Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
396
FXUS66 KSEW 020450 AAC
AFDSEW
Area Forecast Discussion...UPDATED
National Weather Service Seattle WA
850 PM PST Thu Jan 1 2026
.SYNOPSIS...
Multiple weather systems will move across the area
through early next week due to continued upper troughing
offshore. Lowland rain, high elevation mountain snowfall, breezy
winds, and coastal flooding are expected at times into Monday.
Another system will move across Western Washington Tuesday into
Wednesday.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
Light precipitation continues to spread northwards across
Western Washington this afternoon ahead of a frontal system.
However, continued drier air at the surface has resulted in
mainly light amounts, primarily south of Seattle. Lowland rain
will increase tonight into Friday morning with the frontal
system along with a moistening airmass. The main concern through
Friday will be continued wintry mix over the Cascades,
including the Cascade Passes. Temperatures will continue to warm
aloft tonight, but east flow at the Cascade Passes
(particularly Stevens and Snoqualmie) will result in
temperatures remaining near or below freezing into Friday
morning. Freezing rain will continue overnight for both Passes
(in addition to White Pass this evening), with light snowfall at
the onset for Stevens Pass. A Winter Weather Advisory remains
in place through Friday morning for Snoqualmie and Stevens Pass.
If you`re traveling over the Passes through Friday, monitor
WSDOT for road conditions and information.
Generally light precipitation expected Friday afternoon into
Friday night before the next weather system moves northwards
into the area on Saturday. South winds will increase Saturday,
becoming breezy at times for Whidbey Island northwards and along
the coast, with gusts in these areas ranging 25 to 35 MPH. Snow
levels will also remain elevated on Saturday, around 4500 to
5500 feet for high elevation mountain snowfall, and rain or a
rain/snow mix for the Passes.
Coastal flooding concerns also increase going into the weekend
due to abnormally high tides. Initially, coastal flooding is
expected along the coast Friday and Saturday, where a Coastal
Flood Watch has been issued. Moderate coastal flooding is
forecast both days, with major coastal flooding possible on
Saturday for Grays Harbor County.
A compact low pressure system will then drift northwards
Saturday night into Sunday. More information can be found in the
long term section regarding this system. Highs on Friday and
Saturday will warm into the upper 40s to low 50s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
A surface low will strengthen offshore of northern California
and Oregon late Saturday into Saturday night and track
northwards into Sunday. There remains continued uncertainty into
the placement and intensity of this surface low by Sunday
morning. This especially impacts the wind forecast Saturday
night into Sunday. The spread in the 10-90th PCT wind gusts from
NBM remains quite large.. ranging 25-55 MPH for the coast and
north interior, and 25-45 MPH for Puget Sound. The variation in
low placement can also be seen well in the UW WRF GFS ensembles,
with individual members showing the low location offshore, and
others further inland. Additional hi-res guidance (HREF/REFS)
will come into range over the next 12-24 hours, and the wind
forecast will continue to be refined. Continue to monitor the
forecast during this period in regards to potential impacts.
In addition to the winds, coastal flooding concerns will likely
peak on Sunday, particularly due to weather exacerbating the
issue (i.e. lower pressure, stronger winds). Major coastal
flooding is once again possible Sunday for the coast, with
widespread minor to moderate coastal flooding for the interior.
Water levels look to rise up to a maximum of around 2 to 2.75
feet above ground level over the weekend, and up to 3 feet along
the coast.
The aforementioned system will move through on Sunday, with
another round of lowland rain and mountain snow expected on
Monday as an upper trough progresses east over the Pacific
Northwest. There may be a break in the action Monday night,
however, another frontal system looks likely Tuesday into
Wednesday. Ensembles suggest another round of lowland rain,
potentially heavier mountain snow, and breezy winds. JD
&&
.AVIATION...
Mainly southwest flow aloft throughout the period as an upper-
trough remains offshore. Low-level flow light but is gradually
increasing in magnitude out of the south into early Friday
morning. Showers are moving through most of the terminals this
evening. Areas of IFR/LIFR will return overnight with the
arrival of steadier rainfall lowering cigs and vis. IFR/LIFR
conditions will persist into Friday with minimal improvement
into the afternoon. Winds generally light, but increasing around
4-8 kt out of the E-SE into Friday for locations such as KOLM
and KHQM.
KSEA...Rain showers are moving through the terminal this evening,
with ceilings and visibilities dropping to MVFR. High confidence
that a prolong LIFR ceiling (with lower VIS from mist) will form
later tonight into much of Friday, with improvements to MVFR not
taking shape till late in the afternoon. Surface winds generally
light and variable, becoming more consistent out of the SE on Friday
between 2- 5 kt.
McMillian/HPR
&&
.MARINE...
A weak system is moving into the region from the
south tonight into Friday morning. Little to no impacts are
expected but a much stronger disturbance is in line to arrive
Saturday into Sunday morning for increasing winds and seas. Here
we`ll see the next best chance of widespread headlines with SCA
winds. Can`t rule out the potential for gales. Another system
will arrive Monday followed by an additional disturbance on
Tuesday as the pattern looks to remain into next week.
Seas 5 to 8 feet building to 10 to 14 feet Saturday. Seas subsiding
back down below 10 feet Monday but could rise again towards midweek.
McMillian
&&
.HYDROLOGY...
Multiple frontal systems will move through Western
Washington into next week. The Skokomish River, starting from
elevated levels, is forecast to approach flood stage later on
Sunday, before slowly receding next week. No additional river
flooding is expected into next week. JD
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until 7 AM PST Friday for Cascades of
Pierce and Lewis Counties-Cascades of Snohomish and
Northern King Counties-Cascades of Southern King County.
Coastal Flood Watch from Saturday morning through Saturday
afternoon for Grays Harbor County Coast-Northern
Washington Coast.
Coastal Flood Warning from 9 AM to 1 PM PST Friday for Grays
Harbor County Coast.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion