Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
010
FXUS66 KSEW 231014
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
314 AM PDT Sun Aug 23 2026
.SYNOPSIS...
An upper level trough will continue to make its way across the
area this morning, bringing chances of showers and isolated
thunderstorms primarily to the mountains and the northern tier
of western Washington. Upper level ridging will build into the
Pacific Northwest on Monday and Tuesday for warmer and drier
conditions. Another upper level low will approach the area
around midweek, bringing increasing onshore flow and cooler
conditions to western Washington the second half of the week.
&&
.SHORT TERM /TODAY THROUGH TUESDAY/...
An upper level trough will continue to make its way inland
across the area early this morning. Meanwhile, a surface trough
currently extends along the interior of British Columbia, through
Vancouver, and down along the Washington coast. A cluster of showers
and thunderstorms associated with this feature have remained rather
vigorous to the north of the border over the past couple of
hours, with latest radar trends showing shower and thunderstorm
activity slowly starting to drift southeastward early this
morning. Thunderstorms have generally continued to weaken as
they drift closer to Washington, however will need to continue
to keep an eye on trends through the remainder of the overnight
hours as latest hi-res guidance does hint at the possibility of
a few storms drifting into portions of the San Juans, Whatcom,
and Skagit counties through the early morning hours. Otherwise,
expect shower and thunderstorm activity to primarily become
confined to the Cascades by this afternoon and to gradually
wane throughout the day as the upper level trough pushes off to
the east and ridging starts to build in from the west. Widespread
cloud cover across the area will take a bit longer to scatter
today, helping to keep temperatures slightly cooler and primarily
in the low to mid 70s across the interior and in the mid 60s
along the coast.
Upper level ridging will then build into the Pacific Northwest
on Monday, with the ridge axis shifting eastward over the
Intermountain West by Tuesday. This will bring a warming and
drying trend to western Washington the first part of the week,
with Tuesday expected to be the warmest day across western
Washington. Afternoon high temperatures will climb into the 80s
across the interior lowlands and into the low 90s across the
Cascade valleys by Tuesday, reintroducing Moderate HeatRisk to
portions of these areas. Surface flow will also transition to
northerly and then offshore at times, which may allow for some
smoke transport from ongoing wildfires across British Columbia
and eastern Washington to make its way back into western
Washington at times through the early part of the week.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Ensemble guidance remains in decent agreement with an upper
level low approaching the Pacific Northwest on Wednesday. This
would bring the return of onshore flow and cooler conditions to
western Washington the second half of the week. Chances of
precipitation will also increase Wednesday and Thursday, though
overall amounts look to remain light at this time. Will need to
keep an eye on any thunder potential for the area, though
probabilities at this time remain at around 10 percent or less.
Temperatures will generally trend near to slightly cooler than
normal the second half of the week, with afternoon highs topping
out in the low to mid 70s across the interior and mid 60s along
the coast. Ensemble guidance suggests the upper level trough
will remain an influence across the area heading into next weekend,
which would continue to promote onshore flow and near to slightly
below temperatures across western Washington.
14
&&
.AVIATION...
Upper level trough moving east of the area this morning. Flow
aloft becoming northwesterly behind the trough. Upper level
ridge building in tonight with flow aloft becoming westerly. Low
level onshore flow today becoming northerly late tonight into
Monday with thermally induced surface trough along the coast.
VFR ceilings inland with IFR or LIFR ceilings along the coast.
MVFR ceilings developing over the interior 14z-16z. Ceilings
over the interior improving to VFR around 21z.
Showers with embedded thunderstorms from about NAS Whidbey
northward until 18z.
KSEA...VFR ceilings early this morning. MVFR ceilings
developing around 15z continuing to around 20z. VFR ceilings
middle of the afternoon onward with clouds scattering out this
evening. Southwest wind 4 to 8 knots becoming northwesterly
00z-03z. Felton
&&
.MARINE...
High pressure rebuilding over the coastal waters today will
remain through Tuesday. Thermally induced surface trough along
the coast Monday will dissipate Monday night. A weak frontal
system will move across the waters Wednesday night. High
pressure rebuilds over the area Thursday.
Small craft advisory westerlies in the Central and Eastern
Strait of Juan de Fuca Tuesday night otherwise winds 20 knots or
less through the period.
Seas remaining in the 3 to5 foot range through the week. Felton
&&
.FIRE WEATHER...
An upper level trough will pass through the area this morning.
While at the surface, a trough currently extends southwestward
from British Columbia down along the Washington coast. Showers
and isolated thunderstorms will remain possible across the
northern tier of the area, primarily across the San Juans and
Whatcom and Skagit counties, through the morning hours before
waning. While storms have been producing heavy downpours for
areas north of the border, storms have also been associated with
abundant lightning. Should any storms drift into the area over
the next several hours, they will remain capable of producing
abundant lightning and gusty, erratic outflow winds - and could
have an impact to any ongoing fires across the North Cascades
should they make it within the vicinity. Overall chances of
thunderstorms will then decrease by the afternoon and evening as
the upper trough exits the region.
An upper level ridge will then build into the area Monday and
Tuesday, bringing brief periods of low- level offshore flow as a
thermal trough builds along the coast and pushes inland overnight
into Tuesday. Elevated fire weather conditions are likely across
the Cascades on Tuesday with the warm and dry pattern and with
relative humidities dipping into the low to mid 20s. Another
upper level trough will arrive in the middle of next week,
bringing the return of onshore flow- as well as chances for
more showers and the potential for thunderstorms. Upper- level
troughing then looks to linger into the weekend.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion