604
FXUS66 KSEW 250339
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
839 PM PDT Mon Jun 24 2024

.UPDATE...Mostly clear conditions this evening other than some
high clouds as well as dissipating lower clouds over the Olympics.
High clouds at times tonight with perhaps isolated areas of patchy
fog. No major forecast updates this evening.

&&

.SYNOPSIS...High pressure aloft continues to build over the
region, maintaining warmer and dry conditions through Tuesday. The
next upper trough crosses the area Wednesday and Thursday bringing
a return of showers and cooler temperatures. Expect a similar
pattern late in the week with a brief warm up alternating with
weak passing disturbances.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...Lower level clouds
continue to gradually scatter across the area this afternoon, with
patches of clouds most prominent near the higher terrain. This has
led to temperatures warming closer to seasonally normal values
this afternoon. With heights continuing to rise and with
increasingly clear skies, expect that Tuesday will be the warmest
day of the week for most. Expect widespread 70s through the
interior and local 80s in the warmest spots. Meanwhile, low-level
flow remains onshore and an afternoon sea breeze will prevent a
more significant warming for the areas closest to the coastline.
HeatRisk remains in the minor category for nearly all of the area,
with only a few pockets of moderate (orange).

A shift in the pattern Wednesday and lingering into Thursday as
the ridge breaks down and shifts eastward. Expect the next upper
trough to spread widespread cloud cover and a fair amount of
moisture (especially for late June) across western Washington.
Continue to see some increased instability that may allow for the
a few isolated thunderstorms near the Cascade crest (especially in
the North Cascades) during the afternoon Wednesday. Stronger
onshore flow as the trough slides east likely induces a Puget
Sound Convergence Zone on Thursday.

.LONG TERM /SATURDAY THROUGH TUESDAY/...Ensemble guidance in the
extended continues to favor rather unremarkable pattern with
largely zonal flow with some chances (20-30%) on either side
suggesting weak ridging or a few passing weak troughs through the
region. On the whole, expect this to maintain temperatures
generally somewhat close to normal and at least some showers
chances at times for the weekend and the start of next week.

&&

.AVIATION...Zonal flow aloft becoming more southerly into Tuesday
morning as a weak upper level ridge traverses the area. Light
onshore flow will continue in the low levels. Conditions have
rebounded to VFR as of this evening for all area terminals and will
persist through the remainder of the night. A few areas of patchy
fog will be possible for areas along the coast and southwest
interior Tuesday morning, but expect most sites to mostly remain
VFR.

KSEA...VFR conditions through the TAF period. Winds currently
between 7-12 kt. Winds will ease overnight into Tuesday, persisting
at 4-7 kt.

&&

.MARINE...High pressure over the coastal waters will interact with
lower pressure inland through Tuesday, promoting relatively calm
conditions and onshore flow across the region. The strongest winds
will be along the Strait of Juan de Fuca, where diurnal westerly
pushes look likely over the next few days and could result in Small
Craft headlines at times. A frontal system will then move across the
area waters on Wednesday, bringing breezy southerly winds to the
waters. High pressure will build back into the coastal waters
Thursday, with additional systems moving into the area waters over
the weekend.

Seas generally persisting at 6-8 ft this afternoon. Expect seas to
gradually subside back towards 4-6 ft tonight into Tuesday and
persist at this range over the next several days.

&&

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

$$