202
FXUS66 KSEW 051524
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
824 AM PDT Thu Jun 5 2025

.SYNOPSIS...Upper level ridge well offshore with northwesterly
flow aloft through Friday. Ridge shifting east reaching Western
Washington Saturday night. The ridge will remain in place Sunday
before weakening Monday. Surface high pressure will remain
offshore into next week. A thermally induced surface trough will
move up the coastline Saturday night shifting inland Sunday and
east of the area on Monday. Unseasonably warm temperatures Sunday
and Monday before a cool down next Tuesday.

&&

.UPDATE...Minor tweaks to the aviation discussion below for the
morning update. Otherwise forecast below remains on track with
warmer/drier weather ahead.

HPR

&&

.SHORT TERM /TODAY THROUGH SATURDAY/...Satellite imagery shows
stratus along the coast, Southwest Interior, surrounding the
Olympics, over the Puget Sound area south of Seattle and along
the Cascade foothills. Mostly clear skies over the Northwest
Interior. Temperatures at 4 am/11z were in the mid 40s to mid 50s.

Stratus filling in over the remainder of the Puget Sound area
early this morning. IR satellite imagery shows Black Hills above
the tops of the stratus so estimate the tops around 2000 feet.
Light gradients this morning will not reinforce the stratus. With
the layer 1000-1500 feet thick expect a midday breakout for the
interior and early afternoon breakout for the coast. Upper level
ridge well offshore but 500 mb heights over the area in the mid to
upper 570 dms this afternoon. This combined with the light
surface gradients will push temperatures into the mid 60s to mid
70s with the warmer locations in the upper 70s late this
afternoon.

Weak shortwave riding by well to the north tonight. Other than
briefly denting the ridge over the area this feature will not
create any weather. Weak low level onshore flow with stratus
developing along the coast. Lows in the upper 40s to mid 50s.

Upper level ridge building slightly Friday with surface gradients
going flat by afternoon. Stratus along the coast will have trouble
getting very far inland in the morning with the weak onshore
flow. Less morning clouds and slightly warmer temperatures aloft
combining to add a couple of degrees to the highs. Warmer
locations pushing 80 degrees. Most places away from the water
will have highs in the 70s. Afternoon northwesterlies will keep
highs on the coast in the 60s.

Upper level ridge continuing to slowly build over Western
Washington Friday night and Saturday. After lows mostly in the 50s
Friday night another warm day Saturday with highs in the 70s to
lower 80s.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Models in good agreement
with a thermally induced surface trough moving up the coastline
Saturday night. The trough will move inland Sunday making it the
warmest day of the forecast period. Most locations in the mid 70s
to mid 80s with highs near 90 over the Southwest Interior and in
the Cascade foothills. HeatRisk will be moderate over the interior
from about Everett southward as well as in the Cascade foothills.
Low temperatures dropping into the 50s Sunday and Monday morning
will help keep the HeatRisk below advisory levels.

Upper level ridge weakening over the area Monday with the
thermally induced trough moving east of the Cascades late in the
day. High temperatures cooling 5 to 10 degrees along the coast and
up to 5 degrees inland. Still highs well above normal with mid
70s to mid 80s over the interior. Highs in the 60s on the coast.

Temperatures continue to cool Tuesday and Wednesday as the ridge
overhead continues to weaken and a weak upper level trough
approaches Wednesday. Low level flow onshore dropping highs back
into the 70s over the interior with 60s continuing along the
coast. Felton

&&

.AVIATION...High pressure offshore is maintaining onshore flow
across the region this morning. A blanket of low stratus and fog
remains across many of the terminals bringing IFR/LIFR
ceilings/visibilities. Some terminals have slowly been showing
improvement this morning and expecting the stratus to lift and
scatter across most of the interior around 17-19z and around 20-21z
along the coast. Winds will become northerly through the Puget Sound
terminals later this morning through the day, increasing to 7-10 kt
this afternoon after 21z.

KSEA...Conditions have been slow to improve this morning with the
low stratus persisting over the terminal. Expecting the lowered
ceilings to slowly lift and start scattering after 16z. Light
variable winds this morning will become northerly around 16z-17z.
North winds increase later today, with speeds of 7-10 kt this
afternoon after 21z through the evening.

&&

.MARINE...Surface high pressure will remain over the coastal
waters into next week. A thermally induced surface trough will
move up the coastline Saturday night then shift over the inland
waters Sunday and east of the area on Monday.

Brief round of small craft westerlies in the Central Strait of
Juan de Fuca tonight. Small craft advisory for the outer coastal
waters beginning tonight through at least Friday night for choppy
seas of 10 or 11 feet with 9 to 11 second periods. Felton

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 6 PM this evening to 2 AM PDT Saturday
     for Central U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 6 PM this evening to 6 AM 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.

&&

$$