362
FXUS66 KSEW 111633
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
933 AM PDT Tue Mar 11 2025

.SYNOPSIS...Light rain and mountain snow will slowly spread
inland throughout the day today, continuing into Wednesday.
Widespread showers will linger Thursday with lower snow levels and
a chance for thunderstorms in the afternoon. Active weather will
continue Friday night, and later in the weekend.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...The current forecast
remains on track with no planned updates this morning. 33

Previous discussion...Satellite and radar show a warm front
stalled offshore with rain showers continuing across the far
northwestern Olympic Peninsula. The frontal boundary will slowly
move north throughout the day today as the low pressure center
develops and moves towards Vancouver Island. The cold front
doesn`t reach the coast until Tuesday night and moves inland
Wednesday morning. As such, rain chances will be best today across
the coast and the Northwest Interior, with areas Seattle and
southward staying mostly dry until this evening when the system
finally approaches and moves through. Winds will also be breeziest
Tuesday night into Wednesday as the front moves through though
will be well below advisory criteria.

Post frontal showers will dominate the forecast for Wednesday,
with snow levels beginning to lower from around 4000 ft Wednesday
morning to around 1500 ft Thursday morning. Showers will continue
into Thursday as a weak low forms to the south and the upper level
trough axis finally moves overhead and to the east. Thursday will
also be the day with the greatest amount of instability and we may
see a few isolated thunderstorms Thursday afternoon.

Through Friday morning, up to around 5 to 8 inches of snow will
be possible, with the highest amounts mostly focused towards the
northern Cascades around and north of Stevens Pass. Total amounts
are just shy of advisory criteria, but this will also be spread
out over the course of ~36 hours, meaning snowfall rates will be
relatively low and intermittent in nature. Higher amounts will be
possible across the higher elevations including Mt. Baker and
Paradise.

Overall temperatures will be a touch below normal with highs in
the upper 40s to low 50s and lows in the mid to upper 30s, with
lows steadily decreasing each night.

.LONG TERM /FRIDAY THROUGH MONDAY/...Friday morning will be the
coldest of the next seven days, with low temperatures approaching
freezing in the foothills and portions of the Southwest Interior.
As such, snow levels will dip below 1000 ft. With continued light
and scattered shower activity, some higher elevation lowland
locations could see some light snow showers. Little to no
accumulation is expected at this time, however. A relatively weak
frontal system will move through the area on Friday for another
round of rain, as well as a slightly warmer airmass with snow
levels rising back up to 2000-2500 ft. Long range models are
showing a stronger system with more moisture moving through this
weekend, supported by a upper level shortwave embedded in an
incoming long-wave trough. This could bring a bring a period of
steadier rain and heavy mountain snow, though there remains a wide
range of potential outcomes in the model ensemble space.

62

&&

.AVIATION...VFR conditions with broken to overcast clouds remaining
in place ahead of the front stalled off the coast. Showers continue
to move across the coast and northern interior this morning, which
may lead to lower ceilings and visibility. Expect a more widespread
lowering of area ceilings is likely Tuesday afternoon and evening as
more widespread rain moves through as the front finally advances
eastward. Southerly winds will remain today, increasing a bit as the
day goes on.

KSEA...VFR conditions continue today with variable mid and high
clouds ahead of the frontal system. These increase more
significantly and being to trend toward MVFR with the approach of
rain this afternoon, generally 20-23z. Southerly surface winds
around 5 kt through the day.

12/29

&&

.MARINE...A front will remain in place offshore this morning
near the coast, with little movement expected today. The next low
will arrive from the south and move toward Vancouver Island late
tonight into Wednesday. This will bring some increasing winds, with
widespread high-end advisory strength winds expected across the
coastal waters and around the eastern Strait of Juan de Fuca. A
brief burst of 35 kt gusts will be possible immediately ahead of the
front, but guidance continues to suggest that winds around 30 kt
will be more typical as this system slides through. As a result,
small craft advisories are in effect for these areas. As the winds
diminish, seas will continue to build, reaching 10 to 12 ft over the
coastal waters. This will likely require additional extensions of
the SCA for the coastal waters into Wednesday night or beyond. The
pattern looks to remain active as additional systems move into the
area waters late week and into the weekend, allowing for winds and
seas to remain elevated. There`s around a 60% chance of seeing seas
build to 17-19 ft over the coastal waters by the end of the weekend
along with increased chances of gales. 12

&&

.HYDROLOGY...No river flooding is expected over the next 7 days.
The Skokomish River will flux in and out of Action Stage with each
passing system through the week but is presently not forecast to
flood.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 PM PDT this afternoon for Admiralty
     Inlet-East Entrance U.S. Waters Strait Of Juan De Fuca.

     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.

&&

$$