245
FXUS66 KSEW 071116
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
416 AM PDT Sat Jun 7 2025

.SYNOPSIS...Upper level ridge offshore moving over Western
Washington today. The ridge will remain over the area through
Monday then shift east Monday night into Tuesday. Upper level
trough approaching the coast Wednesday will move inland Thursday.
In the lower levels thermally induced trough will develop along
the coast tonight and shift inland Sunday. The trough will remain
over the interior Monday then move into Eastern Washington Monday
night.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...Very warm temperature still
on track for Sunday and Monday. Heat advisory remains in effect
for both days for portions of the interior.

Satellite imagery shows stratus along the coast about half way
down the Strait of Juan de Fuca to the north and into the Lower
Chehalis valley to the south. Just some high clouds for the
remainder of the area. Temperatures at 3 am/10z were in the upper
40s to near 60.

Upper level ridge centered offshore slowly moving towards Western
Washington today. Light onshore gradients this morning will become
flat this afternoon. Stratus this morning staying west of Puget
Sound and I-5. The stratus is shallow with tops estimated between
1000-1500 feet. The shallow layer combined with some slight ridge
building and the strong June sunshine will dissipate the layer by
late morning. Outside of the stratus just some high clouds moving
through today. High temperatures similar to yesterday for the
interior, 70s and lower 80s. Weaker afternoon seabreeze along the
coast will allow high temperatures to warm a few degrees with
highs near 70.

Upper level ridge moving over Western Washington tonight with a
thermally induced surface trough developing along the coast. This
will hinder stratus development along the coast tonight into
early Sunday morning with mostly clear skies across the area. Lows
tonight in the 50s.

Thermally induced trough moving inland Sunday with the upper
level ridge centered over Western Washington. Low level offshore
flow not very strong with 925 and 850 mb winds turning back around
to northwesterly Sunday afternoon after being easterly in the
morning. 850 mb temperatures warming from plus 15 to 17C this
afternoon to plus 17 to 20C Sunday afternoon. High temperatures
warming into the 80s for most places away from the water with
lower 90s possible in the Southwest Interior and in the Cascades
foothills. Along the coast and near the Strait of Juan de Fuca
highs in the mid 70s.

Little change in the pattern Sunday night into Monday morning with
the thermally induced trough and upper level ridge starting to
drift east Monday afternoon. Surface gradients turning light
onshore Monday. With the ridge moving east temperature aloft
dropping slightly as well. On the flip side morning lows Monday
will be a couple of degrees warmer than the previous nights. Highs
cooling along the coast back into the mid 60s. For the interior
the onshore flow will not be string enough to push high
temperatures down much after the warmer start to the day. Up to 5
degrees of cooling for the Southwest Interior, highs in the mid to
upper 80s, and the Northwest Interior, highs in the mid 70s to
near 80, while highs in the Central Puget Sound and Cascade
foothills remain with a couple of degrees of Sunday`s highs, in
the 80s.

.LONG TERM /TUESDAY THROUGH FRIDAY/...Models in good agreement
with upper level ridge axis east of the area Tuesday. Increasing,
but not real strong, onshore flow. This weak marine push scenario
will lower high temperatures 5 to 10 degrees versus the highs
Monday with most places in the interior in the 70s.

Cooling trend continues Wednesday as upper level heights continue
to fall and onshore flow increases with an approaching upper
level trough. Highs back down to near normal, lower 60s along the
coast and mid 60s to lower 70s inland.

Upper level trough moving into Western Washington Thursday with
the trough remaining over the area Friday. Temperatures
continuing to cool with highs in the upper 50s and 60s. Not much
in the way of precipitation with the trough with the most
noticeable change the cooler temperatures and increasing cloud
cover. Felton

&&

.AVIATION...Generally VFR with areas of IFR/LIFR in low
stratus and fog along the Pacific Coast. Northwest flow aloft will
continue into Saturday with upper ridging building into the Pacific
Northwest. Low stratus will slowly expand inland this morning,
reaching as far east as CLM and PWT, but is not expected to expand
over the Puget Sound terminals. Most locations should see a return
to VFR conditions by the late morning, with VFR persisting for the
remainder of the TAF period. Surface winds generally northerly 5 to
10 kt.

KSEA...VFR through the period with passing high clouds. Low stratus
is expected to stay west of the terminal this morning, with light
northerly winds increasing to 7 to 10 kt this afternoon.

15

&&

.MARINE...Surface high pressure will remain over the coastal waters
through Wednesday. A thermally induced trough will develop along
the coast tonight then shift over the inland waters Sunday. The
trough will move east of the area Monday night. Onshore flow will
increase Tuesday into Wednesday.

Small craft advisory remains in effect today for choppy seas over
the outer coastal waters. Small craft advisory northwesterly
winds developing over the outer coastal waters Monday night
continuing through the middle of the week.

Small craft advisory westerly winds likely in the Central and
eastern Strait of Juan de Fuca Tuesday and Wednesday evening.
Felton

&&

.FIRE WEATHER...Conditions will warm up and dry out this weekend
into Monday as an upper level ridge moves over Western
Washington and low level onshore flow comes to an end. This will
elevate fire weather concerns as minimum RH values will likely
reach as low as 20-30% over the Cascades and Cascade foothills
with slightly higher percentages over the interior lowlands Sunday
and Monday. While live fuels remain wet enough to curb fire
spread, dead fuels remain very dry. In addition the snowpack is
below normal and some locations are experiencing drought
conditions. Winds remain light enough into Monday such that
critical fire weather conditions are not expected but the area is
drying out fast. Moist onshore flow will return Monday night into
Tuesday.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory from 10 AM Sunday to 10 PM PDT Monday for City of
     Seattle-Downtown Everett / Marysville Area-Eastern Kitsap
     County-Eastside-Foothills and Valleys of Central King
     County-Foothills and Valleys of Pierce and Southern King
     Counties-Foothills and Valleys of Snohomish and Northern
     King Counties-Foothills and Valleys of Thurston and Lewis
     Counties-Foothills and Valleys of the North Cascades-
     Lowlands of Lewis and Southern Thurston Counties-Lowlands
     of Pierce and Southern King Counties-Northern Hood Canal-
     Olympia and Southern Puget Sound-Shoreline / Lynnwood /
     South Everett Area-Southern Hood Canal.

PZ...Small Craft Advisory until 6 PM PDT this evening 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.

&&

$$