932
FXUS66 KSEW 081512
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
812 AM PDT Tue Sep 8 2026

.SYNOPSIS...High pressure will move in Tuesday and Wednesday
for drier and warmer conditions. A pair of systems look to move
through Thursday through the weekend for more chances for
showers and cooler weather.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...Localized river valley
fog this morning with stratus north of Everett, otherwise,
mostly clear skies across the area. Dry and warmer weather will
prevail through Wednesday with weak high pressure over the
region. Max temperatures will peak on Wednesday with highs in
the mid 70s to lower 80s. The coast will be cooler and in the
60s.

Broad low pressure over western Canada will sag south and send a
trough through western WA on Thursday. The result will be
increasing clouds, cooler conditions, a chance of showers
(mainly central and northern Cascades). 33

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...Low pressure
remains over the Pac NW Friday through the weekend as a closed
low drops down from Canada. This will keep western WA cool and
showery through the period. Expect highs in the 60s with
overnight lows around 50. Look for dry and mild conditions early
next week with temperatures close to average. 33

&&

.AVIATION...VFR conditions prevail across western Washington
and will continue to do so with mostly clear skies. Some fog
remains in place this morning the valleys but is not affecting
any of the terminals and will burn off before 18Z this morning.
Another round of valley fog and patchy marine stratus is
expected to bring widespread MVFR to IFR once again early
Wednesday morning, but is currently favored to remain west of
KSEA/KBFI. Offshore flow overnight should limit its extent.
Winds remain northerly 10 kt or less through the period.

KSEA...VFR conditions prevail through the TAF period. Northerly
winds will generally remain light through Wednesday morning at
around 4 to 8 kt.

15/62

&&

.MARINE...High pressure will continue to build over the coastal
waters through Wednesday. North to northwest winds will
gradually increase into Wednesday as a frontal system slowly
approaches, with potential for Small Craft westerlies through
the Strait of Juan de Fuca Wednesday evening through Thursday
morning. The frontal system weakens as it moves through the
region on Thursday, allowing winds to ease across the region.
Another weather system may move over the waters late Friday into
Saturday, but no headline winds are anticipated at this time.

Seas around 4 to 5 feet will gradually build through Wednesday,
reaching 7 to 10 feet by Thursday afternoon. This will also bring
steep seas as short period waves from the stronger winds over the
coastal waters begin to dominate. Seas will ease to around 5 to 6
feet by Friday and continue to stay near 5 feet through the weekend.

15

&&

.FIRE WEATHER...High pressure through Wednesday will bring
brief elevated fire weather concerns alongside a gradual warming
and drying trend, with weak offshore flow Tuesday night
limiting overnight relative humidity recoveries along the
western Cascades. Additional drying throughout the day Wednesday
will bring minimum relative humidity values over the Cascades
to the 25 to 35 percent range, nearing critical thresholds in
some areas near the Cascade crest.

By Thursday, fire weather concerns across western Washington subside
as an upper level trough brings stronger onshore flow. Although this
system will not bring much in the way of precipitation, relative
humidities will rebound with much higher overnight recoveries.

15

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.

&&

$$