313
FXUS66 KSEW 190355
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
855 PM PDT Fri Jul 18 2025

.SYNOPSIS...A broad upper level trough over Western Canada on
Saturday will drop down over Western Washington Sunday and Monday
for a chance of showers over the higher terrain. The trough
will move east Tuesday with a weak upper level ridge building
into Wednesday. Another trough will approach from the northwest
Thursday.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...Increasing onshore
flow tonight in the wake of an weak shortwave will bring another
round of stratus to the interior by Saturday morning. Expect the
extent of the stratus to be more widespread across the interior
lowlands, with satellite this evening showing areas along the
coast never having scattered out today. Overall, the forecast
remains largely on track, with no significant updates needed. The
remainder of the previous discussion follows below, with updates
made to the aviation section. 14

Morning clouds on Saturday likely linger a little longer as
onshore flow continues, but plenty of afternoon sunshine should
yield a Saturday afternoon similar in sun and temperature as
today for most. The next upper trough approaches closer into
Sunday, spreading additional cloud cover and perhaps a few showers
in the mountains. Otherwise, temperatures will remain similar on
Sunday.

.LONG TERM /MONDAY THROUGH FRIDAY/...For next week, we`ll see
the upper trough track across the area on Monday with a focus
for showers in the Cascades and an increased potential for a
thunderstorm or two in the North Cascades. Expect a slight
warming trend into midweek as the most likely evolution of the
pattern would see heights rising offshore and a weak ridge or
zonal flow over the region. This brings temperatures a couple of
degrees warmer each day into midweek. However, it`s worth
noting that the ensemble members begin to show a wider variety
of solutions at this time and confidence begins to decrease later
in the week.

&&

.AVIATION...VFR conditions persist across the majority of the
interior terminals tonight, while MVFR conditions persist for
terminals along the coast and Strait in stratus. Another push of
marine stratus is expected overnight into Saturday morning,
bringing widespread MVFR ceilings to the interior terminals and
IFR/LIFR ceilings along the coast. Terminals along the Kitsap
Peninsula and Strait of Juan de Fuca have a 20%-30% chance of IFR
conditions developing by early Saturday. Improvement expected by
late Saturday morning into early afternoon with VFR conditions
expected to return between 17z-20z.

Breezy winds, generally between 10-14 kt, with gusts to 20-25 kt
at times, persist this evening for KHQM, KOLM, KCLM, and KBLI.

KSEA...VFR conditions persist this evening. Another push of
stratus will bring ceilings down to MVFR between 10z-12z, with
improvement expected after 17z-19z. S/SW winds will persist
between 6-10 kt throughout the TAF period.

29/14

&&

.MARINE...Broad surface ridging offshore and lower pressure inland
will maintain onshore flow over the waters into next week. An upper
level trough moving across the area today will enhance onshore flow
across the Strait of Juan de Fuca this evening, for which a Small
Craft Advisory has been issued for the Central and Eastern Strait.
The next push that may meet small craft criteria appears to be
Wednesday, with probabilities hinting at a 50%-70% of 21 kt or
higher. Otherwise, generally benign marine conditions, with seas
subsiding into the weekend and into next week to around 3-5 ft.

29

&&

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

&&

$$