737
FXUS66 KSEW 071621
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
821 AM PST Sun Dec 7 2025

.SYNOPSIS...
Active weather continues through the week, with a potent
atmospheric river still on track to impact western Washington
Monday into Wednesday. Additional systems are forecast for late
in the week. Minor coastal flooding due to high astronomical
tides will remain possible for the Salish Sea coastlines into
the first part of the week.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...
The forecast remains largely on track, with radar this morning
showing widespread rain pushing inland across western Washington
ahead of the next frontal system. Rain will taper to showers in
its wake by this afternoon. Expect shower activity to persist
through tonight. The remainder of the previous discussion
follows below, with updates made to the aviation section. 14

KEY MESSAGES:

* RAIN: A weather system has arrived early this morning and will
  produce rain throughout the day. QPF amounts will be around
  1-2 inches in the Cascades, and a quarter to half inch in the
  lowlands. A strong atmospheric river will arrive on Monday,
  producing an extended period of heavy rain through Wednesday.
  The forecast has remained on track from the previous change of
  having a greater focus on QPF shifted slightly south. From
  areas generally of Seattle south, 2.5 to 5 inches of rain is
  still favored. The Olympics and Cascades are on track to
  receive 6-10 inches, with locally higher amounts receiving
  nearly 12 inches of rain through late Wednesday night.

* WIND: Monday will be windy, particularly in areas south of
  Seattle. Southwesterly wind will pick up Monday morning and
  remain elevated into the overnight period. Expect gusts of 35
  to 40 mph, tapering off into late Monday night.

* COASTAL FLOODING: Minor coastal flooding remains possible as
  the high astronomical tide cycle has shifted more so to the
  Salish Sea into Monday. While the tides will generally be
  below or just close to thresholds, affects from heightened
  river flows or wind effects on Monday could exacerbate the
  inundation around high tide.

The rain from the atmospheric river will persist throughout the
day on Monday, sinking slightly southward into the evening. The
moisture axis will lift north and pulse back up again Tuesday
into Wednesday. There will be a number of area rivers reaching
moderate to major flood stage, more of which can be found in the
hydrology section.

21

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The ongoing, strong atmospheric river will impact Tuesday, with
the model indications showing that the moisture plume will pulse
back to the north again, but not enough to keep the heavier rain
rates going in the northern sections of the CWA. By around
midday on Wednesday, the hose like precipitation will be
tapering off more significantly as the atmospheric river loses
steam. That said, don`t expect a full break in the
precipitation. Additional systems bringing rain are forecast for
later in the week. There are some ensemble differences in
whether the ridge will rebuild and force some of the
precipitation to the north, or keep the pattern fairly
progressive.

This will be a significant week of rainfall. The overarching
message has not changed in that there will be widespread river
flooding and likely more urban and small stream flooding as
well.

21

&&

.AVIATION...West-southwest flow aloft will continue through today as
a frontal system moves across Western Washington. Widespread MVFR
cigs early this morning with areas of IFR cigs as well. Rain
continues to spread northwards ahead of the next weather system,
with steady, stratiform rain through this morning. Vsbys may briefly
lower to 2-5 statute miles this morning during the steadier
precipitation. Post-frontal showers are expected this afternoon.
MVFR/IFR cigs into this afternoon, with some localized improvements
to VFR generally after 00z, particularly in central and northern
Puget Sound. Otherwise, MVFR/IFR cigs expected tonight into Monday
morning, and will likely remain low through the day. S/SW surface
winds through the TAF period will increase this morning, with gusts
peaking between 20 to 25 kts in the afternoon. Winds decrease
tonight with stronger winds expected Monday afternoon up to 35-40 kt.

KSEA...Rain showers are moving through the terminal this morning.
Rate of the rain has been enough to knock visibilities down to 2 SM
with mist accompanying the rain. Once the rain showers clear, the
probability has increased to a 50-60% chance of ceilings dipping to
IFR through 22Z. However, ceilings are still expected to improve to
MVFR onwards post-front, with brief periods of low-end MVFR cigs in
the evening. MVFR cigs then expected late tonight into Monday. South
winds of 5 to 10 kts this morning will transition more SW between 19
to 20z and increase, with gusts this afternoon ranging 20 to 25 kts.
WIll drop again back down to 4-8 kt before increasing back to 15-20
kt with gusts to 35 kt possible Monday afternoon. JD/HPR

&&

.MARINE...
A weather system will move across the waters today, with increasing
south to southwest winds. Small Craft Advisory winds are expected
for the majority of waters this afternoon. SCA winds will
mainly be driven by gusts, with wind gusts peaking between 20 to
30 kts during this period. Winds will briefly subside this
evening into tonight. A stronger weather system will then move
into the waters on Monday, with winds peaking Monday afternoon
into Monday evening. A Gale Warning has been issued for the
Coastal Waters due to the high confidence of gale force wind
gusts on Monday. Gale Watches have also been issued for Puget
Sound and northern inland waters on Monday, with the probability
of gales ranging 60 to 90 percent, with the highest probabilities
along portions of Puget Sound. In addition, a westerly push is
expected late Monday into Monday night for the Strait of Juan de
Fuca, and additional headlines will be necessary. Winds will
briefly subside on Tuesday, with another weather system Tuesday
night into Wednesday bringing increased winds.

Seas will range 7 to 9 feet into tonight, before building to 13 to
16 feet on Monday. Seas will remain elevated above 10 feet through
midweek. JD

&&

.HYDROLOGY...
A series of wet weather systems moving across the region will
increase the threat of river flooding early next week. While
there`s still some uncertainty in the precipitation amounts with
an atmospheric river moving into the region, confidence
continues to increase that a widespread river flooding event
will commence late Monday and continue through much of the week.
Multiple rivers flowing off the Cascades and the Olympics are
forecast to reach Minor, Moderate, and Major flood stage. While
uncertainty does remain in regards to the exact flood levels and
stages through the next week, it will be critical to monitor
the forecasts through the next seven days. Additional
precipitation is also possible Thursday into Friday, which will
keep rivers elevated through the second half of the week.

The series of wet systems will also start to elevate the landslide
risk across the region. As soils become more saturated next week,
there will be an increased potential for landslides and debris flows
on burn scars.

Urban and small stream flooding, as well as areas with poor
drainage, should be alert to the potential for localized nuisance
flooding. Low water crossings may become impacted or impassable.

14/62

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Coastal Flood Advisory until 11 AM PST this morning for
     Lowlands of Western Skagit and Northwestern Snohomish
     Counties-Lowlands of Western Whatcom County-San Juan
     County.

     Coastal Flood Advisory from 6 AM to noon PST Monday for
     Lowlands of Western Skagit and Northwestern Snohomish
     Counties-Lowlands of Western Whatcom County-San Juan
     County.

     Flood Watch from late tonight 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.

PZ...Small Craft Advisory until 4 PM PST this afternoon for
     Admiralty Inlet-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-East Entrance U.S. Waters Strait Of
     Juan De Fuca-Northern Inland Waters Including The San
     Juan Islands-Puget Sound and Hood Canal-West Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Gale Watch from Monday morning through Monday evening for
     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 from 7 AM to 7 PM 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.

&&

$$