377
FXUS61 KLWX 210110
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
910 PM EDT Mon Jul 20 2026

.WHAT HAS CHANGED...
Made a few changes to the gridded database to try to hone in on
timing for Tuesday`s severe weather threat, but the overall
message remains the same.

&&

.KEY MESSAGES...
- Strong to severe thunderstorms are likely Tuesday, with
  some thunderstorm risk lingering into Wednesday.

- Cooler than average temperatures anticipated beginning
  Thursday through the end of the week.

&&

.DISCUSSION...
KEY MESSAGE 1...Strong to severe thunderstorms are likely Tuesday, with
 some thunderstorm risk lingering into Wednesday.

Moisture is expected to return in earnest tonight in
strengthening srly flow. Elevated showers and thunderstorms are
possible overnight into Tue morning as a front returns
northward. Morning low clouds and a cap will likely delay
convective initiation until the mid afternoon, but afternoon
temps in the low 90s combined with at least low 70s dewpoints
should result in strong instability with 1500-2000 J/kg CAPE
progged. This combined with approaching anomalous upper level
trough and associated strong wind speeds aloft, particularly for
the peak of summer should provide ample forcing and shear to
result in a significant severe wx episode Tue. Scattered
significant wind damage reports seem likely, with the potential
for isolated tornadoes, and perhaps flash flooding. Flash flood
threat does not appear significant enough for a watch given
anticipated fast storm motions of 30kt or more.

By Wednesday, there is some uncertainty with the cold frontal
position. With the upper trough overhead, additional showers
and thunderstorms are likely, especially across southern
Maryland. While some additional strong to severe thunderstorms
can`t be ruled out if things trend slower, it`s beginning to
appear the best parameters for that to occur will be shunted
toward southeast Virginia.


KEY MESSAGE 2...Cooler than average temperatures anticipated
beginning Thursday through the end of the week.

An upper-level trough centered over southeastern Canada will
track towards the northeast on Thursday, allowing high pressure
to slide into the region from the west. This resulting high
pressure could persist through early Sunday. Dewpoints will also
trend lower during this period, resulting in relatively dry
conditions. Temperatures range in the low-to-mid 80s, trending
slightly below average for July. This high pressure could begin
to break down late this weekend as a strong upper-level trough
begins to form over the Great Lakes region. As the trailing cold
front transitions east, humidity and precipitation chances
could begin to increase again at the start of next week as this
system moves through.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
A few showers and storms are already popping up in central VA
towards CHO. These may increase in coverage through the
overnight hours, and perhaps even reach the other terminals by
just before daybreak. MRB has the lowest chance, with the metro
terminals probably sitting around a 40% chance, but included
PROB30s for all for now.

Multiple rounds of thunderstorms are likely after this initial
activity, one between 19Z-21Z, and the other one coming later in
the evening. Storms could linger well into the overnight.
Especially with the afternoon storms, damaging wind gusts are
possible, along with the potential for some large hail.

More storms are possible Wed, particularly eastern terminals.
Severe wind gusts of 50-kt or greater are the main threat.

Prevailing VFR conditions are likely across terminals Friday and
Saturday. Light northeast winds begin to shift southerly late
Saturday night.

&&

.MARINE...
Strengthening srly flow tonight is expected to result in SCA
conditions. Gusty SSW winds expected Tue through Tue night with
likelihood of strong gusts over 33 kt, which will likely require
SMWs. SCAs have been extended through Tue night into Wed
morning.

Winds stay below SCA thresholds Friday and through the weekend. 5-10
knot winds flow northeast before shifting southerly late Saturday
night.

&&

.TIDES/COASTAL FLOODING...
Increasing SE to S flow from this evening into Tuesday will
lead to water levels reaching Action stages.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 6 AM EDT Wednesday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ530>534-
     537-539>541-543.
     Small Craft Advisory from 2 PM to 8 PM EDT Tuesday for ANZ535-
     536.
     Small Craft Advisory from 2 PM Tuesday to 6 AM EDT Wednesday
     for ANZ538-542.

&&

$$

DISCUSSION...LFR/CJL/SRT
AVIATION...LFR/CJL/SRT
MARINE...LFR/CJL/SRT

NWS LWX Office Area Forecast Discussion