805
FXUS66 KSEW 072310
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
310 PM PST Sun Dec 7 2025

.SYNOPSIS...
Showers will continue tonight in the wake of a frontal system
that moved across the area today. An atmospheric river will
impact the area Monday through Wednesday, bringing periods of
moderate to heavy rainfall and the threat for significant river
flooding to the area. Minor coastal flooding due to high astronomical
tides will remain possible for the Salish Sea coastlines through
the first part of the week. Wet and unsettled conditions will
continue through the end of the week.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
Showers continue across the area this afternoon in the wake of
a frontal system that moved through the area this morning.
Expect shower activity to continue into tonight.

Conditions then become wetter on Monday with a strong atmospheric
river still on track to move into the region and impact the area
through Wednesday. The key messages regarding this system are
highlighted below:

KEY MESSAGES:

* RAIN: A strong atmospheric river will arrive on Monday,
  bringing extended periods of moderate to heavy rain to western
  Washington through Wednesday. The most significant change
  within the last 24 hours has been the shift in the axis of
  moisture with this system. At this time, the moisture plume
  still looks to shift south briefly on Tuesday, however the
  latest guidance has it lifting back northward into the area
  Tuesday night into Wednesday. This has resulted in an increase
  in precipitation totals across the central and south Cascades
  this afternoon. While this will have an impact to river
  forecasts, the overall message is that it will be a wet first
  half of the week for the region. Areas generally south of
  Seattle are still expected to see around 2.5 to 5 inches of
  rain in a 72 hour period. The Olympics and Cascades are on
  track to receive 6-10 inches of rain, though locally higher
  amounts across the central and south Cascades of close to 12
  inches will be possible through late Wednesday night.

* WIND: Monday will be windy across the region area-wide.
  Southwesterly winds will pick up Monday morning, peak Monday
  evening, and gradually ease Monday night into Tuesday. The
  strongest winds are expected along the coast, but expect gusts
  to 40-45 mph at times across the interior. Gusts to 50-55 mph
  will be possible along the immediate Pacific coast.

* COASTAL FLOODING: Minor coastal flooding remains possible for
  the Salish Sea coastlines through the first half of the week
  with high astronomical tides. While the tides will generally
  remain below or just close to thresholds, heightened river
  flows or wind effects could exacerbate inundation in some
  spots around high tide.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Unsettled conditions look to continue across the second half of
the week, though precipitation gradually looks to taper across
the area through the day Thursday. Ensemble guidance does hint
at the building of a ridge along the West Coast Friday into the
weekend, which would help push the storm track further to the
north. This may be short-lived however, as there is some
indication that the ridge axis will shift further inland over
the weekend and open the door for additional, weaker systems to
make their way into western Washington.

14

&&

.AVIATION...
A surface warm front will continue to lift northward across the
terminals this afternoon. Expect surface winds to continue to
increase as the warm sector pushes northward through western WA this
afternoon, with gusts peaking around 25 kt this afternoon and
evening out of the southwest. Ceilings are a toss between MVFR (with
a few interior spots reporting IFR), although some clearing has
taken place around the Kitsap, and will increase across much of the
interior terminals this afternoon. A few rain showers will linger
through tonight with the trailing cold front passing through this
evening. Winds will decrease down to 5-10 kt out of the south
tonight. A stronger atmospheric river system will arrive late Monday
morning with widespread rain (some of which may be heavy at times
reducing visibilities down to IFR). Ceilings will lower through the
day down to MVFR/IFR as the rain progresses through the day. Main
concern will be strong south winds increasing through the afternoon
and evening, with sustained winds peaking around 15-20 kt, with
gusts to 35-40 kt. Soundings show some turning from the W to the
SSW, which may result in marginal wind shear concerns as winds
increase.

KSEA...Few vicinity showers will linger through the afternoon and
evening. Satellite trends shows MVFR ceilings eroding to the west,
which should improve ceilings to VFR mid to late afternoon. The next
system will lower ceilings back to MVFR later this evening as early
as 10Z with rain arriving as early as 15Z (some of which may be
heavy at times reducing visibilities down to IFR). Probabilities of
IFR increase to 30% late in the day. Winds Sunday afternoon remain
SSW 10-15 kt gusting to 25-30 kt, decreases to 5-10 kt out of the S
late, but increases out of the SW 15-20 kt with gusts of 35-40 kt
possible by Monday afternoon/evening.

HPR

&&

.MARINE...
A brief lull in the winds is expected across the region tonight
as the area remains in between weather systems. A stronger
weather system will then move into the waters on Monday, with
winds expected to peak Monday afternoon and evening. Gusts to
gale are likely for the majority of the area waters on Monday,
with latest probabilities still showing roughly a 60 to 90
percent chance of winds reaching 35 kt for much of the area
(especially along the Sound). A push is expected down the Strait
of Juan de Fuca late Monday into Monday night, where a round of
westerly gales looks likely. Winds will subside across the area
waters heading into Tuesday. Additional systems moving into the
area throughout the week may bring elevated winds and seas to
the area waters at times.

Seas between 6 to 8 feet tonight will build to 13 to 16 feet on
Monday. Seas will remain elevated above 10 feet through
midweek, before subsiding to 7 to 9 ft on Thursday.

14

&&

.HYDROLOGY...
A strong atmospheric atmospheric will move through the Pacific
Northwest Monday through Wednesday, bringing significant heavy
rainfall across the area. While there`s still some uncertainty in
the precipitation amounts with an atmospheric river moving into the
region, confidence remains high 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 now and through the next seven days. Additional
precipitation is also possible Thursday into Friday, which may keep
rivers elevated through the second half of the week.

With the wet antecedent soil conditions, the landslide risk across
the region will increase with this system. There may also be
potential impacts to the area burn scars as well.

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

62

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...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.

     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.

PZ...Small Craft Advisory from 10 AM Monday to 4 AM PST Tuesday for
     Grays Harbor Bar.

     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 Warning from 10 AM to 10 PM PST Monday 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-West Entrance U.S. Waters
     Strait Of Juan De Fuca.

     Gale Warning from 1 PM to 10 PM PST Monday for Central U.S.
     Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 4 AM to 10 AM PST Monday 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.

     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.

&&

$$