311
FXUS66 KSEW 242144
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
244 PM PDT Sat May 24 2025

.SYNOPSIS...Upper level ridging will lead to warmer and dry
conditions across western Washington today. A weak front will
bring in cooler temperatures and a round of showers late Sunday
through Monday. Ridging will rebound by Tuesday, bringing a return
of warmer and dry conditions into the middle of next week.


&&


.SHORT TERM /TONIGHT THROUGH TUESDAY/...High pressure will
continue to drift eastward today as a longwave trough deepens
offshore. With limited cloud cover and southwest flow aloft,
temperatures will climb another 5 to 10 degrees from yesterday,
peaking in the mid to upper 70s across the interior lowlands.

A weak front stemming from the low offshore will move inland across
western Washington later on Sunday, bringing in a round of showers
along the coast by Sunday evening and pushing inland overnight into
Monday. Rainfall totals will be fairly light, with rain shadowing
limiting accumulation amounts east of the Olympics. Light showers
will taper off throughout the day Monday over higher terrain as high
pressure begins to rebound. Upper level ridging will build back into
the region by Monday night, with dry and mild conditions returning
by Tuesday.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...High pressure will
continue to amplify into western Washington on Wednesday, with a
thermally induced surface trough on track to develop along the
coast. Wednesday will be the warmest day of the period, and may be
the warmest day so far this year, with high temperatures set to peak
well into the 80s for most inland areas. Some areas along the
Cascade foothills and valleys may even see the first 90 degree day
of the year on Wednesday. This will cause widespread Moderate
(Orange) HeatRisk across lowlands south and east of the Puget Sound,
with Minor (Yellow) HeatRisk elsewhere across western Washington.

Forecast uncertainty increases towards the second half of next week,
with another trough set to cross western Washington on Thursday.
Models show varying degrees of the strength of this trough,
precipitation amounts with it, and the degree of cooling it will
bring to the region. Ensembles hint that above normal temperatures
and drier conditions will persist beyond this frontal passage,
reflected in the latest forecast package.

15


&&

.AVIATION...Southwest flow aloft as the upper-ridge axis remains
east of the area. Mostly clear skies so far this afternoon by aid of
subsidence in the mid to upper-levels. Tonight, VFR will hold for
most but low clouds will make it to the coast (KHQM) by sunrise with
MVFR stratus. Increased onshore flow looks to usher increased cloud
coverage into the interior on Sunday afternoon but VFR will maintain
at this time.


KSEA...Mostly clear skies so far this afternoon. WNW surface winds 4-
8 kt turning SW overnight and increasing between 5-10 kt by late
Sunday morning. VFR persisting into Sunday as well.


McMillian

&&

.MARINE...High pressure persisting over the waters through tonight.
A front arriving by Sunday evening into Monday morning will help to
lessen its influence. This feature doesn`t appear to be strong
enough to produce headlines at this time but, will have to monitor
its associated westerly push through the strait. High pressure looks
to resettle Monday afternoon, likely leading into midweek. A
thermally induced surface trough will move up the coastline Tuesday
night then shift inland Wednesday. Seas 2 to 4 ft then increasing to
4 to 7 ft Sunday-Monday.


McMillian


&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&

$$