786
FXUS66 KSEW 110343
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
843 PM PDT Fri Oct 10 2025

.SYNOPSIS...Seasonally cool and unsettled conditions will settle
across Western Washington through the weekend into early next week.
A system moving southward from British Columbia Sunday will bring
the first noteworthy high elevation snow of the season. Drier
conditions will return toward the middle of next week as high
pressure rebuilds over the region.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...After what felt
like extra innings, upper level low is finally moving onshore over
Oregon. A few showers will continue to rotate into the area
overnight, but will dissipate as they do so. Onshore flow will
increase tomorrow behind the upper trough leading to some
convergence over Puget Sound. Next upper trough is still on track to
drop southward over the area on Sunday with snow levels falling to
most of the higher passes. Current forecasts are on track. Previous
discussion follows with updates to marine and aviation portions.  27

Periods of showers will continue to affect much of western
Washington this evening. It does look like the heavier band of
precipitation that the high resolution ensembles have been showing
moving through the metro area this afternoon is actually keeping to
the east of the Cascades. Guidance consistently showing a break in
the precipitation tonight with another organized band with the front
early Saturday morning. Behind this will likely be another dry break
for most areas except the Cascades until early Sunday morning.
An upper level shortwave moving southward through British
Columbia will start to push precipitation back into Washington
from the north - with lowering snow levels. Heaviest
precipitation looks to be over the Cascades of Whatcom and
Skagit Counties Sunday - with snow levels starting around 4300
feet and lowering to around 2200 feet by early Monday morning.
NBM continues to highlight 60-75% chance of 8 inches or more
above 5000 feet over the northern Cascades, and a winter
weather advisory has been issued for the northern Cascades to
reflect the early season accumulations at high elevations.
Precip amounts taper off through the Cascades from Snohomish
County southward - with snow levels running about 1000 feet
higher than the northern Cascades. This will mean accumulations
will be generally less and limited to the highest elevations
along the crest of the Cascades and Mount Rainier. Stevens pass
may be the only pass that gets any accumulation 60-70% chance of
1 to 2 inches through the day Sunday. Even at Snoqualmie Pass,
where accumulations are not expected, there`s still the
likelihood of periods of snow mixed in with rain. Those that
plan to head to the higher mountain elevations this weekend
should be prepared to encounter snow and cold conditions and
closely monitor the weather forecast in the next few days.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...Ensemble guidance
continues to favor the upper low over Oregon ultimately digging
into California. This will pull precipitation away from the
the Pacific NW and a drier pattern towards mid week. There
remains elevated concern for morning frost Monday and Tuesday
as clearing skies and light winds yield efficient cooling and
temperatures may reach the mid to upper 30s for the sheltered
interior locations away from the water. After a few dry days,
guidance favors a return of a more active pattern, and
associated precipitation chances, late in the week.

&&

.AVIATION...Southerly flow aloft will gradually become more
northwesterly on Saturday as an upper level low pushes onshore.
Conditions are primarily VFR across the majority of the area
terminals this evening, with the exception of KOLM in fog. Latest
radar shows some shower activity pushing northward along the Sound
this evening. Expect showers to linger into the overnight period -
and could see conditions at terminals briefly dip down to MVFR at
times in any heavier showers over the area terminals. Surface winds
remain southerly around 4 to 8 knots. Ceilings will likely remain
predominantly VFR throughout the remainder of the evening but will
slowly lower to MVFR on Saturday morning across most of the area
terminals as a frontal system approaches and moves into western
Washington.

KSEA...VFR conditions continue at the terminal this evening with
light showers within the vicinity. Ceilings will gradually lower
towards MVFR on Saturday morning. South/southwest winds look to
remain around 4-8 knots overnight and look to increase to 7-12 kt
late Saturday morning.  14

&&

.MARINE...High pressure will build in temporarily over the area
waters on Saturday between weather systems. Winds will be elevated
over the outer coastal waters, with a gale warning now posted from
Saturday morning through Sunday morning. Winds over the interior
waters will remain below thresholds, with the only exception being
possible Small Craft Advisory level westerly winds through the
Strait of Juan de Fuca late Saturday night into Sunday morning. As
another low pressure system approaches the coast on Sunday, winds
will turn offshore, with a stronger gradient through the Strait of
Juan de Fuca expected. These winds are suggestive of potential
gales, but will let subsequent forecast details evolve before making
a determination.

Seas will rise to 12-15 feet Saturday night into Sunday, becoming
steep with periods of around 10 to 11 seconds. Seas will then
gradually subside towards 5-8 ft by Monday evening.

21/14

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory from 5 AM Sunday to 5 AM PDT Monday
     for Cascades of Whatcom and Skagit Counties.

PZ...Small Craft Advisory from 5 PM Saturday to 2 PM PDT Sunday 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 10 To 60 Nm-Coastal Waters From Point
     Grenville To Cape Shoalwater Out 10 Nm.

     Gale Warning from 8 AM Saturday to 2 PM PDT Sunday 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.

&&

$$