372
FXUS66 KSEW 170438 CCA
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
756 PM PDT Wed Apr 16 2025

.SYNOPSIS...Upper level ridge building into the British Columbia
coast tonight will slide south over Western Washington by Friday.
The ridge will shift east Friday night with an upper level trough
over the area for the weekend. The trough will move east Monday
with a weaker trough for Tuesday. Another upper level ridge
beginning to build Wednesday.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...Updates from the Space
Weather Prediction Center shows the magnetic field has peaked and
will gradually weaken tonight, decreasing in favorability for a
northern lights display for western Washington. Otherwise, the
latest forecast remains on track with no updates this evening.
Satellite imagery shows clear skies over western Washington this
evening with breezy northerly winds tapering down as a trough
moves to the east of the Cascades.

Upper level ridging will continue to build into the British
Columbia coast tonight with dry northerly flow aloft over the
area, remaining over British Columbia Thursday. Northerly winds
will pick up Thursday afternoon but will not be as strong as
today. This combined with a little warmer temperatures aloft will
push highs into the lower to mid 60s.

Upper level ridge axis sagging south Thursday night. The ridge
axis will be right over Western Washington Friday making it the
warmest day in the next seven days. Many locations in the
interior from Seattle southward will get into the lower 70s. This
will be the second 70 degree plus day of the month for Seattle and
the third one this year. Mid to upper 60s for the remainder of
the interior. Northwesterly winds off the cool ocean will keep
temperatures along the coast in the lower 60s. Lows Friday morning
in the mid 30s to lower 40s.

Upper level ridge shifting east Friday night with an upper level
trough moving into the area Saturday. Trough axis moving through
Western Washington Saturday morning bringing showers to the area.
With the increasing cloud cover Friday night lows will remain in
the 40s. Highs Saturday much cooler with the trough overhead, in
the mid to upper 50s.

.LONG TERM /MONDAY THROUGH THURSDAY/...Extended models in good
agreement with an upper level trough remaining over Western
Washington keeping showers and cool daytime highs in the forecast
Sunday. Trough moving east Monday with showers coming to an end. A
weaker trough arriving Tuesday. Not much moisture with this
feature. Low level onshore flow will keep high temperatures near
60. Upper level ridge building offshore Wednesday with
temperatures aloft warming a little. Northwesterly winds will
again limit high temperatures along the coast to the upper 50s.
For the interior upper 50s to mid 60s. With the clearing there
could be some frost problems Tuesday night/Wednesday morning.

Felton

&&

.AVIATION...An upper level ridge will build into the British
Columbia coast overnight into Thursday producing northerly flow
aloft over Western Washington. The air mass is dry and stable and
the low level flow is northerly. Gusty northerly surface winds over
the interior of Western Washington this evening will ease as surface
high pressure over British Columbia expands southward. VFR will
prevail.

KSEA...Clear skies. Surface winds northerly 10 to 20 knots will ease
this evening and turn northeasterly 6 to 10 knots overnight.

27

&&

.MARINE...Surface ridging will remain over the waters into Friday. A
weak front and associated trough will slip southward along the
British Columbia coast and into the area Friday night into Saturday.
This will initiate an increase in onshore flow with likely headlines
and possible gales in the central/east strait. A secondary system
will produce a similar result later Sunday into early Monday. High
pressure will then rebuild across the waters early next week.

Hazardous coastal seas will subside below 10 feet Thursday and
Friday before building back above 10 feet early in the weekend.

27

&&

.HYDROLOGY...No river flooding is expected over the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...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-Grays Harbor Bar.

     Small Craft Advisory until 10 PM PDT this evening for Puget
     Sound and Hood Canal.

&&

$$