High Surf Advisory 2, NWS Seattle, WA

Area Forecast Discussion
National Weather Service Seattle WA
315 PM PST Sat Jan 20 2018

.SYNOPSIS...A strong front will move through the area tonight and
Sunday morning.  Another strong front should cross Western Washington
Tuesday night and Wednesday. A cool showery upper trough will reach
the area Thursday.

&&

.SHORT TERM...A strong front will move through Western Washington
Sunday morning. Strong southeasterly gradients will develop and a
high wind warning is in effect for the typical windy spots--which
is the coast and the north. There will be heavy rain and snow and
windy weather in the Olympics, and the North Cascades and Baker
ought to do pretty well for heavy snow with this front, so the
watch became a warning. The main Cascade Passes snow will warrant
a lesser winter weather advisory.

The Skokomish river in Mason county should get up above flood stage
for some minor flooding Sunday afternoon and evening after heavy
falls in the lower elevations of the Olympics--strong south flow
aloft ought to give the lower terrain up to three inches of rain
from this front.

Behind the front the precip will turn showery and the air should be
unstable enough for a few thunderstorms--mainly along the coast
Sunday afternoon or evening. Showery weather will continue for the
first part of the week.

.LONG TERM...A vigorous frontal system is likely midweek,
followed by a cool showery upper trough. It is a little early to
sort out the details, but the pattern certainly looks good for
continuing to build the snowpack.

&&

.HYDROLOGY...The Skokomish river in Mason county has a good
chance to get above flood stage Sunday afternoon or evening,
otherwise River flooding is not expected for the next 7 days.

Rainfall through Sunday will probably push the USGS landslide
indices close to thresholds for shallow landslides.

&&

.AVIATION...A strong cold front will reach the coast and move
inland on Sunday morning. S-SE surface wind will become strong in
advance of the front tonight. Strong 850-700 mb winds will peak
near 70 knots from the southwest on Sunday morning. The air mass
will be moist and somewhat stable. A few hours of heavier rain
are expected Sunday morning, just in advance of the front.
Easterly wind component will generally hold cigs above 025, except
lower near Hood Canal.

KSEA...A few passing showers til 02z (6 pm), then dry for this
evening. Cigs will slowly lift through this evening as low-level
wind takes on a drying easterly component. S-SW winds aloft will
strengthen this evening and overnight, meeting the criteria to
include low-level wind shear in the TAF after 04z (8 pm). Strong
winds aloft expected Sunday morning. Winds aloft will peak 15z-18z
Sunday morning. At 045 will peak SW 65 knots, and 2000-foot winds
will peak southerly around 50 knots. Haner

&&

.MARINE...East-southeast gradient will tighten significantly
tonight in advance of a strong cold front that will cross the
waters on Sunday morning. Storm-force winds to near 50 kt appear
likely over the coastal waters and at the east entrance, but
cannot be ruled out over the Northern Inland Waters. The remaining
inland waters will likely see gale force winds. In Puget Sound,
gales should mainly be confined to the north end of the Sound.
Once the front passes late Sunday morning, winds will ease
somewhat abruptly.

Weaker southerly onshore flow will then follow from Sunday
afternoon through Monday morning. A warm front on Tuesday will
cause east to southeast gradients to become strong. Beyond
Tuesday, a series of fronts will continue to bring active weather
to the waters through the week ahead. Haner

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory from 10 PM this evening to 9 AM PST
     Monday for Cascades of Pierce and Lewis Counties-Cascades
     of Snohomish and King Counties.

     Winter Storm Warning from 10 PM this evening to 9 AM PST Monday
     for Cascades of Whatcom and Skagit Counties-Olympics.

     Flood Watch from late tonight through Sunday evening for Hood
     Canal Area-Lower Chehalis Valley Area-Olympics.

     Wind Advisory from 10 PM this evening to noon PST Sunday for
     Everett and Vicinity-Hood Canal Area.

     High Wind Warning from 8 PM this evening to noon PST Sunday for
     Admiralty Inlet Area-San Juan County-Western Skagit County-
     Western Whatcom County.

     High Wind Warning from 6 PM this evening to 10 AM PST Sunday for
     Central Coast-North Coast.

     Wind Advisory from 10 PM this evening to 10 AM PST Sunday for
     Eastern Strait of Juan de Fuca.

PZ...Small Craft Advisory for rough bar until 9 PM PST Monday for
     Grays Harbor Bar.

     Storm Warning from 6 PM this evening to 9 AM PST Sunday 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.

     Storm Warning from 6 PM this evening to noon PST Sunday for East
     Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Warning from 6 PM this evening to noon PST Sunday for
     Admiralty Inlet-Northern Inland Waters Including The San
     Juan Islands.

     Gale Warning from 6 PM this evening to 9 AM PST Sunday for West
     Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Warning from 6 PM this evening to 10 AM PST Sunday for
     Central U.S. Waters Strait Of Juan De Fuca.

     Gale Warning from 10 PM this evening to 10 AM PST Sunday for
     Puget Sound and Hood Canal.

&&

www.weather.gov/seattle