755
FXUS66 KSEW 051012
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
312 AM PDT Sat Sep 5 2026

.SYNOPSIS...Low pressure will bring showers and thunderstorms to
western Washington this weekend, with drier weather moving into
next week. Offshore flow will lead to slightly warmer weather
midweek. A front and trough will bring cooler weather and a
chance of showers toward the end of the week.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...An upper level low will
spin over the Pac NW today with another round of
afternoon/evening showers and thunderstorms over western
Washington. Cells will initially form over the Cascades then
drift west over the lowlands, similar to what was observed
yesterday. Showers and thunderstorms will decrease toward sunset
this evening. We will see a few sunbreaks in between showers
with afternoon highs around 70. The coast will be cooler and in
the 60s.

The upper low continues to wobble overhead on Sunday but showers
will mostly stick over the mountains. The air mass remains
slightly unstable for isolated mountain thunderstorms as well.
With lighter/weaker steering flow, the storms will be slow-
moving with the potential for higher precipitation totals (especially
over the southern Cascades).

The upper low shifts farther east and inland on Monday with just
isolated showers over the Cascades. Low level onshore flow will
be stronger for morning clouds and late afternoon sunbreaks. 33

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...Western WA lies in
between weather systems next week with broad low pressure over
western Canada and a cutoff low (associated with Hurricane
Maria) well offshore along 135W. East/offshore flow will lead
to slightly warmer weather in the mid to upper 70s both
Wednesday and Thursday. Expect lows in the 50s. The Canadian low
will bring troughing over the area by Friday for cooler weather
and a chance of showers. 33

&&

.AVIATION...Variable flow aloft continues as an upper level low
moves slowly over western Washington. Surface winds largely light
and variable this early morning before favoring a north to
northeasterly direction by late this morning and into this evening.
Light and variable winds expected to return tonight.

VFR conditions persist at most terminals, although some locations
such as BLI and OLM have seen fog develop at times...and HQM is also
starting to see low cloud development as of the 10Z ob. As such,
these terminals may dip down into IFR/LIFR conditions at times this
morning before returning to VFR conditions by noon today. Scattered
showers with isolated thunderstorms possible again today but
probabilities do not favor TAF inclusion at this time.

KSEA...VFR conditions in place and expected to remain that way for
the TAF period. Shower/thunderstorm discussion above applies. Winds
light and variable this morning, turning more northerly by this
afternoon before shifting northeasterly around 00Z. Speeds
increasing to around 5-10 kts this afternoon.

18

&&

.MARINE...No significant marine conditions expected on the whole,
with winds and seas largely remaining short of any advisory
criteria. Scattered showers and isolated thunderstorms will be
possible again today as the upper level low over the region has
moved very little. Northerly winds expected over the waters this
weekend into next week. A marginal westerly push through the Strait
of Juan de Fuca around Monday looks to be the next potential period
of advisory strength conditions. Seas mainly 3 to 5 feet, with a
short period component this weekend and into the start of next
week.

&&

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

&&

$$