099
FXUS66 KSEW 181541
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
841 AM PDT Mon Aug 18 2025

.SYNOPSIS...Cooler conditions with cloudy skies and periods of
showers along the coast will continue through the middle of the
week as troughing continues offshore. A warmer and drier pattern
will develop later in the week as high pressure builds over the
southwestern US.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...The latest forecast
remains on track with no updates this morning. Offshore troughing
will keep the area cooler and cloudy through the middle of the
week, with a decaying frontal system likely to provide light
showers (0.01 to 0.02 inches) along the northern coast today. The
core of this trough will move inland on Wednesday for zonal flow
in its wake. This will mean continued onshore flow and marine
stratus in the morning for western Washington, breaking up in the
afternoon for pleasant conditions. Highs are expected to be in the
70s and 60s along the coast through Wednesday.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Almost simultaneously, a
cutoff low develops in the Gulf of Alaska while a Four Corners
high pressure system amplifies into the northwest. The influence
of the high will win out, as temperatures warm and conditions dry
late in the week into early next weekend. Temperatures will be on
the way up on Thursday, reaching the mid to upper 80s by Saturday.
This corresponds to Moderate HeatRisk (orange) for most of the
area, and conditions will be monitored for any changes to the
temperature forecast.

21

&&

.AVIATION...Upper level trough offshore with southwesterly flow
aloft through Tuesday. Light flow in the lower levels.

VFR conditions into Tuesday with patchy IFR ceilings and
visibility along the coast 12z-16z.

KSEA...VFR through Tuesday. Stratus deck around 6000 feet
scattered to broken this morning. Just high clouds this afternoon
and tonight. Light and variable wind becoming south to
southwesterly 4 to 8 knots by 18z. Westerly wind 21z-05z with the
wind returning to southerly after 05z.

&&

.MARINE...Weak high pressure over the waters through Tuesday will
strengthen Tuesday night into Wednesday and remain over the waters
through Friday. A weakening system will try and move through the
high tonight dissipating over the coastal waters Tuesday.

No headlines the next few days. Diurnal westerly pushes through
the Strait of Juan de Fuca each evening Tuesday through Friday but
winds forecast to stay below 20 knots.

Felton

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&

$$