006
FXUS61 KLWX 081933
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
333 PM EDT Mon Sep 8 2025

.SYNOPSIS...
Canadian high pressure will build in from the west today before
settling north of the area by the middle of the week.
Meanwhile, a wave of low pressure passes offshore around mid-
week. A dry cold front will cross the region Thursday,
reinforcing below normal temperatures and a continued dry
stretch. Canadian high pressure will return for the end of the
week into this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Expansive Canadian high pressure at the surface has parked over
the Great Lakes into the northeastern U.S. At the same time, a
stalled frontal zone stretches from near the Gulf Stream down
through northern Florida into the Gulf of America. Combining
these synoptic features has allowed for prevailing dry northerly
winds over the Mid-Atlantic region.

The lack of moisture is evident in multiple water vapor
channels as well as surface observations. After seeing a daily
record for lowest precipitable water on the 12Z IAD sounding,
very little has changed since then. Early afternoon dew points
have fallen into the upper 30s to mid 40s, coupled by
temperatures in the upper 60s to low 70s. Given continued late
summer surface heating, expect temperatures to rise another few
degrees underneath mainly sunny skies. Any cloud cover is
restricted to shallow cumulus fields mainly south of U.S. 50.

High pressure maintains its influence on the local weather with
a chilly and dry night ahead. A lack of clouds and wind should
afford a decent radiational cooling night. Tonight`s low
temperatures are forecast to drop into the mid 40s to low 50s,
locally in the mid 50s across the urban centers and near the
Chesapeake Bay. For portions of the Alleghenies and low-lying
areas across the Shenandoah Valley, some low 40s are looking
possible as well. Any frost development should be very localized
given the marginal temperatures.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
A few changes begin to unfold on Tuesday into Wednesday. A broad
elongated upper trough will push eastward from the Mississippi
River Valley. Along the southern extension of this trough will
be a more defined shortwave that tracks along the mentioned
stalled frontal zone. As showers break out near this boundary,
southwesterly flow aloft will begin to increase high clouds over
areas along and east of I-95. Clouds might be a tad more
concentrated over southern Maryland given closer proximity to
any such showers. Also expect an uptick in northeasterly winds
given the increase in large-scale pressure gradients. Gusts up
to 15 to 20 mph are possible during the day, especially closer
to the Chesapeake Bay. High temperatures are forecast to push
into the low/mid 70s, with mainly 60s over the higher terrain.

As the wave of low pressure traverses the frontal zone, the 12Z
high-resolution model suite shows some activity pivoting back
toward southern Maryland Tuesday evening into Wednesday morning.
The one issue working against showers reaching the ground is the
extensive dry air in place. A few models show hints of
saturation occurring in the surface to 900-mb layer, but aloft
it is very dry (mid-level RH values of 15 to 25 percent).

Overall, expect a milder night given the further increase in
high clouds along with prevailing northeasterly onshore flow.
For areas east of the Blue Ridge where clouds should be more
commonplace, forecast lows will be in the 50s to low 60s. Off to
the west, widespread mid/upper 40s are more likely.

Sparse shower chances persist into Wednesday morning along the
Chesapeake Bay shores. However, it is more likely that these
showers remain over the Eastern Shore and points eastward. Cloud
cover remains over areas east of the Blue Ridge, but these will
edge eastward in time. Some late day sunshine is possible across
the I-95 corridor. High temperatures are forecast to remain in
the low/mid 70s (60s in the mountains). Overnight lows drop into
the 50s, with some mid/upper 40s possible over the central
Shenandoah Valley back into the Potomac Highlands.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
High pressure will dominate the weather Thursday through Sunday.
Dry conditions and below average temperatures each day and night
with highs in the lower 80s and lows in the middle 50s. Winds will
be generally north to northeast 5 to 10 mph gusts to 15 mph in
the afternoon. There could be a brief shift to easterly winds as low
pressure offshore interacts with reinforcing high pressure to the
north during the middle of weekend.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Canadian high pressure settling over the northeastern U.S. will
maintain VFR conditions across all sites. Any patchy fog
development is likely to remain west of the terminals. Initial
winds should generally stay out of the north before shifting to
northeasterly on Tuesday. Gusts up to 10 to 15 knots are
possible as gradients tighten, especially during the afternoon
hours. Winds return to northerly on Wednesday as the coastal
front shifts offshore.

VFR conditions Thursday through Friday night. Winds north to
northeast 5 to 10 knots through the period.

&&

.MARINE...
The combination of Canadian high pressure to the north and a
stalled frontal zone will aid in enhanced north to northeasterly
winds through mid-week. Expect gusts up to around 20 to 25
knots, particularly over the more open waters of the Chesapeake
Bay. Small Craft Advisories will remain effect through early
Wednesday across vast portions of the Chesapeake Bay into the
lower tidal Potomac. This may even persist a bit longer
depending on how quickly the synoptic configuration holds. For
now, the upper/middle tidal Potomac should see winds just short
of advisory criteria.

No marine hazards Thursday through Friday night. Winds north
to northeast 5 to 10 knots gusts to 15 knots.

&&

.TIDES/COASTAL FLOODING...
Due to the combination of winds not quite aligned to push water
south and out of the Bay, and the recent full moon, tides will be
somewhat elevated in the coming days. NE winds during the middle of
the week may assist in locking in higher water levels and pushing
the water toward the western shore. Annapolis is most likely to
reach minor flood stage, but some other locations may be close. The
first opportunity for flooding will be Tuesday evening, and then
could occasionally be an issue through the end of the week with no
real pattern change in sight.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ532>534-537-
     541>543.

&&

$$

SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...KLW
AVIATION...BRO/KLW
MARINE...BRO/KLW
TIDES/COASTAL FLOODING...ADS