Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 211016
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
316 AM PDT Thu Mar 21 2024

.SYNOPSIS...An approaching trough of low pressure will produce
wet and unsettled conditions into the weekend. Additional fronts
will keep lowland rain and mountain snow in the forecast into next
week.

&&

.SHORT TERM /TODAY THROUGH SATURDAY/...The first of several upper
disturbances ejecting from the broad upper trough offshore moved
across Western Washington overnight with scattered showers. Shower
activity will diminish later this morning and we`ll see a relative
lull in activity later today into tonight. The offshore trough
begins to lift northeastward on Friday pushing a slow moving front
toward the coastal waters. This will lead to a gradual increase in
precip coverage across Western Washington through the day on
Friday. Periods of showers will continue into Saturday as a series
of disturbances rotate across the area around an upper level low.
The low finally is expected to shift onshore over southern Oregon
or northern California Saturday night.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Somewhat drier north to
northwest flow aloft develops on Sunday ahead of weak shortwave
ridging. This should give the area a brief break from wet weather
later Sunday and perhaps early Monday before the first of several
seasonal frontal systems spreads additional lowland rain and
mountain snow across Western Washington. Temperatures through the
extended forecast period look to average a smidge below seasonal
norms. 27

&&

.AVIATION...Transient shortwave overhead with mostly southwest flow
aloft. A mix of VFR to IFR out currently with the trend expected to
last throughout the morning. Can`t rule out instances of LIFR also.
Some improvement is possible after 18-19z today to mostly VFR over
area terminals, can`t rule out observations of MVFR under passing
showers. A mix of VFR and MVFR will again be possible Thursday
night into Friday morning.


KSEA...It`s been a mix of VFR to MVFR so far this morning. However,
mostly VFR is slated to return as the day progresses and remain into
the night. Winds generally out of the south between 5-10, turning SW
during the afternoon before becoming light overnight.

McMillian

&&

.MARINE...A weak frontal system is well beyond the offshore
waters of Oregon currently but no impacts are expected here locally.
An additional disturbance is on tap to arrive over the weekend but
at this time, conditions are to remain sub-SCA. Brief high pressure
to start the beginning of next week but the pattern will remain
generally active through the middle of it. Seas 3 to 6 feet
through much of the upcoming week before possibly rising next week.

McMillian

&&

.HYDROLOGY...No river flooding is expected over the next 7 days.

&&

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

$$


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