336
FXUS66 KSEW 241557
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
857 AM PDT Tue Sep 24 2024

.SYNOPSIS...High pressure will bring mostly dry conditions and
warmer temperatures to the region today. A weather system will
move across the region on Wednesday, bringing more widespread
rain, breezy winds, and a chance of isolated thunderstorms to the
area. Another system will move into the region Thursday night into
Friday, before conditions dry out over the weekend.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...Widespread low clouds and
fog over the interior lowlands this morning, thanks to high
pressure, recent wetting rains and a stable low level air mass.
The fog appears shallow on satellite and expecting a burnoff by
late morning. Warm temperatures this afternoon in the 70s with a
few low 80s possible. 33

Previous discussion...High pressure over the region will shift
further inland over the interior West today. This will promote
drier conditions and warming temperatures across western
Washington today. Satellite imagery this morning already shows
stratus pushing inland into portions of the interior. Expect
stratus to lift and scatter by the late morning hours. Weak
offshore flow and earlier scattering of stratus will allow for
temperatures to climb a few degrees from yesterday`s highs - and
to top out in the mid 70s to near 80. A few spots in the Cascade
valleys could reach well into the 80s.

A fall-like frontal system will push into the region on Wednesday,
bringing the next chance of more widespread rainfall, cooler
temperatures, and breezy winds. Rainfall amounts of roughly a
quarter of an inch to half an inch are possible for the interior
lowlands, half an inch to 0.75 inches for the coast, and 1-2
inches for portions of the Olympics and Cascades. Winds will be
breezy as the front moves across the region, with the highest
gusts expected to be across the northern interior and near the
water. Isolated thunderstorms will also be possible, mainly for
the mountains. High temperatures will be in the 60s area-wide.

Precipitation will then taper Wednesday night into Thursday as
the aforementioned system pushes further inland. The break in the
weather will be short-lived, however, as another system moves
into British Columbia and brushes the region late Thursday into
Friday and brings another round of precipitation and breezy winds.

.LONG TERM /FRIDAY THROUGH MONDAY/...Latest guidance has the
system Thursday night into Friday moving inland near Haida Gwaii
and brushing the region. Ensemble guidance is indicative of breezy
winds developing along the North Coast and across portions of the
Northern Interior, mainly from Whidbey Island northward.
Precipitation amounts look to be less than that of the system
midweek, with latest guidance suggesting a tenth to a quarter of
an inch across the lowlands and half an inch to an inch along the
coast and in the mountains.

Precipitation will then taper Friday afternoon and evening.
Ensemble means continue to favor more of a zonal flow pattern
developing over the weekend and with dry conditions for western
Washington expected through Monday. Will need to continue to
monitor how this shapes up, however, as cannot completely rule out
some embedded disturbances crossing the region during this time.
High temperatures look to mainly be in the 60s area-wide. 14

&&

.AVIATION...The very low stratus and fog that settled in over
much of the interior early this morning with widespread LIFR
conditions. The coast remains generally clear and the exception
for the interior being the Hood Canal area including KPWT which is
just on the western edge of the shallow stratus fog layer.
Conditions are expected to linger through the morning with
ceilings lifting and improving late morning or midday as high
pressure holds and light north/northeast low level winds develop.
Flip to southerly winds across the region after 06z this evening
ahead of approaching frontal system.

KSEA...LIFR ceilings in the 100-300 ft range will lift through the
late morning before gradually scattering toward midday. Northerly
surface winds  4-6 knots will return to southerly late Tuesday
evening. 12/45

&&

.MARINE...High pressure remains in place today with northerly winds
over the coastal waters and a north or northeast direction across
the interior. Meanwhile, seas remain generally 7 to 9 ft over the
coastal waters today. A rather strong frontal system will bring a
shift to southerly winds late tonight into Wednesday, before a sharp
switch back to northwest winds behind the front. The resulting push
of westerlies through Strait of Juan de Fuca is expected to bring a
least solid small craft winds with around a 20-30 percent chance of
at least localized gale gusts. Seas will hover closer to 9 to 10 ft
with this front as well. Another, likely stronger, front is likely
to push into the region late Thursday as the associated low lifts
north toward Haida Gwaii. This will bring another round of stronger
winds with a higher likelihood of gusty southeasterlies ahead of the
front followed by a strong push through the Strait of Juan de Fuca
again. Additionally, seas will build into the 13 to 16 ft range
(largest over the outer waters) for the coastal waters Friday. 12

&&

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

$$