Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
201
FXUS66 KSEW 042138
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
231 PM PDT Sun Oct 4 2026
.SYNOPSIS...
Upper level ridging over western Washington will flatten out as a
system passes to the north with near zonal flow aloft expected by
Monday. This will keep temperatures near seasonable normals as well
as return onshore flow to the area. The pattern of morning clouds
giving way to afternoon sun will persist at least through mid-week.
An approaching frontal system for the end of the week could bring
the next chances for precipitation, however some uncertainty exists.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
Mostly clear skies over W WA this afternoon although stratus still
lingers along the coast. With clouds breaking up a little earlier
than yesterday, area temperatures largely on track with the forecast
with current obs ranging in the mid 60s to around 70. This puts
expected highs for most locations in the lower 70s still well within
reach.
Forecast remains consistent in that the upper ridge will continue to
shift eastward today with the ridge axis making it to the Rockies by
this evening. Coupled with a trough passing to the north, zonal flow
aloft will set up overnight, helping to bring a return to onshore
flow at the surface. Forecast dilemma for the immediate short term
is will the return of onshore flow exacerbate the morning fog issues
the area has been having. Currently agreeing with NBM that potential
for widespread fog likely to be mitigated by the clouds that will
move in overnight. Sure, they will be stratus-y, but with the ridge
gone, they should not make it all the way to the ground. Otherwise,
dry conditions remain in place for the short term.
The import of cooler marine air will shave a handful of degrees off
of daytime highs, making them a bit more seasonable. Highs both
Monday and Tuesday are expected to range from the low to upper 60s,
with a few isolated spots in the SW interior shaking hands with 70.
18
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A building upper level ridge off the coast of California mid-week
will nudge zonal flow to a little more northwesterly by Wednesday
evening. This will give daytime highs a bump of about a degree or
two, ranging in the mid 60s to lower 70s. More widespread 70-plus
temps can be found on Thursday as this minor ridging gets a little
more time to work. Coastal sites may not see much change in
temperatures, however interior lowland spots will range from the
upper 60s to mid 70s, with the SW interior being on the higher end
of that scale.
Models remain in agreement about a frontal system moving its way
through W WA Friday...but all the details remain up in the air.
Deterministic GFS has pushed FROPA back to Friday evening or Friday
night while deterministic ECMWF remains consistent, bringing the
system through Friday afternoon and evening. Most ensemble members
favoring the ECMWF timing...providing enough sway to cause the NBM
to reflect this thinking in its forecast. This seems reasonable
enough for now, but no matter the timing, models seem to be in
hearty agreement that this front looks to fall apart as it moves
through. While higher elevations should still see something with
PoPs coming in at 60-70 pct for the event, PoPs in the lowlands are
considerably lower, still largely ranging 20-40 pct. It is still
some time out though, and plenty of opportunity for additional
variances to emerge. This system will cool temperatures regardless
if it rains, with daytime highs for Friday and the weekend in the
mid 50s to lower 60s...with some mid 60s possible, mainly on Friday.
18
&&
.AVIATION...
High pressure continues over the West with dry and stable conditions
across western Washington. The flow aloft is westerly. Low clouds
and fog will likely reform overnight with LIFR to VLIFR ceilings and
visibility across the interior lowlands. Low clouds and fog will
scatter out 18-21z with VFR conditions expected thereafter. 33
KSEA...VFR this afternoon and evening with low clouds returning
overnight and Monday morning. Light N winds becoming S to 5 kt by 09-
12z. 33
&&
.MARINE...
A thermal trough will shift inland tonight with the
flow turning onshore. Highest wind and waves will be through the
Strait of Juan de Fuca - a Small Craft Advisory is in effect.
Another push down the strait is forecast Monday evening. Onshore
flow will continue through the week with another strong push on
Friday as a front moves inland. 33
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 AM PDT Monday for Central U.S.
Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
Strait Of Juan De Fuca.
&&
$$
NWS SEW Office Area Forecast Discussion