Forecast Discussion
Forecast Discussion for SEW NWS Office
026
FXUS66 KSEW 101046
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
346 AM PDT Tue Mar 10 2026
.SYNOPSIS...
Cool upper level trough over Western Washington keeping
the weather unsettled this morning. Rain out ahead of the next
system reaching the area this afternoon with rain in the
lowlands and snow in the mountains through Wednesday. Strong
cold front moving through late Wednesday afternoon/Wednesday
evening bringing blizzard conditions to the mountains and windy
conditions to the lowlands. Atmospheric river taking aim at
Western Washington beginning Thursday. The river will sag south
late Friday night or Saturday morning. Upper level ridge
building offshore Sunday and Monday with a warm front moving
over the top of the ridge.
&&
.SHORT TERM /TODAY THROUGH THURSDAY/...
Change in the forecast this morning. Blizzard warning has been
pushed back to Wednesday night. Heavy snow in the mountains
still on the way.
Busy morning. Lots to talk about. Satellite imagery and doppler
radar shows convergence zone over Snohomish and Southeast
Skagit county. Across the remainder of the area just some
isolated showers west of Puget Sound. Temperatures at 3 am/10z
were in the 30s.
Upper level trough remaining over Western Washington today.
Temperatures are cold enough this morning for lowland snow
showers but there is limited moisture. Best chances for snow
showers this morning will be in the dissipating convergence zone
and in the western portion of Clallam county. Increasing clouds
for the remainder of the area. Upper level shortwave approaching
from the northwest later this morning with rain out ahead of
the shortwave spreading over Western Washington this afternoon.
In addition to the rain it will be a breezy day with wind gusts
in the 30 mph range common in the afternoon. High remaining
cool, in the mid 40s.
Shortwave moving through tonight followed quickly by another
system Wednesday spreading rain back over the area. Western
Washington still on the cool side of the jet with snow levels
remaining below the passes. New snow totals in the Cascades from
this morning through Wednesday afternoon in the one to two foot
range. Lows tonight in the mid 30s to lower 40s. Highs Wednesday
near 50.
Sharp cold front moving through early Wednesday evening
producing a variety of impactful weather. In the mountains model
850 mb winds in the 40 to 55 knot range just ahead, with and
behind the front. This will produce blizzard conditions in the
passes into early Thursday morning with another foot plus of new
snow by sunrise. Along the coast strong post frontal westerlies
with wind gusts as high as 55 mph. A wind advisory has been
issued. Strong push through the Strait of Juan de Fuca as well.
It`s possible a wind advisory will be needed for the Admiralty
Inlet area and Whidbey Island. Windy conditions for the
remainder of the interior with wind gusts in the 30-40 mph
range. Rain turning to showers behind the front. Lows near 40.
Little in the way of a break in the weather Thursday as an
atmospheric river takes aim at Western Washington while the
some cool for atmospheric river conditions air is still in place
over Western Washington. Snow levels around 3000 feet with
heavy snow likely in the Olympics and the Cascades. A winter
storm watch remains in effect for the mountains beginning
Thursday. In the lowlands another round of rain. Highs in the
mid 40s. Felton
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Extended models in good agreement with the atmospheric river
remaining over Western Washington until at least Friday night.
Winter storm watch for the mountains remains in effect through
Friday night. There is a good chance the mountains will see
another two to three feet of snow between Thursday and Friday
night. Upper level ridge building offshore pinching the river
off and pushing it south later Friday night into Saturday.
Possible break Sunday but right now more of the ensemble
solutions pointing towards another atmospheric river getting
over the top of the upper level ridge offshore moving into
Western Washington Sunday night and Monday. Felton
&&
.AVIATION...
Westerly - zonal flow aloft throughout the TAF period. A convergence
zone is maintaining MVFR cigs for Puget Sound terminals (KSEA, KBFI,
KPAE). This feature will continue before petering out around 14-16z
then VFR should rebound. Elsewhere VFR cigs are present and will
maintain before deteriorating towards 21z-00z as rainfall increase
across W WA. MVFR to IFR cigs overnight into Wednesday morning as
well. Surface winds are forecast to increase this afternoon with
southerly gusts up to 20-30 kt for area terminals except for KCLM.
KSEA...MVFR cigs due to lingering PSCZ over the area. This feature
will maintain before petering out towards 14-16z. Then VFR cigs
should rebound before MVFR cigs redevelop (afternoon-early evening)
and continue into early Wednesday as rain increases across W WA.
Southerly gusts increase around 18-20z around 20-25 kt and remain
elevated into the evening.
McMillian
&&
.MARINE...
Onshore flow has eased into the morning but conditions are slated to
remain active. Pre-frontal southerly winds will pick up this morning
as SCAs have been issued for Puget Sound, Admiralty Inlet, East
Strait and Northern Inland waters for today. SCAs for the coastal
waters and Grays Harbor bar remain in effect as well due to winds
and seas. A much stronger disturbance is on tap to arrive on
Wednesday with the potential for widespread gale force winds. A
brief window of storm force gusts are also possible as hi-res
guidance is showing a 30-50% chance of them occuring over the
Central and Eastern Strait on Wednesday evening. A weaker system
will stall over the region Thursday and Friday. The flow will turn
northerly on Saturday, then offshore on Sunday as a warm front moves
into southern B.C.
Seas 8-12 ft today before rising to 10-15 ft Wednesday night. Seas
then fall below 10 ft by Thursday afternoon and remain thereafter.
McMillian
&&
.HYDROLOGY...
Moderate to heavy precipitation over the Olympics will cause
the Skokomish River in Mason County to rise today with flooding
possible beginning Wednesday. The river will remain high
through the end of the week. Flooding is also possible on the
Chehalis river from Grand Mound to Grays Harbor, Newaukum River
and Skookumchuck River near Bucoda beginning Thursday. Crests
on these rivers will occur Friday into the weekend. Several
other rivers from Snohomish county southward are forecast to
reach Action Stage later this week. The lower snow levels with
the atmospheric river Thursday through Friday will make river
forecasting tough during this event. After a short break it is
possible another atmospheric river will move over the area early
next week. With the already high running rivers ahead of the
event this will be closely watched for another round of
possible river flooding. Felton
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until 6 PM PDT Wednesday for Cascades
of Snohomish and Northern King Counties-Cascades of
Whatcom and Skagit Counties.
Blizzard Warning from 6 PM Wednesday to 5 AM PDT Thursday 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.
Winter Storm Watch from late Wednesday night through late
Friday night 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.
Winter Weather Advisory until 6 PM PDT Wednesday for Cascades
of Pierce and Lewis Counties-Cascades of Southern King
County.
Winter Weather Advisory until 11 AM PDT this morning for
Foothills and Valleys of Snohomish and Northern King
Counties-Lake Crescent Area Including US 101-Western
Strait of Juan de Fuca.
Flood Watch from Wednesday afternoon through Thursday
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 5 PM PDT this afternoon for Grays
Harbor Bar.
Gale Watch from Wednesday afternoon through late Wednesday
night 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 from 10 AM this morning to 8 PM PDT this
evening for Admiralty Inlet-East Entrance U.S. Waters
Strait Of Juan De Fuca-Northern Inland Waters Including
The San Juan Islands.
Small Craft Advisory from 10 AM this morning to 11 PM PDT this
evening for Puget Sound and Hood Canal.
Small Craft Advisory until 2 PM PDT Wednesday 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.
Gale Watch from Wednesday afternoon through Wednesday 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