537
FXUS66 KSEW 221643
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
843 AM PST Sat Nov 22 2025

.SYNOPSIS...A frontal system will cross western Washington
tonight, bringing in widespread lowland rain, mountain snow, and
breezy winds. Cooler and unsettled conditions will linger into
Monday, with increased potential for a wetter and cooler system
to enter the region mid week into the Thanksgiving holiday.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...Widespread clouds across
Western Washington this morning as a frontal system remains
draped over British Columbia. Light rain also continues this
this morning along the coast. The bulk of any precipitation
through this afternoon will remain along the Olympic Peninsula
and Snohomish CO northwards before the front slides south
tonight. No major forecast updates this morning, previous
discussion below:

A frontal system stalled over British Columbia will maintain
light shower activity along the Canada border and Pacific Coast
for much of the day today. Onshore flow will promote cloudy
skies throughout the day, with an increase in winds this
afternoon along the northern coast and Whidbey Island northward.
The frontal boundary will shift southward later this evening,
with more widespread precipitation filling in across western
Washington overnight into Sunday. While the bulk of the
moisture with this system will shift eastward by the afternoon
Sunday, post frontal showers will continue to stream inland
through Sunday night with a convergence zone developing over the
northern Puget Sound and central Cascades. Stronger showers
that move inland later Sunday may even produce a few lightning
strikes, with the highest chances along the Pacific Coast. Winds
will also become breezy as this system digs into the Pacific
Northwest, with gusts reaching 20 to 35 mph. Snow levels around
5500-6000 feet will fall to near 2000-2500 feet by Sunday night,
with a high chance (60% to 70%) of 1 to 2 inches of
accumulating snowfall through the Cascade mountain passes.

The upper trough axis will shift inland early Monday morning,
bringing in another round of showers across western Washington.
Snow levels will remain near 2000-2500 feet, with an additional
2 to 4 inches of snow accumulation possible through the Cascade
passes. Precipitation will taper off Monday afternoon and
evening as weak ridging builds inland, giving way to some
occasional sun breaks among cloudy skies.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...High pressure will
continue to build northward into Tuesday, providing a brief
break in wet conditions across western Washington. Tuesday
morning will see the coldest morning temperatures of the period,
with many lowland locations especially away from the water
dipping to near freezing.

Ensembles and operational forecast models remain in good
agreement over the next weather system entering the Pacific
Northwest by late Tuesday, with potential to bring in
significant lowland rain and mountain snow alongside breezy
winds. Snow levels will fluctuate mid week, opening the door for
accumulating mountain snowfall and even a slight chance of
freezing rain through the Cascade passes ahead of the
Thanksgiving holiday. While the details of this incoming
atmospheric river remain somewhat uncertain at this time,
conditions continue to be closely monitored ahead of holiday
travel. Ensembles also highlight active and potentially
impactful weather continuing into next weekend.

15

&&

.AVIATION...MVFR ceilings this morning across most of the
terminals. May see some marginal improvement this afternoon and
evening into high-end MVFR and low-end VFR. Ceilings will lower
again to MVFR overnight, and potentially IFR (20-35% chance).
Rain showers will arrive to the coast this afternoon and the
main band of rain will arrive to inland terminals by early
Sunday morning. SW winds will increase to 8-12 kt today, with a
few guts 20-25 kt possible for terminals along interior
waterways and the coast.

KSEA...MVFR ceilings are expected to remain in place through around
21Z. Some brief improvement to low-end VFR between 21Z-03Z, before
lowering back to MVFR. Showers arriving around 06Z Sunday. Winds
will increase out of the SW this afternoon to 8-12 kt. Occasional
gusts to 20 kt possible after 10Z Sunday through the afternoon.

HPR/29

&&

.MARINE...A frontal system will approach the waters from the
west late this afternoon into Sunday. The seas in the coastal
waters will remain around 10-13 ft Saturday through Sunday as
this system moves through. Increasing S winds are expected with
increasing confidence for 20-25 kt gusts and seas remaining
above 10 ft through Monday resulted in the small craft advisory
(SCA) being extended through Monday. A couple of high-
resolution models also increased confidence in gusty S winds to
25 kt from the Northern Inland Waters, down to the northern
portions of the Puget Sound waters (including the east Strait of
Juan de Fuca and Admiralty Inlet). An additional SCA was issued
for the frequent gusts Saturday evening through late Sunday
morning. Post-front, a strong push may produce frequent gale
gusts for the central/east strait Sunday evening into Monday
morning (gale watch was issued). After Monday, seas will
decrease down to 6 to 8 ft through midweek before another system
brings seas just above 10 ft and gusty winds just above 20 kt.

JD/HPR

&&

.HYDROLOGY...A weather system will move across western
Washington late Saturday into Monday for lowland rain and
mountain snowfall. No river flooding is expected during this
period, but rivers will rise. The potential exists for
additional, heavier precipitation during the middle of next
week. However, uncertainty exists in both the location and
duration of precipitation. River levels will continue to be
monitored during this mid to late week period.

JD

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 6 AM PST Sunday for Grays Harbor
     Bar.

     Small Craft Advisory until 10 PM PST Sunday for West Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Gale Watch from Sunday morning through Monday morning for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 7 PM this evening to 7 AM PST Sunday
     for Admiralty Inlet-East Entrance U.S. Waters Strait Of
     Juan De Fuca-Northern Inland Waters Including The San
     Juan Islands-Puget Sound and Hood Canal.

     Small Craft Advisory until 10 AM PST Monday 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.

&&

$$