Poineer Square, Washington Weather Forecast Discussion

178
FXUS66 KSEW 241103
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
403 AM PDT Wed Sep 24 2025
.SYNOPSIS...High pressure remains in place across western
Washington for one more warm and dry day across the region. The
ridge is replaced by zonal flow over the region Thursday, with
onshore flow increasing and ushering in cooler conditions.
Precipitation chances increase later in the week, but remain
mostly limited to the northwestern portions of the area. A more
significant weather system likely arrives late in the weekend.
&&
.SHORT TERM /TODAY THROUGH FRIDAY/...High pressure remains in
place over the region today. Expect to see a few pockets of
patchy fog or low stratus in the sheltered valleys and the
immediate coastline this morning, but otherwise predominantly
cloud free conditions with light winds continuing this morning.
Offshore flow across the eastern half of the area continues to
ease today. Some spots in the Cascades may again see RH values
dip to near critical thresholds, and temperatures across the
interior will climb in the 70s. Onshore flow begins to pick up
late today and will bring two primary changes: increasing RH
values and helping to mix out some of the smoke and send it
eastward. However, any additional smoke from the Bear Gulch fire
may again spread across the Puget Sound region. Continue to
monitor statements and forecast from air quality agencies for
the latest updates.
With a return of the deeper onshore flow, expect significantly
cooler temperatures Thursday with few sites warming above the
mid 60s and more widespread cloud cover expected. Continued
zonal flow will maintain more typical fall-like conditions
across the region into Friday. This could even leave the door
open to some light rainfall, mostly across the Olympic Peninsula
and San Juans, though chances remain around 20% at best for
Friday and any amounts will be quite light.      12
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...Ensemble guidance is
beginning to converge a bit better with respect to the
evolution of the pattern. Expect a little more mild day on
Saturday with southerly flow ahead of the an approaching frontal
system. This will bring temperatures back into the lower 70s,
but should maintain a generally dry day for much of the region.
Rain chances remain greatest along the coast and into the
northwest portions of western Washington through Saturday. Good
agreement in the guidance that the next front will approach late
Saturday through Sunday and could bring another round of more
widespread rain. Another disturbance could follow into Monday
with another round of rain sweeping through to close out the
month.                                                12
&&
.AVIATION...West to southwest flow aloft will continue over Western
Washington today as an upper ridge over the region weakens in
response to a frontal system passing well north of the area. Low
level flow at the surface will turn increasingly onshore throughout
the day as thermally induced low pressure over the interior shifts
eastward. Smoke and haze aloft remains over the area with only
patchy LIFR stratus expected this morning. Low level onshore flow
will bring IFR low clouds to the coastal areas later this evening
then spreading inland to much of the interior lowlands on Thursday
morning.
KSEA...VFR continues today with haze from regional wildfires
remaining over the area. Low clouds are expected to be more
prevalent on Thursday morning with IFR stratus expected by around
daybreak. Surface winds N/NE 6 to 8 knots will shift more
northwesterly this afternoon. 27
&&
.MARINE...Onshore flow will increase today in response to an
expanding surface ridge over the coastal and offshore waters.
This will lead to increasing northwesterlies over the coastal
waters. Small craft advisories have been posted for the outer
coastal waters and southern inner coastal waters from later this
morning into Thursday for a combination of wind and choppy seas.
Advisories may need to be extended to other portions of the inner
coastal waters as well as the central/east strait later this evening
into Thursday. The overall pattern will begin to turn a little more
active as we approach the weekend. A dissipating front will reach
the area Friday night into Saturday with a more substantial early
autumn front expected to reach the area Sunday night into Monday
with additional potential impacts for area waters.
27
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Air Quality Alert until noon PDT today for Cascades of
     Snohomish and Northern King Counties-Cascades of Southern
     King County-City of Seattle-Downtown Everett / Marysville
     Area-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-
     Lowlands of Pierce and Southern King Counties-Lowlands of
     Western Skagit and Northwestern Snohomish Counties-
     Shoreline / Lynnwood / South Everett Area.
PZ...Small Craft Advisory from 11 AM this morning to 11 AM PDT
     Thursday for Coastal Waters From Cape Flattery To James
     Island 10 To 60 Nm-Coastal Waters From James Island To
     Point Grenville 10 To 60 Nm-Coastal Waters From Point
     Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters
     From Point Grenville To Cape Shoalwater Out 10 Nm.
&&
$$

NWS SEW Office Area Forecast Discussion