867
FXUS66 KSEW 111051
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
251 AM PST Thu Dec 11 2025

.SYNOPSIS...
An atmospheric river system will continue to weaken today as
rainfall intensity and coverage decrease, with significant river
flooding impacts continuing through at least the remainder of
the week. Showers will continue to linger through Saturday
before a stronger frontal system brings additional precipitation
and breezy winds over the weekend. Wet and unsettled conditions
are favored to continue into much of next week.

&&

.SHORT TERM /TODAY THROUGH SATURDAY/...
Western Washington has seen a considerable decrease in
precipitation into the morning as an atmospheric river system
weakens. High pressure will continue to build over the western
US and amplify northward, bringing in more stable air and
gradually nudging shower activity northward towards the Canada
border over the next several days. While showers will continue
to linger for northern areas, Saturday will be the driest day of
the forecast period ahead of continued active weather
conditions. Temperatures will remain mild, peaking in the mid
50s across the lowlands for the next several days.

Throughout the day today, rainfall accumulations will be light
across the lowlands, topping out at roughly half an inch or less
of additional rain. Elsewhere over the central and southern
Cascades, additional rainfall accumulations of up to 2 to 3
inches can be expected in shower activity through this evening.

As activity from the atmospheric river system tapers off today,
the following key messages are outlined below:

* RIVER FLOODING: The threat of significant to locally
  catastrophic river flooding continues despite a tapering off
  of rainfall across western Washington as area rivers respond
  to the heavy rainfall across the region over the past few
  days. While some rivers have crested, primarily those running
  off of the Olympics, other area rivers continue to rise with
  some far exceeding previous record flows. Some rivers that
  are slower to respond, including the Nooksack, Skagit, and
  Snohomish, will take a few more days to fully crest and lower
  below flood stage. Expect significant flooding impacts to
  continue over at least the next several days, with more
  details in the HYDROLOGY section below.

* WINDS: Breezy winds will continue to gradually taper
  throughout the day today, with gusts of 25 to 35 mph lingering
  through the morning. However, with heavily saturated soils,
  additional downed trees and power outages cannot be ruled out
  at this time.

15

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
Ensemble guidance favors an upper level ridge on Saturday, giving
way for drier conditions to Western Washington. These dry conditions
will be shortlived as guidance signals at a weak cold front to move
over the Pacific Northwest on Sunday. Unsettled and wetter
conditions are favored to the early start of the week as a series of
systems move through. Additional rainfall may keep river levels
high, which will need to be monitored.

29

&&

.AVIATION...
Generally low end VFR to IFR across western Washington this
morning as rainfall from a weakening atmospheric river system
continues to slowly shift southward across the region. Low level
moisture and additional rain (some of which may be heavy at
times) will likely keep visibilities down in most terminals
through tonight/Thursday, with rain diminishing during the day
Thursday. Ceilings are expected to be slow to improve to MVFR
through the afternoon, with a low probability of improvement out
of IFR in the south terminals through the day Thursday. Winds
will continue to decrease throughout the morning to 5-10 kt. A
push of northwesterlies through the Strait of Juan de Fuca will
turn winds briefly north/northeast in the Puget Sound terminals
between 06Z- 12Z, before returning to the south. Winds will
become calm to light and variable by this afternoon.

KSEA...IFR conditions likely to continue through the TAF period with
moderate to heavy rain at times, low ceilings, and periods of
reduced visibility in fog. Small chance for improvement to MVFR
late this afternoon before returning to IFR in the evening.
Winds SW 10-15 kt gusting to 30 kt through roughly 12Z, then a
brief window of NE winds 5-10 kt between 12-16Z before returning
to the ESE. Winds drop to under 5 kt late this afternoon,
become light and variable.

&&

.MARINE...
A cold front will push through area waters early Thursday morning
with high pressure building behind the front through Friday. High
pressure will begin to weaken on Saturday as a weak cold front
approaches the coastal waters. This system will bring 40-60% chance
of small craft wind gusts to the coastal waters through the weekend.
A series of stronger systems are expected to move over area waters
starting on Monday. Latest guidance suggests there is high
confidence (70-90%) of gusts exceeding 21 kt, with a small to
moderate chance (20-45%) of seeing gale gusts over area waters
through Tuesday. The highest chances of seeing gales at this time
are over the coastal waters. In addition, guidance suggests that
these systems will be accompanied by large wave heights around
12-16 ft.

29

&&

.HYDROLOGY...
A strong atmospheric river event has brought a significant
amount of rainfall to the Pacific Northwest over the past
several days, and while this storm system continues to weaken,
area rivers continue to respond to the significant rainfall.
Western Washington has seen roughly 2 to 12 inches of rain in
the past 72 hours, with an additional 1 to 3 inches of rain
forecast throughout the day today. While some area rivers have
crested, particularly rivers in the Olympic Peninsula basins,
other rivers continue to rise to significant or record- breaking
levels, especially over the western Cascades. Some rivers that
are slower to respond, including the Nooksack, Skagit, and
Snohomish, will take a few more days to fully crest and lower
below flood stage. The following headlines are in effect across
western Washington as of 2 AM PST:

* Numerous River Flood Warnings remain in effect across western
  Washington, with varying times and flood levels.

* A Flash Flood Watch remains in effect for a potential levee
  failure of the Skagit River below Sedro-Wooley to the mouth of
  the Skagit River through late Friday.

* A Flood Watch remains in effect through Friday across all of
  western Washington.

With very wet antecedent soil conditions, the landslide threat
across the region has increased with this system, and several
landslides and mudslides have already occurred in steep terrain
across western Washington. Potential has also increased for
debris flows over area burn scars, which continue to be
monitored.

While the threat of urban flooding has decreased, the threat of
small stream flooding, as well as for areas with poor drainage,
continues to pose a risk of localized nuisance flooding and
ponding on roadways. Low water crossings may become impacted or
impassable.

The latest river observations and forecasts can be found at
water.noaa.gov.

15

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Flood Watch through Friday afternoon for Cascades of Pierce
     and Lewis Counties-Cascades of Snohomish and Northern
     King Counties-Cascades of Southern King County-Cascades
     of Whatcom and Skagit Counties-City of Seattle-Downtown
     Everett / Marysville Area-Eastern Kitsap County-Eastern
     Strait of Juan de Fuca-Eastside-Foothills and Valleys of
     Central King County-Foothills and Valleys of Pierce and
     Southern King Counties-Foothills and Valleys of Snohomish
     and Northern King Counties-Foothills and Valleys of
     Thurston and Lewis Counties-Foothills and Valleys of the
     North Cascades-Foothills of the Western and Southern
     Olympic Peninsula-Grays Harbor County Coast-Island County-
     Lake Crescent Area Including US 101-Lower Chehalis River
     Valley-Lowlands of Lewis and Southern Thurston Counties-
     Lowlands of Pierce and Southern King Counties-Lowlands of
     Western Skagit and Northwestern Snohomish Counties-
     Lowlands of Western Whatcom County-Middle Chehalis River
     Valley-Northern Hood Canal-Northern Washington Coast-
     Olympia and Southern Puget Sound-Olympics-Port Townsend
     Area-San Juan County-Shoreline / Lynnwood / South Everett
     Area-Southern Hood Canal-Western Strait of Juan de Fuca-
     Willapa and Black Hills.

     Flash Flood Watch through late Friday night for Lowlands of
     Western Skagit and Northwestern Snohomish Counties.

     Wind Advisory until 10 PM PST this evening for City of Seattle-
     Downtown Everett / Marysville Area-Eastern Kitsap County-
     Eastside-Foothills of the Western and Southern Olympic
     Peninsula-Grays Harbor County Coast-Lower Chehalis River
     Valley-Lowlands of Lewis and Southern Thurston Counties-
     Lowlands of Pierce and Southern King Counties-Middle
     Chehalis River Valley-Northern Washington Coast-Olympia
     and Southern Puget Sound-Shoreline / Lynnwood / South
     Everett Area-Southern Hood Canal-Willapa and Black Hills.

PZ...Small Craft Advisory until 4 AM PST Thursday for Admiralty
     Inlet-Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca-Grays Harbor
     Bar-Northern Inland Waters Including The San Juan Islands-
     Puget Sound and Hood Canal-West Entrance U.S. Waters
     Strait Of Juan De Fuca.

     Gale Warning until 10 PM PST this evening 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
     Out 10 Nm.

     Small Craft Advisory until 4 AM PST Friday 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
     Out 10 Nm.

     Small Craft Advisory until 4 AM PST Friday 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-
     Coastal Waters From Point Grenville To Cape Shoalwater 10
     To 60 Nm.

&&

$$