834
FXUS66 KSEW 300934
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
233 AM PDT Sat Aug 30 2025

.SYNOPSIS...An upper level low off the coast will influence the
area this weekend, keeping temperatures seasonable. However, this
system has little moisture associated with it, all but eliminating
any chances for showers. Upper level ridging returns Monday,
bringing another round of hot and dry conditions with well above
normal temperatures are expected by mid-week.

&&

.SHORT TERM /TODAY THROUGH SUNDAY/...Skies over W WA filling in much
like 24 hours ago as per latest satellite imagery while radar
remains mostly clear. There is at least a hint at the upper level
low off the coast in the current radar loop as a weak echo
progresses northeastward just off of Grays Harbor bar.

This echo in some ways heralds what is to come as models suggest
there may be some minor 10-ish PoPs along the coast this morning and
into the early afternoon, but little in the way of any kind of
eastward progression is expected as the upper low simply sits and
churns, mostly held up by the immobile upper level ridge centered
over ID and W MT. While no precip is expected, this system will keep
daytime highs in check, with more seasonal mid 70s to around 80 for
most interior locations and mid 60s to around 70 for coastal and
water-adjacent sites. While Sunday may see temps nudge upward a
degree or two, no significant change is expected. Skies both days
likely to see late night/early morning clouds, burning off by early
afternoon with mostly sunny skies in the late afternoon and early
evening. Overnight lows will also be more seasonable than what the
area has experienced lately, getting down into the mid to upper 50s.

18

.LONG TERM /MONDAY THROUGH FRIDAY/...The aforementioned upper low
gets shunted back westward out over the Pacific as the upper level
ridging mentioned in the short-term intensifies, expanding its
influence into W WA. This will see daytime highs climb back into
above normal as each day will see a progression through the 80s for
most interior sites. It appears the area tops off in the mid to
upper 80s for Wed and Thu...but latest solutions ease up on the
potential for offshore flow during this time frame, keeping out any
amplification by easterly winds. A couple of bursts of onshore flow
both Thursday and Friday will initiate a cooling trend...not so much
for Thursday as highs will still linger in the lower to mid 80s, but
much more significantly Friday, where W WA looks to return to more
seasonable temps in the 70s.

18

&&

.AVIATION...Mostly MVFR to IFR as low stratus expands inland across
much of the lowlands. Stratus will slowly erode to VFR conditions
over the interior throughout the late morning and early afternoon,
with MVFR stratus continuing throughout the day along the coast and
through the Strait of Juan de Fuca. Scattered rain showers will
spread northward along the coast and over the Olympic Peninsula
throughout the afternoon today. Onshore flow overnight will promote
another round of low stratus early Sunday morning.

KSEA...VFR this evening under high clouds, with low stratus
expanding over the terminal by the mid-morning. IFR conditions are
expected to prevail through 17z-19z before the stratus erodes and
conditions return to VFR with mid and high clouds. Southwest surface
winds 4 to 8 kt will become northwesterly after 23z, then shifting
back southwest overnight into Sunday morning.

15

&&

.MARINE...Varying degrees of onshore flow will continue over area
the waters into this weekend. Westerly pushes down the Strait of
Juan De Fuca can be expected each evening, with the strongest push
likely happening Sunday evening. Winds may reach Small Craft
Advisory criteria, but right now confidence is low. Surface high
pressure looks to develop over the coastal waters by midweek next
week.

Combined seas around 2 to 4 feet will continue throughout the
weekend and into the first half of next week. Seas will then build
to 4 to 6 feet by midweek.

Mazurkiewicz

&&

.FIRE WEATHER...Weak onshore flow into the weekend is expected to
keep temperatures in check with good to excellent nightly
relative humidity recoveries. An upper level low parked offshore
over the weekend could trigger isolated showers, however latest
model runs have significantly backed away from any thunder threat.
This offshore low will shift away from the area early next week with
strong upper ridging rebuilding across the area. As a result,
temperatures are expected to climb once again to well above average.
Afternoon relative humidities in the 25-35% range are expected, with
some higher terrain locations could get as low as 15-25%. Wednesday
and especially Thursday are the days of most concern for hot, dry,
and unstable conditions across the majority of the area. Fuel
moisture levels are already low across much of Western Washington
and the upcoming very warm and dry weather will further cure both
live and dead fuels. A strong onshore push Friday will result in
more seasonable temperatures, helping to draw RH values upward. 27/18

&&

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

$$