229
FXUS66 KSEW 122130
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
230 PM PDT Sun Oct 12 2025

.SYNOPSIS...A cool upper low will bring more showers and mountain
snow to western Washington tonight through early Monday morning.
Offshore flow will result in cool and dry conditions through
midweek. A weak system will bring a chance of rain on Thursday and
Friday. Expect wetter weather over the weekend with a stronger
Pacific frontal system.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...A deep upper low is
passing through western WA this afternoon. The air mass is cool
and showery with high elevation snow in the mountains. Snow levels
will lower tonight, down to around 3,000-4,000 ft, with
additional snow in the Cascades. Higher passes like Washington
Pass and Stevens Pass may see accumulations with wet roads
(rain/snow mix) at Snoqualmie Pass. Showers will taper down Monday
morning as this system exits south.

Gusty NE Fraser River outflow winds will develop this evening over
the north interior with strong high pressure over B.C. Winds of 20
to 30 MPH with gusts to 45 MPH are expected across western Whatcom
County and the San Juans. Winds will ease Monday afternoon.

Offshore flow will lead to dry and cool conditions on Tuesday.
Morning lows will be close to freezing with possible frost in the
lowlands (especially sheltered areas and areas near the Cascades).
Expect highs around 60 with clear skies. We may see one more cool
morning on Wednesday before winds turn back to onshore. 33

.LONG TERM /THURSDAY THROUGH SUNDAY/...Weak high pressure moves in
on Thursday but models are showing light warm frontal precip along
the coast. A weak front will move inland Thursday night for a
chance of light rain across the board. Light rain lingers on Friday
with onshore flow. Pops increase on Saturday and Sunday as a
wetter Pacific frontal system moves inland. 33

&&

.AVIATION...Westerly flow aloft as a disturbance continues to pass
over the region this afternoon, bringing scattered showers across
most of the area. A mix of VFR/MVFR conditions this afternoon as
lingering showers dissipate over the area. Conditions will begin
to dry out later this evening and into Monday morning with VFR
returning for all area terminals. Fraser Outflow winds will
develop tonight and impact KBLI with breezy northerly winds 15 to
20 knots sustained with gusts up to 30 kts possible at times
through early Monday morning. Winds will look to slowly decrease
into Monday evening. Elsewhere, southerly winds will turn
northerly by 00z and generally be around 5 to 10 knots.

KSEA...VFR/MVFR this afternoon as showers move away from the
terminal. S/SW winds to 10 to 15 knots this afternoon will
transition to northerly by 00z, and will decrease to 4 to 8 knots.
N/NE winds will increase Monday morning, generally around 16z-19z,
upwards to 14 to 17 knots. VFR continuing into Monday.

Mazurkiewicz

&&

.MARINE...A low pressure system will continue to move southward
along the coast into Monday, with northeasterly winds increasing
tonight and into Monday. Small craft Advisory strength winds will
continue through most of the coastal waters on Monday. Fraser
Outflow winds will develop tonight and bring frequent gale gusts
in the Strait of Georgia north of the San Juan Islands, where a
Gale Warning will remain, along with the small craft advisory
in the Central and East Strait. Winds will gradually decrease
through Monday afternoon and evening as the aforementioned low
pressure system shifts south to California. High pressure looks to
build Tuesday and into Wednesday which will bring light onshore
flow through the area waters.

Combined seas 9 to 11 feet this afternoon will gradually decrease
into Monday morning, with seas still remaining steep with a
dominant period of 10 seconds. Seas will be 7 to 10 feet on Monday
with a dominant period of 7 or 8 seconds. Seas will lower to 4 to
6 feet on Tuesday through midweek.

Mazurkiewicz

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory from 8 PM this evening to 2 PM PDT Monday for
     Lowlands of Western Whatcom County-San Juan County.

     Winter Weather Advisory until 5 AM PDT Monday for Cascades of
     Snohomish and Northern King Counties-Cascades of Whatcom
     and Skagit Counties.

     Winter Weather Advisory until 11 AM PDT Monday for Cascades of
     Pierce and Lewis Counties.

PZ...Small Craft Advisory until 5 PM PDT this afternoon for Coastal
     Waters From Cape Flattery To James Island Out 10 Nm-Coastal
     Waters From James Island To Point Grenville Out 10 Nm-
     Coastal Waters From Point Grenville To Cape Shoalwater Out
     10 Nm-Grays Harbor Bar-West Entrance U.S. Waters Strait Of
     Juan De Fuca.

     Small Craft Advisory from 8 PM this evening to 2 PM PDT Monday
     for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Warning from 8 PM this evening to 2 PM PDT Monday for
     Northern Inland Waters Including The San Juan Islands.

     Small Craft Advisory until 5 PM PDT Monday for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 Nm-
     Coastal Waters From Point Grenville To Cape Shoalwater 10
     To 60 Nm.

&&

$$