357
FXUS66 KSEW 050310
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
810 PM PDT Sat Apr 4 2026

.SYNOPSIS...Warm and dry conditions prevail through Monday with
upper level ridging. A shortwave moving by to the north Monday
evening will bring in cooler, marine air Monday night. Drier
conditions but more seasonable temperatures return mid-week.
Cool nights may allow for localized frost to freeze conditions
in the morning.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...Temperatures have
increased quite a bit compared to this mornings lows in the 30s.
Temperatures as of 1 PM are in the 50s in the islands of the
north interior, but either side of 60 for the interior. With
mostly clear skies, expect highs to low to mid 60s, except mid
to upper 50s in the islands in the north interior. Mid to upper
level cloud coverage will increase tonight, which will help keep
lows much warmer, in the low to mid 40s. Localized patchy fog
cannot be ruled out in the SW interior river valleys tomorrow
morning. High clouds will remain in place for much of the day
Sunday, but with the ridge axis directly overhead, expect highs
to be a bit warmer, in the mid 60s to low 70s, mostly in the SW
interior and the Cascade valleys.

On Monday, the ridge shifts east as a shortwave trough digs in
from the northwest over British Columbia. While we should remain
mostly dry, this will send an onshore marine push into the area
Monday evening. The coast will see much cooler temperatures
Monday, while the forecast for the highs in the interior are a
bit more uncertain depending on how fast the marine air arrives.
Highs remain in the 60s to low 70s in the SW interior, with
upper 50s to near 60 along the coast. Convergence over the
central Puget Sound interior will likely keep conditions cloudy
with a very slight chance for showers Monday evening.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...The aforementioned
shortwave trough continues to dig off into the intermountain
west on Tuesday, leaving the area under northwesterly flow
through much of the remainder of the week. This will allow for
conditions to remain dry and sunnier, but temperatures to remain
closer to normal through the long term period, with highs in
the mid 50s to low 60s and lows in the 30s to low 40s. Wednesday
and Thursday morning will the coldest of the week, reaching
into the lower 30s in the morning. Conditions for frost will be
likely those morning, with localized areas reaching freezing
possible. Temperatures will slowly warm going into the end of
the week.

62

&&

.AVIATION...High pressure aloft remains in place through the
weekend. Northerly surface winds continue over the area with
speeds generally ranging 5- 10 kts. Some northern terminals such
as BLI and CLM have become more light and variable while PWT is
seeing a greater easterly component, boosting speeds to 8-12
kts. While these winds will ease a little bit overnight, expect
another increase Sunday. Increasing high clouds will spread over
the region this evening into Sunday, and a few patches of fog
are again likely tonight in the more prone locations /KOLM south
through KCLS and west along the Chehalis River toward KHQM/.
Elsewhere and otherwise, continued VFR conditions through the
period.

KSEA...VFR is expected through period under mostly clear skies.
Northerly surface winds hold around 10 kt through evening, easing
only slightly overnight before resuming Sunday afternoon. Any low
clouds that form late tonight/early Sunday will remain away from the
terminal area. Cullen/18

&&

.MARINE...Broad high pressure remains in place across the area
through Monday with a weak thermal trough build up along the
west coast, keeping winds northerly. Winds will increase Monday
evening as a front passes by to the north and stronger high
pressure builds in behind it. Small Craft Advisory conditions
look likely across much of the coastal waters, though will have
to continue to monitor the potential for gales (30-50%
probability) through the Strait of Juan de Fuca with a strong
westerly push that moves into Admiralty Inlet and the Puget
Sound. Winds will slowly ease on Tuesday and remain relatively
light through the rest of the week as high pressure remains in
place over the northeast Pacific.

Seas remain 3 to 6 ft through Monday. Seas will then build up to 8
to 11 ft Monday night into Tuesday, and these waves will be steep
with dominant periods of around 8 to 9 seconds. Seas look to remain
in the 5 to 8 ft range through the rest of the week.

62

&&

.HYDROLOGY...No river flooding is expected in the next seven
days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.

&&

$$