294
FXUS61 KLWX 271357
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
957 AM EDT Sun Jul 27 2025

.SYNOPSIS...
A nearly stationary frontal boundary over the region will
slowly lift north as a warm front through this evening. This
front will gradually fizzle out over the next few days as high
pressure returns to the region. However, a warm and humid
airmass will yield daily shower and thunderstorm chances through
midweek. A stronger cold front arrives late in the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
KLWX radar loop as of 9:45 AM shows rain showers moving across
western MD and into the eastern panhandle of WV. Visible
satellite shows cloud cover increasing along the I-81 corridor.
Held off on expanding the Heat Advisory into the Shenandoah
Valley due to cloud cover forecast to increase throughout the
day. This will likely inhibit heat indices from rising to
criteria west of the Blue Ridge. That being said, hot and humid
conditions are already being observed across the area with heat
indices in the 80s and low 90s as of 10AM. No changes were made
to the forecast with the previous forecast discussion below.

Some lingering showers are departing this morning as we have
finally stabilized area-wide. Starting to see some fog develop
across the Shenandoah Valley and in the central VA Piedmont.
Could see that become locally dense in a few spots as we head
towards daybreak.

A weak frontal boundary will gradually lift north through the
region this afternoon. Meanwhile, a potent piece of shortwave
energy will slide across the northern half of our forecast area.
Given the continue heat and humidity, this will result in
widespread showers and thunderstorm chances early this afternoon
through this evening. With plenty of instability, storms will
be capable of becoming strong to severe with the primary hazard
type being damaging wind gusts, as well as torrential rainfall.
Given the increased shear, there could be some isolated more
potent storms, which could produce some larger hail as well.
High temperatures will be in the upper 80s to low 90s with heat
indices 100-105 expected at lower elevations. A Heat Advisory is
in effect for portions of the I-95 corridor eastward from noon
to 8PM Sunday.

Overnight low temperatures will be in the 70s for most with
higher elevations dipping into the 60s. Similar very moist air
trapped near the surface tonight will likely yield some fog in
the lower elevations, some of which could be locally dense.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
A hot and humid airmass remains overhead on Monday, but mid-
level height rises and surface high pressure building over the
region should yield less of a chance for thunderstorms during
the afternoon, at least east of the Blue Ridge. Coverage of
showers and thunderstorms will be much lower, with precipitation
chances largely confined to along and west of the Blue Ridge
where the diurnal terrain circulations will be the primary
driver of convection. High temperatures will be in the 90s for
most with higher elevations staying in the 80s. Heat index
values of 100-105 are expected at lower elevations.

High pressure/weak gradients will remain across the area Tuesday
while the large upper ridge remains centered to the southwest.
Forcing will be nebulous, so thunderstorm chances appear to be
relatively lower and focused on the diurnal terrain circulations.
However, we will be in northwest flow aloft around the ridge, so
will have to be mindful of any remnant MCVs that could provide an
extra source of lift. Heat will build further with the hottest
conditions of the week expected to start on Tuesday. Highs
return solidly to the mid 90s with perhaps upper 90s. Drier air
aloft may allow dew points to mix down a little, but heat index
values will still likely top out in the 100-110 range across
much of the area.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Warm and humid conditions continue through midweek as weak surface
high pressure remains to the southwest of the forecast area. A cold
front will slowly approach from the northwest through Wednesday,
before moving through the area on Thursday. This will yield
afternoon shower and thunderstorm chances Wednesday and Thursday. As
the cold front settles over the Carolinas, precipitation chances
will linger Friday before drying out overnight. Primarily dry
conditions are expected on Saturday as high pressure builds north of
the area. An isolated shower in the southern portions of the
forecast area cannot be ruled out as the aforementioned front
remains nearby.

In addition to the thunderstorm chances, heat indices will near Heat
Advisory criteria. High temperatures  Wednesday will be in the 90s
for most with higher elevations staying in the upper 80s. Dewpoint
temperatures in the low/mid 70s will yield heat indices of 100-105
for most of the lower elevations. High temperatures cool on Thursday
in the wake of a cold front, with highs in the 80s to low 90s (70s
mtns) expected. Heat indices fall below criteria level, with values
in the 80s and 90s. High temperatures continue to cool on Friday and
Saturday with highs in the 70s to low 80s across the area.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
A few showers remain over the metro terminals (DCA, BWI, and
MTN) at this time. Those are quickly either pushing off to the
east or dissipating. Expect lower CIGs to take hold as we move
into the next few hours, with several spots dropping to IFR, or
at least low end MVFR. Some fog may also develop, primarily at
CHO and MRB, which could also cause some flight restrictions
through daybreak. CIGs and VSBYs should quickly increase through
mid-morning.

Showers and thunderstorm chances will be at their highest today
as a weak frontal boundary lifts north as a warm front. This
occurs as a potent piece of upper-level energy sweeps through
the region. Winds will shift out of the SW as the front lifts
north at around 5 to 10 knots. Damaging wind gusts and
torrential rainfall will be the primary threats with storms
today, and perhaps some large hail in the strongest storms.
Unlike this past evening, storm chances should dwindle as we
head into the overnight period. Patchy fog could again be an
issue for some spots, especially in the typical low-lying and
rural areas.

Showers and thunderstorms remain possible Monday, mainly at
MRB and CHO. With high pressure moving back into the region,
areas further east should remain dry. Otherwise, prevailing VFR
conditions expected. On Monday, winds shift to northerly,
blowing at only around 5 knots.

VFR conditions should prevail Tuesday. Thunderstorm coverage
will likely be a minimum Tuesday under high pressure. Can`t
completely rule out an isolated storm developing over the higher
terrain along/west of the Blue Ridge, so CHO and MRB could
potentially see effects from this. However, that chance is below
20 percent at this time, so not a likely scenario at this point
in time.

Prevailing VFR conditions are expected across all terminals
Wednesday and Thursday. On Wednesday, afternoon showers and
thunderstorms may lead to brief periods of flight restrictions. As a
cold front approaches from the west and pushes through the forecast
area on Thursday, coverage of showers and thunderstorms increase.
Sub-VFR conditions are possible again Thursday.

&&

.MARINE...
Lingering showers continue across the northern Chesapeake Bay
waters early this morning. These will taper off over the next
hour or two.

A potent piece of upper-level energy moving across the region
today amidst a continued hot and humid air mass will result in
likely thunderstorms this afternoon/evening. SMWs are likely to
be needed during this time, with gusty winds and frequent
lightning the primary threats.

Showers and thunderstorms are expected to stay well west of the
waters on Monday as high pressure returns to the region. No
marine hazards expected at this time.

High pressure Tuesday will result in light gradient winds. At
this time, thunderstorm coverage is forecast to be more isolated
Tuesday once again, and primarily focused well to the west of
the waters.

Daily shower and thunderstorm chances may lead to hazardous
conditions over the waters each afternoon/evening Wednesday and
Thursday. SMWs may be needed if storms become strong to severe.
Otherwise, no marine hazards are expected with winds remaining below
SCA criteria.

&&

.TIDES/COASTAL FLOODING...
Tides remain elevated over the next several high tide cycles,
partially due to the recent new moon, and partially due to light
flow not really allowing water to exit southward out of the
Chesapeake Bay. No areas are forecast to hit minor at this time,
but sensitive tidal locations will continue to reach Action
Stage during the high tide cycles through mid-week.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Heat Advisory until 8 PM EDT this evening for DCZ001.
MD...Heat Advisory until 8 PM EDT this evening for MDZ013-016>018.
VA...Heat Advisory until 8 PM EDT this evening for VAZ037>039-050-
     051-053>057-502-527.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...CJL
NEAR TERM...AVS/CJL
SHORT TERM...AVS/CJL
LONG TERM...AVS
AVIATION...AVS/CJL
MARINE...AVS/CJL
TIDES/COASTAL FLOODING...LWX