Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
946
FXUS66 KSEW 282209
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
309 PM PDT Mon Sep 28 2026
.SYNOPSIS...A frontal system will move across Western Washington
tonight through Tuesday with increasing rain and breezy winds.
Upper ridging begins to build over the Pacific Northwest
Thursday and Friday with just a slight chance of precipitation.
The upper ridge further builds next weekend for drier, warmer
conditions.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...Mid and high
clouds continue to increase this afternoon across the area ahead
of an approaching frontal system. Rain will begin to spread
along the northern coast this evening, with rain becoming more
widespread for areas north of Snohomish County tonight. The
front drifts southwards on Tuesday, with rain moving from north
to south by the afternoon. Rainfall amounts will be heaviest
across the western slopes of the Olympic Peninsula, Skagit and
Whatcom Counties, as well as the Cascades from King County
northwards. Generally 1 to 3 inches of rain is expected for the
mountains, with 0.50-1.25 inches in the lowlands of Skagit and
Whatcom Counties. Significantly lighter QPF from Seattle
southwards as the front weakens.
The more impactful aspect to this system will be the increasing
southerly winds tonight through Tuesday. South winds are
expected to be strongest over western Whatcom County, with gusts
of 35 to 45 MPH. Gusty south winds are also expected for the San
Juan Islands, western Strait of Juan de Fuca, and a region from
Hood Canal to Everett, where gusts of 30 to 40 MPH are
anticipated. Elsewhere, winds will be breezy, ranging 25 to 35
MPH. Due to the continued foliage on trees, gusty winds may
cause localized power outages and tree limb damage. Winds will
slowly subside later Tuesday into Tuesday night for most areas,
the exception being a westerly push through the Strait of Juan
de Fuca late Tuesday.
An upper ridge slowly begins to build over the Pacific Northwest
on Wednesday, resulting in drier conditions. Areas of stratus
and morning fog may occur Wednesday AM due to residual moisture
at the surface. Temperatures will be cooler Tuesday and
Wednesday in the low to mid 60s.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...Zonal flow aloft
continues Thursday into Friday. A system will weaken as it
approaches Western Washington during this period, resulting in
just a slight chance of precipitation at this time, mainly for
northern areas. Ensembles are in general agreement in the ridge
becoming more pronounced across the Western US this weekend,
resulting in drier and warmer conditions. Some uncertainty in
the ensembles in regards to the return of more onshore flow
early next week, but overall, warmer and drier conditions are
expected during this period. JD
&&
.AVIATION...
West-northwest flow this afternoon turning predominantly westerly.
Widespread VFR observed so far today (with the exception of KHQM)
but ceilings are favored to progressively lower into tonight as a
frontal system enters. Rainfall and MVFR cigs will start for KBLI,
KCLM, and KOLM between 04-08z and the remainder of interior
terminals by 10-12z. Areas of IFR cigs can`t be ruled out as well.
MVFR/IFR conditions are favored to remain well into the day on
Tuesday and possibly into the evening as rainfall gradually tapers.
Windy conditions are also favored throughout the period as the
strongest gusts at KBLI could reach up to 35-40 kt between 06-12z
Tuesday. Gusts up to 20-30 kt are favored elsewhere overnight Monday
into Tuesday. Winds will gradually decrease area-wide by Tuesday
afternoon but a westerly surge through the Strait of Juan de Fuca
will bring an additional round of gusty winds for KCLM around 20-25
kt.
KSEA...VFR conditions through the evening but cigs will gradually
fall. MVFR ceilings expected to develop around 10-12z, as a front
brings widespread rainfall. S-SW winds at 5-10 kt this afternoon
becoming 10-15 kt with gusts up to 20-25 kt after 06z tonight. Gusts
will gradually diminish after 00z Wednesday but lower cigs are
favored to remain at this time.
41
&&
.MARINE...
The next frontal system arrives tonight starting at the coastal
waters with increasing southerly winds over all waters - Small Craft
Advisories are in effect for most waters. The Northern Inland waters
have a Gale warning in effect. Winds will turn more westerly through
the strait Tuesday afternoon where gale gusts are a possibility for
the central/eastern strait. Meanwhile, expect elevated seas with
swells reaching 10-11 ft. Onshore flow will ease late Tuesday night.
The flow will then turn offshore on Wednesday with a thermal trough
along the coast. Light offshore flow continues through the end of
the week.
41
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory from 2 AM to 2 PM PDT Tuesday for Lowlands of
Western Whatcom County-San Juan County.
PZ...Small Craft Advisory until 5 PM PDT Tuesday 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-
Puget Sound and Hood Canal-West Entrance U.S. Waters
Strait Of Juan De Fuca.
Small Craft Advisory until 5 AM PDT Wednesday for Central U.S.
Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
Strait Of Juan De Fuca.
Gale Warning from 11 PM this evening to 5 PM PDT Tuesday for
Northern Inland Waters Including The San Juan Islands.
&&
$$
NWS SEW Office Area Forecast Discussion