711
FXUS61 KLWX 300803
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
403 AM EDT Mon Jun 30 2025

.SYNOPSIS...
A cold front will approach from the northwest on Tuesday, before
moving through Tuesday night into Wednesday morning. High
pressure will build into the region on Thursday and remain in
control through the end of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Some patchy fog has developed early this morning beneath a
broken deck of high clouds. Any fog isn`t expected to become
dense, and should quickly burn off after sunrise this morning.

Yet another hot and humid day is expected today, with
temperatures climbing into the upper 80s and low 90s, and
dewpoints holding in the low to mid 70s. A mix of sun and high
clouds is expected this morning, before showers and
thunderstorms ultimately form in response to daytime heating
this afternoon. Model soundings show an environment relatively
similar to yesterday, with strong instability, deep moisture,
and only modest shear and DCAPE. MLCAPE is a bit higher at
around 2000-3000 J/kg, shear is ever so slightly higher at
around 15-20 knots, and DCAPE is very similar at around 600-700
J/kg. In such an environment, localized wet microbursts may be
possible with any stronger storms, but it doesn`t appear to be
an environment that`s overly conducive for widespread strong
wind gusts. As a result, SPC currently has most of the area
outlooked in a Marginal Risk for severe thunderstorms.

While a brief thunderstorm could be possible anywhere in the
forecast area, model guidance clearly shows the greatest
coverage of storms across the northwestern half of the forecast
area, where they`ll start to experience weak height falls aloft
this afternoon well in advance of an upper trough approaching
from the Western Great Lakes/Upper Midwest. Storms should
initiate during the early to mid afternoon hours in the higher
terrain to the west of the Blue Ridge, and potentially also
along bay/river breezes further east. Most of the activity
should gradually lift off toward the north and east over time,
although some of the CAMs suggest that storms that form along
the bay breeze may be slower moving. Strong instability and high
PWAT values (over 2 inches) will make any storms today capable
of producing very heavy rainfall. The progressive nature of the
storms should keep the flash flooding threat relatively
minimized, but isolated instances of flash flooding may be
possible, particularly if a storm becomes anchored to the bay
breeze. The most likely area for this to occur, if at all, would
be in the vicinity of Baltimore. The 00z WRF-NSSL and 3km-NAM
show a situation like that playing out. WPC currently has most
of the area outlooked in a Marginal Risk for excessive rainfall.

Thunderstorm activity should gradually wind down through the
evening and early overnight hours, with dry conditions expected
during the second half of the night. Some patchy fog could form
later tonight in locations that see breaks in the clouds.
Overnight lows will be in the low-mid 70s for most, with upper
60s in the mountains.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
A seasonably strong upper trough will approach from the Great
Lakes tomorrow, while an associated surface low tracks across
Quebec. A trailing cold front will stretch to the southwest
through the Ohio Valley, while a pre-frontal trough sets up
overhead. Numerous storms are expected to form during the
afternoon in response to daytime heating as height falls aloft
overspread a very warm, humid, and unstable airmass. Model
soundings once again show saturation through a deep layer
tomorrow, with PWAT values approaching 2.2 inches. While this
could temper potential for cold pool driven winds slightly,
winds aloft will be on the increase tomorrow as the upper trough
approaches, with most soundings showing around 30 knots of
effective bulk shear. As a result, thunderstorm activity should
be better organized tomorrow, and capable of producing damaging
winds. SPC has locations to the east of the Blue Ridge outlooked
in a Slight Risk for severe thunderstorms, with a Marginal Risk
further west. There also could be some potential for flash
flooding. While storms should move along at a fairly good clip,
flow aloft starts to become aligned with the 850 hPa front and
pre- frontal surface trough, suggesting that some training could
be possible.

Storms could continue into the overnight as the upper trough and
surface cold front start to move through. Guidance differs on
how much progress the front makes though the area by Wednesday
morning. Depending on the progression of the front, some
additional showers and thunderstorms may be possible on
Wednesday, especially across southeastern portions of the
forecast area.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Dry conditions and seasonable temperatures Thursday through
Sunday. There could be a dry backdoor cold front that moves
through the region Thursday night into early Friday, but it
should be a dry frontal passage. This backdoor front may just
enhance our dry conditions and seasonable temperatures right
into the weekend. High temperatures each day generally in the
middle 80s.

&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
Some patchy fog is starting to form across the area early this
morning, but has for the time being avoided the terminals. Some
of this fog could briefly impact the terminals around daybreak.
Any fog would quickly burn off after sunrise.

Prevailing VFR conditions are expected through the day today.
Showers and thunderstorms will form in response to daytime
heating this afternoon and evening. Confidence in timing of the
storms at specific terminals is low, so have maintained PROB30s
over a broad time window. Winds today will be light out of the
south. Patchy fog may be possible again overnight, but
otherwise VFR conditions will continue. More widespread shower
and thunderstorm activity is expected tomorrow. Dry and VFR
conditions are expected behind a cold front on Wednesday. Winds
will be out of the southwest tomorrow, and northwest on
Wednesday.

VFR conditions at all terminals Thursday through Friday night.
Winds will be out of the northwest on both Thursday and Friday.

&&

.MARINE...
Winds will gradually pick up out of the south over the course of
the day, reaching low-end SCA levels by late afternoon/early
evening in the wider waters of the Middle Bay. SCA conditions
will be possible for a time tonight over most waters, with the
Upper Tidal Potomac being a potential exception. Threshold SCA-
level winds may be possible tomorrow over most of the waters
within southwesterly flow. Sub-SCA level northwesterly winds are
expected on Wednesday.

SMWs may potentially be needed as a result of thunderstorms
during the afternoon and evening hours both today and on
Tuesday.

No marine hazards Thursday through Friday night. Light northwest
winds are expected on both Thursday and Friday

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory from 11 PM this evening to 6 AM EDT
     Tuesday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 11 PM this evening to 6 AM EDT
     Tuesday for ANZ530-531-536-538-539.
     Small Craft Advisory from 5 PM this afternoon to 6 AM EDT
     Tuesday for ANZ532>534-537-540>543.

&&

$$

SYNOPSIS...KJP
NEAR TERM...KJP
SHORT TERM...KJP
LONG TERM...KLW
AVIATION...KLW/KJP
MARINE...KLW/KJP