545
FXUS66 KSEW 250535 CCA
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
850 PM PST Mon Nov 24 2025

.SYNOPSIS...
Lingering showers mainly over the higher terrain will taper off
overnight. Precipitation will return to the area Tuesday, with
lowland rain, and mountain snow through Tuesday becoming mostly
rain through the day Wednesday. Unsettled weather is expected
through the holiday and into the weekend with periods of
precipitation and cooler conditions.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
Western Washington is experiencing a brief break between systems
tonight. The next in a series is slated to bring a rather wet day to
the region on Tuesday as a slow moving system gradually lifts a warm
front northward over the area. Impactful snowfall is expected in the
passes before turning to a wintry mix Tuesday night into early
Wednesday. A relative lull in precip is still expected on Wednesday
before the next system arrives Wednesday night into Thanksgiving
Day. Ensembles have a shown a considerable spread in solutions with
this system in terms of strength, but a look at recent model runs
suggests that the secondary system will come in vertically stacked.
And in the absence of any jet support, it`s looking less likely that
this system will be impactful in terms of winds. It will, however,
be a traditionally wet Thanksgiving. Previous discussion follows
with update to the aviation portion.  27

Lingering showers, mainly over the higher terrain will taper off
overnight, aided by a brief period of short wave ridging. A stronger
system will approach the Pacific Northwest Tuesday,  with widespread
precipitation beginning to move onshore during the morning. Snow
levels will begin the day Tuesday 1500 to 2000 feet with snow
accumulations as precipitation moves into the area - particularly
through the Cascade Passes. 8 to 10 inches is possible at all of the
Cascade passes before snow levels begin to rise Tuesday evening. In
addition there is a chance of a wintery mix at Snoqualmie Pass
during the evening hours as warmer air rides over cold easterly flow
in the pass, with a 30% chance of freezing rain for a period before
the pass transitions over to rain later Tuesday night.

Snow levels should rise to well above 5000 feet by midday
Wednesday with precipitation transitioning to rain for all but
the higher ridges and volcanos. Ensembles continue to highlight
a trailing system setting up a second surge of moisture with a
warm front later Wednesday afternoon into to the evening. Snow
levels will remain generally above 6000 feet, with the heaviest
precipitation - mainly rain over the coast and Olympics
Wednesday night.


&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
The trailing system is expected to move into the coastal waters.
Ensemble guidance at this point in good agreement at the cold
front moving onshore through the day Thursday with the
associated surface low moving onshore somewhere along the
Washington coast to the west coast of Vancouver Island in
British Columbia. The approaching surface low and its landfall
will result in some breezy to gusty winds - most likely along
the coast. The nature and location of the strongest winds will
depend ultimately on the track of the low, and this will be one
of the details going into the Holiday that will be monitored.
Temperatures should cool somewhat behind the cold front into
Friday, with snow levels dipping back down to around 3500 feet.

Ensemble mean forecast suggest some degree an upper level ridge
settling in over the Eastern Pacific Saturday into Sunday -
setting up the Pacific Northwest for a cool north-to northwest
flow aloft and some possibility of weak system brushing the area
late in the weekend.

&&

.AVIATION...Westerly flow aloft will continue into Tuesday as a warm
front gradually lifts northward toward the area. High and mid level
moisture will increase overnight ahead of this system. Brief
clearing this clearing allowed for the formation of areas of LIFR
across portions of the Southwest Interior this evening, but this is
expected to dissipate overnight. Ceilings will deteriorate
regionwide on Tuesday morning with widespread low MVFR or occasional
IFR in rain persisting into Tuesday night.

KSEA...Ceilings will likely straddle MVFR thresholds overnight
before lowering to low MVFR or occasional IFR by mid-morning Tuesday
in rain with surface visibility of 3-5SM at times. Said conditions
will persist throughout the day tomorrow. Surface winds light
southerly this evening backing to east/southeasterly 6 to 10 knots
on Tuesday morning.   27

&&

.MARINE...
A frontal system is expected to pass over area waters, bringing
increased winds to area waters starting Tuesday morning. Winds for
the coastal waters, east entrance of the Strait, and Admiralty Inlet
are likely to meet small craft thresholds for which a Small Craft
Advisory has been issued. Low-end gale gusts possible at times for
the outer coastal waters Tuesday morning. Seas with this system will
build to 7-11 ft by Tuesday afternoon, with the highest waves for
the outer coastal waters.

A stronger system on Thursday will bring another round of elevated
winds and waves. Latest guidance highlights a 50-70% chance of gusts
exceeding 21 kt for the coastal waters and Strait of Juan de Fuca.
In addition, guidance suggests seas will build to 13-17 ft Thursday
evening.

29

&&

.HYDROLOGY...
A stronger weather system will move into Western Washington late
Tuesday, with continued precipitation at times through Thursday. The
storm total precipitation are higher today but there remains
uncertainty in the QPF among models.  Rivers will rise as a result
of the steadier precipitation, especially for rivers off the central
and southern Cascades, as well as the Olympics. Snow levels will
also rise to 5500 to 6500 feet by late Wednesday. At this time, the
Skokomish River in Mason County is the primary river being monitored
for river flooding by Thursday. The potential is there and as such a
Flood Potential Outlook for Mason County. Current rainfall and river
forecasts indicate a crest on the Skokomish right around flood
stage. This, as well as other rivers, will continue to be monitored.

18

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory from 10 AM Tuesday to 4 AM PST
     Wednesday for Cascades of Pierce and Lewis Counties-
     Cascades of Snohomish and Northern King Counties-Cascades
     of Southern King County.

PZ...Small Craft Advisory from 8 AM Tuesday to 1 AM PST Wednesday
     for East Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 10 AM to 10 PM PST Tuesday for
     Admiralty Inlet.

     Small Craft Advisory from 4 AM Tuesday to 1 AM PST Wednesday
     for Coastal Waters From Cape Flattery To James Island 10
     To 60 Nm-Coastal Waters From Cape Flattery To James
     Island Out 10 Nm-Coastal Waters From James Island To
     Point Grenville 10 To 60 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.

&&

$$