854
FXUS66 KSEW 240236
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
736 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/...No significant changes to
the forecast this evening. The previous discussion can be found
below along with updated aviation and marine sections:

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...Mostly VFR with areas of IFR/LIFR in fog and low stratus
along the coast. Another marine push early Tuesday morning will
bring in low stratus and patchy fog to the Puget Sound terminals,
with confidence increasing over IFR to LIFR ceilings developing.
Conditions on track to improve in the late morning to early
afternoon. Surface winds will generally be light out of the N.

KSEA...VFR this evening with light winds out of the NW. Another
round of marine stratus will develop early Tuesday morning, with
ensemble guidance increasing to a 40% to 60% chance of IFR ceilings
near 1k ft through much of the morning. Conditions improving to VFR
by 19z-21z with northerly flow throughout the day Tuesday.

15

&&

.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.
&&

$$