Gale Warning 39, NWS Seattle, WA

Area Forecast Discussion
National Weather Service Seattle WA
939 AM PST Sun Nov 3 2024

.SYNOPSIS...Unsettled weather conditions will linger over the
weekend with showers continuing, especially in the Cascades. A
stronger frontal system will arrive on Monday for more rain,
widespread windy conditions, mountain snow and high surf
conditions. Drier weather is possible by midweek.

&&

.UPDATE...The system on Monday has become increasingly dynamic
with the primary threats being mountain snow, strong winds, and
high surf. The Winter Storm Watch has been upgraded to a Winter
Storm Warning for the Cascades above 3500 feet Monday into
Tuesday, with a Winter Weather Advisory added for the higher
elevations of the south central Cascades (mainly for the higher
passes and locations around Mt Rainier). Additionally, with the
strong winds both ahead and behind the system Monday, High Wind
Warnings and Wind Advisories were hoisted. At this time, the
central Puget Sound was left out of these products as current
guidance suggests sheltering in these areas. Furthermore, while
wind gusts may be somewhat borderline with this event, given there
is still ample foliage on trees in the region we believe the
level of alert is justified given the potential level of impact.

The updates this morning were primarily for the new/upgraded
products and we will be digging into updating the forecast
parameters next. In addition, we will be looking at potential High
Surf products for Monday. The good news is tides should remain
below any flood thresholds, even along the outer coast where wave
activity will be significant.
-Wolcott-

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...Western WA is under NW flow
today with a strong ridge offshore and troughing over the
Intermountain West. On radar, lingering showers over the region
with a weak ripple in the flow. Light snow showers still expected
in the Cascades this morning with snow levels around 3500-4000' -
a Winter Weather Advisory remains in effect. Expect drier weather
by the afternoon with temps in the 50s.

A stronger Pacific frontal system will reach WA on Monday for
more rain, wind, mountain snow and high seas. Classic baroclinic
leaf pattern spotted in the satellite imagery offshore with rapid
cyclogenesis and deepening over the next 24 hours. Much of western
WA will be breezy to windy through the day with highest winds
over the coast and north interior. Winds switch to westerly Monday
afternoon and evening with a strong push through the Strait of
Juan de Fuca. Meanwhile, up in the Cascades, strong/westerly
upslope winds will help generate snow showers in a cool air mass
(snow levels around 3500-4000'). There's potential for periods of
heavy snow in the north and central Cascades and a Winter Storm
Watch is in effect. As for rainfall, we're looking at another inch
for the coast and around 0.25-0.50" in the interior with the
wettest period during the morning hours. And lastly, high seas, as
mentioned below in the marine section, with swells reaching 18-22
ft.

Showers lingering into Tuesday with onshore flow and light warm
frontal precip but overall the weather will be quieter compared to
Monday. 33

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...High pressure brings
drier weather from Wednesday through the end of the week as
moisture is deflected north into B.C. Temperatures will be cooler,
though, with lows dipping into the 30s Wednesday and Thursday
mornings. The ridge shows signs of weakening/flattening toward the
weekend with rain returning to western WA. 33

&&

.AVIATION...Northwesterly flow will persist aloft as a series of
upper level troughs move over the region. Rain shower coverage has
decreased over the area, and should remain isolated throughout the
day today. Ceilings are primarily MVFR across western Washington,
with periods of IFR under isolated showers. Ceilings should remain
MVFR and slowly rise to VFR, first this morning along the coast,
then through the interior late morning into early this afternoon.
Lower ceilings and rain will begin appear towards the end of the TAF
period as a cold front begins to approach the region.

Winds will generally persist from the south at 4-8 kt, though will
begin to increase to 8 to 15 kt at the end of the TAF period. The
exception is KCLM and KHQM, where winds will transition to more
westerly.

KSEA...MVFR ceilings will continue through this morning, rising to
VFR early this afternoon, around 21Z, and remain VFR through most of
the TAF period. Today should be mostly dry, but a few isolated
showers are possible around the terminal. Winds will generally
persist out of the south at 4-8 kts and will begin to increase
around 12Z Monday as the next system approaches the area.

LH/Mazurkiewicz

&&

.MARINE...A weak cold front has moved through western Washington
this morning, with slightly elevated winds over the coastal
waters.

A break in windy conditions across the area waters this afternoon
will be brief before the next system approaches the area late
tonight into Monday. Gale force winds are likely across the coastal
waters as well as through the Strait of Juan de Fuca as a cold front
passes through the area, for which Gale Watches have been issued. A
brief period of gale force winds are possible through the Northern
Interior Waters as well, but look to a brief period Monday morning
as the front moves through. Winds will likely reach small craft
advisory levels through Admiralty Inlet, Puget Sound, and Hood Canal
as well on Monday. Latest guidance this morning continues to
indicate the potential for gusts to reach storm force (up to 50
kt) through the Central Strait of Juan de Fuca Monday afternoon
and evening, which will be once again monitored for the afternoon
forecast package.

High pressure building back into the area on Tuesday will allow
for winds to gradually ease across the area waters. High pressure
then looks to persist into Wednesday, though a weakening warm
front may skirt the coastal waters as it approaches British
Columbia. High pressure will then remain situated over the coastal
waters through Thursday before a weakening system approaches the
region on Friday into next weekend.

Seas 8 to 12 ft early this morning will continue to rise up to 14 to
18 ft through the day as long period swell generated by a low
pressure system in the Gulf of Alaska moves into the coastal waters.
The dominant period of these waves will be around 19-20 seconds.
Seas then look to rapidly rise again on Monday morning up to 18 to
22 ft as the strong cold front approaches the area. Seas will then
start to gradually subside on Tuesday, though likely not subsiding
below 10 feet until early Wednesday. Seas will then hover between 5-
8 ft through the remainder of the week.

LH

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...High Wind Warning from 4 AM to 2 PM PST Monday for North Coast-
     San Juan County-Western Skagit County-Western Strait of
     Juan De Fuca-Western Whatcom County.

     Wind Advisory from 4 AM to 2 PM PST Monday for Central Coast-
     East Puget Sound Lowlands-Everett and Vicinity-Lower
     Chehalis Valley Area-Southwest Interior-Tacoma Area.

     High Wind Warning from 4 AM Monday to 4 AM PST Tuesday for
     Admiralty Inlet Area-Eastern Strait of Juan de Fuca.

     Winter Storm Warning from 4 AM Monday to 10 AM PST Tuesday for
     West Slopes North Cascades and Passes-West Slopes North
     Central Cascades and Passes.

     Winter Weather Advisory until 10 AM PST this morning for West
     Slopes North Central Cascades and Passes-West Slopes South
     Central Cascades and Passes.

     Winter Weather Advisory from 4 AM Monday to 10 AM PST Tuesday
     for West Slopes South Central Cascades and Passes.

PZ...Small Craft Advisory until 4 PM PST Monday for Grays Harbor Bar.

     Small Craft Advisory until 4 AM PST Monday 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-West Entrance U.S. Waters Strait Of
     Juan De Fuca.

     Gale Watch from late tonight through Monday evening for West
     Entrance U.S. Waters Strait Of Juan De Fuca.

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

     Gale Watch from Monday morning through late Monday night for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Gale Watch from late tonight through Monday evening 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.

&&