Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
595
FXUS66 KSEW 051521
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
821 AM PDT Mon Oct 5 2026
.UPDATE...
Areas of dense fog continue to move through parts of western
Washington this morning. Based on satellite and webcams, no
changes were made to the advisory areas yet this morning.
Ceilings look to remain around 100-300 ft, so the areas closest
to sea level may no longer see dense fog. Guidance continues to
indicate fog starting to lift around 10-11 AM, with more
clearing shortly thereafter with high clouds continuing to
stream overhead. See below for updates the the aviation
discussion. 62
&&
.SYNOPSIS...
Near-zonal flow aloft and onshore flow at the surface will
maintain seasonable conditions across western Washington through
much of the week, with morning clouds and afternoon sun breaks.
Chances for rain increase towards the end of the week alongside
cooler temperatures as troughing develops over the Pacific
Northwest.
&&
.SHORT TERM /TODAY THROUGH WEDNESDAY/...
An upper level ridge over the Great Basin has weakened and
flattened, allowing for zonal flow to develop aloft over the
Pacific Northwest with a return to onshore flow at the surface.
The pattern is set to remain steady throughout the short-term,
resulting in little change day to day through Wednesday. Daily
marine pushes will result in expanding stratus across the
lowlands each morning, with potential for patchy fog to develop
in fairly stagnant overnight conditions. The fog and stratus
will erode for most lowland areas by the afternoon each day,
although areas along the coast may stay socked in with little
sunshine. The cooler marine air will allow for seasonable fall
temperatures, with highs generally in the 60s to lower 70s, and
lows in the mid 40s to lower 50s. The upper level ridge over the
southwestern US will rebound slightly on Wednesday, resulting in
little more than temperatures a degree or two warmer across the
region.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The upper level high pressure ridge over the southwestern US
will continue to nudge into the Pacific Northwest slightly on
Thursday, resulting in continued warming with high temperatures
in the mid 60s to lower 70s. However, conditions on Thursday will
feel similar to past days with another potential round of low
stratus in the morning and sunny skies in the afternoon.
Forecast models remain in good agreement of troughing developing
over the region on Friday into the weekend, but the details
still remain fairly uncertain. Models have continued to back off
on incoming rainfall on Friday with a frontal system splitting
as it moves into western Washington, though ensembles hint at a
potential Puget Sound convergence zone developing into Saturday.
A cutoff low is also expected to develop overhead by Saturday,
bringing cooler temperatures and chances for light showers
lingering into Sunday. The exact details remain uncertain at
this time, but next weekend looks to be cooler and unsettled
with highs peaking in the mid 50s to lower 60s.
15
&&
.AVIATION...
Onshore flow this morning has led to widespread areas of fog this
morning, primarily from central Puget Sound southward, and north of
Everett. The areas of fog/mist will likely begin lifting as early as
18Z, and then fully scatter out for all except the coast/Strait of
Juan de Fuca by 20-22Z. The two coasts likely retain MVFR ceilings
into the afternoon/evening. Given the continuing/stagnant onshore
pattern with high pressure offshore, another round of fog/mist is
likely to develop Tuesday morning. Light and variable winds this
morning will increase out of the north around 4-6 kt this afternoon,
becoming calm/light and variable again tonight.
KSEA...Fog/LIFR conditions will continue at the terminal through
18Z, with conditions improving from 18-21Z this afternoon to VFR.
Another round of lower ceilings/fog is likely Tuesday morning,
although uncertainty exists as to how far fog will make it up to the
terminal. Calm/light and variable winds will be present this
morning/Tuesday morning, with winds picking up out of the northeast
at around 4-6 kt both Monday/Tuesday afternoon.
HPR
&&
.MARINE...
Onshore flow has returned into today as low pressure shifts inland
and surface high pressure builds offshore. Areas of fog continue
across portions of Puget Sound, the Strait of Juan de Fuca, and the
Northern Inland Waters where dense fog advisories continue through
11 AM this morning. Fog will be likely over portions of the waters
next few mornings. Westerly pushes are favored throughout the
upcoming week of varying strength. A more organized system appears
favorable towards Friday with a better chance of widespread
headlines.
Seas through Wednesday hold at 4-6 ft, and increase to 6-10 ft late
this week with the late week systems passing through.
41/HPR
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Dense Fog Advisory until noon PDT today for City of Seattle-
Downtown Everett / Marysville Area-Eastern Strait of Juan
de Fuca-Eastside-Foothills and Valleys of Pierce and
Southern King Counties-Foothills and Valleys of Thurston
and Lewis Counties-Grays Harbor County Coast-Island
County-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-Middle Chehalis River
Valley-Olympia and Southern Puget Sound-San Juan County-
Shoreline / Lynnwood / South Everett Area-Western Strait
of Juan de Fuca-Willapa and Black Hills.
PZ...Dense Fog Advisory until 11 AM PDT this morning for Admiralty
Inlet-Central U.S. Waters Strait Of Juan De Fuca-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.
&&
$$
NWS SEW Office Area Forecast Discussion