Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
004
FXUS66 KSEW 010328
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
828 PM PDT Mon Aug 31 2026
.SYNOPSIS...
Weak upper ridging over the Pacific Northwest keep conditions
dry through late Tuesday. A stronger early season system
Wednesday into Thursday results in more widespread rainfall and
gusty winds. The deep upper low lingers over the Pacific
Northwest into next weekend for continued unsettled weather and
cooler conditions.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
The latest forecast remains on track this evening with no
updates. High clouds continue to stream overhead of western
Washington this evening, but otherwise a dry and very mild day
with high temperatures right around normal-- in the low to mid
70s. Marine stratus will develop overnight and move inland from
the coast but remain mostly confined to west of the Salish Sea;
high clouds remain overhead. Low temperatures in the upper 40s
to mid 50s.
An anomalously strong (for this time of year) low pressure
system will begin to move towards western Washington from the
north on Tuesday with a weak warm front moving through in the
afternoon. Clouds will increase and most locations will stay dry
but there will be a slight chance for a few showers across
portions of the area. High temperatures will be a few degrees
cooler for most, in the upper 60s to mid 70s.
The associated cold front with this low pressure system will
begin to approach the Olympic Peninsula overnight Tuesday into
Wednesday morning, before then slowly traversing the area late
Wednesday into early Thursday. This system will bring in some
significant early-season rainfall across the entire region. In
particular, the Pacific coast and the Olympic Mountains will
have the highest chances of seeing greater than 1" of rainfall.
The highest peaks of the Olympics could see up to 1-2" (50-60%
chc in the 24 hours ending 5AM Thursday). Areas around the
Seattle metro and southward, as well as the Cascades, will
likely see around 0.5"-0.75" of rain, with areas north of
Seattle seeing between around 0.25-0.5" due to the rain
shadowing of the Olympics. Nevertheless, everyone is forecasted
to see measurable rainfall. In addition to rainfall, winds will
also increase across the area on Wednesday. The Pacific coast
and the northwest interior and Salish Sea islands have the best
(50-80% chc) chances to see wind gusts of over 35 mph, while
gusts between 20-30 mph are expected elsewhere. Full foliage on
trees may produce more significant or widespread impacts than
otherwise expected during the winter when trees are bare,
especially in areas experience gusts greater than 35 mph.
Temperatures will be cool on Wednesday with the rain, with highs
in the 60s and lows in the upper 40s to mid 50s.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Unsettled conditions are expected to continue on Thursday as
the low pressure system continues to moves southward along the
coast on Thursday. Chances for showers and isolated
thunderstorms will be possible throughout the day, with the
highest chances across southwestern Washington (up to 25-30%
chc). 10-20% chances exist elsewhere across western Washington.
Winds will also begin to taper throughout the day and become
light by Thursday evening. Broad upper level troughing is
expected to persist over the Pacific Northwest Friday into the
weekend, through model solutions begin to diverge on exactly how
to handle the weakening and departure of this system. Ensemble
cluster analysis shows highly divergent solutions for next week,
or in other words, high uncertainty.
62
&&
.AVIATION...
Southwesterly flow aloft continues with upper level troughing
offshore. VFR conditions prevail this evening into tonight with
high clouds streaming overhead. Marine stratus will redevelop
along the coast tonight and slowly creep inland Tuesday morning.
The areas with the best chances of seeing low ceilings will be
OLM, HQM, and CLM with a 40-50% chance. However, there will be a
20-25% chance of seeing them farther inland across the Seattle
metro. VFR conditions continue afterwards through the day
Tuesday through mid- level clouds increase throughout the day
with chances for showers beginning in the evening.
N winds this evening will become light overnight, switching to S/SW
tomorrow and increasing to around 8-15 kt by Tuesday afternoon.
Gusts 20-25 kt will be possible along the coast and around the Puget
Sound area.
KSEA...VFR conditions through the TAF period. There remains a 25-30%
chance of MVFR or lower cigs between 14-17z. NE winds this evening
around 5-6 kt will become light tonight. Winds switch S early
Tuesday morning and increase to 8-12 kt with gusts up to 20 kt
Tuesday evening.
62/29
&&
.MARINE...
High pressure will ease tonight into Tuesday before a stronger
low pressure system begins to approach the coastal waters late
Tuesday night. South to southeasterly winds will begin to
increase Tuesday evening, with winds peaking during the day on
Wednesday. Likelihood remains high through the coastal waters
(60-90% chc) and through portions of the East Strait of Juan de
Fuca, Strait of Georgia, and Admiralty Inlet (50-70% chc) for
seeing gale force wind gusts through Wednesday evening.
Elsewhere, winds will remain in Small Craft Advisory thresholds.
The cold front will traverse the area waters Wednesday evening,
following which winds will begin to decrease. Additional
advisories may be needed into Thursday as southerly winds
remain elevated through the interior waters from Puget Sound to
the Northern Inland Waters, through winds greatly decrease
area-wide by Thursday afternoon as the low pressure system
weakens and moves southward into Oregon. Broad low pressure
will remain over region through the end of the week.
In addition to winds, chances for thunderstorms will pose a
threat to the area waters Wednesday and Thursday, through
probabilities are marginal (10-20% chc). Lightning and an
isolated waterspouts are the primary threats.
Seas 4-6 ft will increase Wednesday as the system moves through.
Seas rise to around 8-12 ft, with the largest waves in
conjunction with the strongest winds. Seas return to around 6-8
ft Friday into the weekend.
62
&&
.FIRE WEATHER...
Fire weather concerns remain low through the next week. A
stronger fall weather system will bring significant rainfall
starting early Wednesday, with wetting rains expected area-
wide. 1-2" will be possible along the Pacific Coast and the
Olympic Mountains. 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.
The bulk of the rain will fall on Wednesday. Chances for showers
and isolated thunderstorms continue through the end of the
week, 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...None.
PZ...Gale Watch from Tuesday evening through Wednesday evening 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.
&&
$$
NWS SEW Office Area Forecast Discussion