Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
871
FXUS66 KSEW 020320
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
820 PM PDT Tue Sep 1 2026
.SYNOPSIS...
A strong early-season system will bring rain and gusty winds to
western Washington Wednesday into Thursday. The deep upper level low
lingers over the Pacific Northwest through the weekend for continued
cooler and unsettled conditions.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
The latest forecast remains on track this evening with no
updates. A cold front will begin to approach the coast early
Wednesday morning and slowly move across western Washington
throughout the day. Winds will start to increase tonight with a
push of southwesterlies through Puget Sound and Hood Canal that
will eventually make its way to the north interior by early
Wednesday morning. South to southeasterly winds will also
increase along the coast early Wednesday morning. Winds will
peak across the area as the frontal system moves from northwest
to southeast, so first along the coast late morning then across
the interior in the afternoon. Maximum wind gusts across the
aforementioned areas look to reach up to 35-40 mph, where Wind
Advisories have been issued. Elsewhere, gusts up to 25-35 mph
are the most likely scenario. Full foliage on the trees may
cause more widespread impacts that would otherwise be expected
in the winter when trees are bare. Localized power outages and
downed trees will be possible. Winds will be slow to ease
overnight before really easing Thursday morning.
The main bulk of the rain will begin to arrive along the coast this
morning then moving across the interior in the afternoon.
The coast and Olympic Mountains will get the most precipitation,
with forecast amounts remaining in the 1-2" range by Thursday
morning. Forecast amounts have gone down slightly for the interior
and Cascades with stronger rain-shadowing effects and the more
southerly track of the cold/occluded front across the area, losing
the some of the orographic enhancements in the mountains and
focusing the strongest onshore moisture transport farther south.
Amounts of around 0.25-0.75" are forecast, with around a 40% chance
of seeing 0.5" at SeaTac airport.
Behind the frontal passage, most notably along the coast (15-20%
chc), there will be a chance for thunderstorms Wednesday afternoon.
As the fronts move south and the low pressure center moves down near
the coast on Thursday, showers will continue across the area. There
will also be a 15-20% chc of thunderstorms, with the best chances
across southwestern WA and areas south of the Seattle metro/Olympic
Mountains.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
The upper level trough that has been supporting this weather system
will reach the Pacific Northwest by Friday and essentially remain
overhead through the weekend. This will maintain chances for showers
and low chances for thunderstorms in the afternoon each day. The day
with the best chances for thunderstorms will be Friday, mainly along
the southern WA Cascades. Model solutions begin to diverge greatly
going into next week as models try to figure out how or if to
progress the trough off to the east. The operational runs are
pushing troughing off to the intermountain west, but we still remain
under their influence and chances for rain remain in the forecast.
Quite a few ensemble members (about 55% of members), however, are
bringing in some upper level ridging for the beginning of next week
which would keep conditions warmer and drier. The NBM mean forecast
shows temperatures near climo and broadbrushed slight chances for
showers.
62
&&
.AVIATION...
Generally VFR cigs this evening across the interior terminals
this evening. Lower ceilings continue to linger within the
vicinity of the terminals and at times ceilings may briefly go
down to MVFR. Some light showers are moving across the terminals
and may also briefly reduce visibility and cigs. Along the
coast, deteriorated ceilings will continue into Wednesday. High-
end MVFR is possible (20-35%) for the interior terminals
Wednesday morning. Breezy conditions in the interior will
gradually subside tonight. Stronger winds are expected after 06z
Wednesday first along the coast and fill in across the interior
through the morning. These stronger winds will persist through
Wednesday afternoon. The strongest winds are expected along the
coast, north of PAE, and southern interior, with gusts 35-40 kt.
As for the other terminals, gusts will be around 25-30 kt.
Winds will gradually subside throughout the evening hours on
Wednesday.
Rain will arrive at the coast Wednesday morning and will reach the
interior terminals by the afternoon. Additionally, there is a 20%
chance of thunderstorms along the coast, Olympic Peninsula, and
Cascades on Wednesday. Elsewhere, chances for thunderstorms are
around 10-15%. Gusty/erratic winds, heavy downpours, and constant
lightning will pose a threat within thunderstorms.
KSEA...VFR conditions today. Light transient showers may lower
visibility and ceilings to MVFR briefly at times. Models continue to
highlight the chance (20%) for high-end MVFR Wednesday morning.
Breezy winds SW this evening will subside overnight to around 5-7
kt. Stronger winds expected Wednesday morning after 12Z and lasting
through the afternoon hours, with gusts to 25-30 kt. Winds will
gradually subside throughout the evening hours. There is a slight
chance (15%) of thunderstorms Wednesday afternoon.
MGF
&&
.MARINE...
A low pressure system will begin to work its way across the region
starting tonight. The cold front will move through on Wednesday with
the low center moving down through the waters on Thursday. Winds
will increase tonight across the region late tonight. Despite
sustained winds falling just short, wind gusts remain likely (60-
90%) to reach gale force across most of the coastal waters, and
through the northern Salish Sea from Admiralty Inlet up through the
East Entrance and into the Northern Inland Waters. Wind gusts
through the Puget Sound and Hood Canal look to begin to increase as
early as tonight and reach Small Craft Advisory criteria and will
continue through much of the day tomorrow. Portions of the central
Strait of Juan de Fuca south and east of Victoria may also see Small
Craft to gale force gusts, but the majority of the zone should stay
sheltered from the strongest winds. The strongest winds area-wide
should start to decrease following the frontal passage Wednesday
night, but additional headlines may need to follow overnight into
Thursday morning as winds look to stay elevated before finally
easing by Thursday afternoon. Broad low pressure will remain over
region through the end of the week into this weekend though winds
look to remain light.
Chances for isolated thunderstorms will pose a threat to the area
waters Wednesday and Thursday, through probabilities remain marginal
(10-20% chc).
Seas 4-5 ft increasing tonight to 7-9 ft before peaking Wednesday
afternoon, in conjunction with the winds, up to 9-12 ft from the
south. Waves ease a bit late Wednesday before westerly swell arrives
on Thursday, pushing seas back up to around 10 ft. Seas ease to
around 4-6 ft by Thursday night and remain like so through the
weekend.
62
&&
.FIRE WEATHER...
Fire weather concerns remain low through the next week. A stronger
fall weather system will bring significant rainfall to the coast and
Olympic Mountains through the remainder of the week, with 1-2"
possible there. Elsewhere, amounts will be lower but most areas
should see a wetting rain. Rainfall may pose a minor threat to
highly sensitive and brand- new burn scars. Windy conditions are
also expected across the area with gusts ranging from 20 to 35
mph, or up to 40 mph under areas with a Wind Advisory. Chances
for showers and thunderstorms will continue Thursday into this
weekend, but the risk of new starts is lower due to the isolated
coverage and the increased fuel moisture from the wetting
rains.
62
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory from 2 AM to 8 PM PDT Wednesday for Island
County-Lowlands of Western Whatcom County-Port Townsend
Area-San Juan County.
Wind Advisory from 2 AM to 5 PM PDT Wednesday for Grays Harbor
County Coast-Northern Washington Coast.
PZ...Gale Warning from 2 AM to 11 PM PDT Wednesday for Admiralty
Inlet-East Entrance U.S. Waters Strait Of Juan De Fuca-
Northern Inland Waters Including The San Juan Islands.
Small Craft Advisory until 11 PM PDT Wednesday for Puget Sound
and Hood Canal.
Gale Warning until 5 PM PDT Wednesday 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.
&&
$$
NWS SEW Office Area Forecast Discussion