884
FXUS66 KSEW 200341
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
841 PM PDT Wed Jun 19 2024

.SYNOPSIS...High pressure continues to build over the region this
week, maintaining much warmer and continued dry conditions for
most of area. A few isolated thunderstorms are possible in the
North Cascades near the crest this afternoon. The ridge will break
down late this week, bringing a return to a cooler and wetter
pattern across the region for the weekend.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...Mostly clear skies
across the majority of the area this evening with some stratus
over the coastal waters and a few remaining areas of cumulus
build- ups along the Cascades. A few isolated thunderstorms had
developed along the Cascade crest this afternoon and evening,
however the majority of the activity has remained on the east side
of the crest. Expect showers and isolated thunderstorms to wane
across the Cascades as the sun sets. The forecast remains largely
on track this evening and the remainder of the previous
discussion follows below. Updates were made to the aviation and
fire sections. 14

High pressure will strengthen and an offshore flow pattern will
develop Thursday, which will warm temperatures another 5-10
degrees tomorrow afternoon compared to today`s highs. Friday will
be similar across the interior, with some cooling at the coast as
onshore flow resumes during the day. This cooler marine air will
begin to seep into the interior, but temperatures east of Puget
Sound likely remain well above normal for one more day on
Saturday.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...The pattern shifts more
significantly into Sunday as more significant onshore flow returns
as the ridge shifts eastward. Ensemble guidance suggests this next
upper trough will take up position over the region and allow a
series of frontal systems to spread through the region. This will
bring temperatures back closer to seasonal normals and maintain at
least some rain chances. These rain chances will be most prominent
along the coast and in the Cascades.

&&

.AVIATION...Light west-northwesterly flow aloft this evening as
a surface high pressure continues to remain situated over W WA.
Clear skies over the region today will keep VFR conditions
throughout the TAF period, the exception being KHQM - where once
again patchy fog/low clouds may develop along the coast around 10z-
16z, leading to MVFR/IFR conditions through early Thursday morning.
North/northeasterly surface winds will remain around 8 to 10 kts
through Thursday morning.

KSEA...VFR this evening as clear skies prevail and persist
throughout the TAF period. N/NE winds 8 to 10 knots into Thursday
morning.

Maz/McMillian

&&

.MARINE...A broad area of high pressure situated just offshore
will continue to influence the pattern through the end of the
week, with weak onshore flow continuing. Onshore flow will
increase later on Friday as an incoming frontal system approaches
the area waters. Latest guidance indicates at least small craft
westerlies in the Central and Eastern Strait of Juan De Fuca, with
some low-end probabilities of gale force winds. Additional pushes
down the Strait will be likely into early next week.

Combined seas 4 to 6 feet will remain through the rest of the
week, rising around 6 to 8 feet beginning on Sunday.

Maz

&&

.FIRE WEATHER...Isolated thunderstorm chances along the Cascade
crest will wane as the sun sets tonight. High pressure will build
with warmer and dry conditions the next few days with daytime
humidities dipping into the 20-30% range in the driest spots as
light offshore flow develops. This will be short- lived, with a
few days of these warm and dry conditions through Saturday. The
return of cooler air and increased moisture looks to arrive by
Sunday and continue early next week.

&&

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

$$