464
FXUS66 KSEW 170238
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
738 PM PDT Thu Oct 16 2025

.SYNOPSIS...A weak frontal system will move across the area
tonight into Friday bringing light rain showers to the area. A
stronger, wetter system will follow Saturday evening into Sunday,
bringing gusty winds, lowland rain, and mountain snow to the
area. A brief drying trend is expected on Monday, before unsettled
conditions look to return Tuesday and continue through the rest of
the week.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...The current forecast
remains on track with no planned updates tonight. 33

Previous discussion...Recent satellite imagery shows mid to high
level clouds streaming in ahead of an approaching system. This
system is fairly weak and will spread light rain showers across
the area, with showers moving in throughout the evening. QPF is
pretty minimal so most areas may not even see rain, with only a
few hundredths of an inch rain likely across the lowlands, which a
quarter to a half an inch expected for the mountains. Increasing
onshore flow into Friday will help develop a weak convergence zone
across the Central and South Sound early Friday morning with
showers tapering off by the afternoon for most of the area. High
temperatures on Friday look to remain in the upper 50s to low 60s.

A stronger and wetter system will cross over the region Saturday
evening into Sunday, with widespread rain, breezy conditions, and
mountain snow. Snow levels will rise upwards to 7000-9500 feet
late Saturday evening as widespread rain will spread across most
of the region. Winds will also become breezy, with gusts up to 20
to 30 mph at times throughout the overnight period. Winds will
continue to remain breezy Sunday morning with showers continuing
across most of the area - with areas along the Olympics and
Cascades getting the bulk of the precipitation. Snow levels will
fall back down towards 4500 feet in the wake of the front on
Sunday, likely bringing some snow to the higher elevations of the
mountains. The weekend system will bring QPF totals somewhere
around a half an inch to an inch of rain across the interior
lowlands, along with 1-3 inches along the coast and 2-4 inches for
the Olympic and the Cascades. Though this event will be a good
primer for area rivers, the antecedent dry conditions lend little
concern for any flooding at this time.

.LONG TERM /MONDAY THROUGH THURSDAY/...A transient upper ridge
looks to move over the area on Monday which will help dry
conditions out, with temperatures in the mid to upper 50s.
Low confidence in the forecast starting on Tuesday as ensemble
clusters still show a wide spread of solutions. A few weak systems
look to move across the area midweek which would allow for
showery and unsettled conditions. Will need to keep and eye on
the intensity and exact placement of a ridge which could keep
these systems away from western Washington, but for now, looks
like unsettled conditions will continue at the end of the long
term.

Mazurkiewicz

&&

.AVIATION...Flow aloft turning northwesterly this evening and
remaining that way throughout Friday. Surface winds are generally
light and variable at most terminals, however those that are seeing
speeds generally 4-8 kts are seeing a prevailing direction from the
south to southwest. Southerly winds expected to increase overnight
for SEA, BFI, PAE and OLM to 5-10 kts by 12Z with all terminals
reaching this direction and speed range by 19Z.

A mix of MVFR to VFR conditions over W WA this evening as cigs
continue to lower in advance of a weak system expected to pass
through overnight. At the time of this writing, VFR conditions
observed along the east side of the Sound and along the shores of
the Strait with MVFR conditions elsewhere. Widespread MVFR
conditions expected to accompany said system, with IFR/LIFR
conditions at terminals more prone to lower cigs such as OLM, PWT
and HQM...being in place by 12Z early Friday morning. Cigs expected
to lift back into VFR conditions Friday afternoon, although timing
may be difficult to pin down depending how much moisture is able to
move over the area. Models seem to be leaning toward a 19-21Z
time frame for area terminals to return to VFR cigs.

KSEA...MVFR to VFR conditions this evening, as latest /02Z/
observation had cigs just under VFR threshold at 2800 ft. There may
still be a little wiggle room to that before 06Z, but will start to
see MVFR conditions emerge more persistently by 10Z, bottoming out
around 1500 ft by 12Z. Recovery to VFR expected by 19Z, with
additional lifting/clearing throughout the remainder of the
afternoon.

18

&&

.MARINE...A weak frontal system will cross area waters tonight into
early Friday with weak high pressure building in thereafter through
Saturday morning. Post-frontal winds will increase through the
Central Strait of Juan de Fuca on Friday, reaching Small Craft
Advisory strength. A much stronger frontal system will move over
area waters Saturday into Sunday, with numerous headlines expected
across the outer and inner waters over the weekend. A series of
additional frontal systems will cross the region through next week.

Seas generally 4 to 6 feet will gradually build to 5 to 7 feet
through Friday morning, then increase to 9 to 12 feet by Friday
evening. Seas will remain elevated through the weekend, building as
high as 19 feet across the outermost outer waters and 15 feet along
the coastal waters on Sunday. Seas may be steep at times, especially
Saturday night into Sunday. Seas are expected to fall below 10 feet
briefly on Monday before building back to 10 to 16 feet through the
remainder of the week.

15

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 AM to 5 PM PDT Friday for Central
     U.S. Waters Strait Of Juan De Fuca.

&&

$$