Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS66 KSEW 140444
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
844 PM PST Mon Nov 13 2017

.SYNOPSIS...Wind will ease this evening as a system over British
Columbia weakens and moves farther inland. Heavy snow is still
expected in the mountains through tonight. A second frontal
system will bring more rain and mountain snow Tuesday into
Wednesday, with snow levels near 3000 feet. Showery weather
Thursday will transition to a wet and warmer pattern with higher
snow levels through the weekend.

&&

.SHORT TERM...Winds are easing across Western Washington this
evening as the strong Pac system moves into southern B.C. and
weakens. The High Wind Warnings will expire as planned. However,
there are still impacts with moderate to heavy rain in the
interior and heavy mountain snow, mainly at the volcanoes. There
is also minor flooding on the Skokomish river in Mason county.

Tuesdays weather will be active as well as another strong frontal
system moves inland. Winds will be lighter compared to today but
may still see Wind Advisories for the coast and possibly the north
interior. Heavy snow is still an issue for the mountains where 1-3
feet of snow will fall, highest amounts again at the volcanos.
There is also a Winter Storm Watch in effect for the Cascades
Tuesday night into Wednesday as the slow-moving front drags
through. 33

.LONG TERM...Previous discussion...The second deep upper level
trough trailing the Tuesday/Wednesday frontal system will move
over Western Washington Thursday and Thursday night resulting in
cool showery weather. Snow levels will dip to around 2500 feet. An
short lived upper ridge will build over the region on Friday,
given the region a break. Medium range models continue to
highlighting transition to wet and much warmer pattern for the
weekend with snow levels reaching to around 4500 to 6000 feet.

&&

.AVIATION...Moist southwesterly flow aloft will continue tonight
and Tuesday. At the surface, southerly gradients will ease tonight,
then increase Tuesday. The air mass is slightly unstable. Ceilings
will be mainly MVFR tonight with occasional VFR. Another front will
move inland Tuesday for more rain and breezy winds.

KSEA...MVFR through the night. Southerly winds 12g22kt tonight will
ease somewhat overnight, then become southeast and increase to
15g25kt Tuesday. CHB

&&

.MARINE...The deep low that brought storm force winds to many waters
moved onto Vancouver Island and weakened considerably this evening.
Winds have eased to gale force or even lower. Gradients will ease
overnight, then tighten again Tuesday as another front moves inland.
Gales are likely on the coast Tuesday morning. Gales are also likely
Tuesday afternoon over the northern inland waters and east entrance,
with small craft advisory winds elsewhere.

A weaker surface low is forecast to approach Vancouver island
Wednesday, then move southeast across southern Vancouver Island
Thursday. A strong but slow moving cold front will approach the
coast Friday. CHB

&&

.HYDROLOGY...Minor flooding will continue on the Skokomish river
in Mason county due to heavy rain today. The river will continue
running high through Tuesday with more heavy rain in the forecast.

Aside from the Skokomish River, river flooding is not expected on
forecast area rivers through at least Friday.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...High Wind Warning until 9 PM PST this evening for Admiralty
     Inlet Area-Bellevue and Vicinity-Bremerton and Vicinity-
     East Puget Sound Lowlands-Eastern Strait of Juan de Fuca-
     Everett and Vicinity-Hood Canal Area-Lower Chehalis Valley
     Area-San Juan County-Seattle and Vicinity-Southwest
     Interior-Tacoma Area-Western Skagit County-Western Whatcom
     County.

     Winter Storm Warning until 4 PM PST Tuesday for Cascades of
     Pierce and Lewis Counties-Cascades of Whatcom and Skagit
     Counties.

     Winter Storm Watch from Tuesday afternoon through Wednesday
     morning for Cascades of Pierce and Lewis Counties-Cascades
     of Whatcom and Skagit Counties.

     Winter Weather Advisory until 4 PM PST Tuesday for Cascades of
     Snohomish and King Counties-Olympics.

     High Surf Advisory until midnight PST tonight for Central Coast-
     North Coast.

PZ...Small Craft Advisory for rough bar until 6 AM PST Wednesday for
     Grays Harbor Bar.

     Gale Warning until 10 AM PST Tuesday 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.

     Gale Warning until 4 PM PST Tuesday for East Entrance U.S.
     Waters Strait Of Juan De Fuca-Northern Inland Waters
     Including The San Juan Islands.

     Small Craft Advisory until 10 AM PST Tuesday for West Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from midnight tonight to 4 PM PST Tuesday
     for Admiralty Inlet-Central U.S. Waters Strait Of Juan De
     Fuca-Puget Sound and Hood Canal.

     Gale Warning until midnight PST tonight for Admiralty Inlet-
     Central U.S. Waters Strait Of Juan De Fuca-Puget Sound and
     Hood Canal.

&&

$$

www.weather.gov/seattle

You can see an illustrated version of this discussion at
www.wrh.noaa.gov/sew/gafd/latest_webafd.html


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.