Small Craft Advisory 275, NWS Seattle, WA

Area Forecast Discussion
National Weather Service Seattle WA
759 PM PST Wed Dec 15 2021

.UPDATE /0900 PM/...Showers continue to move through the area this
Wednesday night. For the lowlands it is not looking good for snow
chances as current temperatures are in the mid to upper 30s, with
dew points in the mid to upper 30s. So even if a heavier showers
were to pass through and cool things down, it would only be a
couple of degrees. Snow levels are forecasted to be between 1000
and 1500 through tonight, so the hills could see some snow with
minor accumulations possible. Looking at satellite imagery we do
see some areas of clear sky (mainly off the coast). If conditions
clear out during the overnight temperatures in some locations
could drop down to freezing. Meaning we could see some icy roads
come the morning.

The previous forecast discussion with an updated aviation and
marine sections is below.

Butwin

&&

.SYNOPSIS...A system sliding south along the coast this
afternoon is bringing rain and some rain/snow mix to the area into
this evening. A trough will slide across the interior Pacific
Northwest on Thursday for light precipitation. A stronger system
will move through Saturday into Saturday night. A cooler weather
pattern next week.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...Areas of rain across the
coast and into the southern/central Puget Sound this afternoon as
a system slides along the coast. A light snow or rain/snow mix has
been observed along the Hood Canal area this afternoon, although
little to no snow accumulation across this area. The Winter
Weather Advisory has been cancelled for the Mason/Kitsap County
areas with mainly light precipitation into this evening, with
snow or rain/snow mix possible. Precipitation will taper this
evening into tonight as the system slides to the south. A trough
will slide across the interior Pacific Northwest into Thursday for
light snowfall across the Cascades and possibly a mix into the
Cascade Foothills.

Dry weather Friday as some weak ridging moves across the area. A
weather system will move through Friday night and Saturday for
increasing lowland rain, breezy winds, and mountain snow. Snow
levels will increase on Saturday to 3500-4500 feet, for a
rain/snow mix or rain at Snoqualmie Pass. The winds will be
breezy, especially along the coast and across the northern
interior areas of Western Whatcom/Skagit Counties, Admiralty
Inlet, and the San Juan Islands. The heaviest precipitation will
slide across the area Saturday afternoon into Saturday night.
Temperatures into the 40s through Friday, with highs in the upper
40s to near 50 on Saturday.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Some precipitation across
the area on Sunday as troughing slides offshore along the coastal
area. Ensembles are consistently highlighting troughing offshore
of the West Coast, particularly southwest of the area Monday into
mid week. The forecast does have a chance for precipitation with
the troughing, with the potential for drier weather Monday into
mid-week, however, some uncertainty in the actual setup of the
trough area. The weather pattern will be cooler with air filtering
in from BC, highs in the 40s, and lows in the 30s. JD

&&

.AVIATION...An area of rain moving north through the central
Puget Sound area will likely move northward and weaken over the next
few hours, followed by scattered showers that will likely linger
through the evening before tapering off early Thursday morning. MVFR
ceilings may improve somewhat behind the stratiform rain - but will
likely lower again through early Thursday morning at many locations
through the interior and coast - with some dipping down to IFR
levels particularly south of Puget Sound. Temperatures remain pretty
marginal with the coolest areas - in the mid 30s - over the central
Kitsap Peninsula westward to the Olympic Mountains. A rain/snow mix
is possible there. The gusty easterly winds will ease through the
evening.

KSEA...MVFR conditions with stratiform, light rain will transition
to showers before midnight. Ceilings 2500 to 3000 feet this evening
will lower to closer to 2000 feet by 12Z then improve to 3500 feet
by late morning. Milder temperatures tonight - aided by the easterly
winds - will keep any precipitation that falls overnight as rain.
The easterly winds will ease over the next few hours- but linger
through 12-14Z, then become more southerly.

&&

.MARINE...Elevated winds over the coastal waters will ease
this evening. Seas are expected to remain enhanced advisory level
conditions are expected for seas between 9-12 feet at 11-14 seconds.
Weak high pressure will build over area waters Thursday into early
Friday followed by another, stronger front late Friday into
Saturday. This will bring another round of potential gales for
portions of the forecast area, and seas building to above ten feet.

&&

.HYDROLOGY...River flooding is not expected over the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 4 PM PST Thursday 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.

     Small Craft Advisory until 1 AM PST Thursday for Grays Harbor
     Bar.

     Small Craft Advisory until 10 PM PST this evening for Admiralty
     Inlet-East Entrance U.S. Waters Strait Of Juan De Fuca.

&&

www.weather.gov/seattle