Gale Warning 4, NWS Seattle, WA

Area Forecast Discussion
National Weather Service Seattle WA
855 AM PST Mon Jan 7 2019

.SYNOPSIS...Showers will taper today and end by this evening as an
upper ridge moves overhead. Wind and rain will return Tuesday and
Wednesday as a another frontal system moves through. Additional
weather systems will keep things wet at times for the remainder of
the week into the weekend.

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.SHORT TERM.../TODAY THROUGH WEDNESDAY/ A cool upper level trough
knocked snow levels down overnight with a few lowland snow
reports, mainly near the Cascades and in Snohomish county (in the
Lake Stevens area). Amounts are low, an inch or less, and roads
looks good on the cams. Surface temperatures are above freezing
and we should see highs in the low to mid 40s. Up in the
mountains, we could see an additional 1-3 inches of snow in the
central Cascades this morning so the Winter Weather Advisory was
extended in time. Otherwise, showers in general will be tapering
off this afternoon and evening as onshore flow weakens and the
gradients flip to offshore. Highlights for the next system, as
mentioned below, will likely be gusty east winds below the Cascade
gaps with Wind Advisories possible. 33

Previous discussion...Showers will end entirely this evening as
an upper ridge moves across the area. Rain will spread into the
area from the southwest on Tuesday as the next frontal system
approaches the area. It will remain wet at times through Wednesday
with the frontal system eventually moving onshore. A deep surface
low will move into the Offshore Waters on Tuesday with increasing
easterly gradients. This could bring some windy conditions to the
East Puget Sound Lowlands near gaps in the terrain. Breezy to
windy conditions are likely coast and north interior on Wednesday
as the low moves north well offshore and easterly gradients become
southeasterly. Schneider

.LONG TERM.../THURSDAY THROUGH SUNDAY/ A frontal wave will lift
through the area on Thursday for rain at times. High pressure
aloft will build east of the area on Friday pushing most of the
rain north and west of the area for a mainly dry day. A couple of
weak fronts will move onshore over the weekend for a little rain
at times. Schneider

&&

.AVIATION...Westerly flow aloft today as an upper level trough exits
the region and a weak upper ridge moves into the coastal waters. The
air mass is moist and somewhat unstable this morning, but will
gradually dry this afternoon with low level onshore flow weakening.

Generally VFR conditions over much of W WA this morning...although
some lingering stratus are keeping cigs MVFR over SEA and BFI. Those
conditions are expected to improve by late morning. Low level flow
will turn offshore tonight with high level moisture increasing
across the area ahead of the next approaching weather system.

KSEA...MVFR cigs this morning becoming VFR after 18Z as showers
diminish. Remaining VFR tonight with increasing high level moisture.
Surface winds S-SW to 10 knots shifting to NE after 00Z. 27/SMR

&&

.MARINE...Onshore flow will ease and turn offshore today. A deep
surface low will move into the Offshore Waters tonight through
Tuesday night with small craft advisory strength easterly winds
developing over the Coastal Waters and in the Strait of Juan de
Fuca. Gale force east winds are possible for the West Entrance to
the strait and the adjacent northernmost Coastal Waters Tuesday and
Tuesday night. Models remain consistent with this solution...so will
likely upgrade inherited gale watches into warnings for the
afternoon package. The low will lift north offshore on Wednesday
with an associated front that is progged to move through the area.
Another frontal system will approach W WA Thursday. Schneider

&&

.HYDROLOGY...A series of somewhat wet systems could push the
flood-prone Skokomish River in Mason County above flood stage
Thursday or Friday. Otherwise, rainfall is not expected to be
heavy enough to cause flooding on other rivers across Western
Washington for the next week or so. Albrecht

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until 1 PM PST this afternoon for
     Cascades of Snohomish and King Counties.

     Winter Weather Advisory until 10 AM PST this morning for
     Cascades of Pierce and Lewis Counties.

PZ...Small Craft Advisory from 10 PM this evening to 4 AM PST
     Wednesday for Central U.S. Waters Strait Of Juan De Fuca-
     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 Watch from this evening through late Tuesday night for
     Coastal Waters From Cape Flattery To James Island 10 To 60
     Nm-Coastal Waters From Cape Flattery To James Island Out 10
     Nm.

     Small Craft Advisory from 7 AM Tuesday to 4 AM PST Wednesday for
     East Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from midnight tonight to 4 AM PST Wednesday
     for Northern Inland Waters Including The San Juan Islands.

     Gale Watch from Tuesday morning through Tuesday afternoon for
     West Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 10 PM this evening to 10 AM PST
     Tuesday for West Entrance U.S. Waters Strait Of Juan De
     Fuca.

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