755
FXUS61 KLWX 161438
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1038 AM EDT Wed Jul 16 2025

.SYNOPSIS...
A front remains stalled overhead this morning before dissipating
throughout the day. Another front approaches the forecast area at
the end of the week before stalling overhead through the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Current visible satellite imagery shows low clouds in place for
most locations to the east of the Blue Ridge this morning,
although there are some notable breaks along the shores of the
Bay extending into northeast Maryland. More in the way of
sunshine is present to the west of the Blue Ridge, although
there are some passing high clouds and a few lower clouds across
the Central Shenandoah Valley. Thicker high clouds are present
across western WV into OH ahead of a shortwave/MCV-like feature
centered over southern IN. This feature will continue to lift
east-northeastward over the course of the day, eventually
reaching eastern OH/western PA by this evening. Weak mid-level
height falls and large scale ascent attendant to this feature
should reach locations to the west of the Blue Ridge by later
this afternoon, with the strongest lift occurring across western
MD and the WV Panhandle. These locations should also experience
the strongest daytime heating with the lack of low clouds in
place currently.

Most guidance shows precipitable water values increasing to near
or in excess of two inches across the majority of the forecast
area later this afternoon as rich low level moisture is drawn
northward ahead of the aforementioned shortwave, while deeper
moisture in the mid-upper levels currently over Ohio
simultaneously advects east- northeastward atop the low-level
moisture. The 12z IAD sounding shows a precipitable water value
of 2.04 inches, which is well above the 90th percentile for this
time of year. The 12z ILN (Wilmington, OH) sounding shows the
much deeper saturation that will move overhead later today. The
00z HREF mean has PWATs increasing to in excess of 2.2 inches to
the east of the Blue Ridge this evening, which would challenge
the daily record at the IAD sounding site. GFS forecast
precipitable water standardized anomalies exceed 2 sigma across
the bulk of the forecast area by later this evening, which
confirms that a highly anomalous level of moisture will be
present.

Showers and thunderstorms are expected to form later this
afternoon to the west of the Blue Ridge as large scale ascent
ahead of the aforementioned shortwave overspreads a highly
unstable and uncapped atmosphere. With such anomalous levels of
moisture and ample instability in place today, any thunderstorms
will be capable of producing very heavy rainfall. Flow in the
850-500 hPa layer will increase to around 20-25 knots by later
this afternoon, which suggests that storms should have some
decent forward motion. However, with the LLJ speed being
comparable to the main steering flow, localized backbuilding may
be possible. With the potential for very heavy rainfall
producing, backbuilding storms there is some flash flooding
concern later today, especially to the west of the Blue Ridge,
where the daytime heating and large scale forcing should be
greatest. A Flood Watch for flash flooding may need to be
considered, especially to the west of the Blue Ridge. Overall
storm coverage is expected to be lower further east, where low
clouds are inhibiting daytime heating and synoptic scale forcing
for ascent will be a bit weaker. That isn`t to say that there
couldn`t be localized issues with flash flooding further east,
as the highest PWAT values will actually be in place to the east
of the Blue Ridge. The model signal for high rainfall totals is
lower to the east of the Blue Ridge, but a few CAMs indicate
that heavy rainfall producing storms could form along the Bay
Breeze near Baltimore. WPC has the northern half of the forecast
area outlooked in a Slight Risk for Excessive Rainfall.

Model soundings show strong instability, with around 2000-3000
J/kg of MLCAPE. DCAPE is only around 500-600 J/kg, and low-level
lapse rates are only around 7-8 C/km, which could limit
downdraft strength and wind production a bit. The increasing
winds in the 850-500 hPa layer could be a factor that would
work in favor of wind production. Some CAMs (notably the HRRR)
show storms producing strong winds later this afternoon. SPC
currently has most of the area outlooked in a Marginal Risk for
severe thunderstorms, driven by damaging wind potential.

Outside of storms it will be another hot and humid day, with
highs in the upper 80s to lower 90s, and dewpoints holding in
the 70s. Storms should gradually wind down through the evening
hours, giving way to dry conditions during the second half of
the night.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Thursday will be the driest day of the short term period with
afternoon shower and thunderstorm chances peaking between 20 and
40%. Those along the Allegheny ridge will have precipitation
chances around 50% in the afternoon due to a cold front
approaching from the west. In addition to the drier conditions,
Thursday will be the warmest day of the week with high
temperatures forecast in the upper 80s to mid 90s. Given the
warm and humid airmass, dewpoints in the 70s on Thursday will
yield heat indices in the upper 90s to low 100s. Isolated
locations along and east of I-95 may briefly reach heat indices
of 105, with confidence on duration and coverage being to low to
issue Heat Advisories at this time.

Shower and thunderstorm chances increase on Friday as a cold
front slowly approaches and stalls over the region.
Precipitation chances increase to 50 to 60% across the western
portions of the forecast area with the I-95 corridor staying
around 30-50%. High temperatures will be in the 80s to 90s on
Friday with higher elevations staying in the 70s. Overnight low
temperatures will be in the 60s to 70s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
High pressure will hold onto the eastern half of the region on
Saturday. Most areas to the east of the Blue Ridge will be
either dry or there could be an isolated shower or two. To the
west and into the mountains, scattered showers and a few
thunderstorms could develop Saturday afternoon and evening. A
developing warm front will shift northward Saturday night into
Sunday. This warm front will pave the way for extra humidity and
moisture. More widespread showers and thunderstorms are
expected to develop from midday Sunday through late Sunday
evening. Highs on Saturday will be in the upper 80s to near 90.
Highs Sunday could reach the lower 90s.

Additional showers and thunderstorms could develop Monday afternoon
and evening with the added instability, a warm front pushing
northeast and an approaching trough of low pressure. Highs in the
upper 80s to lower 90s.

The chance of showers and thunderstorms is less on Tuesday into
Tuesday evening, but not zero. This time of year and with a trough
of low pressure nearby, a few showers and a thunderstorm may still
develop in parts of the region. Highs in the upper 80s.

&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
Low clouds at IAD, DCA, BWI, and CHO are slowly starting to lift
and should gradually transition from IFR to MVFR to VFR over the
remainder of the morning. Showers and thunderstorms will likely
impact terminals this afternoon with reduced visibilities and
ceilings possible during precipitation. The greatest coverage of
storms today is expected in the vicinity of MRB, but
thunderstorms are mentioned at all TAF sites. After an initial
round of showers and thunderstorms track across the forecast
area, stratiform rain and isolated thunderstorms remain possible
through the evening. Conditions dry out overnight with
prevailing VFR conditions expected on Thursday. A brief
thunderstorm may still be possible at any of the terminals
tomorrow afternoon. Shower and thunderstorm chances increase
again on Friday with flight restrictions possible.

VFR conditions Saturday for the most part. Some scattered showers
and thunderstorms could bring MVFR conditions to CHO and MRB
Saturday afternoon and evening. Winds light and variable except for
any gusty thunderstorms. MVFR conditions in showers and
thunderstorms on Sunday into Sunday evening with an advancing warm
front. Winds generally southwest 5 to 10 knots, but higher in
thunderstorms.

&&

.MARINE...
Winds remain below Small Craft Advisory criteria through this
afternoon, blowing out of the south/southwest. Winds shift to
southerly this evening with southerly channeling leading to SCA
criteria winds, especially in the southern portions of the
waters, through Thursday morning. Small Craft Advisories may be
needed late this evening and into Thursday as winds gust 15 to
20 knots. Winds drop below SCA criteria Thursday afternoon and
will remain light through Friday.

Showers and thunderstorms may impact the northern portions of
the waters this afternoon and into this evening, with SMWs
possible. Shower and thunderstorm chances decrease Thursday
before returning on Friday.

No marine hazards Saturday into Saturday evening. Special Marine
Warnings may be warranted Sunday afternoon and evening with
developing showers and thunderstorms along and ahead of a warm
front. Winds Saturday light and variable. Winds becoming southwest
10 knots Sunday into Sunday evening.

&&

.TIDES/COASTAL FLOODING...
Southerly winds will lead to elevated tidal anomalies through
the end of the week. Annapolis is forecast to reach Action
Stage during high tide through tomorrow morning. However,
outside of freshwater influences from heavy rainfall, the threat
for tidal flooding appears low.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from midnight tonight to 1 PM EDT
     Thursday for ANZ533-534-537-541-543.

&&

$$

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