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705
FXUS66 KSEW 280359
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
859 PM PDT Mon May 27 2024

.SYNOPSIS...
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A cold front will move across the region tonight
bringing a round of showers tonight into Tuesday. The front and
associated upper level trough will exit on Wednesday with
decreasing shower coverage. An upper level ridge builds on
Thursday into Friday for warmer and drier conditions. Another
trough looks possible for the weekend for another round of
showers.
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&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...
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Satellite imagery shows an
incoming frontal system just offshore, with rain being observed
over Vancouver Island and approaching Cape Flattery as of 8PM.
Temperatures across the region are in the upper 50s to low 60s.

The front will move across the region tonight into Tuesday with
rain spreading through the interior by the afternoon and onshore
flow increasing. Hi-res guidance continues to indicate a
convergence zone developing in the late afternoon and evening,
especially in and around the Snohomish/King county line. High
temperatures on Tuesday will cool back down to the upper 50s.

As the front exits the region on Wednesday, the aforementioned
troughs axis shift inland, keeping lingering showers in the
forecast across much of western Washington. Along with showers in
the area, cooler air aloft may promote instability that could lead
to a few convective showers over the interior and the Cascades
Wednesday afternoon. Lightning, small hail, gusty winds, and
brief heavy downpours will be possible in any thunderstorms that
do develop.

The upper level trough will move eastward on Thursday, allowing
for an upper level ridge to build in the Pacific. Conditions will
start to warm and dry out, with afternoon high temperatures
topping out in the mid 60s for the interior, and the upper 50s
for coastal locations.

.LONG TERM /SATURDAY THROUGH TUESDAY/...Ensemble and deterministic
guidance supports drier and warmer conditions late week, as an
upper level ridge takes shape over western Washington.
Temperatures look to warm into the upper 60s to low 70s by
Saturday. The ridge axis looks to push inland on Saturday, which
could open the door for additional systems to move through western
Washington by late Saturday into early Sunday. While
discrepancies in the ensemble data remain in regards to the
evolution of the ridge and subsequent troughing (that being the
dominant solution), but generally chances for showers return for
the weekend and into early next week.

Mazurkiewicz/LH
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&&

.AVIATION...
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Southwesterly flow aloft through Tuesday with upper
level trough offshore. Weakening front moving inland Tuesday.
Light low level flow becoming onshore post frontal Tuesday.

VFR ceilings overnight lowering to MVFR 12z-15z. Ceilings lifting
back up to VFR again behind the front 21z-00z except in
convergence zone near KPAE where ceilings remaining MVFR.

KSEA...VFR ceilings overnight lowering to MVFR 12z-15z. Ceilings lifting
back up to VFR again behind the front 21z-00z. Northerly winds 4
to 8 knots becoming southerly around 12z. Felton
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&&

.MARINE...
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Weak high pressure over the inland waters tonight. Weak
front moving through western Washington Tuesday with increasing
onshore flow Tuesday late afternoon and evening (Small Craft
Advisory winds likely through the Strait of Juan de Fuca). Strong
high pressure over the NE Pacific will maintain onshore flow
through the end of the week. 33/Felton
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&&

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

$$