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295
FXUS66 KSEW 290334
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
834 PM PDT Sat Jun 28 2025

.SYNOPSIS...High pressure will begin to build across the region
into the first part of next week. Temperatures will increase into
the 80s for much of Puget Sound and the South Interior, and a few
Cascade Valleys may break 90 on Monday. The pattern will cool down
mid week with a trough passing through. There is a slight chance
of showers in the Cascades with this trough, otherwise remaining
areas will stay dry with increased cloud coverage.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
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Satellite imagery shows
clouds continuing to clear out this evening across the area.
Overhead zonal flow is becoming more meridional over the Pacific
Northwest as a ridge begins to amplify tonight into Sunday. The
forecast remains largely on track this evening, with no significant
updates needed. The remainder of the previous discussion follows
below, with updates made to the aviation section. 14

With the ridge amplifying early next week, and surface high
pressure building, temperatures will increase Sunday through
Tuesday under mostly clear skies (Monday being the warmest day).
Highs Sunday will climb into the upper 70s to mid 80s across the
entire region (except for higher elevations and coastal areas
which will stay in the mid 60s to 70s). Could potentially see a 90
around Matlock/Elma areas Sunday afternoon. Monday will see
temperatures increase a few degrees across the entirety of
western WA (for more 90 degree temps likely in the Southwest
Interior and for some Cascade Valley areas). The temperatures will
drop several degrees Tuesday as the ridge weakens and the flow
becomes more zonal. The Pacific Coast/Northwest Olympic areas will
see the best cooling Tuesday (thanks to morning clouds and a
stronger push of some onshore cooler air).

HeatRisk for the region will remain mostly yellow/minor Sunday
through Tuesday (with Monday having the largest area of
moderate/orange HeatRisk in the Cascade Valleys/South Puget
Sound/Southwest Interior areas). Additionally, relative humidity
(RH) values could drop substantially due to the warmer/drier air
Monday (combined with light northeast winds) - dipping down to
25-35% during the day.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...As onshore flow
increases on Wednesday, high temperatures will remain below 80 for
much of the region as the flow becomes more zonal. An approaching
shortwave trough Wednesday through Thursday will increase cloud
coverage for much of the region (with still some sun getting
through late morning and afternoon). The trough at this time is
only expected to produce a few showers in the northern Cascades.
However, this may change some as models are still in limbo with
the 4th of July weekend being either warm and dry, or cool with
potentially some showers.

HPR
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&&

.AVIATION...
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High pressure builds over the region tonight and Sunday
for dry and stable conditions. Most low clouds have scattered out,
but could see some stratus along the coast by early Sunday morning,
where MVFR conditions would result. Otherwise, VFR conditions
expected. Northerly winds at the surface. 33/18

KSEA...VFR conditions prevail. N winds increasing to 10-15 kt
Sunday afternoon. 33
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&&

.MARINE...High pressure over the offshore waters will lead to
varying degrees on onshore through through early next week.
Strongest pushes look like Monday night and Tuesday night, with
gales possible Tuesday night. A weak front will cross the waters
on Wednesday. 33

&&

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

$$