Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
574
FXUS66 KSEW 312046
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
146 PM PDT Fri Jul 31 2026
.SYNOPSIS...An upper ridge will shift east tonight. A front
will move across the area on Saturday, with increasing onshore
flow into Sunday. Upper level ridging builds offshore Sunday
night and moves over Western Washington on Monday. The ridge
will remain in place through at least midweek for dry, warm
conditions.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...Mostly sunny skies
across Western Washington this afternoon with temperatures in
the 70s to low 80s. High pressure will move east of the Cascades
into tonight ahead of a frontal system. The front moves across
the area on Saturday, resulting in increased light rain,
especially for the Olympic Peninsula, Cascades, and from
Snohomish County northwards. There is also a 10-20% chance for
thunderstorms over the northern Cascades Saturday afternoon. In
addition, winds will be rather breezy in a post-frontal
airmass, with west wind gusts ranging 15 to 25 MPH (with
localized gusts to 30 MPH) on Saturday.
Onshore flow continues post-front later Saturday into early
Sunday, resulting in the development of weak convergence over
Snohomish County and vicinity. Light rain may continue at times
into Sunday morning for this region before drier conditions
return by Sunday afternoon. Upper level ridging then begins to
build offshore by Sunday night. Temperatures will be quite a bit
cooler this weekend, with highs only in the mid 60s to mid 70s.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...The upper level ridging
continues to build over Western Washington early next week,
resulting in drier, warming conditions. Widespread Minor
HeatRisk is expected Monday, with areas of Moderate HeatRisk
Tuesday and Wednesday. Upper level flow also transitions more
northeasterly on Monday, which may result in increasing wildfire
smoke into midweek, this continues to be monitored. Some
uncertainty exists in ensembles by later next week in regards to
the ridge flattening a bit for a slight cooling trend. Either
way, continued dry conditions are expected through late week. JD
&&
.AVIATION...Southwest flow aloft will increase tonight as a weak
frontal system approaches from the west and pushes inland Saturday
morning. Ceilings will lower to MVFR along the coast late tonight
then spread inland across the interior lowlands early Saturday
morning. Gusty post-frontal west to southwesterly surface winds are
expected at times on Saturday and a convergence zone is expected
to develop later Saturday afternoon into Saturday night.
KSEA...VFR will continue into this evening. Ceilings are expected to
lower to MVFR near or after 12Z Saturday and persist into at least
early afternoon. Surface winds west to northwest 6 to 10 knots
will back to southerly overnight and rise to 10 to 15 knots with
gusts to 20 knots by mid-morning Saturday before easing late in the
day.
27
&&
.MARINE...A weak frontal system will reach the waters tonight and
Saturday. Increasing onshore flow will lead to small craft advisory
westerly winds in the central/east strait late this afternoon and
evening and again much of Saturday. Additionally, post-frontal
onshore flow will lead to small craft advisory southwesterlies in
Puget Sound/Hood Canal during the day on Saturday. High pressure
will rebuild over the coastal waters Sunday and remain in place into
early next week as thermally induced low pressure expands northward
across the interior.
27
&&
.FIRE WEATHER...Elevated fire weather concerns will continue
today as a warming and drying trend peaks. Relative humidities
will drop into the upper 20s and 30s over portions of the
western Cascades and lowlands south of the Puget Sound, though
an approaching system will bring onshore flow tonight with
healthy overnight humidity recoveries.
A frontal system will cross western Washington Saturday morning,
bringing a chance of wetting rain to the northern Olympic Peninsula
and North Cascades, alongside breezy winds area-wide and increased
onshore flow. Ridgetops in the Cascades will see wind gusts of 30 to
40 mph Saturday afternoon, though incoming cooler and wetter
conditions will prevent humidities from reaching critical levels. In
addition, the North Cascades will see a 20% chance of thunderstorms
developing midday Saturday, though widespread lightning is not
expected with this system.
A ridge will build over the western US during the first half of next
week, bringing additional warming and drying to the region. Minimum
relative humidity values will drop into the 20s and 30s for most
inland areas, bringing elevated fire weather concerns. Surface flow
is also expected to turn offshore, though flow will be fairly weak.
Northerly and easterly winds at times may bring in smoke from
wildfires across eastern Washington and British Columbia.
15
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 7 PM PDT Saturday for Central U.S.
Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
Strait Of Juan De Fuca.
Small Craft Advisory from 5 AM to 7 PM PDT Saturday for Puget
Sound and Hood Canal.
&&
$$
NWS SEW Office Area Forecast Discussion