176
FXUS66 KSEW 190322
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
822 PM PDT Wed Jun 18 2025

.SYNOPSIS...Showers in the Cascades will decrease tonight. A deep
upper low will spin offshore on Thursday. Showers will increase
Friday and Saturday as the low moves inland. Mountain snow showers
are also expected above 5000 feet. Warmer and drier conditions
will return by early next week.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...Gusty winds are
beginning to ease this evening as onshore flow behind today`s front
gradually decreases. Clouds will fill in overnight then we`ll see
some partial sunshine Thursday afternoon away from the coast with
near seasonal temperatures. Friday and Saturday are still on track
to be a sharp departure from what we`ve seen most of this month. In
fact, they might wind up being the coldest high temperatures some
parts of the region have seen in almost 4 weeks. Current forecasts
are on track and no forecast updates are anticipated. The previous
discussion follows with updates to the marine and aviation portions.

27

We`re in post-frontal onshore flow this afternoon with showers
mostly focused over the Cascades. Winds are a little gusty in the
south sound (SW gusts to 20-25 MPH) but will ease this evening.

Thursday is mainly dry as an upper level low slowly wobbles south
off southern B.C. Winds are lighter overall and temperatures will
track close to average.

Showers increase on Friday as the upper low starts to shift east
and inland. The air mass is slightly unstable for a chance of
afternoon thunderstorms in SW WA. Friday will be cooler too with
highs around 60 degrees.

The air mass will be cool and showery moving into Saturday with
the upper low overhead. Snow levels in the mountains are down to
around 5000 ft with a few inches of snow on the higher peaks. The
morning and early afternoon will be wet with 0.25-0.50" rainfall
ranges across the lowlands. And like Friday, peak temps are only
around 60s, well below average. 33

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...The upper low shifts
farther E/NE on Sunday and weakens, with broad troughing over the
Pac NW. There will be lingering showers but mainly light and not
as wet compared to Friday-Saturday. We`re back to a warm and dry
pattern through Wednesday with high pressure. Temperatures will
reach the lower 80s again in the interior. The coast will be
cooler and in the 60s with northwest flow. 33

&&

.AVIATION...Mostly VFR with areas of MVFR/localized IFR ceilings
developing overnight along the coast. Onshore flow will continue to
promote mid level clouds across western Washington overnight into
Thursday, but conditions are expected to remain VFR for most inland
areas through the forecast period. Gusts will continue to taper off
this evening, with light winds generally 5 kt or less overnight
becoming N to W 5 to 10 kt by Thursday afternoon with gusts to 15 kt
mainly south of the Puget Sound.

KSEA...VFR conditions through the TAF period with mid-level clouds.
Winds slowly easing this evening and becoming variable, then
shifting south/southeast by 09z. Winds turning E/NE around 15z-17z
and increasing to NW 7-10 kt after 21z.

15

&&

.MARINE...Onshore flow will continue over area waters under surface
high pressure with as an upper level low will slowly make its way
inland throughout the weekend. A Small Craft Advisory remains in
effect through the central and eastern Strait of Juan de Fuca
through early Thursday morning, with another strong westerly push
through the Strait Thursday evening which may reach Gale Force.
Westerly SCA winds will occur once again Friday evening through the
Strait before the low pressure system moves inland and winds across
area waters ease.

Seas around 4 to 6 feet will gradually build to 6 to 8 feet by
Saturday, then ease to 4 to 5 feet beyond the weekend.

15

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 2 PM this afternoon to 3 AM PDT
Thursday for Central U.S. Waters Strait Of Juan De Fuca-     East
Entrance U.S. Waters Strait Of Juan De Fuca.

&&

$$