Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 161111
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
311 AM PST Fri Feb 16 2018

.SYNOPSIS...A weather system will move onshore today with rain
changing to showers. A stronger system will reach the area later
tonight and Saturday resulting in windy conditions and more rain.
Cold air will push into the region Sunday with the snow level
falling to sea level. Dry conditions are expected for the first
part of next week.

&&

.SHORT TERM...A front is currently moving onshore with rain and
mountain snow. Advisory level amounts of snow are expected for
the Cascades today. There will be a brief and relative lull in
between weather systems this evening then the next front will
arrive. This system is a notch stronger that the one today. Windy
conditions are expected many areas - advisories will probably be
needed for some zones. Heavy snow is expected in the mountains - a
winter storm watch is currently in effect.

A cold upper trough will settle over the area on Sunday. At the
same time, strong Fraser outflow will develop, pushing a modified
arctic front south through Western Washington during the day.
Snow levels will fall to near sea level. Accumulations of an inch
or two are possible for parts of the lowlands. Highs will probably
occur early in the day for many areas with steady or even slowly
falling temperatures during the day. Schneider

.LONG TERM...Monday and Tuesday will be dry but chilly with
northerly flow aloft. Fraser outflow will ease but modified arctic
air will linger over the area. Highs will be mostly in the mid to
upper 30s and lows will be in the 20s with some teens in spots.
Some of this will depend on if there is any snow on the ground
from Sunday. A weather system will drop down from the north later
Wednesday or Wednesday night for another chance of rain or snow.
Schneider

&&

.AVIATION...Strong northwest flow aloft will continue into the
weekend. Cold front moving through the area mid morning reaching the
Cascades in the early afternoon hours. Rain out ahead of the next
much stronger system reaching the area overnight.

MVFR ceilings this morning with local IFR ceilings especially over
the Kitsap peninsula. Visibilities lowering to 3-5sm at times 15z-
20z. Onshore flow behind the front this afternoon and evening will
result little improvement in the ceilings outside of the end of the
pockets of IFR ceilings. Rain spreading into the area overnight
keeping the widespread MVFR ceilings intact.

KSEA...Low end MVFR ceilings through midday. Slight improvement in
the ceilings this afternoon and evening into the 2000-3000 foot
range. Southerly winds around 10 knots increasing to 12-18 knots
with gusts to 25 knots in the afternoon. Winds easing back down to 5
to 10 knots this evening. Very strong, sustained 20-30 knots with
gusts to 40 knots, southwesterly winds expected late Saturday
morning into Saturday afternoon. Felton

&&

.MARINE...A cold front will move southeast through the
waters today with southerly gradients and winds increasing. Not much
in the way of an immediate impact for most waters...however does
look like SCA conditions will be met in the outer coastal waters and
as such...will hoist the advisory with the morning forecast package.
Speaking of SCAs and the short term...headline in place for the
Central Strait looks to be a bust and will cancel with upcoming
forecast.

A strengthening low pressure center will move southeast down
Vancouver Island and across the Northwest Washington waters Saturday
afternoon before continuing to northeast Washington late Saturday.
Models remain on track that wind speeds with this system will meet
gale speeds and as such...although it is a bit far out in
time...will go ahead and issue a gale watch for all waters save for
Puget Sound.

Strong northeast Fraser outflow wind will spread out across the
waters on Sunday and Sunday night, possibly allowing for gales to
continue for the northern inland waters, the Strait and maybe
Admiralty Inlet. This Fraser outflow is expected to ease Monday.
Light gradients are expected Tuesday. Haner/SMR

&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until 7 PM PST this evening for Cascades
     of Pierce and Lewis Counties-Cascades of Snohomish and King
     Counties-Cascades of Whatcom and Skagit Counties.

     Winter Storm Watch from late tonight through late Saturday night
     for Cascades of Pierce and Lewis Counties-Cascades of
     Snohomish and King Counties-Cascades of Whatcom and Skagit
     Counties-Olympics.

PZ...Gale Watch from Saturday morning through Sunday morning for
     Admiralty Inlet-Central U.S. Waters Strait Of Juan De Fuca-
     Coastal Waters From Cape Flattery To James Island Out 10 Nm-
     Coastal Waters From James Island To Point Grenville Out 10
     Nm-Coastal Waters From Point Grenville To Cape Shoalwater
     Out 10 Nm-East Entrance U.S. Waters Strait Of Juan De Fuca-
     Northern Inland Waters Including The San Juan Islands-West
     Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Watch from late tonight through Sunday morning for Coastal
     Waters From Cape Flattery To James Island 10 To 60 Nm-
     Coastal Waters From James Island To Point Grenville 10 To
     60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater 10 To 60 Nm.

     Small Craft Advisory until 4 PM PST this afternoon for Coastal
     Waters From Cape Flattery To James Island 10 To 60 Nm-
     Coastal Waters From James Island To Point Grenville 10 To
     60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater 10 To 60 Nm.

&&

$$

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