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899
FXUS66 KSEW 122207
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
307 PM PDT Sat Jul 12 2025

.SYNOPSIS...
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Warm and dry conditions will continue through the
weekend with upper level ridging over the region. A brief reprieve
in temperatures is likely on Monday as a system slides southward
from British Columbia and skirts the area. Warmer and drier
conditions are expected again around midweek, with highs
potentially reaching the 90s for some lowland locations.
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.SHORT TERM /TONIGHT THROUGH TUESDAY/...
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Upper level ridging over
the region will continue promote warm and dry conditions across
western Washington today and Sunday. Modest onshore flow will
continue into Sunday for some morning stratus, but do not expect
as much cloud cover across the area as this morning. Afternoon
high temperatures today will climb into the upper 70s to mid 80s
across the interior and into the upper 60s to low 70s along the
coast. Highs look to climb a few degrees on Sunday as ridging
starts to amplify offshore, with temperatures looking to top out
in the 80s to low 90s across the interior and in the 70s along the
coast. Morning lows on Sunday will generally be in the 50s for
most spots, but may not dip down past the low 60s for the urban
corridors east of the Sound (generally from Tacoma to Everett).
As a result, Moderate HeatRisk will be present across the majority
of the interior lowlands.

A brief reprieve in temperatures is likely 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, this system will not bring much
in the way of precipitation, but will mostly bring additional
cloud cover and an increase in onshore flow in the low levels.
High temperatures are expected to be roughly 5 to 10 degrees
cooler areawide- with afternoon highs expected to be in the mid
70s to low 80s across the interior and in the 60s along the coast.

The next warm up commences on Tuesday as high pressure offshore
starts to build back into the area. Afternoon highs will rebound
into the 80s for the majority of the interior lowlands, with
temperatures along the coast expected to climb into the upper 60s
to mid 70s. This will again bring another round of Moderate
HeatRisk to portions of the interior lowlands.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Wednesday currently
looks to remain the warmest day of the week, with the most widespread
Moderate HeatRisk across the area. Under the influence of high
pressure and a thermal trough at the surface, expect temperatures
to climb into the upper 80s to low 90s across the interior
lowlands. Areas along the coast will warm as well, but will mainly
be in the 70s. This warm and dry trend could bring elevated to
critical fire weather conditions during this time frame- see the
fire weather section below for more details.

Ensembles continue to have a tough time converging on solutions
after Wednesday, though the ensemble mean has started to indicate
some weak troughing over the area by Thursday and Friday. The
overall trend leans towards temperatures cooling a few degrees
both Thursday and Friday. However, with highs still expected to be
in the 80s across the interior lowlands into the weekend, temperatures
look to continue to trend above normal through the long term at
this time. 14
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&&

.AVIATION...
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Northwest flow aloft through the period as upper-ridging
holds stubbornly offshore. VFR all areas this afternoon with clear
skies. Mostly clear skies are expected tonight into Sunday also but
can`t rule out patchy fog along with stratus along the immediate
coast. Northerly winds for interior terminals around 8 to 12 kt.
KCLM and KHQM looks to remain westerly with similar magnitudes.
Winds become lighter overnight.

KSEA...VFR conditions today and throughout the TAF period. North-
northwest winds this afternoon between 8 to 12 kt with gusts up to
20 kt. Winds trend lighter after 00-02z but remain northerly before
increasing again Sunday afternoon with gusts up to 20 kt.

McMillian
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&&

.MARINE...
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Surface high pressure continues offshore with low level
onshore flow through area waters. A westerly push this evening will
be weaker than the previous day`s, but can`t rule out isolated gusts
near SCA tonight for the central/eastern strait. Diurnally driven
pushes will continue through the strait into early next week. The
next best chance for SCA level (possibly near gales) winds through
the strait and Admiralty Inlet appears to be Sunday evening.
Northerly winds will increase over the outer coastal waters Sunday
night with the potential to reach small craft advisory strength as
well along with steep seas. Weak offshore is showing signals towards
midweek as a thermal trough builds along the coast.

Combined seas 4 to 6 feet will gradually increase to around 6 to
8 feet late Sunday into Monday. Seas look to remain elevated for
the first half of next week.

McMillian
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.FIRE WEATHER...
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High pressure over the region will maintain warm
and dry conditions across Western Washington this weekend. Modest
onshore flow will provide for excellent overnight recoveries for
most of the lowlands. However, Sunday afternoon will see RH values
dip down into the 25-30% range for areas in the interior. A weak
trough slides through the region on Monday, boosting cloud cover
and humidities, as well as bringing cooler temperatures into the
region. This is a short break as elevated fire weather concerns
return by the middle of next week, with minimum RH values
approaching critical thresholds. While flow remains mostly
northerly or northeasterly, the combination of daytime breezes
overlaying the lowest RHs may elevate concerns around Wednesday
and Thursday for much of Western Washington as a thermal trough
may build over the region. This could further enhance instability
as well. That said, ensemble guidance continues to exhibit a wide
range of potential outcomes for this time period and confidence
remains a bit lower in the details of potential elevated or
critical conditions during the middle to late portion of next
week. Cullen
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&&

.SEW WATCHES/WARNINGS/ADVISORIES...
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WA...None.
PZ...Small Craft Advisory from 3 PM Sunday to 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 from 5 PM Sunday to 3 AM PDT Monday for
     Admiralty Inlet.
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&&

$$