637
FXUS66 KSEW 141002
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
302 AM PDT Tue Oct 14 2025

.SYNOPSIS...Weak high pressure building into the region, combined
with offshore flow, will bring cool and dry conditions to western
Washington today and Wednesday. Showers will return Thursday into
Friday as a weak system moves into the area. A stronger, wetter
system moving into the area over the weekend will bring locally
gusty winds, lowland rain, and another round of snow for the
mountains.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...Weak high pressure building
back into the region, combined with offshore flow, will bring
cool and dry conditions to western Washington today and again on
Wednesday. Clear skies and lighter winds overnight have allowed
for temperatures across portions of the interior to dip down into
the mid 30s already this morning for areas across the southern
Sound. A Frost Advisory remains in effect for much of the interior
lowlands with overnight lows still on track to bottom out in the
low to mid 30s (the coolest temperatures of the season so far).
Morning temperatures on Wednesday will be cool as well, with many
areas likely seeing another round of morning frost. Winds will
transition back to onshore during the day on Wednesday and
afternoon highs both days will be in the upper 50s to mid 60s
under sunny skies.

Shower chances will start to increase along the coast during the
day on Thursday as a weak frontal system approaches the region.
Expect showers to push further inland into the interior Thursday
night into Friday as the frontal system slowly starts to make its
way inland. Rainfall amounts look to remain rather light, with
most areas likely only seeing a few hundredths of an inch. Morning
low temperatures on Thursday will be in the upper 30s to mid 40s
across the area, with afternoon highs expected to be in the upper
50s to mid 60s.

.LONG TERM /FRIDAY THROUGH MONDAY/...Light showers will linger
across the region on Friday, however the focus in the long term
then shifts to the weekend as a stronger, wetter weather system is
slated to move into western Washington. This system has the
potential to bring locally gusty winds, lowland rain, and another
round of snow to the mountains Saturday night into Sunday. Ensemble
clusters then look to favor upper level troughing remaining over
the region into Monday for an unsettled start to early next week.

14

&&

.AVIATION...An upper-ridge will position over BC today bringing dry
northeasterly flow aloft. As a result, VFR skies are expected
throughout much of the upcoming TAF period for area terminals. Must
express the development of patchy valley fog this morning. KOLM is
mostly likely to see impacts with a period of IFR/LIFR possible
between 12-16z. As mentioned, mostly VFR through tonight. However,
an additional period of patchy fog is favored to develop into early
Wednesday morning as well. Northerly surface winds are expected.

KSEA...Mostly clear skies throughout the TAF period. North-northeast
surface wind 6 to 12 kt becoming lighter tonight into Wednesday
morning.

McMillian

&&

.MARINE...High pressure over area waters through Thursday. Here
we`ll see a period of light onshore flow and calmer seas compared to
what we`ve experienced recently. The next system will arrive
Thursday night into Friday but latest guidance indicates this
disturbance won`t pack much of a punch but we could see an increase
in seas. However, a more impactful front will enter around the
Saturday-Sunday timeframe with a better chance for widespread
advisories and warnings.

Combined seas remaining around 4 to 6 feet through midweek before
potentially rising above 10 ft towards the weekend.

McMillian

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Frost Advisory until 8 AM PDT this morning for Downtown Everett
     / Marysville Area-Foothills and Valleys of Central King
     County-Foothills and Valleys of Pierce and Southern King
     Counties-Foothills and Valleys of Snohomish and Northern
     King Counties-Foothills and Valleys of Thurston and Lewis
     Counties-Foothills and Valleys of the North Cascades-
     Lowlands of Lewis and Southern Thurston Counties-Lowlands
     of Western Skagit and Northwestern Snohomish Counties-
     Middle Chehalis River Valley-Olympia and Southern Puget
     Sound-Southern Hood Canal.

PZ...None.
&&

$$