452
FXUS66 KSEW 250334
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
834 PM PDT Fri May 24 2024

.SYNOPSIS...Showery and cooler conditions will continue into
Saturday as an upper level trough moves through the region. Upper
level ridging will slowly begin to build over the Interior West on
Sunday, with troughing over the Pacific still keeping an influence
over western Washington. Additional chances of showers will be
likely heading into the first half of next week.

&&

.UPDATE...Weak convergence zone showers continue for Clallam,
Jefferson, Island, Snohomish, and Skagit counties this evening.
These showers will continue well into the night, and remain over
these areas. Remaining areas will stay dry overnight ahead of the
next system Saturday afternoon into Sunday. Please see discussion
below for more details.

HPR

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...An upper level trough
moving from British Columbia and associated frontal system will
continue to move through western Washington this afternoon. Per
recent radar imagery, light rain showers continue to move through
central Puget sound and the North Interior. Showers will continue
to move through the area through this evening and into Saturday,
with meager QPF values in the interior. As this frontal system
moves across this evening, onshore flow will also increase in its
wake. Latest hi- res guidance depicts a convergence zone to
develop overnight into Saturday, with the main position being in
Snohomish/King county. Locations within the convergence zone will
likely see some higher rainfall amounts - possibly a half a inch.
QPF in the mountains will generally be in the 0.50 to 1.50 range
(higher in locations in the convergence zone).

Afternoon high through Saturday will generally remain in the mid
to upper 50s. Leftover shower and convergence activity will
linger into Saturday, with mostly dry conditions elsewhere.

High pressure will start to build into the Interior West on
Sunday, with troughing situated just offshore western Washington.
Most ensemble guidance suggests that western Washington will be
influenced more by troughing on Sunday, with a weak warm front
brushing the area. Another round of showers will enter the area
but mainly be focused along the coast, the Olympics and in the
Cascades. Interior areas look to trend a little bit more drier,
with QPF amounts looking meager in the interior.. around a few
hundredths of an inch of rain. The North Coast looks to receive
almost a half of inch of rain as well.

Brief upper level ridging building into Monday will give way to
warmer conditions, with temps warming into the upper 60s, even
possibly hitting 70 on Memorial Day, with locations near water
getting around to the lower to mid 60s. With the aforementioned
trough still offshore, shower chances will increase in the later
half of the day heading into Tuesday as a front inches closer our
area.

.LONG TERM /TUESDAY THROUGH FRIDAY/...Ensemble guidance and model
guidance agree on a front moving through western Washington on
Tuesday for another round of showery and cool conditions, with
temperatures trending below normal. Clusters although are in
disagreement heading into the end of the work week, with
uncertainty of a upper ridge building, or an upper level trough
taking its place. As of now, kept a chance of showers in the long
term forecast, but ensemble guidance does suggest temperatures
in the 60s.

Mazurkiewicz

&&

.AVIATION...A weak cold front continues to dissipate over the region
with northwest flow aloft, turning more westerly Saturday. The low
level air mass is moist with pockets of MVFR to IFR conditions.
Shower activity will mostly be found in the interior and Cascades
after midnight tonight. Moisture lingers into Saturday morning with
VFR conditions expected by the afternoon.

KSEA...Showers across the area tonight, mostly north of the
terminal. CIGs expected to settle to MVFR through the night (80%
probability). S winds continue around 10 kt. Low level moisture
lingers through Saturday morning with VFR conditions expected after
18z.

Davis/33

&&

.MARINE...Weakening cold front dissipating along the coast tonight.
Meanwhile, north-northwest winds will increase over the outer
Coastal Waters with seas near 10 ft. Winds will be borderline for
Small Craft Advisory criteria in the inner coastal waters. On
Saturday, onshore flow will increase with a westerly push down the
Strait of Juan de Fuca. Another, stronger, front approaches by early
Sunday, with the pattern remaining active through early next week.

Davis/33

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 AM to 11 PM PDT Saturday for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 8 AM PDT Saturday for Coastal Waters
     From Cape Flattery To James Island Out 10 Nm-Coastal Waters
     From James Island To Point Grenville Out 10 Nm-Coastal
     Waters From Point Grenville To Cape Shoalwater Out 10 Nm.

     Small Craft Advisory until 11 AM PDT Saturday 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.

&&

$$