343
FXUS66 KSEW 232133
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
233 PM PDT Mon Sep 23 2024

.SYNOPSIS...High pressure will result in mostly dry conditions
through Tuesday along with warming temperatures. The next weather
system will bring widespread rain, breezy, and cooler conditions
to the region Wednesday, along with a chance of isolated
thunderstorms. Another weaker system will arrive Thursday into
Friday before dry conditions return this weekend.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...After a rather dreary
morning, widespread stratus is thinning this afternoon and
patches of blue sky are expected by late in the day. An axis of
high pressure is moving across the region today and will shift to
our east by Tuesday. Another round of stratus is likely in the
lowlands overnight but should burn off fairly quickly Tuesday.
This will allow temperatures to warm several degrees, likely
reaching the mid-70s to around 80 in the western Washington
lowlands. In areas that don`t see stratus in the morning (mainly
the Cascade valleys) could reach well into the 80s.

On Wednesday, a fall-like frontal system will push through the
region bringing widespread beneficial rainfall, cooler
temperatures, as well as breezy to locally windy conditions. At
this time, widespread peak winds in the 25-35 mph range look most
likely, with locally higher gusts possible near the northern
interior waters. With plenty of deciduous foliage still out there,
wind impacts in the form of minor tree damage cannot be ruled
out.

Precipitation will taper off Wednesday night into Thursday
morning. The break will be short lived as another, weaker system
clips the area late Thursday into Friday bringing another round of
precipitation to the region. Precipitation will taper
off across the region through the day Friday.

.LONG TERM /SATURDAY THROUGH MONDAY/...Forecast confidence in
details over the weekend falls off quickly as ensemble mean favors
largely zonal flow with dry conditions. However, embedded
disturbances can`t be ruled out that could throw a wrench in the
the forecast. With little moisture to work with, impacts from any
disturbances should be minimal.
-Wolcott-

&&

.AVIATION...With the exception of coastal terminals, all are MVFR to
VFR this afternoon. Surface winds will continue out of the
southwest, with a gradual veering motion to the NNW after 02Z to
03Z. Trends indicate that MVFR to VFR cigs will continue through
much of the overnight hours, with stratus and some fog reemerging
after 10Z. Throughout Puget Sound, the probability of cigs below 020
ranges from 50 to 70 percent from midnight on through Tuesday
morning. As of now, the breakout to more scattered clouds and MVFR
to VFR cigs on Tuesday will likely be earlier than today, closer to
18Z to 19Z as opposed to late afternoon. This could change with
updated guidance this evening.

KSEA...MVFR at the terminal this afternoon as ceilings have lifted
more appreciably from this morning`s IFR cigs. Surface winds are
turning more southwesterly, and are still expected to veer to the
NNW this afternoon, generally after 02Z. Once the winds are
northerly, speeds are expected to stay below 6 kt. Another round of
marine stratus is likely on Tuesday morning, with ensemble guidance
giving 30 to 40 percent probabilities that ceilings will be below
030 after 10Z. An earlier breakout on Tuesday is possible and is
progged for 18Z-19Z, but is subject to change pending updated
guidance. Northerly flow remains through current data.

Kristell

&&

.MARINE...High pressure continues to influence the region through
Tuesday for relatively calm seas and a period of offshore flow.
Conditions are expected to change rather quickly as another frontal
system arrives on Wednesday, bringing with it breezy conditions,
rain and elevated seas. Winds through the Strait of Juan de Fuca on
Wednesday afternoon could reach low end gale force. 8 to 10 ft seas
are likely through Thursday morning over the coastal waters with
heightened winds that may also approach small craft criteria at a
minimum.

A stronger frontal system is anticipated Thursday into Friday, where
probabilistic wave height guidance is still keying in on above 50
percent likelihoods of seas of 12 to 13 feet over the coastal
waters. This system will also be breezy, but information on
anticipated speeds will come into more focus over the next few
forecast iterations.

Kristell

&&

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

$$