University, Washington Weather Forecast Discussion

521
FXUS66 KSEW 171641
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
941 AM PDT Wed Sep 17 2025
.SYNOPSIS...Cooler and calmer conditions will resume across
western Washington through the remainder of the week as onshore
flow returns. A low pressure system will move into the region
Saturday, bringing widespread rain and breezy winds. Conditions
are favored to dry out early next week.
&&
.SHORT TERM /TODAY THROUGH FRIDAY/...There`s a large smoke plume
over the eastern Olympics from the Bear Gulch fire. Most of the
smoke will be aloft but there are pockets of degraded air quality
over the eastern strait. The fire weather threat will be lower
overall with cooler temps and higher RHs. 33
Previous discussion...Onshore flow will resume through the
remainder of the week, bringing cooler temperatures and calmer
conditions to western Washington. High temperatures will dip back
into the 60s and 70s through Friday, returning to near normal for
mid September. Marine stratus will develop along the coast each
morning and expand inland, burning off back towards the coast each
day allowing for afternoon sun breaks.
.LONG TERM /SATURDAY THROUGH TUESDAY/...A broad upper level trough
will swing a cold front across western Washington on Saturday,
bringing in cooler temperatures, widespread rain, and breezy
conditions. Rain is favored to continue over higher terrain on
Sunday with cloudy skies over the lowlands. Ensembles have trended
slightly drier with this storm system, with preliminary rainfall
totals of a third of an inch over the lowlands and up to 2 to 3
inches of liquid over the mountains. The bulk of the moisture with
this system is on track to fall over the northwestern Olympic
Peninsula.
Forecast models begin to show a larger spread in solutions
starting next week, with operational models showing drying and
warming on Monday and Tuesday whereas ensembles show potential for
unsettled conditions to continue across western Washington. For
now, a chance of rain has been maintained through the extended
forecast with continued cooler temperatures.
15
&&
.AVIATION...MVFR low stratus along the coast, with VFR conditions
inland. Conditions are expected to improve into VFR along the coast
by mid to late afternoon before another round of marine stratus
redevelops and pushes inland early Thursday morning. Winds will
increase this afternoon to 6 to 12 kt, with gusts up to 20 kt
possible along the Strait of Juan de Fuca. Smoke from the Bear Gulch
fire continues to advect to the north and latest satellite has the
smoke just to the east of KCLM. As a result, may see visibility
decrease at times to around 4SM.
KSEA...VFR conditions this morning at the terminal and will persist
for the rest of today. Southerly winds generally 4 to 7 kt will
continue through the early afternoon, switching northerly around 21z-
23z and increasing to 7 to 12 kt. Winds will shift more
northeasterly this evening and will stay predominantly northerly
through Thursday. Latest forecast models show a higher chance (40%
to 45%) of MVFR low stratus developing over the terminal early
Thursday morning.
15/29
&&
.MARINE...Surface high pressure will build over area waters
through Friday with lower pressure inland. This will result in a
westerly push through the Strait of Juan de Fuca this afternoon and
evening, and a Small Craft Advisory remains in effect. Small Craft
northwesterlies will also start over the coastal waters later today
into Thursday. Onshore flow will continue into the weekend as a low
pressure system moves over the region. High pressure will resume
early next week with continued onshore flow.
Combined seas 5 to 6 feet will continue to build to 8 to 10 feet
later today, remaining elevated through Thursday. Seas will be steep
with a dominant period of 10 to 11 seconds. Seas will subside to 5
to 8 feet over the weekend, and are favored to stay below 10 feet
into next week.
15
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 2 PM this afternoon to 2 AM PDT
     Thursday for Central U.S. Waters Strait Of Juan De Fuca-
     East Entrance U.S. Waters Strait Of Juan De Fuca.
Small Craft Advisory from 2 PM this afternoon to 5 PM PDT
     Thursday 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