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000
FXUS66 KSEW 091102
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
402 AM PDT Tue Apr 9 2024

.SYNOPSIS...Gusty winds and widespread rain, and higher Cascade
snow, continues this morning as a front pushes through the
interior. Showers linger in a Puget Sound Convergence Zone into
the day, but otherwise a break in the weather with an upper ridge
developing over the region. This will bring warmer and drier
conditions through the middle of the week. Another cooler and more
active weather system then returns late in the week.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...Widespread rain and gusty
southerly winds continue across the region ahead of the advancing
cold front. Temperatures also remain rather mild, in the upper 40s
to lower 50s, with the region mostly in the warm sector of the
frontal system and the atmosphere remaining well mixed given the
winds. Have continued the ongoing Winter Weather Advisory for the
Cascades for now, but with the snow level remaining fairly high,
expect that any impacts will be confined to those engaging in
activity in the high Cascades rather than impacts to travel.
Expect the heaviest precipitation rates in the next few hours this
morning as the front sweeps across the interior, as well as
potentially in a Puget Sound Convergence Zone that develops later
today. Otherwise, expect showers to begin to taper into the
afternoon as heights begin to rise and upper level high pressure
builds. This will bring about a warming and drying trend through
Wednesday, though the clearing skies will likely bring a much
cooler nights with the temperature dipping into the lower or mid
30s with the coolest spots away from the cities and water.

Another weak disturbance may clip the region on Thursday, enough
to bring a return of rain across much of the region. That said,
this system likely brings little if any measurable rain to the
interior and only a bit (less than a quarter inch of rain) to the
coastal areas, so the bigger impact will be additional cloud cover
for most of the area.

.LONG TERM /FRIDAY THROUGH MONDAY/...Ensemble guidance continues
to favor the next disturbance remaining offshore and dipping to a
position off the California coastline. This would bring a return
to a more zonal flow pattern across the area, with some clusters
of guidance even boosting heights further. This will keep
temperatures near to slightly above normal for the end of the week
(Friday and Saturday) along with likely dry conditions, though
some low end rain chances do return. Snow levels remain around
5,000 feet or higher for Friday and Saturday, which should
preclude any travel impacts in the Cascades. Confidence remains
lower for the start of next week, with a fairly even split among
ensemble guidance suggesting the potential for a cool trough or a
continuation of the drier and warmer pattern. Will need to keep an
eye on this evolution as some of the cooler and more active depictions
would bring the potential for snow levels to dip to near or below
the Cascades passes by Monday.

&&

.AVIATION...Westerly flow turning more northwesterly this morning
as a front moves through western Washington. Rain has been
persistent over the region early this morning, with a range of VFR
to IFR conditions throughout interior terminals. This trend will
likely continue this morning as showers will continue to maintain
MVFR/IFR ceilings and visibilities. Conditions look to improve
into the afternoon, with shower activity decreasing and ceilings
rising gradually to VFR by 18z-20z. A weak convergence zone
developing around KPAE in the early afternoon will possibly keep
conditions around MVFR/IFR briefly. VFR will generally maintain
throughout the evening and into the overnight through area
terminals.

Breezy S/SW winds around 10 to 15 knots early this morning will
turn northerly by the afternoon around 19z-22z and start to
gradually decrease in speed to around 4 to 8 knots by 00z-02z.

KSEA...IFR conditions early this morning as heavier rain showers
continue to impact ceilings and visibilities. Showers will
gradually start to become more disorganized later this morning
which will help ceilings and conditions improve to MVFR. By the
late afternoon (18z-20z), ceilings will rebound to VFR and stay
that way through the evening and overnight period.

South/southwesterly wind around 12 to 15 knots early this morning
will shift northerly around 19z-21z and decrease to around 5 to
10 knots.

Mazurkiewicz

&&

.MARINE...A cold front has moved through the waters early this
morning, with small craft advisory southerlies already decreasing
over the waters. Small craft advisories over the coastal waters
and Puget Sound will be allowed to expire this morning as winds
will be under any threshold. A small craft advisory will remain
over the Central and Eastern Entrance of the Strait of Juan De
Fuca this afternoon for a westerly push down the Strait.

Broad high pressure will begin developing offshore this afternoon,
allowing for calm and benign marine conditions through midweek.

Combined seas around 7 to 9 feet will hover around that range
through much of the midweek, before decreasing around 5 to 7 feet
into the first half of the weekend.

Mazurkiewicz

&&

.HYDROLOGY...Rivers draining from the Olympics continue to run
high after heavy rainfall, but will crest well below flood stage.
Elsewhere, river flooding is not expected with today`s frontal
passage or through the remainder of the next seven days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until midnight PDT tonight for West
     Slopes North Cascades and Passes-West Slopes North Central
     Cascades and Passes-West Slopes South Central Cascades and
     Passes.

PZ...Small Craft Advisory until 9 AM PDT this morning for Grays
     Harbor Bar.

     Small Craft Advisory until 5 AM PDT early this morning 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-Puget Sound and Hood
     Canal-West Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 8 PM PDT this evening for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 11 AM PDT this morning for Admiralty
     Inlet.

&&

$$