639
FXUS66 KSEW 161042 CCA
AFDSEW

Area Forecast Discussion...CORRECTED
National Weather Service Seattle WA
342 AM PDT Thu Oct 16 2025

.SYNOPSIS...A weak frontal system will move across the area
tonight into Friday, bringing the return of showers to western
Washington. A stronger, wetter system will follow over the weekend,
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 persist into midweek.

&&

.SHORT TERM /TODAY THROUGH SATURDAY/...Upper level ridging
offshore will continue to flatten today, allowing for a weak
frontal system to move into western Washington tonight into
Friday. Expect an increase in cloud cover area-wide through the
morning hours, with showers starting to push inland late this
afternoon into this evening. Overall impacts with this system
remain minimal, with QPF amounts expected to be rather light
across western Washington. Only a few hundredths of an inch of
rain are expected for most lowland locations outside of the coast,
with a quarter to half an inch expected for the mountains.
Increasing onshore flow in the wake of the front will help support
the development of a weak convergence zone across the central
Sound by Friday morning. Showers will then become more confined
to the Cascades by late morning and look to taper by late afternoon.
Afternoon high temperatures both days will be in the upper 50s to
low 60s across the area, with overnight lows expected to be in
the 40s on Friday morning.

The focus then shifts to the weekend as a wetter, stronger
frontal system approaches the region Saturday night into Sunday.
Snow levels will rise to 7500-9500 ft in the warm sector during
the day on Saturday, with some rain starting to move inland along
the coast and into the North Interior throughout the day. The
bulk of the precipitation will move inland Saturday night into
Sunday as the front moves into the area. Southerly winds will
become breezy as the front approaches, increasing to 20-30 mph
across the area.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Snow levels will fall
back down towards 4500 ft in the wake of the front on Sunday,
bringing snow to the higher elevations of the mountains. Overall,
most likely QPF amounts with this system generally range between
0.75 of an inch to 1.15 inches across the interior lowlands, 1-3
inches along the coast, and 2-4 inches across the Olympics and
North and Central 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. The upper level trough
trailing the frontal system will swing across the area by Sunday
evening, allowing for a transient upper ridge to move into the
area on Monday. While some showers will linger into Monday,
expect a brief, but overall drying trend throughout the day.

Confidence in the forecast details wanes heading into Tuesday
and Wednesday, with ensemble clusters still showing a spread in
solutions. At this time, it looks as if a few weaker systems may
brush western Washington for a return to overall showery, unsettled
conditions. However, will need to keep an eye on the intensity
and exact placement of a ridge to the south the area as it may
lessen the impacts of any subsequent systems moving towards
western Washington mid to late week. 14

&&

.AVIATION...Northerly flow aloft as an upper-ridge axis punches into
SW BC. Flow then turns more west-northwest tonight into Friday.
Currently, VFR all areas but patchy low clouds (MVFR to LIFR) are
developing over the coast at this time. Models indicate this
action tracking inland as the morning progress, but should remain
over the SW interior and Kitsap County with a lesser chance
(10-20%) of it reaching Puget Sound. This action will burn off to
widespread VFR but a weak front will increase low-level onshore
flow, maintaining the threat for MVFR cigs to redeveloped Thursday
night into Friday morning with rain showers.

KSEA...VFR likely through most of the TAF period except Friday
morning where low clouds are most likely to return. Mid to high
level clouds will increase over the terminal today as a weak front
draws near overnight into Friday. Low confidence in showers passing
through the terminal early Friday morning (but high enough
probability to put a PROB30 group with the 12z TAFs). Winds
generally out of the south between 4 to 8 kt.

McMillian

&&

.MARINE...Benign conditions remaining over area waters today. A weak
front will arrive tonight into Friday with an increase in coastal
seas (from 4 to 6 ft rising to 6 to 8 ft) but impacts are not
favored. A stronger frontal system will reach the waters Saturday
night into Sunday with headlines expected for most of the waters.
Coastal seas will build into the double digits this weekend and
could exceed 15 feet by later Sunday and remain above 10 ft into
early next week.

McMillian

&&

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

$$