820
FXUS66 KSEW 052053
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
153 PM PDT Sat Jul 5 2025

.SYNOPSIS...A warming trend will begin the new 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 an upper ridge rebuilds.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...The warming trend begins
Sunday as flow aloft becomes more zonal. Interior temperatures
will climb into the mid to upper 70s, with some locations in the
Southwest interior and Cascade valleys reaching around 80F. By
Monday, the upper level ridge strengthens in response to strong
ridging over the Southwest US, leading to more widespread 80s
across interior areas, particularly from Seattle southward. The
ECMWF and GFS deterministic models, along with their respective
ensembles, show strong agreement on the continuation and
strengthening of the upper-level ridge through Tuesday. This will
result in the warmest temperatures of the forecast period, with
low to mid-80s across much of the Puget Sound region, and some
areas pushing into the upper 80s. Moderate HeatRisk could be a
concern on Tuesday.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Ensemble guidance indicates
a flattening of the ridge as a trough crosses northern British
Columbia. This will promote increasing onshore flow and a
cooling trend. There`s a slight chance of a shower near the coast
or North Cascades, but the overall forecast remains dry. Upper
ridging returns late week with temperatures rising back above
normal.

&&

.AVIATION...Westerly flow aloft continues with onshore flow in the
lower levels as an upper level trough moves eastward. VFR
conditions at all of the terminals this afternoon with some high
clouds moving across the area. This trend will continue throughout
the evening with westerly winds increasing at KCLM and areas
around Whidbey Island. Elsewhere, winds will turn northerly across
the interior and generally be around 8 to 12 knots. VFR looks to
continue into Sunday morning, although marine stratus may bring MVFR
conditions to KHQM and KOLM throughout the morning.

KSEA...VFR conditions will continue throughout the TAF period.
Westerly winds this afternoon 4 to 8 knots will turn northerly
around 23z-02z and increase in speed to 8 to 12 knots. Wind speeds
will decrease by the morning but will remain northerly. Guidance
is highlighting 20-25% chance of MVFR stratus nearing the terminal
early Sunday morning, but confidence is low. VFR will likely
prevail.

Mazurkiewicz

&&

.MARINE...Surface high pressure will continue to remain offshore
throughout the weekend and into early next week. Diurnal westerly
pushes down the Strait will continue over the next several
evenings, especially this evening as a Small Craft Advisory
remains in effect. A weak system may approach the area waters
during the middle of the week with an uptick in winds and seas.

Combined seas look to hover between 4 to 6 feet throughout the
weekend and into the early half of next week. Seas may become
steep at times with continuous northerly winds over the waters.

Mazurkiewicz

&&

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

&&

$$