985
FXUS61 KLWX 190049
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
849 PM EDT Tue Aug 18 2026

.WHAT HAS CHANGED...
No significant changes were made to the latest forecast package.
Will continue to monitor the upcoming model guidance as more
unsettled weather returns late this week and into the weekend.

&&

.KEY MESSAGES...
- 1) After a break Wednesday, showers and thunderstorm chances
  increase Thursday and Friday.

- 2) Numerous showers and thunderstorms Saturday with lingering
  showers Sunday. Turning cooler and dry for next week.

&&

.DISCUSSION...
KEY MESSAGE 1...After a break Wednesday, showers and
thunderstorm chances increase Thursday and Friday.

Any shower activity remaining over far southern Maryland has
decayed with the loss of daytime heating. While the main frontal
zone has shifted down into the Carolinas, a diffuse moisture
gradient remains over the local area. However, this boundary has
slowly pushed south and east in time with higher dew points now
confined to central Virginia over into southern Maryland. Most
notably, this shows up on the 00Z IAD sounding which has seen a
drop in precipitable water values from 1.85 inches to 1.17
inches in the last 12 hours.

Surface high pressure builds eastward from the Ohio Valley
tonight. Some clearing takes place, though more uncertainty
exists across southern portions of the forecast area. Where
skies are clear, fog may form, especially in the river valleys.
The high will slide across the area Wednesday, providing dry
conditions. Temperatures will be near or slightly above average.

As a shortwave trough pivots through the Great Lakes and St.
Lawrence Valley, the next cold front will approach the area
Wednesday night. The chance for showers, and perhaps a
thunderstorm, will increase the second half of the night from
the north. Although timing remains a bit uncertain, the cold
front looks to enter the area Thursday morning, then slowly
cross southward through Thursday night. Questions regarding
early day precip and cloud cover lend to uncertainty in how much
instability builds Thursday afternoon, though a few stronger
storms are certainly possible given increased flow aloft and
lift along the front. AI/ML severe probabilities have been
consistent showing higher values across southeastern portions of
the CWA. The bulk of 12Z NWP guidance is in general agreement
with the strongest convective signals near or just south of the
southern CWA border. Temperatures will depend on clouds and
frontal position, with a range from the upper 70s to near 90
possible across the CWA.

There could be a relative break in some areas on Friday if high
pressure over the St. Lawrence valley shoves the front to the
south. Relatively speaking, rain chances will be higher farther
south, closer to the frontal zone. Troughing will begin to
amplify Friday night, with low pressure perhaps developing
and/or lifting northeastward from the Carolinas. Overrunning
moisture will spread northward late in the day and overnight,
though there remain questions on how quickly and how far north
and west the rain reaches.


KEY MESSAGE 2...Numerous showers and thunderstorms Saturday with
lingering showers Sunday. Turning cooler and dry for next week.

The longwave pattern is forecast to amplify significantly this
weekend into next week as trough digs across the Great Lks and OH
Valley. This will drive a pair of cold fronts across the area Sat
and Sun providing focus for showers and thunderstorms. Saturday
looks like the more active and more unstable day as shortwave energy
moves across. By Sunday, the first cold front should have pushed the
deep moisture and instability to the south limiting the coverage
and intensity of showers.

As trough axis shifts east of the area Sunday night or Monday,
expect a cooler and drying trend to start the new work week.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Light northwest flow continues through Wednesday. Clearing
skies and light to calm winds can be expected tonight as high
pressure builds eastward. CHO and MRB may see some fog
development. Some cloudiness could linger near CHO, but if it
clears, LIFR conditions could develop. Winds will gradually turn
more southwesterly Wednesday afternoon with VFR conditions
expected.

Rain may approach the TAF sites ahead of a cold front late
Wednesday night, with more numerous showers and possible
thunderstorms Thursday afternoon and evening. Some lower
ceilings are possible, especially around MRB Thursday morning.
Showers may linger at CHO Thursday night and Friday, along with
potential lower ceilings.

Depending on the placement of a stationary front and track of
low pressure along it, showers, thunderstorms, and low ceilings
are possible at times Friday night through Sunday.

&&

.MARINE...
Light winds are expected through Friday. North to northwest
winds continue into Wednesday before briefing becoming southerly
by late Wednesday. A brief enhancement is possible along the
Chesapeake Bay Wednesday evening due to channeling, but
prospects of advisory conditions are marginal at best. Winds
then shift back to the northwest and north Thursday and Friday
as a cold front pushes southward.

A cold front may bring some thunderstorms to the waters on
Thursday into Friday.

Small Craft Advisory conditions are possible Saturday and again
Sunday night into Monday morning as a series of fronts and low
pressure centers move near the waters. Additional thunderstorms
are possible Saturday.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

DISCUSSION...ADS/LFR/BRO/DHOF
AVIATION...ADS/LFR/DHOF
MARINE...ADS/LFR/DHOF