779
FXUS66 KSEW 232239
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
239 PM PST Sun Nov 23 2025

.SYNOPSIS...Post-frontal, onshore flow will continue through
tonight. An upper trough will move inland on Monday for
additional light precipitation. Another frontal system will move
onshore on Tuesday, with a warm front lifting northwards
Wednesday. Unsettled weather continues on Thursday as a weather
system moves through the Pacific Northwest. Precipitation
lingers through Friday with a cooler weather pattern developing
next weekend.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...Onshore flow
continues this afternoon with continued clouds across the
interior, and some clearing along the Olympic Peninsula. A
weak convergence zone will linger over King County into this
evening, with the bulk of the moisture focused into the
Cascades. Another round of light precipitation will move through
on Monday as an upper trough over Western Washington moves
inland. Snow levels will fall to 2000 to 2500 feet into Monday,
resulting in a few inches of snow for the Cascade Passes (mainly
less than 3 inches of snow). Temperatures will cool a few
degrees on Monday with highs in the mid to upper 40s.

Precipitation will slowly increase on Tuesday as a frontal
system approaches Western Washington. Locally breezy winds are
also expected on Tuesday, mainly for Whidbey Island and the
coast with southeast wind gusts approaching 25-30 MPH. Snow
levels will initially be 2000 to 3000 feet late Tuesday at the
onset of the precipitation, resulting in snow for the Cascade
Passes. Snow levels then look to rise to near 3500 feet for the
central Cascades by late Tuesday night. Despite rising snow
levels and increasing warm air aloft, continued E/SE surface
flow at Snoqualmie Pass may result in a brief period of freezing
rain late Tuesday night into Wednesday morning. However,
uncertainty continues to exist in regards to the frontal
position and precipitation transition timing. At this time,
probabilities of 6" of snow (or more) from Tuesday-Wednesday
morning range from 30% at Snoqualmie Pass and 60% at Stevens
Pass. If you`re traveling over the Passes Tuesday afternoon into
midweek, continue to monitor the forecast and pass conditions.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...The aforementioned
frontal system will stall generally across southern Washington
on Wednesday. There remains some uncertainty into the northern
extent of the precipitation shield on Wednesday, perhaps
resulting in a brief period of dry conditions near the BC
border. Otherwise, continued lowland rain and higher elevation
mountain snowfall expected on Wednesday (especially for southern
areas). Snow levels will continue to rise on Wednesday as a
warm front lifts northwards late. As noted above, we will
continue to monitor any potential wintry mix Wednesday morning
for Snoqualmie Pass before surface temperatures warm. Primarily
snow or rain/snow mix for Stevens Pass on Wednesday.

A more consolidated low pressure system will approach the
Pacific Northwest on Thursday. This will result in continued
lowland rain and high elevation mountain snowfall on Thursday.
In addition, will need to monitor the track of the low pressure
system early Thursday for any wind related concerns. Quite a bit
of spread exists in the ensembles for Thursday, for example the
10th-90th PCT (from NBM) max wind gusts is 11 MPH-40 MPH,
suggesting significant uncertainty. However, gusts at this time
are forecast to remain below headline thresholds. Otherwise,
consistent precipitation on Thursday will lead to rises on
rivers, especially the Skokomish River in Mason County. Refer to
the .HYDROLOGY discussion for more information.

Continued troughing over Western Washington on Friday will lead
to unsettled conditions, and more showers at times. A cooler
airmass will develop next weekend as troughing digs southwards
across the interior West. Northerly flow with ridging offshore
will allow for predominantly drier conditions by late weekend
over Western Washington, although have kept NBM POPs of 20-35%
due to some uncertainty in additional systems overtop the ridge.
There remains decent spread in the ridge position offshore and
troughing over the interior West by Sunday. This can be seen
well on the NBM percentile data, with the 10th-90th Min T by
next Sunday ranging from 31-43 degrees for Seattle and 20-37
degrees for Bellingham (aided by Fraser Outflow). Thus, it will
be important to continue to monitor forecasts. Either way, as
noted on the CPC outlook, a cooler weather pattern is expected
beginning next weekend for Western Washington. JD

&&

.AVIATION...A mix bag of ceilings this afternoon in the wake of
a frontal passage. Guidance suggests some improvement in
ceilings is possible after 00Z for some interior terminals to
low-end VFR. However, low ceilings are expected to remain at
terminals (PAE, BFI, SEA) impacted by the convergence zone
through 06Z. Low-end VFR ceilings will hover throughout Monday
morning and will gradually lower in the afternoon to high-end
MVFR after 21Z. PWT is unlikely to improve beyond MVFR, with
guidance hinting of a 25-30% chance of IFR/LIFR ceilings
returning on Monday.

KSEA...Low ceilings and visibility continues at the terminal as a
convergence zone persist over the terminal. Expecting the
convergence zone to dissipate after 06Z, with improvement to low-end
VFR ceilings following shortly after. Ceilings will lower again
Monday afternoon and expecting MVFR after 20Z. N/NE winds at 4-6 kt
expected to continue through 06Z/07Z. Winds will then become S/SW
and increase Monday afternoon 8-10 kt.

29

&&

.MARINE...Onshore flow will continue through Monday. Small Craft
Advisory west winds are expected at times across the central
and eastern Strait of Juan de Fuca through tonight. There will
likely be a period where winds drop below SCA threshold this
evening, with another increase in onshore flow later tonight. In
general, occasional gusts to 25 kts are expected before winds
taper off early Monday. Elsewhere, winds will remain generally
lighter, with continued northwest winds for the Coastal Waters.
Southeast winds will increase on Tuesday, especially for the
Coastal Waters, as well as eastern Strait of Juan de Fuca, where
headlines will likely be necessary. Winds will remain elevated
through Thursday as a weather system moves through the waters.
Winds will lighten on Friday before transitioning more
northeasterly next weekend.

Seas of 10 to 13 feet this afternoon will subside below 10 feet
on Monday. Seas will build above 10 feet again late Tuesday into
Wednesday. JD

&&

.HYDROLOGY...Light precipitation at times is expected through
Monday. No hydro concerns during this period. A stronger weather
system will move into Western Washington late Tuesday, with
continued precipitation at times through Thursday. 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. However, other rivers will continue to be monitored
as well. JD

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 10 PM PST this evening for Grays
     Harbor Bar-West Entrance U.S. Waters Strait Of Juan De
     Fuca.

     Small Craft Advisory until 4 AM PST Monday for Central U.S.
     Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
     Strait Of Juan De Fuca.

     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.

&&

$$