Wind Advisory 17, NWS Seattle, WA

Area Forecast Discussion
National Weather Service Seattle WA
936 PM PDT Thu Nov 3 2022

.SYNOPSIS...An atmospheric river will bring heavy rain, gusty winds,
mountain snow, and river flooding to the area through early
Saturday. The system will shift south on Saturday with cooler air
moving in on Sunday and lasting into the first part of next week.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...Satellite imagery shows
warm front approaching Western Washington this evening with rain
out ahead of the front across most of the area. Snow levels near
3500 feet for the most part with the cold air a little slow to
arrive. Shallow layer of cold air trapped at Snoqualmie pass
keeping the snow level right at the Snoqualmie summit in the pass.
Southeasterly winds ahead of the front over the Northwest Interior
with winds gusting 25 to 35 mph at 9 pm. Temperatures were in the
lower to mid 40s over the interior. Warmer air starting to arrive
along the coast with temperatures there near 50.

Breaking down the variables tonight...

Heavy Rain: Later tonight through early Saturday will feature the
heaviest rainfall. Several inches of rain are expected along the
coast and central Cascades as a warm front drapes itself from west
to east over western Washington. Heavy rain is expected to taper
off from north to south Friday night, but the westerly push
associated with the cold front arriving Friday evening may
invigorate a convergence zone along the King/Snohomish County
border Saturday.

Snowfall: Warmer air a little slow to arrive keeping snow levels
at the lower pass levels into the early morning hours. Snow levels
will rise quickly especially over the Central and Southern
Cascades early Friday morning. A winter weather advisory is in
effect for the north Cascades beginning this evening for areas
above 4,000 feet. Six to twelve inches of snow is possible over
Mount Baker. A winter weather advisory is also in effect for the
central Cascades for 4 to 8 inches of snow before the change to
rain overnight.

Wind: Gusty winds along the coast and north interior through the
overnight hours. 30 to 40 mph winds with gusts to 50 mph are
expected, which could blow unsecured objects around and
potentially cause minor tree damage. Isolated impacts to power may
also be possible. As the trailing cold front reaches the area
Friday evening, a strong westerly push will occur and impact the
Strait of Juan de Fuca, as well as Admiralty Inlet and western
Snohomish County. Storm force winds possible for the Central and
Eastern Strait of Juan de Fuca and Admiralty Inlet Friday night.
High wind watch will remain in effect for the adjacent land areas
around Admiralty Inlet. Westerlies could be strong enough for
possible high wind as far east as Western Snohomish county and a
high wind watch for Friday night will continue for this location
as well. Felton

.LONG TERM /MONDAY THROUGH THURSDAY/...Previous discussion
follows. Much cooler temperatures and showery weather will
prevail by the start of next week. Afternoon highs will struggle
to get much higher than the mid 40s, with the overnight lows
securely in the 20s and 30s. It is not too early to think about
things and people that are vulnerable to the cold, including pets,
pipes, sensitive plants, and demographics such as the elderly and
young children. There is a chance of a wintry mix in areas east
of I-5 and along western Kitsap County on Monday morning,
transitioning to showery conditions in the afternoon. Confidence
in this is very low and not much more details beyond a chance can
be expanded upon at this time. Much of the weather over the next
week will be drier by Tuesday with little to no widespread
precipitation.

Kristell

&&

.AVIATION...Widespread rain will continue increase in intensity
through the overnight, with moderate to heavy rainfall through the
day Friday before a cold front pushes into the region from the
northwest Friday night. Ceilings mostly in the 1500-2500 foot
range with local ceilings below 1000 feet and visibility 3-5sm in
moderate rain through Friday afternoon.

KSEA...Ceilings near 4000 feet will lower to near 2000 feet by 09z
and remain in the 1000-2000 foot range into Friday afternoon.
Southerly winds 8 to 12 knots becoming southwest 10 to 15 knots
with gusts 25 to 30 knots by 18z Friday. Felton

&&

.MARINE...Frontal system stalling over the waters tonight into
Friday with gale force winds over most of the waters into Friday
morning. The exception is the Puget Sound and Hood Canal with
small craft advisory winds. Increasing onshore flow behind the
front with a strong push of westerlies down the Strait of Juan de
fuca for possible storm force winds Friday night in the Central
and Eastern Strait as well as Admiralty Inlet. Winds will then
gradually subside Saturday night into Sunday, before
transitioning offshore early next week. Guidance does hint at the
potential for Fraser Outflow winds Monday-Tuesday.

Seas across the coastal waters in the 10 to 15 foot range tonight
building to 15 to 20 feet Friday into Friday night. Seas subsiding
slightly Saturday. Maz/Felton

&&

.HYDROLOGY...An atmospheric river will bring a period of moderate
to heavy rainfall to the area tonight through Friday night. Total
precipitation for this time frame range from 5 to 8 inches in the
Cascades and Olympics, except for the North Cascades with 3 to 4
inches forecast. The Seattle area will be in the rain shadow
initially. This will lower rain amounts down to 1 to 1.5 inches.
For the remainder of the lowlands 2 to 3.5 inches expected. Along
the coast, forecasted rain amounts are in the 3 to 5 inch range.
Rain will come to an end from north to south Saturday morning.

Flood watches are in effect for most of the counties from Lewis
county northward. Rivers will begin to reach flood stage Friday
afternoon with the Skokomish and the Snoqualmie near Carnation
approaching major flood stage Saturday.

Rain rates are forecast to be high enough that a flash flood
watch is in effect for the Bolt Creek burn scar for late Friday
morning through early Saturday morning. Even with front moving
south the post frontal convergence zone Friday night will be
close to the burn scar extending the watch into early Saturday
morning. Felton

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory until 8 AM PDT Friday for Admiralty Inlet Area-San
     Juan County-Western Skagit County-Western Whatcom County.

     Flood Watch through Saturday afternoon for Admiralty Inlet Area-
     Bellevue and Vicinity-Central Coast-East Puget Sound
     Lowlands-Eastern Strait of Juan de Fuca-Everett and
     Vicinity-Hood Canal Area-Lower Chehalis Valley Area-North
     Coast-Olympics-Seattle and Vicinity-Southwest Interior-
     Tacoma Area-West Slopes North Cascades and Passes-West
     Slopes North Central Cascades and Passes-West Slopes South
     Central Cascades and Passes-Western Skagit County-Western
     Strait of Juan De Fuca-Western Whatcom County.

     High Wind Watch Friday evening for Admiralty Inlet Area-Everett
     and Vicinity.

     Wind Advisory until 5 AM PDT Friday for Central Coast-North
     Coast.

     Winter Weather Advisory until 5 AM PDT Friday for West Slopes
     North Cascades and Passes.

     Winter Weather Advisory until 1 AM PDT Friday for West Slopes
     North Central Cascades and Passes.

     Flash Flood Watch from Friday morning through late Friday night
     for West Slopes North Central Cascades and Passes.

PZ...Small Craft Advisory from 6 AM Friday to 6 AM PDT Saturday for
     West Entrance U.S. Waters Strait Of Juan De Fuca.

     Storm Watch from Friday afternoon through late Friday night for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Gale Warning until 2 PM PDT Friday for Admiralty Inlet-East
     Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland
     Waters Including The San Juan Islands.

     Storm Watch from Friday evening through late Friday night for
     Admiralty Inlet.

     Small Craft Advisory until 11 AM PDT Friday for Puget Sound and
     Hood Canal.

     Gale Warning until 11 PM PDT Friday 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.

&&