Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 140311
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
808 PM PDT Wed Mar 13 2024

.SYNOPSIS...Decreasing clouds across the region as high pressure
builds over western Washington. This will usher in a period of warm
and dry conditions through the early portions of next week. A return
of cooler temperature and precipitation chances is then expected
later next week.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...Current satellite imagery
shows some high clouds drifting south over W WA this evening...with
maybe a little bit of mid level clouds mixed in along the coast.
Radar remains clear, which given the recent active pattern, feels
weird. Many locations saw high temps pretty close to, if not
slightly above, seasonal normals today. That said, temps over much
of the area mainly in the mid to upper 40s as of 7 PM PDT. Dewpoints
linger in the lower to mid 30s in most spots, upper 30s for sites
close to water...advertising the expected lows for tonight given the
clearing. As such, current inherited forecast appears to be on track
with no evening updates planned. For additional forecast details,
please refer to the previous discussion section below.

From Previous Discussion...Clouds have continued to scatter out,
especially in the lowlands, through the afternoon today as the upper
trough shifts eastward and heights begin to rise. Expect this upper
level ridge to build across the Pacific northwest starting Thursday
and continuing into the weekend. As the ridge builds, can expect to
see some lingering low clouds each morning in the more fog prone
locations. With increasing offshore flow each day, however, expect
the air mass to steadily dry and warm. This will yield increasingly
sunny days into the weekend and daytime high temperatures climbing
into the lower or mid 60s by Friday and the potential pockets of
temperatures near 70 in locations in the foothills and on the
western slopes of the Olympics. With the increase in offshore winds,
expect some breezy east winds through the Cascade gaps by Friday and
into Saturday.
Ensemble guidance continues to suggest the ridge axis centered
over the region for the weekend, which in conjunction with the
offshore flow and abundant sunshine, with the warmest days of the
stretch likely to be over the weekend.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...From Previous
Discussion...As mentioned above, the ridge and lower-level offshore
flow will dominate the pattern into Sunday. Expect that Sunday may
be a few degrees cooler for locations along the coastline as a bit
of an sea breeze kicks back in. Ensemble guidance suggests the ridge
will gradually weaken early next week and shift east toward the
Great Basin or Rockies by around Tuesday. This would favor
temperatures gradually returning back toward seasonal normals, along
with the renewal of increased precipitation chances. As a result,
the forecast continues to indicate a return of some precipitation
(lowland rain/mountain snow) by the middle of next week, but
confidence in the timing/evolution of this return remains rather low
at this time. Cullen

&&

.AVIATION...Skies have mostly cleared out this evening, and all
terminals are reporting VFR conditions. An upper level ridge
continues to build and lift into Canada/Alaska, This will broaden
the northern flow and it will become more offshore going into
Thursday and Friday. Ceilings will remain VFR tonight with any mid
level clouds dissipating. Given the recent rains and wet grounds,
moisture mixing may lead to fog in the early Thursday morning hours
(between 12 and 18Z). This would primarily affect the
Olympia/Shelton area. Will watch the slight potential that the fog
drifts towards the Kitsap Peninsula and into Seattle. Surface winds
will remain out of the north at around 3 to 5 kt, and become more
northeasterly Thursday afternoon.

KSEA...VFR conditions generally expected through the TAF period with
mostly clear skies. Slight chance for low stratus/fog sneaking in
the terminal between 12-18Z, however confidence is still low and
will remain out of the TAF forecast unless confidence increases.
Surface winds remain out of the north tonight at 3 to 6 kt, with a
shift to the northeast Thursday afternoon.

HPR

&&

.MARINE...Ridging at the surface and aloft will build across
the area before the surface portion shifts inland Thursday into
Friday as thermally induced low pressure expands northward along the
coast. This will lead to a period of offshore flow, but speeds
should remain below any headline criteria. The ridge will deflect
any weather systems well to the north, keeping tranquil conditions
in place over the waters for much of the forecast period. Coastal
seas are expected to subside below 10 feet by tonight then remain
there through at least the upcoming weekend. 18

&&

.HYDROLOGY...River flooding is not expected through the next week.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for Coastal
     Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-
     Coastal Waters From Point Grenville To Cape Shoalwater Out
     10 Nm.

&&

$$


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