from the southern U.S. toward the local area. While
the current radar mosaic shows mainly light activity, the
expectation is for a ramp up to occur late tonight as the
frontal zone returns northward as a warm front. In particular, a
wave of low pressure forms along this boundary which will
locally augment vertical motions. The 12Z high-resolution
guidance continue to paint some locally heavier elements
impacting a location somewhere between the D.C. and Baltimore
metros. However, 18Z/later QPF forecasts suggest amounts well
under an inch through Sunday morning, so an isolated flood
threat seems to be declining. Will have to monitor however as
rain processes should be efficient given precipitable water over
1.5 inches and warm cloud depths of 3500-4000 m. Otherwise, a
seasonably cool night lies ahead with lows in the upper 40s to
50s. Some patchy fog is possible in areas that see a break in
the rainfall, although lowering stratus and mist will likely
reduce visibility everywhere. Eastern facing ridges will likely
remain stuck with dense fog.

By Sunday morning, the warm front is forecast to be located
along the Virginia/North Carolina border while arcing up into
central West Virginia. Expect a continuation of warm advection
aided rain through the morning into the early afternoon. There
might be further breaks in the action as this front nears U.S.
50 during the afternoon/evening hours. While the entire region
should not get into the warm/moist sector, many locations should
push into the low/mid 70s. As this occurs, any cloud breaks
could yield some shower or thunderstorm development. However,
confidence is low given the continued low clouds. With such
clouds in the forecast, low temperatures on Sunday night drop
into the mid 50s to low 60s.

While Memorial Day is looking unsettled, do not expect a
complete washout. The north to south oscillating front is likely
to pull well north of the Mid-Atlantic region on Monday. Unlike
preceding days, some peeks of sunshine are possible which would
lend itself to a mostly cloudy forecast. High temperatures are
forecast to reach the mid 70s to low 80s, coupled by dew points
in the upper 60s to low 70s. This combination supports a humid
feel to the air which comes with the threat of diurnally forced
showers and thunderstorms. Any severe threat would be minimal
given the lack of vertical shear.


KEY MESSAGE 2...Chances for showers and thunderstorms persist
through much of next week.

A split flow regime is forecast to develop across the CONUS by
Tuesday, with high amplitude ridging over the Northern
Plains/Canadian Prairies and troughing much further to the south
across the Lower Mississippi Valley and Northern Gulf. These two
streams will converge again just to our north over New England. Such
a pattern will result in a diffuse surface boundary becoming stalled
out across the Mid-Atlantic. Showers and thunderstorms are expected
to form on Tuesday, Wednesday, and potentially Thursday as well in
an environment characterized by deep moisture through the column,
with surface dewpoints near 70.

As we move toward the end of the week, a deep trough and embedded
upper low are forecast to drop nearly due southward from near
Hudson Bay toward the Mid-Atlantic. Various sources of model
guidance differ with respect to how quickly this trough will dive
southward. A surface cold frontal passage associated with this
trough will likely occur during this time as well, with most
solutions show it passing through later Thursday night into Friday
morning. Northerly flow behind the front should clear out the low-
level moisture, dropping dewpoints into the 40s or 50s. More in the
way of sunshine and cooler temperatures are expected behind the
front by Friday, although there are still a few ensemble members
that hold the front up to our north, keeping us in the deeper
moisture. If such a solution were to occur, we`d see more in the way
of cloudy conditions, with continued chances for afternoon showers
and thunderstorms.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
A cold air damming signature persists which has favored a
prolonged period of east to northeasterly onshore flow. The
combination of low stratus and passing bands of rain will
maintain IFR conditions into the night with the potential for
LIFR conditions at times, particularly in areas that see a few
breaks in the rain. This is most likely to occur toward daybreak
as some moderate showers will push across the area overnight.
And isolated thunderstorm is possible across the metro areas,
but the chance is too low to include in the TAF. The combination
of drizzle and lowering stratus could reduce visibility below a
mile at times as well.

The first half of Sunday remains unsettled with additional rain
chances and continued low clouds. Some dry time is possible for
the second half of Sunday as ceilings recover to MVFR for
portions of the area. BWI/MTN/MRB in particular could remain
IFR all day. Any lifting ceilings will likely be somewhat short
lived as ceilings lower into Sunday night which may come with
patchy fog. Some heavier showers and perhaps a thunderstorm
could approach the area later Sunday evening.

The warm front clears the area by Monday with some improvements
possible. Some showers and thunderstorms may develop with
daytime heating. These could yield some restrictions across the
terminals. Gradients are rather weak so winds will be variable
at times.

Sub-VFR ceilings may be possible at times on Tuesday and
Wednesday. Winds are expected to be light and variable, and an
afternoon thunderstorm can`t be ruled out either day.

&&

.MARINE...
The combination of robust high pressure across New England and a
wavy frontal zone over the southeastern U.S. supports a
continued east to northeasterly wind. Small Craft Advisories
remain in effect across all waters through early Sunday morning.
The strongest winds are across the northern bay, and there may
be a bit of a ramp up later this evening as low pressure lifts
up from southeastern Virginia. Winds will be tapering off from
south to north however, and the advisory will likely be
cancelled for at least the middle/upper Potomac by late evening.
Gradients weaken quite a bit for the remainder of Sunday into
early portions of next week. Thus, outside of impacts from
showers and thunderstorms, the background winds stay below
advisory levels.

Light and variable winds are expected over the waters on both
Tuesday and Wednesday. A few stronger gusts may be possible either
afternoon if thunderstorms track over the waters.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 6 AM EDT Sunday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Sunday for ANZ530>543.

&&

$$

DISCUSSION...ADS/BRO/KRR
AVIATION...ADS/BRO/KRR
MARINE...ADS/BRO/KRR

NWS LWX Office Area Forecast Discussion