443
FXUS66 KSEW 121549
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
849 AM PDT Sun Oct 12 2025

.SYNOPSIS...Cool and unsettled conditions will continue across
Western Washington today as a system moving southward tonight
brings the first noteworthy high elevation snow of the season
to the area. Drier conditions return by Tuesday with weak high
pressure over the area through midweek. Another disturbance
likely brings cooler and cloudier conditions and another round
of precipitation late in the week.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...Showers and mountain snow
today - Winter Weather Advisories remain in effect for the
Cascades. Cool with temperatures in the low to mid 50s today
(close to current readings). 33

Previous discussion... A lingering convergence zone has steadily
weakened overnight and early this morning, with the lingering
remnants moving east near a Sultan to North Bend line. This will
continue to push east and fade out toward daybreak. Elsewhere, a
few areas of showers remain in the onshore flow, but a bit of a
temporary lull in between these two weather systems within the
broad upper trough. This next disturbance will drop south from
British Columbia today, maintaining more widespread showers and
lowering snow levels that will bring snow in the mountains. Expect
the largest snow totals above 5000 feet at places like Mount
Baker and Paradise on Mount Rainier, with some accumulations down
to 3000 ft or so in the North Cascades and around Stevens Pass in
the central Cascades, where a 2-4 inches of snow may fall through
Monday morning. While accumulations are unlikely at Snoqualmie
Pass, some snow mixing in with rain down to pass level is
possible. This will be the first notable snowfall of the season in
the mountains, and those heading into the higher Cascade
elevations should be prepared for snow and colder conditions.

As this upper low tracks south off the Oregon coast and down to
California, expect to see an increase in offshore flow and
Fraser outflow setting up across western Whatcom County and
across the San Juan Islands with gusts up to 40-45 mph. Breezy
northerly winds across other portions of the interior may follow
early Monday morning, but only topping out closer to 25 mph in
these other locations. This disturbance pushing away from the
area will also bring a drier trend and decreasing cloud cover.
This will lead to rather cool nights, especially as the air mass
dries cools efficiently, with some potential for frost starting
Tuesday morning. 12

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...As mentioned
above, There`s potential for frost in some of the outlying,
sheltered location both Tuesday and Wednesday mornings, with
even around a 15% chance for some of the cool spots south of
Olympia through Centralia and west toward Aberdeen approaching
the freezing mark for an hour or three on Wednesday morning.
Daytime highs will reach into the lower 60s with mostly sunny
skies through the midweek period. Ensemble guidance then begins
to split late in the week with the potential for at least a weak
system to get close to the area by late Thursday. A resumption
of typical fall weather then follows with stronger frontal
systems favored to arrive Friday through the weekend. 12

&&

.AVIATION...The next upper disturbance is beginning to drop
across the region, spreading isolated showers and maintaining
widely variable ceilings. Ceilings are generally VFR/MVFR as
scattered showers move across the area. Fraser outflow winds will
impact KBLI Sunday night with breezy northerly winds for the
Puget Sound terminals. Expect lingering precipitation Sunday night
into early Monday with drying trend early Monday morning onward,
with terminals seeing a rebound back to dominate VFR conditions.

KSEA...Southerly winds at the terminal early this morning with
lower MVFR stratus firmly in place and scattered showers at
times. There could be some scattering of the lowest layer later
this morning, with a 60% chance of improving to VFR later this
morning 17-22z. Expect another lowering in ceilings with
increasing showers this evening and overnight with winds becoming
northerly or northeasterly at around 7-8 kt.

12/Mazurkiewicz

&&

.MARINE...Northwesterly winds will ease today over the coastal
waters as a low pressure system begins to form along the southern
coast of Vancouver Island. The system will then begin to move
southward along the coast on Monday. Winds will turn to become
northeasterly and increase late Sunday night into early Monday
morning. Small Craft Advisory level winds will continue across the
coastal waters through most of the day on Monday. Outflow winds will
develop over the Northern Inland Waters as well as through much of
the Strait of Juan de Fuca. Frequent gusts up to gale force are
expected in the Strait of Georgia north of the San Juan Islands, but
elsewhere SCA conditions are expected. Some gusts may meet SCA
criteria through the West Strait of Juan de Fuca, but sustained
winds should be lower than in the central zone and confidence is
lower in the outflow winds making it all the way there. Winds will
ease area-wide Monday night as the low rides down the coast into
California. Broad high pressure will build in the wake of the
system, allowing winds over the coastal waters to return to
northwesterly and light onshore flow through the interior waters.
Conditions look to remain benign through much of the week, with the
next system not moving into the area until Friday.

Seas 11 to 13 ft across the coastal waters this morning will slowly
ease throughout the day, becoming 8 to 10 ft tonight. Seas will
remain steep with a dominant period of 10 seconds. Seas remain
around 7 to 10 ft with a dominant period of 7 to 8 seconds on
Monday. Seas return to 4 to 6 ft Tuesday through late week. The
system on Friday may rise seas back above 10 ft.

62

&&

.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.

&&

$$