908
FXUS66 KSEW 250942
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
242 AM PDT Tue Mar 25 2025

.SYNOPSIS...Building high pressure will result in a dry,
unusually warm day Tuesday. A system Wednesday will bring a chance
for widespread thunderstorms to the region. Showery and somewhat
unsettled weather will linger Thursday through Saturday, followed
by a break in the weather late this weekend. Another round of
active weather greets us next week.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...A warm and mild air mass is
in place today with arcing high pressure over the region. Radar
still shows lingering showers near the Canadian border that will
shift farther north this afternoon. But the main story is the warm
temperatures on tap. Temps have been balmy overnight with mid 50s,
which is near our normal highs. There`s also patchy low clouds and
fog around the coast and interior where dew point depressions
remain tight. But by this afternoon, we`re looking at highs
reaching the upper 60s to lower 70s (warmest of the season so far)
that will likely break record daily maxes for a few spots.

Wednesday`s main focus is on developing convection/thunderstorms
over OR/WA as a cold front moves in. Across western WA, the air
mass will remain moist and unstable under S/SW diffluent flow.
Mean CAPE values from the HREF model are over 1,000 J/kg during
the afternoon and early evening - pretty high for our region
during any season. From the Storm Prediction Center, there is a
Marginal Risk of severe weather across the region (isolated severe
storms are possible). Hail and wind are the main threats, along
with cloud-to-ground lightning and periods of heavy rainfall.
Severe weather parameters decrease late Wednesday evening as the
cold front moves inland (after 03-06z).

Thursday`s weather will remain showery with a deep/stacked low
spinning offshore. It`ll be cooler overall but still mild with
highs in the 50s to lower 60s. Expect breezy conditions along the
coast and north interior with S/SE gusts to 30-40 mph. 33

.LONG TERM /FRIDAY THROUGH MONDAY/...Upper level troughing over
the Pac NW will maintain showers as we move toward the end of the
week. Temperatures will be back to our seasonal averages with
highs in the lower to mid 50s. A weak ridge brings a short break
in the weather moving into Sunday. More wet and windy weather is
headed our way next week as low pressure shifts inland. 33

&&

.AVIATION...Southwesterly flow aloft this morning as weak ridging
moves over western Washington. Showers across the area this
morning has diminished, with widespread MVFR/IFR conditions at
most area terminals. Abundant low level moisture will keep
conditions lowered at MVFR/IFR and even LIFR in some locations
throughout the morning. Latest guidance shows fog development
possible within the interior, especially across the Puget Sound
and the Southwest Interior, with a 40% chance of IFR and a 35%
chance of LIFR conditions through 17z. Can expect lower
visibilities during this time, generally around 3-5SM. Conditions
look to improve later this afternoon to VFR, low end MVFR, around
19z-21z. Surface northerly winds 4 to 8 knots through the
evening.

KSEA...MVFR/IFR conditions this morning as abundant moisture has
kept ceilings low. Fog is possible this morning, with latest
guidance suggests around a 40% chance of IFR becoming dominant at
least through 16z-18z with fog. Overall, deteriorated conditions
bouncing from MVFR/IFR, and even LIFR at times (a 30% chance) can
be expected this morning into the early afternoon. Conditions will
gradually improve, with VFR looking to rebound around 19z-21z.
Northerly winds generally around 4 to 8 knots.

Mazurkiewicz

&&

.MARINE...Surface high pressure offshore will continue to linger
over the coastal waters today, giving way to calmer and benign
conditions. A strong frontal system will start to approach the
waters Wednesday into Thursday, with increasing southerlies across
the area waters. Increasing southerlies will approach small craft
advisory criteria Wednesday afternoon, but as the low approaches
closer to the coast, winds will continue increase in strength.
Latest guidance highlights gale winds over the coastal waters
through Thursday, with a w low 10-20% chance of Storm Force Gusts
over the coastal waters. For the uncertainty in wind strength,
have issued a Gale Watch for late Wednesday into Thursday for all
of the coastal water zones. Elsewhere, small craft southerlies can
be expected in the interior (the exception being the Eastern
Entrance of the Strait, where winds could be stronger).

In addition to winds, a chance of thunderstorms will exist over
most of the waters on Wednesday. The main threats from these
thunderstorms are - small hail, erratic changes in wind
direction, and heavy rain.

Combined seas 7 to 9 feet through Wednesday afternoon, before
gradually building upwards to 10 to 14 feet by Thursday morning.
Seas will continue to build through Thursday, upwards to 18 to 22
feet by late night Thursday. The highest seas during this time
(20-22 feet) will mainly be in the outer coastal water zones. Seas
will decrease into the weekend to around 10 feet.

Mazurkiewicz

&&

.HYDROLOGY...The Skokomish River will drop below flood stage this
morning and all rivers will recede today with dry weather. A round
of heavy showers and thunderstorms are likely on Wednesday with
heavy showers focused over the Olympics on Thursday. Round after
round of heavy rain may keep the Skokomish River running high with
renewed flooding possible.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Gale Watch from Wednesday evening through late Thursday night
     for Coastal Waters From Cape Flattery To James Island 10 To
     60 Nm-Coastal Waters From Cape Flattery To James Island Out
     10 Nm-Coastal Waters From James Island To Point Grenville
     10 To 60 Nm-Coastal Waters From James Island To Point
     Grenville Out 10 Nm-Coastal Waters From Point Grenville To
     Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point
     Grenville To Cape Shoalwater Out 10 Nm.

&&

$$