Poineer Square, Washington Weather Forecast Discussion

830
FXUS66 KSEW 210902
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
202 AM PDT Sun Sep 21 2025
.SYNOPSIS...A cold front will move through this morning, bringing
a round of widespread rain, breezy winds, and cooler temperatures
today. Drier and warmer weather will return Monday and linger
through much of the week, followed by what looks to be more
typical late September weather for the end of the week.
&&
.SHORT TERM /TODAY THROUGH TUESDAY/...A surface cold front is
currently progressing across western Washington this morning. Rain
is presently falling across the Olympic Peninsula, and will track
across the interior through the next few hours. Rainfall amounts
remain on track, with around 0.5-1" expected across parts of the
Cascades, with around 0.25-0.5" across the interior. Quillayute
has already received over an inch of rain up through midnight. The
front is very vertically stacked, meaning that skies are expected
to clear up fairly quickly behind the frontal passage. The
exception to that will be the development of a convergence zone
over the central Puget Sound area, that will keep chances for
showers in the forecast through this afternoon. Very marginal
instability with the trough axis directly overhead this afternoon
as well will permit a 10-15% chance for a couple of isolated
lightning strikes with the convergence zone. Precipitation chances
end area-wide this evening. While this won`t be enough to end
fire season, this will certainly bring a temporary reprieve for
the active fires in the area and help improve air quality.
South to southeasterly winds will continue to increase early this
morning, ahead of the frontal passage. The strongest southerly
winds will be across areas north of Everett in the north interior
where gusts could reach 30-45 mph. Elsewhere, wind gusts look to
remain in the 20-30 mph. Winds will quickly swing over to westerly
behind the front, allowing for a good push of westerlies down the
Strait of Juan de Fuca. Winds over land will begin to weaken
behind the frontal passage (except in areas close to the Strait
and over Whidbey Island).
As for temperatures, lows this morning will be relatively warm as
we remain cloudy and rainy, in the mid to upper 50s. Highs will
be below average, only getting into the mid to upper 60s. Skies
should clear out fairly quickly behind the frontal passage this
evening, allowing for lows Monday morning to fall into the 40s.
Areas of fog are expected Monday morning.
Temperatures will begin to warm as upper level ridging quickly
begins to build and persist through the first half of the week.
Monday`s highs should reach a few degrees on either side of 70,
rising on Tuesday into the 70s to perhaps low 80s south of
Olympia and the Cascade valleys. Lows remain in the mid 40s to mid
50s.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Upper level ridging
looks to hang on into the middle to end of this week. Ensembles
are indicating the ridge beginning to flatten and start to welcome
upper level troughs towards the Pacific Northwest. However, there
is significant uncertainty as to how much or how fast the ridge
will flatten and allow the troughs to reach our region. The mean
solution is temperatures close to climatology, with slight
chances for rain and showers beginning Friday through the weekend.
62
&&
.AVIATION...A cold front will move onshore across Western
Washington this morning followed by a weak upper level trough.
Southwesterly flow aloft will become west to northwesterly this
afternoon and evening. Increasing low level onshore flow behind the
front will lead to a brief convergence zone over Puget Sound later
this morning. Areas of MVFR ceilings in rain will persist through
the morning before lifting and scattering by afternoon. Lower
ceilings may persist a little later into the afternoon around any
lingering post-frontal convergence. Gusty southwesterly surface
winds can be expected near the front this morning with gusty
westerlies persisting through late today in the Strait of Juan de
Fuca.
KSEA...Ceilings will solidify into mainly MVFR in rain through mid-
morning as the main frontal band sweeps inland before lifting back
to VFR by around 20Z. Surface winds will be south to southwesterly
10 to 15 knots early this morning. A wind shift associated with the
convergence zone is expected to reach the terminal 16Z-18Z with
winds becoming variable or light E/NE before returning to light
southerly this evening. 27
&&
.MARINE...Surface high pressure will rebuild across the waters
tonight and Monday behind a weak frontal system. Thermally induced
low pressure will expand northward along the coast on Tuesday
turning the flow northerly or weakly offshore. Onshore flow will
resume around midweek as another frontal system passes well to
the north of the area. 27
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.
Small Craft Advisory until 9 AM PDT this morning for Puget Sound
     and Hood Canal.
Small Craft Advisory until 2 AM PDT early this morning for
     Coastal Waters From Cape Flattery To James Island 10 To 60
     Nm-Coastal Waters From Cape Flattery To James Island Out 10
     Nm-Coastal Waters From James Island To Point Grenville 10
     To 60 Nm-Coastal Waters From James Island To Point
     Grenville Out 10 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