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378
FXUS66 KSEW 080936
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
236 AM PDT Tue Jul 8 2025

.SYNOPSIS...
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Warm and dry conditions will persist today under high
pressure. A weak system will cross the region on Wednesday,
bringing light rain and cooler temperatures. High pressure will
rebound towards the end of the week, bringing a return of warmer
and dry conditions by Friday and into early next week.
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.SHORT TERM /TODAY THROUGH THURSDAY/...
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High pressure will remain
in place over the western US today, maintaining well above
normal temperatures. Highs today are on track to peak in the mid
to upper 80s across the interior, warmest along the Cascade
Foothills and Valleys. This will bring another day of Moderate
(orange) HeatRisk to most metro areas surrounding the Puget Sound,
with Minor (yellow) HeatRisk elsewhere. Areas along the coast
will see fog and low stratus this morning, with increasing onshore
flow throughout the day moderating temperatures along the coast
into the mid to upper 60s. While most inland areas will start the
day with clear skies, onshore flow will pick up by the afternoon
and cloudy skies will fill in by the evening as the next system
approaches.

An approaching disturbance will bring a significant cool down on
Wednesday as a strong push of marine air moves into the region.
Light rain will spread inland throughout the day Wednesday, with
the bulk of the moisture focused over the Cascades, where
generally up to half an inch of rain is possible through Thursday
morning. Areas in the North Cascades may see locally higher
rainfall amounts closer to an inch. Elsewhere, lower elevations
will see light accumulations, generally ranging from a few
hundredths to a quarter of an inch. The moist marine air will cool
temperatures considerably, with highs Wednesday peaking in the
mid to upper 60s for most lowland areas.

Conditions will dry out by the late morning Thursday as high
pressure starts to build inland, with cloudy skies in the morning
clearing by the afternoon. Temperatures will rebound several
degrees and return to near normal, with most of the interior
seeing highs in the low to mid 70s.

.LONG TERM /FRIDAY THROUGH MONDAY/...Ensembles remain in good
agreement over high pressure building into the region over the
weekend and into early next week. Friday will bring a return of
warm and dry conditions across western Washington, with widespread
areas of Minor (yellow) HeatRisk across the lowlands and highs
returning into the 80s east and south of the Puget Sound.
Temperatures will continue to warm up through the weekend as a
ridge offshore amplifies. This will give another potential
period of increased HeatRisk as well as an increase in fire
weather concerns over the weekend and into the start of next
week.

15
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.AVIATION...
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A ridge will begin to slide eastward this morning with a
low/trough to the west, beginning to transition the zonal flow
pattern aloft to southwesterly today. Interior terminals are
reporting VFR with variable north or south winds throughout Puget
Sound at around or less than 5 kt. The winds are westerly along the
waterways (KHQM and KCLM, with potential for gusty winds just
offshore making their way to the terminal this morning). The marine
stratus is expected to remain confined to the Pacific Coast this
morning, with ceilings dropping to IFR/LIFR and potential for
visibilities to also drop in these categories. The ongoing push
through the Strait of Juan de Fuca may also push lower CIGs to some
nearby adjacent terminals (between KBLI and KAWO).

The remainder of today stays dry with high clouds (marine stratus
will linger the longest along the coast with only a brief break to
MVFR/VFR expected this afternoon). The next disturbance
tonight/Wednesday morning will bring showers across all terminals,
with ceilings lowering to MVFR and widespread pockets of IFR
Wednesday morning. Southwest flow aloft will translate down to the
surface later this morning, with winds ranging 8-12 kt (couple gusts
to 20 kt possible). Another push through the Strait of Juan de Fuca
may cause some diffluence and turn winds northerly down to KBFI.

KSEA...VFR conditions expected all of Tuesday, with a 70% chance of
MVFR (20% chance of IFR) Wednesday morning - generally after 12Z.
Clear skies today with increasing cloud coverage later today with
showers likely after 12Z Wednesday. North winds early this morning
at 8 kt will become light and variable under 5 kt through 18Z, then
pick up out of the west/southwest 8-12 kt, with a couple gusts to 18
kt possible). The northwesterly winds are expected at this time to
hold to the north of KSEA (down to KBFI).

HPR
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&&

.MARINE...
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This morning: currently have gusty winds continuing in
portions of the East/Central Strait of Juan de Fuca up to 25 kt.
Have continued the small craft advisory through 9 am local time.
Much of coastal waters and the Strait of Juan de Fuca have marine
stratus and/or fog covering much of these waters, which may limit
visibilities at times through this morning.

A trough over the coastal waters will bring a weak frontal system
across the coastal waters Tuesday night into Wednesday with showers.
There is a small possibility that seas could briefly uptick. Pushes
through the Strait of Juan de Fuca will continue through much of the
week, with another strong push likely again Tuesday
afternoon/evening. Opted to issue another small craft advisory for
the East/Central Strait of Juan de Fuca zones (especially with the
front moving through and increasing onshore flow). Another weak low
may pass the waters Thursday. High pressure will build offshore
Friday into the weekend.

Seas are expected to hold between 3-6 ft through much of the week
and could become steep at times with persistent northerly winds over
the coastal waters.

HPR
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.FIRE WEATHER...
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Dry, warm weather will lead to elevated fire weather
conditions continuing through Tuesday with high pressure situated
across Western Washington. Despite low level onshore flow bringing
good RH recoveries overnight, conditions will dry out this
afternoon with minimum RH values dropping towards 25% to 35% over
the mountains and through the Cascade Foothills and Valleys.

A weak frontal system will move across Western Washington on
Wednesday. This will increase onshore flow, with much cooler
temperatures and incoming precipitation for some areas Tuesday
night through Wednesday. There remains a moderate (50% to 70%)
chance of wetting rain for the Cascades of Snohomish County
northwards, with lighter rainfall amounts elsewhere.

Upper ridging will then build back into Western Washington late
Thursday and continue into next weekend, resulting in the return
of warm, dry weather and elevated fire weather conditions. Friday
will be the driest day of the period, with RH values dropping into
the 25% to 35% range over the mountains and across the lowlands
south of the Puget Sound.

15
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&&

.SEW WATCHES/WARNINGS/ADVISORIES...
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WA...None.
PZ...Small Craft Advisory until 9 AM PDT this morning for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 2 PM this afternoon to 10 PM PDT this
     evening for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.
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&&

$$