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FXUS66 KSEW 052137
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
237 PM PDT Sat Apr 5 2025

.SYNOPSIS...Dry and mild weather this afternoon and evening with
increasing high and mid level clouds. Rain will spread slowly from
the coast inland Sunday. Next week will see a typical Spring
pattern with what looks to be a couple of frontal systems
early and late in the week with drier weather midweek.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...Satellite imagery this
afternoon showing high level clouds working through much of
western Washington ahead of the very slow system approaching the
area from the west. Despite the high clouds there has been a good
mix of sunshine this afternoon and very mild mid-April
temperatures in the upper 60s as of mid afternoon. It wouldnt be
much of stretch to see a few spots hit the lower 70s, especially
away from the water late this afternoon. The upper level ridge
shifting east of the area tonight and the front expected to make
very slow progress. Rain ahead of the front is expected along
coast in the early morning hours - but will take its time to reach
inland. Hires ensembles like the HREF and UW system all pretty
consistently showing light rain reaching the metro area in the
early afternoon and the Cascades by late afternoon. The frontal
system will moving through Sunday night with heaviest
precipitation - mostly rain - along the coast and Olympic
Peninsula - especially over the Olympic Mountains. Snow levels
will remain 6500 to 7500 feet, so it will be a rainy evening for
all but the highest elevations in the mountains. There may be some
gusty winds during the afternoon in the usual spots like Whidbey
Island, with only a 10 to 20% of gusts above 45 mph. Near normal highs
in the mid and upper 50s. Lows in the mid and upper 40s.

The upper level trough will move into the area Monday leaving it
more of a transition day with showers in over much of the area as
well as perhaps enough instablilty for a 10 to 20% chance of
thunderstorms - mainly along the coast during the afternoon
hours. Highs will remain in the mid 50s. The longer range grand
ensembles continue to highlight a good chance for a quick moving
system for Tuesday/Tuesday evening. Heavier precipitation looks
to be to the south - mainly over Oregon, and it continues to look
very progressive.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...The grand ensembles
follow up the Tuesday system with some degree of upper level
ridging Wednesday. This will result in some degree of drier
weather and a bump in temperatures mid week, but will likely be
shortlived. There continues to be a good bet at another fast
moving system being region late in the week - right now looking
like Thursday. This looks like a progressive and weaker system
mostly focused north of Washington - over Vancouver Island and
British Columbia. This may be followed by another shortlived upper
level ridge late in the week/early in the weekend for some drier
weather. All in all pretty typical Spring weather with temperatures
near or slightly above normal through the period.

&&

.AVIATION...Southwesterly flow aloft continues as an upper level
trough begins to move towards western Washington. VFR conditions
will prevail through the rest of today. A frontal system will begin
to slowly approach the coast tonight. Chances for rain will begin
along the coast overnight in the early morning hours on Sunday and
will slowly move into the interior late Sunday morning into Sunday
afternoon. Ceilings will slowly lower tonight but remain VFR. MVFR
to IFR conditions (isolated LIFR in heavier rain) will begin along
the coast tomorrow morning as the front slowly moves inland, with
MVFR conditions not arriving into the interior until around 18-21Z
Sunday.

Southwesterly winds 5 to 10 kt this afternoon through the Seattle
metro terminals, elsewhere, winds are light and variable. Winds will
remain light tonight. Tomorrow, winds will be south to southeasterly
5 to 10 kt.

KSEA...VFR through the majority of the TAF period. Ceilings will
slowly lower tonight. Rain beings to reach the terminal tomorrow
morning, with ceilings lowering to MVFR shortly thereafter.
Southwesterly winds 5 to 10 kt will ease and turn to southeast 5 kt
or less tonight, winds light and variable at times. Winds will pick
back up again tomorrow south/southeasterly to 5 to 10 kt.

62

&&

.MARINE...High pressure will depart tonight as a frontal system
will traverse the area waters tonight into Sunday. Winds will
increase across the coastal waters ahead of the front but look to
remain below thresholds. Several additional systems will traverse
the area early next week, but the system Monday night into Tuesday
does look to bring a round of breezier winds that will likely
require additional small craft advisory headlines. High pressure
looks to briefly rebuild on Wednesday for a break in the active
pattern.

Seas, presently 3 to 6 ft, will slowly increase tonight, reaching
the 10 to 12 ft range Sunday afternoon and evening, and remaining in
the 8 to 13 ft range through Tuesday. Seas look to ease to around 5
to 7 ft on Wednesday.

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&&

.HYDROLOGY...Periods of Spring rain next week will result in rises
on area rivers. The heaviest period of rain is forecasted for the
Olympics into Tuesday with the Skokomish River expected to reach
action stage and possibly minor flood stage Tuesday night. River
flooding is not expected elsewhere.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 AM Sunday to 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.

&&

$$