000
FXUS66 KSEW 141736
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
1035 AM PDT Sun Apr 14 2024

.SYNOPSIS...Weak high pressure overhead today before upper-
level troughing returns on Monday bringing cooler temps and showers
back to western Washington. Ridging will return later this week with
the potential for more warm and dry weather.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...Current satellite imagery
shows that some low stratus are still present along the coast...some
some even getting as far east as just shy of Shelton. The remainder
of W WA however is seeing mostly clear skies with perhaps a stray
cirrus here and there.

Upper level ridging in place is likely to keep things that way for
much of the day today before clouds associated with the incoming
frontal system start to work their way into the area tonight. Timing
still remains a little fuzzy as deterministic models continue to
waffle on timing...the GFS favoring a later frontal entry than the
ECMWF. Neither model seems to be particularly impressed with precip
amounts, each one showing the system to be far weaker than in
previous runs. Ensembles tending to agree with these current
reduction in expected precip amounts and both deterministic and
ensemble data all seeming to agree on letting the chances for precip
linger throughout much of Tuesday...with ensemble QPF guidance even
showing a bit of a bimodal split as opposed to grouping precip all
together as in previous runs. Ultimately, current forecast tries to
straddle the line of incorporating the new data into the old
trend...and this appears to be the best way to go for now...keeping
the earlier starting time with the front making it to the coast at
or around 12Z Monday morning, then allowing PoPs to linger
throughout much of Tuesday with highest chances during the event
still remaining over the Cascades.

Temps today still expected to be split with mid to upper 50s
expected along the coast and water adjacent locations while the
interior will top out in the mid to upper 60s. Monday and Tuesday
will see temps more uniform throughout the area as well as cooler,
with highs in the lower to mid 50s.

Inherited forecast is on track with no need for any updates at this
time.

18

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...From Previous
Discussion...Conditions are continuing to trend drier again midweek
onward. Deterministic guidance continues to hint at a ridge
amplifying around Wednesday-Thursday and lasting towards the
weekend. But, questions remain on its exact location and intensity.
Nevertheless, the brief cool down to start the week on Monday may
not last too long as temps could possibly top out in the upper 60s
to near 70 F on Friday. Ahead, much uncertainty is present this far
out, but a weak front could brush the area on Saturday.

McMillian


&&

.AVIATION...Zonal flow aloft as W WA is situated between an upper
level low to the south in NV and the incoming system still off the
BC coast. Surface winds mostly onshore.

VFR conditions in place over much of W WA although along the coast,
stratus will result in MVFR to IFR conditions at times. This is
expected to burn off by 20Z. Widespread VFR conditions expected this
afternoon and evening. Most interior sites will remain VFR during
the overnight, however clouds will increase and cigs lower while
still remaining VFR. Coastal spots, being closer to the incoming
system, will see cigs emerge quicker with MVFR conditions possible
again as early as 00-06Z.

KSEA...VFR cigs with high clouds at times into tonight. Another
round of stratus may be possible again Sunday morning, however
confidence is low, with generally a 15-20% chance of IFR cigs. North-
northeasterly winds 5 kt or less tonight turning to the northwest 5
to 10 kt after 17Z Sunday morning.

15/18

&&

.MARINE...High pressure will continue through the weekend with Small
Craft Northwest winds along the coastal waters today. Winds will
then increase with a frontal system this evening into Monday,
particularly for the Strait of Juan de Fuca and adjacent interior
waters, including Admiralty Inlet and the Northern Inland Waters. A
Gale Warning remains in effect for the central and eastern Strait of
Juan de Fuca with the increasing west winds. Northwest winds will
continue to remain breezy into Monday for the Coastal Waters with
this system. Winds will likely weaken Monday morning before
increasing once again Monday evening through the Strait of Juan de
Fuca with another round of gales possible Monday evening into Monday
night. Winds look to ease Wednesday into Thursday with building high
pressure over the area waters.

Seas will remain 9 to 12 feet through Monday with the highest waves
over the northern Coastal Waters. Waves will also be steep into
Sunday with a 9 to 10 second period. Seas will begin to subside
Tuesday and further Wednesday towards 4 to 6 feet.

15/18


&&

.HYDROLOGY...No river flooding is expected through the next seven
days.


&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 7 AM PDT Monday 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-
     West Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Warning until 7 AM PDT Monday for Central U.S. Waters
     Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of
     Juan De Fuca.

     Small Craft Advisory until 7 AM PDT Monday 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.

&&

$$