Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
038
FXUS66 KSEW 170228
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
728 PM PDT Mon Mar 16 2026
.SYNOPSIS...
An atmospheric river will impact the region through
much of the week, bringing multiple rounds of rain and warmer
temperatures to western Washington. Higher snow levels and
periods of moderate to heavy rain will bring rises to area
rivers this week, with river flooding possible.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
Strong high pressure over the Southwest is helping to steer
moisture through western WA for a prolonged period of warm and
wet conditions. High snow levels, over 8000 ft, are forecast
over the region leading to mainly rain in the mountains. Periods
of heavy rain, combined with melting snow and runoff, will lead
to rising rivers with flooding possible. Most of the focus is
over the central and northern Cascades (and into B.C.) and a
Flood Watch is in effect. The period of likely flooding would
occur over the Wednesday-Friday time period. A Flood Watch is
also in effect for the Skokomish River in Mason County with
heavy rain in the Olympics as well.
In the lowlands, the air mass will be mild this week with highs
in the 50s to lower 60s. Lows will track in the 40s to lower
50s. 33
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
The AR event will continue through Friday with mild
temperatures, rain, and rivers running high. Rivers will recede
over the weekend with drier weather, cooler temperatures and
lower snow levels. Total rainfall through Friday is on the order
of 1-2" across the lowlands with 3-6" over the coast (highest
north coast). Temperatures will be cooler Sunday morning with
areas around the south sound near freezing. Expect highs near
normal in the lower to mid 50s. 33
&&
.AVIATION...
Zonal flow aloft as upper-ridging resides over the US West Coast. S
to SW flow is present in the lower levels. Largely VFR across most
area terminals, while starting to see some MVFR/IFR conditions along
the coast as an atmospheric river begins to enter the area from the
NW. Cigs will lower as this system continues its progress eastward
with widespread MVFR to IFR cigs expected by 12Z Tuesday. Rainfall
will also become increasingly stratiform as well. Once MVFR/IFR
conditions settle in, there will not be any improvement for the
remainder of the TAF period. Southerly wind gusts upwards of 20-25
kt possible at times for the Puget Sound terminals and KBLI.
KSEA...VFR currently and should remain in place into the overnight
hours. MVFR cigs will return between 12-14z Tuesday as rainfall
becomes more steady across the area. Once they develop, MVFR cigs
will remain in place throughout the TAF period. Breezy southerly
gusts up to 20-25 kt at times.
41/18
&&
.MARINE...
Southerly flow over the waters tonight into Tuesday as an incoming
system begins its trek over the area. Seas will remain elevated (+10
ft) through Tuesday before diminishing Tuesday night. Southerly flow
will prevail through Thursday generally within 10-20 kt range. Grays
Harbor Bar conditions will be close to SCA criteria come Tuesday as
the seas approach ten feet. SCA also remain for the inland waters
such as East Entrance, Admiralty Inlet, Puget Sound, and Northern
Inland waters due to southerly winds.
41/18
&&
.HYDROLOGY...
Flooding on the Chehalis River at Porter continues
this afternoon. the river has crested and will fall below flood
stage tonight.
A Flood Watch is in effect for central and northern Cascades due
to periods of heavy rain, high snow levels, snow melt and
runoff. Rivers will see rises by midweek and several rivers will
reach Action Stage. A few rivers will be close Minor Flood Stage
including the Snoqualmie River near Carnation and the Tolt River
near Carnation. River will be running high through Friday then
recede over the weekend.
Flooding may also occur on the Skokomish River in Mason County
Tuesday night or Wednesday due to heavy rain in the Olympics as
well. 33
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Flood Watch from Wednesday afternoon through Friday afternoon
for Cascades of Snohomish and Northern King Counties-
Cascades of Southern King County-Cascades of Whatcom and
Skagit Counties-City of Seattle-Downtown Everett /
Marysville Area-Eastside-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 the North
Cascades-Lowlands of Pierce and Southern King Counties-
Lowlands of Western Skagit and Northwestern Snohomish
Counties-Lowlands of Western Whatcom County-Shoreline /
Lynnwood / South Everett Area.
Flood Watch from Tuesday afternoon through Friday afternoon
for Foothills of the Western and Southern Olympic
Peninsula-Middle Chehalis River Valley-Olympia and
Southern Puget Sound-Olympics-Southern Hood Canal-Willapa
and Black Hills.
PZ...Small Craft Advisory until 3 PM PDT Tuesday for West Entrance
U.S. Waters Strait Of Juan De Fuca.
Small Craft Advisory until 11 AM PDT Tuesday 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.
Small Craft Advisory until 5 PM PDT Tuesday 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.
&&
$$
NWS SEW Office Area Forecast Discussion