Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
115
FXUS66 KSEW 271604
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
904 AM PDT Sun Sep 27 2026
.UPDATE...
No changes made to the inherited forecast. The previous
discussion remains below along with an updated marine/aviation
section.
&&
.SYNOPSIS...
Split flow aloft with high pressure at the surface producing a
dry day today for Western Washington. Flow aloft consolidating
tonight into Monday with surface high pressure weakening. Next
system moving down the British Columbia coast moving through
Tuesday. Weak upper level ridge building Wednesday. Possible
system moving by to the north later Thursday into Friday. Strong
upper level ridge building Saturday with the low level flow
trying to turn offshore.
&&
.SHORT TERM /TODAY THROUGH TUESDAY/...
Satellite imagery shows just a few high clouds moving through
the area early this morning. Temperatures were a little cool at
3 am/10Z ranging from 39 in Shelton to the lower 50s in the
Seattle metro area.
Split flow aloft combining with surface high pressure for a dry
day today. High clouds moving through this morning with plenty
of sunshine this afternoon. Patchy fog developing in mainly in
sheltered valleys will be gone by mid morning. With the cool
start to the day even with sunshine highs ending up a little
below normal, in the lower to mid 60s.
Another cool night tonight with mostly clear skies and light
winds at the surface. Lows in the mid 30s to upper 40s.
Flow aloft consolidated Monday with surface high pressure
weakening. Next system moving down the British Columbia coast
between Haida Gwaii and Vancouver Island by late Monday
afternoon. Increasing middle and high level clouds with a chance
of rain late in the day along the North Coast. Highs in the
60s.
Front continuing to move slowly southeast Monday night with a
rain developing over the North Coast and a chance of rain over
the northern portion of the interior. Winds picking up over the
Northwest Interior with southeast winds in the 20 to 30 mph
range after midnight. Low temperatures much warmer with the
cloud cover, in the mid 40s to mid 50s.
Front moving into the area Tuesday with rain spreading over the
entire area from the north early in the morning. Windy
conditions continuing over the Northwest Interior. There is a
chance wind advisories made be needed. Highs in the lower to mid
60s. Felton
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Models in good agreement with the front moving through late
Tuesday afternoon/Tuesday evening. Not much cool air behind the
front with just a chance of showers overnight. Lows in the mid
40s to lower 50s.
Post frontal showers coming to an end Wednesday morning with
high pressure, both at the surface and aloft, building into the
area. At least partly sunny skies in the afternoon. Highs in
the lower to mid 60s.
High pressure remaining over the area Wednesday night with lows
in the mid 40s to lower 50s.
Models having trouble again in the day 5 and 6 period.
Operational runs are dry Thursday but there remains a few
ensemble solutions trying to bring a weak system over the top of
the ridge. Like last night enough of solutions with light
precipitation to have a slight chance of showers over the
northern portion of the area. Highs in the 60s. Lows in the mid
40s to lower 50s.
Friday the operational ECMWF brings a dissipating system into
Western Washington. The GFS has this feature not making it to
the area. Ensembles mostly dry but like Thursday enough
solutions for a slight chance of showers along the coast and
over the North Cascades. Highs in the lower to mid 60s. Lows in
the mid 40s to lower 50s.
Better agreement in the models on day 7 with a strong upper
level ridge, 500 mb heights in the lower to mid 580 dms,
building over the Pacific Northwest. Thermally induced surface
trough as far north as the Northern Oregon Coast by late
Saturday afternoon. Highs in the 60s. Models keep the pattern
intact Sunday. If this continues could easily see some highs in
the 70s next Sunday. Felton
&&
.AVIATION...
Southwesterly flow aloft this morning as W WA finds
itself under split flow with a ridge to the north and upper
level low to the south. This will transition to northwesterly
this afternoon and into Monday. Most terminals reporting light
and variable surface winds this morning with speeds less than 5
kts, although terminals with faster winds reporting north to
northeasterly winds with speeds 5 to 10 kts. Widespread north to
northeasterly winds at these speeds expected to emerge late
this morning through the afternoon before light and variable
conditions emerge again this evening and tonight.
Widespread VFR conditions persist under weak high pressure, although
isolated patches of low clouds can result in occasional MVFR to IFR
conditions this morning. VFR area-wide expected late this morning
and for the remainder of the TAF period with generally high clouds
present.
KSEA...VFR conditions will persist throughout the TAF period.
Northerly winds around 10 kts.
&&
.MARINE...
A weak front will dissipate over the offshore waters today
with minimal impacts expected for local waters. Southerly flow will
increase Monday night and Tuesday with a stronger frontal system.
Weak high pressure and offshore flow will follow on Wednesday.
Seas generally 3-6 ft although some locations in the outer coastal
waters could see seas reach 7 ft this morning. Seas will increase
throughout the afternoon before reaching 7-9 ft this evening. The
front Monday night/Tuesday will boost waves up to 10-12 ft before
receding quickly starting Tuesday afternoon.
33/18
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion