376
FXUS66 KSEW 012209
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
309 PM PDT Tue Jul 1 2025

.SYNOPSIS...Southwest flow aloft will maintain warm and dry
conditions through Wednesday. A weak, dry trough will pass over
the region towards the end of the week, promoting onshore flow and
bringing in cooler temperatures through the holiday weekend. Zonal
flow will develop by the beginning of next week, maintaining mild
and dry conditions across western Washington.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...The eroded morning stratus
has given way to clear skies across western Washington this
afternoon. As high pressure aloft slowly shifts eastward and
onshore flow strengthens, temperatures will follow a cooling
trend. High temperatures today will lower a few degrees from
yesterday, peaking in the low 80s across the interior and in the
mid to upper 60s along the Pacific Coast.

The aforementioned upper level ridge will continue to shift
eastward into Wednesday with an approaching weak upper trough
offshore. Onshore flow will promote another round of widespread
marine stratus in the morning, burning off by the afternoon and
giving way once again to mostly sunny skies. Temperatures will
continue to moderate, with highs Wednesday reaching the mid to
upper 80s across the interior and the low to mid 60s along the
coast.

A weak trough will push inland on Thursday, bringing in stronger
onshore flow and cooler temperatures. Localized drizzle may
develop below the stratus layer early Thursday morning, with
potential for an isolated shower or two over the Cascades Thursday
afternoon. Otherwise, the region will see clearing skies into the
afternoon with highs limited to the low to mid 70s across the
interior and in the upper 50s to low 60s along the coast.
Independence Day is on track to bring more of the same, with near
normal temperatures paired with another round of morning clouds
and afternoon sunshine.

.LONG TERM /SATURDAY THROUGH TUESDAY/...Zonal flow aloft will
develop over the Pacific Northwest over the weekend and into early
next week as a cutoff low strengthens over northern California.
This will result in continued mild conditions and mostly clear
skies throughout the holiday weekend and beyond. With this
pattern, this opens the door to the chance of a few light showers
near the northern coast and the North Cascades over the weekend,
although the chance of any precipitation remains fairly low at
this point. Ensembles indicate some potential for high pressure
to rebound over the western US towards the middle of next week,
which could result in another warm-up across western Washington,
but the exact details remain uncertain at this time.

15

&&

.AVIATION...Upper level ridge to the east with weak trough
developing offshore giving southwesterly flow aloft over the area
through Wednesday. In the lower level increasing onshore flow this
afternoon and evening. Light stratus remains over the coast this
afternoon, with generally VFR skies throughout western Washington
this afternoon.

The forecast is still expecting possible IFR to low end MVFR stratus
reforming along the coast 03z-06z with the stratus moving inland
Wednesday morning. Stratus could get as far east as KSEA by 12z-15z.
Given the increase in southwesterly flow overnight, any stratus that
arrives further inland likely won`t linger past 18Z or 19Z.

KSEA...Just some high clouds at times today, generally VFR. Expect
northerly surface winds to continue this afternoon, between 8 and 10
kts. Occasional gusts to 15 kts cannot be ruled out through 04Z-05Z.

Stratus will be close to the terminal Wednesday morning 12z-15z for
cigs between 015 and 020. Wind switching to southwesterly 4 to 8
knots 09z-12z Wednesday. Any stratus that makes it to the terminal
will likely only linger until around 17Z.

21

&&

.MARINE...High pressure will remain in place across the coastal and
offshore waters this week with thermally induced low pressure east
of the Cascades. A weak front will dissipate over the offshore
waters Wednesday.

Diurnal westerly pushes through the Strait of Juan de Fuca each
evening. The gale warning tonight for the Central and Eastern Strait
with small craft advisory northwesterlies in Admiralty Inlet have
been left in place. Late day small craft advisory westerlies
possible in the Strait each evening into the weekend.

21

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Gale Warning from 6 PM this evening to 3 AM PDT Wednesday for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 6 PM this evening to 5 AM PDT
     Wednesday for Admiralty Inlet.

&&

$$