Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
724
FXUS66 KSEW 281613
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
913 AM PDT Mon Sep 28 2026
.SYNOPSIS...Surface high pressure weakening today. Zonal flow
aloft. Next system moving down British Columbia coast moving
through the area Tuesday. Post frontal convergence zone Tuesday
evening. High pressure, both surface and aloft, rebuilding
Wednesday. Upper level ridge remaining over the area through the
weekend. Thermally induced surface trough moving up the Oregon
coast reaching the Washington coast Saturday turning the low
level flow offshore. Surface trough moving inland Sunday.
&&
.SHORT TERM /TODAY THROUGH WEDNESDAY/...Dry conditions continue
into the afternoon. Next system to move into Western Washington
currently near Haida Gwaii and slowly moving southeast. High
clouds out ahead of the system will spread over the area this
morning into the afternoon hours. Chance of rain by the evening
along the north coast. Highs in the 60s.
Front continuing to slowly move southeast tonight. By 12z
Tuesday front still north of the area. Surface pressure
gradients tightening up over the Northwest Interior as the front
approaches. Have issued a wind advisory for the Northwest
Interior and the San Juans beginning at 2 am Tuesday morning for
southeast winds increasing to 20 to 30 mph with gusts 40 to 45
mph. Rain out ahead of the front reaching the north coast and
Northwest Interior by midnight. Chance of rain as far south as
Olympia by early Tuesday morning. With the cloud cover lows will
be much warmer than the previous mornings, in the lower to mid
50s.
Front slowly moving through Western Washington Tuesday. Rain
over most of the area by mid morning. Front moving through the
Northwest Interior and north coast early afternoon. Winds
easing behind the front. Highs in the lower to mid 60s.
Front moving through the remainder of the area by early in the
evening with rain coming to an end. Post frontal convergence
zone over Snohomish county will dissipate after midnight. Not
much in the way of cool air behind the front with just limited
shower activity outside the convergence zone. Lows in the mid
40s to lower 50s.
High pressure, both surface and aloft, building over Western
Washington Wednesday. Winds easing overnight. Patchy fog
developing early in the morning. What little fog that does form
will be gone by mid morning. Skies clearing with plenty of
sunshine especially in the afternoon. Highs in the lower to mid
60s. JD/Felton
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...Extended models
have finally gotten rid of the slight chance pops for Thursday
and Friday. Upper level ridge over the area with high pressure
at the surface. Thermally induced surface trough moving up the
Oregon coast Friday extending north to the Washington coast
Saturday. Low level flow turning offshore. In this scenario this
time of year it is not uncommon for the coast to be the warmest
location in Western Washington. Thermally induced surface
trough moving inland Sunday making it the warmest day for the
interior. Lows in the 40s Thursday morning, mid 40s to lower 50s
Friday through Sunday morning. Highs in the mid to upper 60s
Thursday and Friday, 60s and lower 70s Saturday and Sunday.
Even with the normal high in Seattle starting October at 66
degrees, the normal number of 70 degree plus in Seattle in
October is only 2. Out of the 170 days total ( in 81 years of
records ), 51 ( 30 percent ) are 75 degrees or warmer. 75
percent of the 70 degree plus days in October have occurred in
the first 10 days of the month and all of the 75 degree plus
days have occurred in the first 16 days of the month. Felton
&&
.AVIATION...Zonal flow aloft with occasional shifts to the NW
at times today, strengthening tonight as gradients tighten.
Light and variable surface winds this morning becoming southerly
5-10 kt this afternoon in advance of approaching front. Speeds
increase further this evening and overnight generally ranging
10-15 kt with gusts up to 20 kt possible.
Widespread VFR conditions in place this morning. Cigs expected to
lower throughout the day as incoming front approaches, however VFR
expected to persist for the majority of the TAF period for most
terminals. Western-most terminals will begin to encroach on MVFR
conditions this evening between 03-06Z while remaining terminals
likely will not see these conditions emerge until around 12Z
Tuesday as rainfall spreads across the area.
KSEA...VFR conditions through today and tonight even though cigs
will gradually fall throughout the day. MVFR conditions expected to
develop near the end of the TAF period, around 10-12Z, as front
draws nearer. Start of precip also expected during this time frame.
Light and variable winds this morning before turning more southerly
at 5-10 kt this afternoon. SW winds 10-15 kt with gusts up to 20 kt
after 03Z tonight with best chances for gusts holding off until
closer to FROPA starting in the aforementioned 10-12Z time frame.
18/41
&&
.MARINE...The next frontal system arrives later today into Tuesday with
increasing southerly winds over all waters - Small Craft Advisories
are in effect for most waters, although it appears the Northern
Inland Waters run a good chance for consistent gusts exceeding Gale
criteria. As such, have upgraded the SCA there to a Gale Warning.
Winds will turn more westerly through the strait Tuesday afternoon.
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. 18/33
&&
.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 from 5 PM this afternoon to 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 from 5 PM this afternoon to 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