079
FXUS66 KSEW 121053
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
253 AM PST Wed Feb 12 2025

.SYNOPSIS...Dry conditions, with cold morning temperatures,
continue through early Thursday. A frontal system will spread
precipitation northwards Thursday afternoon and continue at times
into Friday morning. Lowland rain and mountain snow returns
Saturday and continues into early next week.

&&

.SHORT TERM /TODAY THROUGH FRIDAY/...Very cold temperatures again
this morning, with most areas in the teens to mid 20s across
Western Washington. Wind chills down into the single digits in
localized spots, mainly across Whatcom County. Once again, dry
weather expected for Wednesday with temperatures rising into the
upper 30s to low 40s. Another round of cold temperatures then
Wednesday night into Thursday morning, although most areas look to
be about 5 degrees warmer compared to this morning. A Cold Weather
Advisory continues for most of Western Washington, make sure to
bundle up if you`re heading outside, especially in the mornings.

A weather system will then approach the Oregon coast tonight into
Thursday morning. This will allow for a tightening pressure
gradient along the Cascades, resulting in breezy easterly winds,
especially in the Cascade gaps. 00z HREF probabilities of gusts
greater than 45 MPH range around 60-75% near North Bend, as well
as along the Foothills of US-2. Given the elevated gradients, have
issued a Wind Advisory for the East Puget Sound Lowlands from
tonight through midday Thursday. Localized power outages and tree
damage is possible with gusts of 40 to 50 MPH near the Cascade
gaps.

Along with the increased easterly flow at the surface,
precipitation will spread northwards midday Thursday and into
Thursday evening. Although some uncertainty remains in the
temperatures, given the T/Td spread, and continued easterly flow,
would expect primarily snowfall initially, although a rain/snow
mix may be possible as well by later Thursday afternoon. At least
through Thursday afternoon, the best potential for accumulating
snowfall would be from Pierce County southwards, and along the
Hood Canal, due to the continued east flow. Precipitation then
looks to continue across most of Western Washington Thursday night
into Friday morning, resulting in additional chances for snow or
rain/snow mix for most of the lowlands. NBM probabilities through
Friday morning continue to highlight the aforementioned areas of
Tacoma southwards, as well as Hood Canal for the best potential of
1" of snow (generally 40 to 60%). However, these probabilities
are higher on the 00z LREF (GFS, ECMWF, CMC ensembles), ranging 70
to 90% of 1" of snow and 50 to 75% of 2" of snowfall. There
remains a decent amount of spread in the 24 hour snowfall amounts
(through 18z Fri) on the UW-WRF ensembles in both location of
accumulating snowfall and amounts. Will have to continue to
monitor the potential for possible headlines if confidence
continues to increase, especially as hi-res guidance further comes
in range. Otherwise, although rain/snow or snow would likely the
primary precipitation type based on the temp profile, will have to
monitor any concerns for brief freezing rain, at this moment
mainly around Grays Harbor CO due to continue east winds at the
sfc and slow warming aloft. Temperatures likely will be in the
upper 20s to low 30s by Friday morning.

.LONG TERM /SATURDAY THROUGH TUESDAY/...The next frontal system
will approach Western Washington Saturday bringing a slow warming
trend in temperatures, resulting in mainly lowland rain and
mountain snowfall. Although should note, can`t rule out a brief
mix at the onset of precipitation, mainly around Whatcom County
and the Cascade Foothills Saturday before warming continues. The
unsettled weather pattern then continues Monday and potentially
into Tuesday as another trough moves across the Pacific Northwest
around midweek. If you`re traveling over the Cascade Passes over
the weekend, make sure to monitor the forecast. Temperatures will
be near to slightly below normal by early next week. JD

&&

.AVIATION...Northerly flow aloft will back to west to southwesterly
tonight as a weak upper ridge axis moves onshore and a broad upper
level trough approaches offshore. The air mass will remain quite dry
today with VFR expected areawide into tonight.

KSEA...VFR with clear skies. Surface winds E/NE 5 to 8 knots rising
to 9 to 13 knots after 03Z this evening with gusts of 15 to 20 knots
at times overnight tonight into early Thursday A.M. 27

&&

.MARINE...A broad surface trough will move into the offshore
waters tonight into Thursday enhancing offshore flow with Small
Craft Advisory easterly winds expected in the west entrance to the
strait and portions of the coastal waters adjacent to gaps in
terrain. The low will weaken as it moves into the Oregon coastal
waters late in week. A more organized frontal system will reach the
area over the weekend with headlines for both wind and seas expected.

27

&&

.HYDROLOGY...No river flooding expected over the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Cold Weather Advisory until noon PST Thursday for Admiralty
     Inlet Area-Bellevue and Vicinity-Bremerton and Vicinity-
     Central Coast-East Puget Sound Lowlands-Eastern Strait of
     Juan de Fuca-Everett and Vicinity-Hood Canal Area-Lower
     Chehalis Valley Area-North Coast-San Juan County-Seattle
     and Vicinity-Southwest Interior-Tacoma Area-Western Skagit
     County-Western Strait of Juan De Fuca-Western Whatcom
     County.

     Wind Advisory from 7 PM this evening to 1 PM PST Thursday for
     East Puget Sound Lowlands.

     Cold Weather Advisory from 4 PM this afternoon to noon PST
     Thursday for West Slopes North Central Cascades and Passes-
     West Slopes South Central Cascades and Passes.

PZ...Small Craft Advisory from 7 PM this evening to 4 PM PST Thursday
     for Central U.S. Waters Strait Of Juan De Fuca-Coastal
     Waters From Cape Flattery To James Island 10 To 60 Nm-
     Coastal Waters From Cape Flattery To James Island Out 10 Nm-
     Coastal Waters From James Island To Point Grenville 10 To
     60 Nm-West Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 4 PM this afternoon to 4 PM PST
     Thursday for Coastal Waters From Point Grenville To Cape
     Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville
     To Cape Shoalwater Out 10 Nm.

&&

$$