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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS66 KSEW 151644
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
944 AM PDT Mon Apr 15 2024

.SYNOPSIS...Upper-level troughing returns on Monday with showers
and cooler temps. Then, ridging will rebound around midweek with
the potential for more warmer and drier weather followed by the
potential for a weak frontal passage over the weekend.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...
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Recent radar imagery
depicts a developing convergence zone mainly around southern
Snohomish county generally moving southward, along with scattered
showers alongside the coast. Expect showers to continue
throughout the day along with convergence zone activity through
much of the afternoon. The previous discussion can be found below
along with updated aviation and marine discussions:

Near-zonal flow aloft as we`re transitioning from weak ridging to
upper-level troughing. The weekend`s above normal temperatures
and dry weather will come to an end on Monday. The main feature
will be convergence zone activity through much of central Puget
Sound today and tonight. However, scattered showers are to also
track across western Washington and given current hi-res guidance
they appear to be rather hit or miss. Light rainfall amounts are
expected but locations in and around the convergence zone could
see up to 0.25 to 0.50" in the foothills and higher elevations
with locally higher amounts possible. Snow levels will also start
off around 3,000 ft before falling to 2,000 ft tonight. With that,
a few inches of snow won`t be hard to achieve at the passes.
Noticeably cooler highs are in the forecast with lower to mid 50s
expected with overnight lows in the mid 30s to lower 40s.

Lingering showers and cooler temperatures will linger into
Tuesday. However, most showers will be in and around the confines
of the mountains given orographic enhancement. But, we`ll begin
to trend much drier on Wednesday as troughing progresses and
upper-level ridging builds over the NE pacific. Because of this,
not only will we see drier weather but highs will increase with
mid 50s to lower 60s expected.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Conditions are
continuing to trend drier Thursday and Friday. Deterministic
guidance continues to hint at a ridge amplifying near the region.
But, questions remain on its exact location and intensity.
Nevertheless, the brief cool down to start the week on Monday may
not last too long as temps could possibly top out in the upper 60s
on Friday. Ahead, much uncertainty is present this far out, but a
weak front could brush the area over the weekend.

McMillian/Mazurkiewicz
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&&

.AVIATION...
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Conditions mainly VFR to MVFR this morning across the
region. Westerly flow will continue aloft in the wake of a frontal
passage this morning. Radar shows that a convergence zone has
developed across southern Snohomish County this morning and will
continue to drift southward over the next few hours, bringing
lower cigs and a shift in wind direction to the north for interior
terminals. A PSCZ looks to linger across the interior into Tuesday
morning. Outside of the PSCZ, scattered light rain showers and
drizzle are likely through much of the day today.

KSEA...MVFR conditions. Southwesterly surface winds are favored
to shift to the NE around 19z as a convergence zone sinks southward
and into the terminal. Ceilings look to rebound towards VFR as
convergence zone activity looks to drift further south of the
terminal this afternoon. However, CZ activity looks to linger
into Tuesday morning, so could see additional periods of showers
and MVFR ceilings into early Tuesday. 14
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&&

.MARINE...
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Gusty onshore flow will continue in the wake of a
frontal passage today, with gales expected through Admiralty
Inlet and the Central and East Strait of Juan de Fuca this
afternoon and evening. Small Craft Advisories remain in effect for
portions of the coastal waters and for the West Entrance to the
Strait through today. High pressure will build across the coastal
waters Tuesday into Wednesday and will interact with lower
pressure inland. This pattern will bring overall calmer conditions
to the area waters through much of the week, before the next
frontal system arrives over the weekend.

Seas continue to hover between 8 and 10 feet over the coastal
waters this morning and will gradually lower back to 7 to 9 feet
through the day. Seas will continue to lower through the week,
trending below 5 feet Thursday and Friday.

Lindeman/14
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&&

.HYDROLOGY...No river flooding is expected through the next seven
days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
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WA...None.
PZ...Small Craft Advisory until 5 AM PDT Tuesday for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From Cape Flattery To James Island Out 10 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 Nm-
     Coastal Waters From James Island To Point Grenville Out 10
     Nm-West Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 11 AM PDT this morning for Central
     U.S. Waters Strait Of Juan De Fuca-Coastal Waters From
     Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal
     Waters From Point Grenville To Cape Shoalwater Out 10 Nm-
     East Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Warning until 5 AM PDT Tuesday for Central U.S. Waters
     Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of
     Juan De Fuca.

     Gale Warning from 5 PM this afternoon to 5 AM PDT Tuesday for
     Admiralty Inlet.
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&&

$$