580
FXUS66 KSEW 061608
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
908 AM PDT Fri Jun 6 2025

.SYNOPSIS...Upper level ridge centered offshore building over
Western Washington today through Saturday. The ridge will move
over Western Washington Saturday night and remain into Monday
morning before moving east Monday afternoon and night. At the
surface thermally induced trough will develop along the coast
Saturday night then move inland Sunday. The thermally induced
trough will also move east Monday afternoon. Warming trend into
the weekend with very warm highs Sunday and Monday. Cooling trend
beginning Tuesday with an upper level trough arriving Thursday.

&&

.UPDATE...Few morning clouds linger this morning and will continue
to linger throughout the day today. Still looking at temperatures
getting up into the 70s and lower 80s for the interior. Minor
update to the aviation discussion below for the morning update.
Otherwise the rest of the forecast below remains on track.

HPR

&&

.SHORT TERM /TODAY THROUGH SUNDAY/...Warming trend into the
weekend with the hottest days of the year so far Sunday and
Monday.

Satellite imagery shows high clouds over Western Washington early
this morning with low stratus along the coast. The high clouds
have kept temperatures mild overnight with 3 am/10z readings in
the 50s and lower 60s.

Upper level ridge centered offshore extending east over Western
Washington will slowly build through Saturday. High clouds moving
east this morning. Surface gradients remaining light northwesterly
which will prevent high temperatures from getting too warm. Light
gradients both mornings will make it hard for the stratus along
the coast to get very far inland. Highs today in the 70s and lower
80s for the interior. The afternoon northwesterly winds off the
cool ocean will keep highs in the mid 60s along the coast. A
couple of degrees of warming Saturday for the interior with a
little more warming along the coast with a weaker afternoon
seabreeze.

Thermally induced surface trough developing along the coast
Saturday night shifting inland Sunday. By Saturday night the upper
level ridge will be overhead. The upper level ridge will remain in
place Sunday with the thermally induced surface trough moving
inland. High temperatures warming with 70s along the coast and
mid 70s to near 90 inland.

Lows in the 50s Saturday and Sunday morning. Slightly warmer lows
Monday morning, in the 50s to lower 60s.

HeatRisk moving into the moderate category for most of the
interior Sunday. Still looking at lows in the 50s which will help
mitigate the risk. It is possible a heat advisory will be needed
for Sunday for portions of the interior. Even with the very warm
air temperatures, water temperatures are still very cool across
the area. River water temperatures range from 47 to 60 degrees. In
the Puget Sound water temperatures are a cool 51 or 52 degrees.

In addition to the cool water temperatures, relative humidity
percentages dropping down into the upper 20s in some locations
Sunday. Fuels are drying out across the region. Lets be careful
out there.

.LONG TERM /MONDAY THROUGH THURSDAY/...Monday trending slightly
warmer with the upper level ridge axis and the thermally induced
trough not shifting east of the Cascades until the afternoon.
Warmer overnight lows Monday morning will counteract the slight
cooling due to increasing afternoon onshore flow in the interior.
End result highs Monday pretty similar to Sunday for the interior
from about the Puget Sound eastward, in the mid 70s to near 90.
Southwest Interior could see a couple of degrees of cooling down
into the mid to upper 80s. More cooling along the coast with highs
having a hard time getting out of the 60s. A heat advisory may be
needed for portions of the interior Monday.

Thermally induced surface trough and upper level ridge east of the
Cascades Tuesday. Marine push that began Monday afternoon
continuing Monday night with onshore pressure gradients
continuing to rise. With the push highs Tuesday cooling 5 to 10
degrees over the interior, in the 70s to lower 80s. Highs on the
coast remaining in the 60s.

500 mb heights continue to lower Wednesday with an upper level
trough arriving Thursday. Not much in the way of precipitation
with the upper level trough. Maybe a shower in the Cascades
Thursday. More cloud cover and cooler temperatures will be the
main result from the trough. Highs for the interior Wednesday in
the upper 60s to mid 70s and Thursday only in the 60s with mostly
cloudy skies. Highs on the coast both days in the lower 60s.
Felton

&&

.AVIATION...Upper ridging will continue to build into Western
Washington today with northwesterly flow aloft. VFR high clouds
across Western Washington this morning, along with stratus across
portions of the coast that is slowly clearing. Otherwise, VFR this
afternoon. Stratus will develop again this evening into tonight
along the coast and towards the Southwest Interior. W/NW surface
winds increasing this afternoon.

KSEA...VFR conditions with high clouds at times through today. Will
have to monitor any potential stratus development Saturday morning
(mainly after 12z), although confidence is low at this time. N/NW
continuing through today. JD

&&

.MARINE...Surface high pressure will remain over the coastal
waters through Tuesday. A thermally induced trough will develop
along the coast Saturday night. The trough will move over the
inland waters for Sunday then shift east of the Cascades Monday.

Another round of small craft westerlies for the Central and
Eastern Strait of Juan de Fuca late this afternoon and tonight.
A small craft advisory remains in effect for the outer coastal
waters beginning tonight through Saturday afternoon for choppy
seas of 8 or 9 feet with 8 to 10 second periods. There will be a
brief spell of northwest winds 20 to 25 knots in the Northern
Outer Coastal Waters this afternoon.

Small craft advisory westerlies possible for the Central and
Eastern Strait of Juan de Fuca again Monday and or Tuesday
evening. Felton

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 PM this afternoon to 2 AM PDT
     Saturday for Central U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 6 PM this evening to 2 AM PDT Saturday
     for East Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 6 PM PDT Saturday for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 Nm-
     Coastal Waters From Point Grenville To Cape Shoalwater 10
     To 60 Nm.

&&

$$