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000
FXUS66 KSEW 241601
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
901 AM PDT Wed Apr 24 2024

.UPDATE...Surface observations have the front from just east of
Bellingham to just east of Hoquiam at 8 am this morning. Front
will continue to move slowly east today moving into the Cascades
this afternoon. Rainfall amounts along the north coast were around
a tenth of an inch with just a few hundredths in the Northwest
Interior. Weakening front combined with westerly flow aloft will
create a rain shadow over the Central Puget Sound but even outside
of the Central Puget Sound rain amounts with the front expected
to be 0.05 inches or less. Main weather story today is the cooler
temperatures with highs in the 50s. Today will be the first day of
at least the next 7 days with highs in the 50s for Western
Washington. Forecast on track this morning. Previous discussion
follows plus updated aviation and marine sections.

&&

.SYNOPSIS...Weak front moving inland today. This will mark the
beginning of a cool and wet last week of April with an upper level
trough over the area and a couple of systems moving through over
the weekend and Monday. Snow levels will lower over the weekend to
near 2500 feet Monday for possible snow on all the mountain
passes the first part of next week.

.SHORT TERM /TODAY THROUGH FRIDAY/...A pattern change brings
cooler and wetter weather back to western WA starting today. This
is due to an upper low moving through B.C. while dragging a weak
front over the region. KLGX is picking up on light rain along the
coast this morning. Rain will spread into the interior this
afternoon with light amounts expected - trace to 0.05" along I-5.
With onshore flow and cloudier conditions temperatures will track
closer to average and in the 50s.

Wet weather continues on Thursday with an upper level trough
crossing the area. Precipitation totals, overall, are greater
compared to Wednesday with measurable rain expected across all
lowlands.

Showers linger into Friday with a deep trough across the West.
Widespread measurable rain is expected again across the area.
Three-day rainfall totals are around 0.50-1" in the interior with
1-2" along the coast. Snow levels are around 4500` for mainly
rain at the Cascade highway passes. 33

.LONG TERM /SATURDAY THROUGH TUESDAY/...Upper level troughing
over the Pac NW continues into this weekend for more rain and
(high elevation) mountain snow. There`s little break in the action
with a pair of frontal systems pushing inland, thus maintaining
moist S/SW flow over the area. A deep upper low wobbles overhead
as we move into next week, keeping the air mass cool and showery.
Lows will track cooler than average and in the mid to upper 30s to
lower 40s. The cool spots will be over the south sound. Highs
will also be a few degrees below average and in the mid 50s. Snow
levels will lower to around 2500` on Monday and the mountain
highway passes may see a few inches of snow. Overall, a cool and
wet end to the month. 33

&&

.AVIATION...Winds W/SW aloft as an upper-trough builds in. Surface
winds are beginning to pick up, generally S/SW through the interior
and W along the coast. A mix of MVFR to VFR ceilings (with isolated
IFR along the coast) across the area this morning. CIGs will likely
bounce around between high MVFR to low VFR through this afternoon
into tonight. Scattered showers across the area this morning. While
generally light in nature, temporary visibility restrictions are
possible in heavier showers that pass over the terminals. Another
frontal system will approach early tomorrow morning which will bring
widespread MVFR to IFR ceilings and more persistent visibility
restrictions with stronger rain showers. Winds W 10 kt or less along
the coast, SW to S through the interior.

KSEA...MVFR ceilings with scattered showers in the vicinity this
morning. Ceilings will likely remain high-end MVFR with some breaks
to VFR possible through this afternoon and evening. A return to
lower MVFR ceilings is expected tomorrow morning, with some possible
visibility restrictions in heavier showers. Winds S to SW between 5-
10 kt.

LH

&&

.MARINE...A weak frontal system is approaching the area from the
northwest. Winds through the Strait of Juan de Fuca have diminished,
allowing the Small Craft Advisory to expire this morning. A more
substantial system will move through the area waters on Thursday.
Some uncertainty remains in how strong this winds will be along the
coastal waters. With probabilities of seeing SCA winds highest in
the waters south of Point Grenville (from 50-75%), a Small Craft
Advisory has been issued for Thursday. A weak surface ridge will
momentarily ease wind speeds for Saturday before an active pattern
re-emerges Sunday.

Seas look to remain 4 to 6 feet at about 10 seconds through the rest
of the week and into Saturday.

McMillian/LH

&&

.HYDROLOGY...No river flooding expected in the next 7 days.
Heavier rain over the south slopes of the Olympics Thursday and
Thursday night could push the Skokomish River in Mason county
close to action stage Friday. Felton

&&

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

&&

$$