814
FXUS66 KSEW 061008
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
308 AM PDT Sun Jul 6 2025

.SYNOPSIS...A warming trend will start the week as an upper ridge
strengthens over western Washington. The ridge will weaken and
onshore flow will increase for a brief cooling trend midweek
before warmer conditions return as upper ridging rebuilds.


&&

.SHORT TERM /TODAY THROUGH TUESDAY/...A warming trend will begin
today as an upper-ridge settles overhead and remain into Monday.
Subsidence aloft will decrease cloud coverage as the day
progresses and increase max temps 5-6 degrees higher from
Saturday`s highs. Temperatures will top out in the mid 70s to
lower 80s throughout the interior. Coastal areas are expected to
be the coolest as always with values in the 60s. The
aforementioned ridge axis will track right over W WA on Monday as
temperatures peak 7-10 degrees above average. Widespread 80s are
in the forecast with Cascade valley locations topping out near 90
F.

With the previous night`s overnight lows near 60 F across the
Seattle Metro along with another round of highs in the 80s, a
Moderate (Orange) threat for HeatRisk must be expressed on
Tuesday for the metroplex. This level mainly affects those
sensitive to heat, especially those without adequate
cooling/hydration. The rest of W WA will see a Minor (Yellow)
threat. Fortunately, a reprieve will soon be on the way as the
ridge tracks well off towards the east by Tuesday night. Overnight
lows will bottom into the mid 50s to near 60 F.



.LONG TERM /WEDNESDAY THROUGH SATURDAY/...A pattern change is in
the offing on Wednesday as temperatures cool substantially.
Ensemble guidance indicates a trough crossing northern British
Columbia with influence as far south as W WA. This will promote
increasing onshore along with precipitation chances with the coast
and northern half of the Cascades seeing the best probabilities.
Upper ridging returns late week with temperatures rising back
above normal.

McMillian

&&

.AVIATION...Zonal flow aloft will gradually become more
northwesterly today as upper ridging starts to build across the
area. Onshore flow will continue in the low levels. All area
terminals remain VFR this morning, with satellite showing just
some high clouds over the region and some stratus developing
across the far northern portions of the coast. Overall, expect VFR
conditions to prevail for the majority of the terminals today.
The exception remains KHQM, which could still see some reductions
to cigs and vis in any stratus development or fog early this
morning. Any low cigs that do develop will likely scatter out
between 15-18Z.

Surface winds remain mostly northerly across the sites early this
morning, primarily persisting at 5-10 kt. Exceptions include KHQM
and KCLM, which remain more westerly. Winds will ease slightly
through the morning, before increasing back towards 8-12 kt again
by late this afternoon.

KSEA...VFR conditions to prevail throughout the TAF period.
Northerly winds persist at 10-14 kt early this morning. Expect
winds to ease through the morning hours, before increasing back to
8-12 kt between 21-00Z.

14

&&

.MARINE...Surface high pressure will remain centered offshore and
will continue to influence the coastal waters today and Monday.
Meanwhile, diurnal westerly pushes will occur along the Strait of
Juan de Fuca over the next several evenings. The current push of
westerly winds is starting to weaken and will continue to do so
over the next few hours. The push tonight does not look as strong,
with probabilistic guidance indicating a 40-50 percent chance of
gusts making it to Small Craft strength. Have opted to leave the
central and east Strait out of an advisory for now, but this will
bear watching.

A weak frontal system will approach the region Tuesday night into
Wednesday and may bring a brief uptick in winds and seas. High
pressure will build back into the coastal waters in its wake.

Seas will generally hover between 3-6 ft over the next week and
could become steep at times with persistent northerly winds over
the coastal waters.

14


&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 3 AM PDT early this morning for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

&&

$$