774
FXUS66 KSEW 102159
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
259 PM PDT Wed Jul 10 2024

.SYNOPSIS...An upper level ridge remains over Western Washington
through the weekend with continued low-level onshore flow. This
will maintain above normal temperatures, but still notably cooler
than the start of the week. Little change through the week ahead,
with no rain expected and only subtle variations in the strength
of the marine pushes each night.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...A much cooler afternoon
across most of the area today than this time yesterday, with
temperatures generally running 5 to 10 degrees cooler than 24
hours ago. The overall pattern will not change too much through
the remainder of the week with high pressure in place over the
region and light onshore flow maintaining some cloud cover along
the coast, into the lower Chehalis valley, and also through the
Strait of Juan de Fuca. This will remain a somewhat shallow push
though - enough to bring the cooling marine influence progressively
into the interior, but unlikely to bring stratus to fill the
interior. This will bring overnight lows back down into the 50s
and closer to seasonal normals, while abundant sunshine will
maintain highs in the 80s.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Strong ensemble agreement
to support very little impactful changes to the weather pattern in
the first half of next week. Expect continued influence from high
pressure aloft with onshore low-level flow persisting through the
week. This will bring additional rounds of stratus pushes in the
morning and plenty of afternoon sun for most, along with high
temperatures generally in the 80s through the interior. A weak
disturbance around Monday or Tuesday may be responsible for a
slightly deeper push of marine stratus and favor temperatures more
in the lower 80s as opposed to mid to upper 80s, but that`s really
the biggest change in the day to day pattern through the next
week.

&&

.AVIATION...Upper level ridging over the central US with weak
troughing over the eastern Pacific will keep SW flow in place aloft
into tonight before becoming more zonal overnight. Surface winds for
most terminals will see transition from southwesterly during the
early afternoon to more westerly through late afternoon. Early
evening should bring more northwesterly winds to the region with
speeds generally 8-10 kts, before becoming light and variable
overnight. Exceptions will be HQM and CLM, where westerly marine
push will be dominant direction and BLI, where winds will remain
southerly throughout the TAF period.

Widespread VFR conditions in place and are expected to remain that
way for most sites through the majority of the TAF period. Onshore
push overnight may allow for MVFR to IFR conditions impact HQM and
PWT as marine stratus seep inland. PWT will likely see skies improve
first...by around 18Z Thursday while HQM will likely wait to break
out in the early to mid afternoon hours.

KSEA...VFR throughout the TAF period. Above surface wind discussion
applies.

18

&&

.MARINE...Surface ridge over the NE Pacific will strengthen
just off the coastal waters through the week. A gradual increase in
onshore flow is expected over the area...resulting in gales forecast
for the central and eastern Strait. Current obs show Race Rocks
blowing gale speeds, however surrounding obs are far lower...barely
reaching SCA level winds on gusts. Expectation is for these speeds
to increase during the early evening, so will leave inherited
headline in place. Forecast also suggesting SCA level winds emerging
in the outer coastal waters overnight...however this might be
slightly overdone. Have capped winds there at 15 to 20 kts with
potential to reach SCA during the day tomorrow. Will advise future
shifts to monitor, as an SCA for this area is not too far out of the
question. Persistent onshore flow will remain in place into the
weekend with diurnally driven westerly pushes through the Strait,
possibly accompanied with additional headlines.

Seas generally 4 to 6 ft before increasing to 6 to 8 ft Thursday and
nearing 10 ft by Friday for the outer coastal waters.

18

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory until 5 PM PDT this afternoon for Bellevue and
     Vicinity-Bremerton and Vicinity-East Puget Sound Lowlands-
     Everett and Vicinity-Hood Canal Area-Seattle and Vicinity-
     Tacoma Area-West Slopes North Cascades and Passes-West
     Slopes North Central Cascades and Passes-West Slopes South
     Central Cascades and Passes.

PZ...Small Craft Advisory until 5 PM PDT this afternoon for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Gale Warning from 5 PM this afternoon to 5 AM PDT Thursday for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

&&

$$