248
FXUS66 KSEW 221037
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
237 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/...
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. Whlie 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...
An upper level ridge will move out of the region this morning as a
trough approaches late tonight/Sunday with a frontal system. Flow
aloft will increase out of the W/SW. For this morning: MVFR ceilings
are currently ongoing across most terminals (with pockets of IFR
ceilings/mist along the coast and the south interior). With the
increased low-level moisture ahead of the next system, the ceilings
will only marginally improve to upper-end MVFR/low-end VFR late this
afternoon and evening (best chance for VFR improvements are
terminals from KBFI south to KOLM). Ceilings will lower again to
MVFR late tonight/Sunday (pockets of IFR possible). Rain showers
will arrive on the coast early this afternoon, with organized rain
showers encompassing most terminals early Sunday morning. SW winds
will pick up to 8-12 kt today (with a few gusts to 20-25 kt for
terminals along interior waterways, and the coast).

KSEA...MVFR ceilings are expected to remain in place through around
21Z (with a brief improvement to VFR decks just above 3,000 ft from
21Z-03Z before lowering back to MVFR). Showers arriving by around
06Z Sunday. Winds SW 8-12 kt (occasional gusts to 20 kt possible
from 10Z Sunday onwards through the afternoon).

HPR

&&

.MARINE...
An upper level region will move south of the region, giving way to a
trough and frontal system approaching 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.

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 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-Grays Harbor Bar.

     Small Craft Advisory until 4 PM PST this afternoon for West
     Entrance U.S. Waters Strait Of Juan De Fuca.

&&

$$