Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 221553
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
853 AM PDT Fri Mar 22 2024

.UPDATE...A band of rain over SW Washington will continue to slide
northward through today for light QPF amounts across the area.
Snow levels today will range 5000-5500 feet. Otherwise, cloudy
conditions with highs in the mid to upper 50s for most areas. No
forecast updates this morning.

&&

.SYNOPSIS...An upper level low offshore will slowly move east
reaching Western Washington on Saturday. This will produce periods
of showers. A weak upper ridge will give a short-lived drying
trend later Sunday. A series of weather systems will move across
Western Washington Monday through Thursday with lowland rain and
mountain snow.

&&

.SHORT TERM /TODAY THROUGH SUNDAY/...A upper level low centered
west of the Oregon/California border will gradually shift onshore
over the weekend. This will lead to increasing shower activity
across Western Washington later today and continuing into
Saturday. The trough will shift into the Intermountain West on
Sunday as weak shortwave ridging noses into the region. This will
give us a short-lived drying trend Sunday afternoon into Sunday
night. Temperatures through the short term forecast period will
be close to seasonal averages.

.LONG TERM /MONDAY THROUGH THURSDAY/...The ridge will quickly
flatten on Monday allowing another frontal system to reach the
area. This initial system looks fairly weak, but, crucially, it
will open the door for a series of stronger systems to impact
Western Washington as the week progresses. Models are in fairly
good agreement with the idea of a much stronger system arriving
around the middle of next week. With it comes the potential for
broader impacts in the form of heavy mountain snow, gusty winds
for portions of the area, and some large surf reaching our
shores. 27

&&

.AVIATION...Southwest flow aloft will turn more southerly today as
an upper-low churns offshore. Mostly VFR currently but a few
terminals are showing MVFR to even LIFR as patches of lower clouds
and fog drift around. Any lingering low stratus/fog should give way
to mainly VFR by 18-21z but can`t rule out occasional MVFR
observations under heavier shower activity during the afternoon.
Overnight, MVFR cigs may become more widespread along with patchy
fog developing over terminals such as KOLM where LIFR is possible.

KSEA...VFR currently and will likely remain that way for much of
the day. Rain showers will increase over the terminal between
18-22z. Can`t rule out brief instances of MVFR visibilities under
heavier showers in the afternoon timeframe. North winds this
morning around 4 to 8 knots, with the potential of increasing to
around 10 knots this afternoon. Winds look to shift more southerly
tonight and become lighter.

McMillian/Mazurkiewicz

&&

.MARINE...An occluded surface low continues to meander well offshore
with little to no impact across area waters. This disturbance will
gradually move through the region this weekend, but again,
conditions will remain under any headline thresholds. Conditions
will generally be generally benign into the beginning of next week,
before possibly turning active by midweek as models hint at a
stronger disturbance arriving. Combined seas 3 to 6 feet will
persist this weekend and into the beginning of next week, before
rising midweek.

McMillian

&&

.HYDROLOGY...No river flooding expected in the next 7 days.

&&

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

$$


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