450
FXUS66 KSEW 132307
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
407 PM PDT Sun Jul 13 2025

.SYNOPSIS...A brief reprieve in warm temperatures is expected on
Monday as a system slides southward from British Columbia and
skirts the area. Warmer and drier conditions will return Tuesday
through Thursday, with some lowland locations potentially seeing
highs in the 90s by Wednesday. Elevated fire weather conditions
are also expected during this warm up. A cooling trend then
commences late in the week and into next weekend.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...Warm and dry conditions
continue across the area this afternoon with temperatures generally
ranging in the 80s to low 90s across the interior. Areas along
the coast remain much cooler, with temperatures ranging in the
60s to low 70s under onshore flow and with stratus still present
along the coast.

A brief reprieve in temperatures is expected on Monday as a positively
tilted trough slides down across British Columbia and skirts
western Washington. Outside of a slight chance of showers across
the far Northern Cascades, the main impact from this system will
be cooler temperatures, an increase in cloud cover, and an
increase in onshore flow in the low levels. High temperatures on
Monday will primarily be in the 70s to low 80s across the interior
and in the 60s along the coast.

Conditions start to ramp up again on Tuesday as high pressure
offshore starts to build into the region and a thermal trough at
the surface builds northward into the area. Afternoon highs on
Tuesday will rebound into the 80s for the majority of the interior
lowlands, with temperatures along the coast expected to climb
into the 70s to low 80s. Temperatures will continue to warm and
will peak on Wednesday, with highs expected to be in the 80s to
low 90s across the interior. With overnight lows generally
expected to be in the upper 50s to low 60s, this will bring
another round of Moderate HeatRisk to the majority of the interior
lowlands. This warm and dry trend will also bring elevated to
critical fire weather conditions to portions of the area both
Tuesday and Wednesday. More details on fire weather can be found
below in the fire weather section.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Ensembles continue to have a
tough time converging on solutions late in the week. At this time,
Thursday looks to remain warm for much of the area outside of the
coast, however there remains a decent spread in temperatures
amongst the ensemble members. Guidance starts to show more of a
cooling trend by Friday with an increase in onshore flow, though
highs are still expected to be above normal and in the 80s for
the interior lowlands. At this time, temperatures look to cool
closer to seasonal norms over the weekend. 14

&&

.AVIATION...West-northwest flow aloft as upper-ridging continues
offshore. VFR for all terminals this afternoon with clear skies
overhead. Marine stratus continues to hug the immediate coastline.
Onshore flow will strengthen this evening as stratus spreads inland
overnight into Monday morning. A mix of MVFR/IFR appears favored
starting at KHQM by 06-08z then towards Puget Sound and surrounding
areas around 11-14z. Northerly winds through the interior this
afternoon-evening between 8 to 12 kt, becoming lighter overnight.
KCLM seeing more westerly winds 10 to 15 knots later this evening
and gusts up to 20 to 25 kts. VFR will return into the day on Monday
as stratus lifts and clears during the afternoon.

KSEA...VFR this afternoon but stratus is favored to return Monday
morning. NW winds this afternoon around 8 to 14 knots, with the
potential of some gusts up to 20 kts as well. Northerly winds look
to remain elevated throughout most of the evening before dimming
after midnight local time. MVFR stratus is favorable to return
around 11-13z Monday morning and stick around before lifting towards
18-20z.

McMillian

&&

.MARINE...Surface high pressure remains offshore with onshore flow
throughout the area waters. Diurnally driven westerly pushes down
the strait will continue over the next several days of differing
magnitude. Latest guidance has shown more strength in the westerly
push tonight, therefore a Gale Warning remains in effect for the
Central and Eastern Strait for this evening. Northerly winds also
look to increase over the coastal waters this evening along with
steep seas, so A Small Craft Advisory also remains in effect well
into Monday. Thermal troughing looks to build along the coast
through midweek, with periodic increases of northerly winds through
the area waters.

Combined seas 6 to 8 feet look to increase to 8 to 10 feet by Monday
morning. Seas will likely remain elevated throughout the first half
of the week.

McMillian

&&

.FIRE WEATHER...A passing disturbance Monday will bring a brief
relief from the very warm and dry conditions of the weekend. This
system will bring much stronger onshore flow, spreading widespread
clouds and cooler conditions. However, attention will then turn to
the return of high pressure over the region. Expect to see afternoon
RH values dip down close to critical thresholds Tuesday afternoon
with a thermal trough building north over the Cascades. While some
uncertainty remains with respect to how far north and west this
builds, expect to see at least some east component to the surface
winds near the Cascade gaps in zone 659 and perhaps portions of 657
and 658. Confidence is lower in seeing more widespread easterly wind
and speeds may not be strong enough to raise fire weather concerns
to critical, but this may serve to further reduce RHs. Additionally,
depending on the placement of the thermal trough, expect to see a
deeper mixed layer and increased instability with mixing heights
potentially rising into Wednesday. While confidence in the specific
timing of elevated fire weather concerns is still lower, the mid
week period bears close watching for both existing incidents and for
the potential for conditions to remain of concern if new ones were
to begin. Looking ahead to the end of the week, expect conditions to
remain warmer and drier than normal but forecast guidance continues
to exhibit a large range of potential scenarios that leave
confidence lower than normal.                    Cullen

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Gale Warning until 6 AM PDT Monday for Central U.S. Waters
     Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of
     Juan De Fuca.

     Small Craft Advisory until 5 AM PDT Monday for Admiralty Inlet.

     Small Craft Advisory until 7 AM PDT Monday for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From Cape Flattery To James Island Out 10 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 Nm-
     Coastal Waters From James Island To Point Grenville Out 10
     Nm-Coastal Waters From Point Grenville To Cape Shoalwater
     10 To 60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater Out 10 Nm.

&&

$$