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197
FXUS66 KSEW 031619
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
919 AM PDT Fri May 3 2024

.SYNOPSIS...A pattern change is on track for today, in which warm
and dry conditions will transition to a cooler and wetter pattern
as a deep trough digs into the region. Precipitation and below-
normal temperatures will continue into mid-week next week before
a potential return to drier and warmer weather.

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.SHORT TERM /TODAY THROUGH SUNDAY/...
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Rain is approaching the coast
this morning then pushing inland this afternoon/evening (mainly
after 00z in the interior). Until then, mild, with highs in the
interior reaching the mid to upper 60s with a few low 70s in the
Cascade foothills. 33

Previous discussion...High pressure will remain in place across
western Washington for much of the morning as a deep low pressure
system drops southward along the Pacific Northwest coast.
Temperatures ahead of an incoming warm front will continue to warm
up from yesterday, with some areas east of the Puget Sound
surpassing 70 degrees. A front will approach the coast early this
morning and push inland throughout the afternoon, draping
widespread rainfall across the region with the exception of
snowfall above 6000 ft. The track of this low pressure system is
forecast to dive southwards towards California, so the bulk of the
incoming moisture will be focused over the Olympic Peninsula and
southwest Washington. The low will meander inland over the
weekend, injecting continual moisture into western Washington.
Showers, cooler conditions, and periods of breezy winds will
continue through the weekend, with highs in the 50s across the
lowlands.

.LONG TERM /MONDAY THROUGH THURSDAY/...Onshore flow will maintain
cooler temperatures heading into next week as moist westerly flow
maintains shower activity across the region. A series of weak
fronts will cross the region on Monday and Tuesday, with snow
levels slowly lowering to below pass level by Tuesday. Any snow
accumulations through the Cascade passes will be light, with less
than an inch carried by ensembles. A warm front will lift across
western Washington mid-week as a ridge settles into the region,
allowing for conditions to dry out and warm up to near-normal.
While some uncertainty remains on how long the warmer and drier
conditions will stick around, models suggest some potential for
these conditions to continue into next weekend.

Lindeman
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.AVIATION...
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Winds aloft will become southwesterly today as an
upper ridge pushes inland and an upper level trough moves into
the region. Mostly clear skies across western Washington early
this morning, with satellite showing some mid to high cloud cover
starting to approach the coast ahead of the next frontal system.
Surface winds have shifted back to the south-southeast for most
terminals this morning and can expect winds to become gusty at
times along portions of the coast this afternoon. Overall
conditions are VFR this morning and expect this trend to continue
for most terminals through much of the day today. Rain ahead of
the front looks to approach the coast between 20-23Z, with cigs
for coastal terminals looking to gradually decrease to MVFR in the
evening (likely between 03-06Z). Rain then looks to slowly make
its way into the interior later this afternoon into this evening,
with areas north of Seattle likely not seeing much in the way of
rain until late tonight into Saturday. Cigs look to slowly lower to
more widespread MVFR across the interior by late tonight into
early Saturday morning.

KSEA...VFR conditions through much of the day today, with high
clouds already streaming in overhead as the next front
approaches. More widespread MVFR cigs look to hold off until late
tonight into early Saturday. Southeasterly winds persisting at 3-7
kt this morning will pick up to 8-10 kt and shift southwesterly
by this afternoon. Rain showers expected to move into the terminal
late this afternoon into this evening (00-03Z), and will only be
showery in nature. 14/Maz
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.MARINE...Weak high pressure over the area waters early this
morning will make way for the next frontal system moving into the
waters today into Saturday. Southerly winds will increase across
the outer coastal waters this morning and persist at small craft
strength through this evening. Several westerly pushes are
expected along the Strait of Juan de Fuca this weekend into early
next week, likely yielding additional headlines at times. Another
system looks to arrive in the region late Sunday into Monday.
High pressure then looks to build over the northeastern Pacific on
Tuesday.

Seas across the coastal waters will generally hover between 3-6
ft through Friday, before increasing towards 6-8 ft over the weekend.
Seas then look to build and approach 9-11 ft Monday night into
Tuesday. 14

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

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.SEW WATCHES/WARNINGS/ADVISORIES...
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WA...None.
PZ...Small Craft Advisory until 7 PM PDT this evening for Coastal
     Waters From Cape Flattery To James Island 10 To 60 Nm-
     Coastal Waters From James Island To Point Grenville 10 To
     60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater 10 To 60 Nm.
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