Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
348
FXUS66 KSEW 121638
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
938 AM PDT Thu Mar 12 2026
.SYNOPSIS...
Cold front east of the area early this morning. Atmospheric
river to the south lifting north over Western Washington this
afternoon with the river remaining over the area Friday. Upper
level ridge building offshore will pinch off the river and push
it south Friday night. Weak upper level trough Saturday keeping
showers in the forecast. Warm front moving over the top of the
ridge brushing Western Washington Sunday. Atmospheric river
aimed at Southern British Columbia the first part of next week
with the southern portion of the river over the area. Warming
trend beginning Monday into the middle of next week.
&&
.SHORT TERM /TODAY THROUGH SATURDAY/...No significant changes
made to the forecast this morning. The previous discussion can
be found below along with updates to the aviation and marine
sections:
The winter storm warning is still in effect for today into
Friday evening. It`s certainly not going to be an easy go across
the Cascades today through Friday. Satellite imagery shows the
cold front east of the Cascades early this morning. Doppler
radar has plenty of showers over the area with a bit of a rain
shadow over the Central Puget Sound with the strong westerly
flow aloft. Convergence zone hanging out over Snohomish county.
Post frontal shower activity continuing this morning.
Atmospheric river aimed at Western Oregon will lift to the north
this afternoon spreading steady rain back over the area. Winds
will continue to ease throughout the day. Snow levels dropping
with Western Washington remaining slightly on the cool side of
the jet. By this afternoon snow levels will be back down to 1000
to 2000 feet in the Cascades. Highs will be cool, in the lower
to mid 40s.
Little change in the pattern tonight into Friday with the
Western Washington remaining on the north side of the
atmospheric river. Forecast gets a little tricky late tonight
into Friday morning as the air mass continues to cool. Onshore
surface gradients going light. Snow levels getting down to
around 500 feet by sunrise Friday. This brings up the
possibility of a rain/snow mix for the precipitation type late
tonight into early Friday morning. Daytime "heating" warming the
air mass up in the afternoon to lift snow levels back up to at
least 1000 feet. Could an inch or so of snow in the Cascade
foothills in the morning hours Friday. Lows in the mid 30s.
Highs in the lower to mid 40s.
Atmospheric river moving south Friday night as an upper
level ridge builds offshore. Cooler air mass moving into the
area with the snow level down to the surface in many locations
by early Saturday morning. At this point it is the game we play
frequently around here with the moisture decreasing as the air
mass cools. Precipitation type changing to showers overnight
making snow accumulation forecast tough. If there is enough
moisture around as the snow levels lower to near the surface
could see some small snow accumulations. With the precipitation
being showers lowland snow will be localized and not
widespread. Lows in the upper 20s to mid 30s.
Cool northwesterly flow aloft Saturday with the upper level
ridge axis well offshore. Models showing a weak trough embedded
in the flow aloft moving through during the day keeping showers
in the forecast. Snow levels will be low but once again with
limited moisture if there are any snow accumulations in the
lowlands they will not be widespread and will be early in the
day. Like Friday daytime heating will lift the snow level back
up to at least 1000 feet in the afternoon. Highs in the mid 40s.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Extended model solutions have been consistent with the general
pattern solution of an upper level ridge offshore and an
atmospheric river moving over the top of the ridge. Where the
river moves inland has been bouncing around a bit but the
general consensus is it will move inland over Vancouver Island
and Southern British Columbia. There is also good consensus that
the ridge will not be strong enough to keep the tail end of the
river north of Western Washington Sunday through Tuesday giving
Western Washington a rain at times or rain likely forecast.
Some of the solutions for Wednesday drop the weakening
atmospheric river over Western Washington. Confidence not real
high at this point so will stay with the rain likely or rain at
times forecast. Warming trend next week with the area being on
the south side of the jet. Highs near 60 for both Tuesday and
Wednesday. Snow levels rising significantly ending up in the
7000 to 8000 foot range. Felton
&&
.AVIATION...
Majority of terminals remain VFR this morning with a few locations
MVFR as light scattered showers move across the region. Another
system will impact the terminals today, bringing steadier rain after
14z. There is a slight chance of snow mixing in with the rain early
Friday morning for an all snow or rain/snow mix with showers
falling. The probability of accumulating snow for the major interior
terminals remains very low. Widespread MVFR cigs/vis are expected
after 16z-20z. IFR cigs are possible (20-40% chance) after 00z, with
the highest chances for the coast, Kitsap Peninsula, and southern
interior. Breezy SW winds will continue this morning with gusts to
20-25 kt, with the gusts expected to subside by the evening. Gusty
winds aloft out of the west (due to the jet max over the region)
will continue, but decrease into Friday.
KSEA...VFR cigs this morning, with cigs/vis expected to deteriorate
this afternoon after 20z. Stratiform rain expected to arrive at the
terminal by 17z. Guidance hints at a small chance (20%) of IFR cigs
after 06z, with probabilities slightly increasing to 30% after 16z.
There is also a slight chance of the showers falling as snow or a
rain/snow mix early Friday morning (as temperatures fall to a couple
degrees above freezing at the surface). Breezy SW winds continue at
the terminal early this morning with gusts 20-25 kt. Winds will ease
throughout the day, with winds decreasing to 5-10 kt by the evening
hours.
29/HPR
&&
.MARINE...
The latest observations show winds have been on a decreasing trend
early this morning and the Storm Warning for the East Strait of Juan
de Fuca has been downgraded to a Gale Warning. Conditions will
remain breezy along the Strait of Juan de Fuca this morning through
this evening, for which a Small Craft Advisory will follow the Gale
Warning. In addition, the Gale Warnings for Puget Sound, Admiralty
Inlet, and the Northern Interior waters have been downgraded to
Small Craft Advisories. Seas early this morning are hovering around
12-14 ft and are expected to continue decreasing throughout the day,
with seas around 8-10 ft by the afternoon hours. A weak front will
stall over the coastal waters today and Friday, with surface winds
shifting northerly Friday morning through the weekend. Brief small
craft gusts possible (45-65%) for the outer coastal waters on
Saturday. Seas are expected to remain below 10 ft through the
weekend. A warm front will move over the waters on Monday. Seas may
build near 10 ft. In addition, there is moderate chance (40-60%) of
small craft winds for the coastal waters.
29
&&
.HYDROLOGY...
The Skokomish River went above flood stage overnight and has
crested this morning. The river will recede back below flood
stage later today. More rain in the forecast through Friday will
keep the threat of flooding along the Skokomish Friday into
Saturday. With the heaviest precipitation over the Southwest
Interior there is also a threat of flooding Friday into the
weekend for a few rivers in the Chehalis Basin including but not
limited to the Skookumchuck, Newaukum and the Chehalis River
from Grand Mound to Grays Harbor. The flooding threat will ease
Sunday into next week for the southern portion of the area.
Atmospheric river forecasted to move inland to the north during
the first part of next week. If the river ends up a little
further south rivers over the northern portion of the area will
bear watching the first part of next week.
Felton/Mazurkiewicz
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Storm Warning until 5 AM PDT Saturday for Cascades of
Pierce and Lewis Counties-Cascades of Snohomish and
Northern King Counties-Cascades of Southern King County-
Cascades of Whatcom and Skagit Counties-Olympics.
PZ...Small Craft Advisory until 2 PM PDT this afternoon for
Admiralty Inlet-Grays Harbor Bar-Northern Inland Waters
Including The San Juan Islands-Puget Sound and Hood Canal.
Small Craft Advisory until 5 PM PDT this afternoon for Central
U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
Waters Strait Of Juan De Fuca-West Entrance U.S. Waters
Strait Of Juan De Fuca.
Small Craft Advisory until 11 PM PDT this evening 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