724
FXUS66 KSEW 230505
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
905 PM PST Sat Feb 22 2025

.SYNOPSIS...An atmospheric river has set up over Western
Washington Saturday evening with rain rates increasing over the
area. The river will sag south Sunday morning then lift back up
over the area Sunday afternoon into Sunday evening. Rain, heavy
at times, gusty winds, and high snow levels across the region this
weekend. After a brief break early Monday, a front will bring
more rain and gusty winds through Tuesday. High pressure rebuilds
over the region around the middle of the week with mild and mostly
dry conditions, though some shower chances linger near the coast.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...Doppler radar showing
the heaviest rain associated with this first phase of the
atmospheric river along the coast and over the OLympics this
evening. Rain rates also increasing over the Cascades between
Stevens Pass and Mount Baker. Lighter rain over the remainder of
the area except Whatcom county with just cloudy skies there.
Temperatures were mild, in the upper 40s to mid 50s.

Moderate to heavy rainfall will track through the region tonight
with several inches falling over the Olympics and Cascades. Rivers
flowing off the mountains will see sharp rises. Snow levels over
6,000 ft meaning mostly rain in the mountains (also creating very
dangerous avalanche conditions per NWAC). There`s another round of
heavy precip slated for Sunday afternoon/evening keeping rivers
running high. The current batch of county Flood Watches will
remain in effect given some uncertainty in total rainfall amounts
and timing.

Moving forward into Monday, lower snow levels will limit further
flood concerns due to additional precipitation. However, the focus
will then shift toward another round of potential strong wind as
a 980 mb low tracks northward offshore, then weakens as it moves
inland. This is prompting Storm/Gale Watches for the marine waters
with possible high surf (see below). For land winds, it`s worth
noting that a few ensemble members show high wind in the interior
(likely based if the low tracks NE through southern B.C.). Will
need to keep a close eye on the storm track as we close in.

Forecast on track. No updates this evening. 33/Felton

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...A ridge brings a break
in the pattern moving into Wednesday. The air mass will remain
mild with forecast highs in the upper 50s to around 60. A weak
front splits as it tries to move inland on Thursday (rainfall
amounts are light with just a few hundredths if anything). The
ridge then rebuilds, keeping the next system offshore through the
end of the week. 33

&&

.AVIATION...Ceilings this a mix of MVFR to IFR this evening and will
persist that way into the overnight hours. Another round of moderate
to heavy rain will move through the area tonight, and along with it
ceilings and visibility lower between MVFR to IFR. MVFR to IFR
conditions will likely persist through the rest of the TAF period as
waves of rain push through western Washington on Sunday.

Winds will be from the south to southwest and become gusty to
between 20-25 kt tomorrow afternoon. Sustained speeds overnight will
range from 5 to 10 kt.

KSEA...MVFR cigs presently at the terminal this evening. Another
round of rain will arrive shortly, and linger through much of the
overnight period. Short lived reductions to IFR in the heaviest
bands of rain cannot be ruled out. Winds will remain southerly
between 8-12 kt and become gusty as the cold front moves through
tomorrow afternoon around 00Z.

62/Kristell

&&

.MARINE...A series of frontal system will maintain active conditions
this weekend into Monday. Gale force winds over the coastal waters
and the East Entrance to the Strait of Juan de Fuca will ease
tonight with a break in the strong winds tonight. Winds will
increase again on Sunday afternoon into early Sunday night.
A much stronger low pressure system will move across the offshore
waters Monday night into Tuesday. Models are beginning to come more
to a consensus and have shifted the track further east, closer to
shore. This would focus the strongest winds south of Point Grenville
and near Grays Harbor. Strong gale force winds with gusts to storm
force may be possible, and a Storm Watch has been issued. Winds look
to also increase through the interior waters as well with at least
wind gusts nearing gale force, for which a Gale Watch has been
issued. These hazards will become more refined as we get closer to
Monday. Winds will decrease on Tuesday and active conditions will
cease as broad high pressure develops across the Pacific Northwest.

Combined seas are expected to increase to 14-17 ft today and then
gradually subside to 10-12 ft by Sunday morning. Waves will rapidly
build on Monday night through early Tuesday morning. Waves in the
nearshore waters look to build up to 18 to 34 ft, though waves
approaching 30 ft cannot be ruled out in the outermost coastal
waters. Waves will gradually begin to decrease Tuesday into
Wednesday but look to remain above 10 ft.

62

&&

.HYDROLOGY...The potential for river flooding remains through
early next week. One in a half to two in a half inches of rain
has already fallen over the Olympics Saturday. Another 3 to 5
inches is possible for the remainder of this event. Snow levels
around 7500 feet in the Olympics tonight and will remain elevated
into Sunday. A flood warning is already out for the Skokomish
River in Mason county.

Rain picking up over the Cascades tonight as well with snow
levels at least 6000 feet. A total of 3 to 5 inches of rain is
forecast through Monday for the Cascades.

The flood watch will continue for Sunday into Wednesday for most
of western Washington for the threat of river flooding. A
hydrologic outlook remains for Jefferson, Clallam, and Whatcom
Counties for a much lower chance of river flooding.

Heavy rain tonight into Sunday morning could lead to some urban
flooding. The accumulation of rainfall into Tuesday will also
increase the landslide threat the next dew days. Felton

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Flood Watch from Sunday morning through late Tuesday night for
     Bellevue and Vicinity-Central Coast-East Puget Sound
     Lowlands-Everett and Vicinity-Lower Chehalis Valley Area-
     Olympics-Seattle and Vicinity-Southwest Interior-Tacoma
     Area-West Slopes North Cascades and Passes-West Slopes
     North Central Cascades and Passes-West Slopes South Central
     Cascades and Passes-Western Skagit County.

PZ...Small Craft Advisory until 10 AM PST Monday for 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-
     Coastal Waters From James Island To Point Grenville Out 10
     Nm-Coastal Waters From Point Grenville To Cape Shoalwater
     10 To 60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater Out 10 Nm-Grays Harbor Bar-West Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Gale Watch from Monday morning through late Monday night for
     Coastal Waters From Cape Flattery To James Island 10 To 60
     Nm-Coastal Waters From Cape Flattery To James Island Out 10
     Nm-West Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Watch from Monday afternoon through Tuesday morning for
     Admiralty Inlet-East Entrance U.S. Waters Strait Of Juan De
     Fuca-Northern Inland Waters Including The San Juan Islands-
     Puget Sound and Hood Canal.

     Storm Watch from Monday morning through late Monday night for
     Coastal Waters From James Island To Point Grenville 10 To
     60 Nm-Coastal Waters From James Island To Point Grenville
     Out 10 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville
     To Cape Shoalwater Out 10 Nm.

&&

$$