Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
420
FXUS66 KSEW 061017
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
317 AM PDT Thu Aug 6 2026
.SYNOPSIS...
Upper level ridge axis and thermally induced surface trough
over the area today shifting east tonight. Low level flow
turning onshore tonight. Western Washington still on the
backside of the ridge through Saturday with just slight cooling
Friday and Saturday. Upper level flow becoming zonal Sunday.
This combined with increasing low level onshore flow will give
the area a few days of normal first half of August weather.
&&
.SHORT TERM /TODAY THROUGH SATURDAY/...
Satellite imagery shows stratus along the coast moving down the
Strait of Juan de Fuca and moving inland through the Lower
Chehalis Valley. Smoky skies elsewhere. Temperatures at 3 am/10z
were in the mid 50s to mid 60s.
Upper level ridge over the area today. Ridge axis along the
coast will move inland today. At the surface, thermally induced
surface trough over the interior. Stratus will retreat back to
the coast then dissipate by midday. High temperatures cooler
along the coast today, near 70. High temperatures inland
similar to Wednesday, in the 80s to lower 90s. Light flow in
the lower levels will keep smoke over the area today with
degraded air quality.
Increasing low level onshore flow tonight as the upper level
ridge axis and the thermally induced trough move east of the
Cascades. Stronger onshore flow will help scour out the low
level smoke while increasing west southwesterly flow aloft
pushes the upper level smoke out of the area as well. Stratus
reforming along the coast spreading inland in the early morning
hours but remaining west of Puget Sound. Lows in the 50s and
lower 60s.
Low level onshore flow Friday but temperatures aloft remain
warm. 500 mb heights still in the upper 580 dms. Shallow marine
layer will have a tough time getting east of Puget Sound and
with the warmer air remaining aloft high temperatures will only
cool by a couple of degrees over the interior into the upper
70s and 80s. Highs along the coast remaining near 70.
Slow cooling trend continuing Friday night into Saturday.
Temperatures aloft cooling slightly with a little bit deeper
marine layer. Stratus will still have a tough time getting east
of Puget Sound. Best chance will be in Snohomish county with the
stratus coming down the Strait of Juan de Fuca. Lows in the 50s
and lower 60s. Highs over the interior in the mid 70s to mid
80s. Highs along the coast in the upper 60s. Felton
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Extended models continue to show good consistency with 500 mb
heights slowly falling in response to an upper level low well to
the northwest. Low level onshore flow each day. Stratus
developing along the coast in the evening spreading inland in
the early morning hours each morning. Stratus most of the time
only making it as far inland as the Puget Sound. Stratus
dissipating in the late morning/early afternoon hours. Highs
inland in the 70s and lower 80s and in the upper 60s along the
coast. Lows mostly in the 50s.
The normal high in Seattle is currently at its peak of 79
degrees. It will drop to 78 degrees Monday the 10th. The first
step in lowering down to bottoming out at 46 degrees December
19th. Felton
&&
.AVIATION...
An upper level ridge will move across the terminals today into
Friday, with flow aloft southwest to west. A weak onshore push has
commenced along the coastline this morning as ceilings drop to
IFR/LIFR, but given the weaker gradients towards the thermal trough
moving inland, probabilities remain the greatest along the immediate
coastline. Haze/smoke continues in the interior this morning, and
there remains a 20-40% chance of visibilities dropping to MVFR (3-5
SM) this morning into the afternoon as some residual near-surface
smoke slowly begins to clear out today into tonight. The smoke will
continue to affect horizontal visibilities, but slant-wise
visibility impacts should decrease as smoke is removed. Early
indications for Friday morning has the push advancing a little
further to this morning, but remaining west of Puget Sound. Winds
will pick up out of the north/northwest 5-10 kt today.
KSEA...VFR generally expected through the TAF period, though there
remains a 30% to 40% chance of visibility reductions to MVFR due to
wildfire smoke/haze that will slowly clear out today. Stratus
expected to remain west of the terminal this morning, and likely
Friday morning too. Winds picking up from the northwest late this
morning/afternoon 5-10 kt, then decreasing to 5 kt or less tonight
from the northeast.
HPR
&&
.MARINE...
A thermal trough will begin to move inland today, with higher
pressure remaining offshore through the end of the week. Onshore
flow will slowly begin to trickle back into the waters through the
end of the week/weekend. This will primarily affect the Strait of
Juan de Fuca as early as Friday night, with beginning chances of
daily occurrences of winds/gusts over 20 kt into next week. Coastal
waters may also see wind increases towards 20 kt, but likely below
until Saturday night/Sunday, and Thursday as a couple of weak
troughs move through.
Seas at 4-6 ft today through Friday at around 8 seconds. This
increases to 6-8 ft this weekend into Monday, and decrease back to 4-
6 ft Tuesday and Wednesday before increasing again to 6-9 ft.
HPR
&&
.FIRE WEATHER...
Elevated fire weather concerns across the area the next couple of
days with warm and dry weather. Minimum relative humidity values
lowering into the 20s in the drier locations like the Southwest
Interior and Cascade foothills. While no significant wind or
instability is expected today for a red flag warning, maximum
caution over new fire starts still should be emphasized.
The thermally induced trough will shift into Eastern Washington
tonight. Some uncertainty still remains over potential
instability and incoming wind in combination with the eastward
movement of the thermal trough. This may briefly promote fire
growth late tonight into early Friday morning. Hot and dry
conditions hold Friday for most of the interior. Elevated fire
weather concerns continuing through the day.
Increased onshore flow Saturday into into next week will bring
cooler temperatures and increased moisture with much better humidity
recoveries across the region.
Wildfire smoke over the area today could cause localized
impacts to fire operations. Felton
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory until 10 PM PDT this evening for City of Seattle-
Downtown Everett / Marysville Area-Eastern Kitsap County-
Eastern Strait of Juan de Fuca-Eastside-Foothills and
Valleys of Central King County-Foothills and Valleys of
Pierce and Southern King Counties-Foothills and Valleys
of Snohomish and Northern King Counties-Foothills and
Valleys of Thurston and Lewis Counties-Foothills and
Valleys of the North Cascades-Foothills of the Western
and Southern Olympic Peninsula-Island County-Lake
Crescent Area Including US 101-Lowlands of Lewis and
Southern Thurston Counties-Lowlands of Pierce and
Southern King Counties-Lowlands of Western Skagit and
Northwestern Snohomish Counties-Lowlands of Western
Whatcom County-Middle Chehalis River Valley-Northern Hood
Canal-Olympia and Southern Puget Sound-Port Townsend Area-
San Juan County-Shoreline / Lynnwood / South Everett Area-
Southern Hood Canal-Willapa and Black Hills.
Air Quality Alert until 5 PM PDT this afternoon for Cascades
of Snohomish and Northern King Counties-Cascades of
Southern King County-Cascades of Whatcom and Skagit
Counties-City of Seattle-Downtown Everett / Marysville
Area-Eastern Kitsap County-Eastside-Foothills and Valleys
of Central King County-Foothills and Valleys of Pierce
and Southern King Counties-Foothills and Valleys of
Snohomish and Northern King Counties-Foothills and
Valleys of the North Cascades-Foothills of the Western
and Southern Olympic Peninsula-Grays Harbor County Coast-
Lower Chehalis River Valley-Lowlands of Pierce and
Southern King Counties-Lowlands of Western Skagit and
Northwestern Snohomish Counties-Lowlands of Western
Whatcom County-Middle Chehalis River Valley-Northern Hood
Canal-Olympia and Southern Puget Sound-Olympics-Shoreline
/ Lynnwood / South Everett Area-Southern Hood Canal.
Air Quality Alert until 11 PM PDT this evening for Cascades of
Pierce and Lewis Counties-Foothills and Valleys of
Thurston and Lewis Counties-Lowlands of Lewis and
Southern Thurston Counties-Willapa and Black Hills.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion