285
FXUS66 KSEW 061055
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
355 AM PDT Sun Apr 6 2025

.SYNOPSIS...Front moving through Western Washington tonight with
rain out ahead of the system spreading over the area today. Upper
level trough behind the front Monday with the trough axis moving
through Tuesday. Upper level ridge trying to build Wednesday. Next
system arriving late Thursday with another upper level trough
behind it for Friday.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...Satellite imagery shows weak
front moving into Western Washington this morning with another
front on its heels back near 130W. Lots of precipitation echoes on
the doppler radar but most of the rain is not making it to the
surface. Mild temperatures at 3 am/10z, mostly in the lower to mid
50s.

First system over the area this morning will continue to stretch
out and weaken with a little light rain over the area. Second
system near the coast by late afternoon with more consolidated and
widespread rain over Western Washington this afternoon. Little
change in temperatures with highs near the current readings.

Front moving through the area this evening with rain giving way
to showers after midnight. Could see a brief convergence zone east
of the Strait of Juan de Fuca mid evening but even if one forms
it will not last very long. Lows tonight in the mid to upper 40s.

Upper level trough over Western Washington Monday and Monday night
keeping showers in the forecast. High and low temperatures will be
a couple of degrees cooler than today, mostly mid 50s for highs
and lower to mid 40s for lows.

Upper level trough axis moving through Western Washington Tuesday
with an organized band of showers moving through the area midday
into the afternoon hours. Increasing onshore flow behind the
trough axis giving the area some breezy conditions with southerly
wind gusts as high as 30 mph. Convergence zone forming over
Snohomish county in the afternoon. Air mass unstable enough
behind the trough axis for a slight chance of thunderstorms along
the coast. Highs in the lower to mid 50s.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Upper level ridge
trying to build over Western Washington Wednesday. Ridge not very
impressive with 500 mb heights in the lower to mid 560 dms. Will
keep a chance of showers in the forecast.

Extended models showing good consistency bringing another system
into the area Thursday night with rain out ahead of the front
moving over the area mostly in the afternoon. Elevated snow levels
will keep the precipitation type as rain in the passes.

Trailing upper level trough moving into Western Washington Friday
keeping showers in the forecast.

Model consistency breaks down Saturday with the ECMWF showing a
weakening system moving down from the northwest approaching the
area while the operational GFS has a front spinning out of a cool
upper level low moving into Western Washington. ECMWF ensembles
hold the system together better than the operational run while the
GFS ensembles are weaker with the front than the operational run.
With the uncertainty will just go with chance pops.

Temperatures a little above normal the first couple of days, highs
in the mid 50s to mid 60s, cooling to a little below normal, in
the lower to mid 50s for Friday and Saturday. Felton

&&

.AVIATION...A trough over the NE PAC will bring SW flow aloft
throughout the period. A front offshore is ushering rain along the
coast. Rainfall is favored to track from west to east as steady
precipitation makes its way inland by this afternoon but pre-frontal
showers are a possibility as the morning progress. VFR currently but
MVFR conditions will become more widespread (after 18-20z) with
localized IFR/LIFR possible. Rain, low clouds/vis will persist
Sunday evening before gradually decreasing in coverage overnight
into early Monday before the next disturbance arrives before midday.

S/SE winds this morning 5-10 kt. Surface winds will become more S/SW
late Sunday morning with similar magnitude. Gusts up to 20 kt are
possible for terminals such as KBLI during the afternoon. Wind
speeds are favored to decrease overnight.

KSEA...VFR for much of the morning. Rain showers will increase
before transitioning to steadier rain around 21-22z. Here MVFR
conditions are favored to pick up as rain persists before breaking
up overnight into early Monday morning. S-SW winds between 5-10 kt.

McMillian

&&

.MARINE...A frontal system will track across area waters today.
Sustained winds are to remain below advisory criteria but can`t rule
out isolated wind gusts near SCA for the coastal waters and East
Strait. Nevertheless, a SCA remains in effect over the coastal
waters for high seas. Additional disturbances will traverse the area
for both Monday and Tuesday. Brief high pressure second half of
Wednesday into Thursday before the next area of low pressure enters
Thursday night.

Seas increasing to 10-11 ft today, starting at the outer coastal
waters first this morning. Seas are to remain elevated around 9-10
ft through Tuesday before easing to around 5 to 7 ft on Wednesday
and Thursday.

&&

.HYDROLOGY...Rainfall amounts over the Olympics in the next 72
hours have decreased in the 00z model run. The elevated snow
levels are still a little worrisome so can`t rule out the
Skokomish River getting to flood stage Wednesday morning. Right
now the forecast has the river cresting about a half a foot below
flood stage.

No river flooding expected on the remainder of the rivers for the
next 7 days. Felton

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 PM PDT Monday 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-Coastal Waters From Point Grenville To Cape Shoalwater
     10 To 60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater Out 10 Nm.

&&

$$