Four Corners, Washington Weather Forecast Discussion

863
FXUS66 KSEW 170941
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
241 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/...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/IFR in low stratus and patchy fog along the
coast with mostly VFR conditions inland. Marine stratus will
continue to filter inland this morning, likely reaching KOLM and
KPWT. Terminals east of the Puget Sound are favored to remain VFR
through the morning. Conditions will improve inland by the late
morning, with brief improvement to MVFR or VFR along the coast in
the mid to late afternoon before another round of marine stratus
redevelops and pushes inland early Thursday morning.
KSEA...VFR conditions early this morning with a low (10% to 15%)
chance of MVFR to IFR low stratus developing over the terminal.
Southerly winds generally 4 to 7 kt will continue through the
early afternoon, switching to northerly around 21z-23z this
afternoon and increasing to 7 to 11 kt. Winds will shift more
northeasterly this evening and will stay predominantly northerly
through Thursday. Forecast models show a higher chance (40% to
45%) of MVFR low stratus developing over the terminal early
Thursday morning.
15
&&
.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