High Surf in Washington, January 10 to 12, 2021

Area Forecast Discussion
National Weather Service Seattle WA
835 PM PST Sat Jan 9 2021

.UPDATE...The current forecast remains on track this evening and
no changes are planned. Showers associated with the frontal system
currently pushing onshore at this hour and will spread across the
region tonight. Current hi-res guidance suggests showers will
cease across most of western Washington by Sunday afternoon.

Pullin

&&

.PREV DISCUSSION... /issued 320 PM PST Sat Jan 9 2021/

SYNOPSIS...A weak system will approach the coast this evening
and move inland into Sunday with light lowland rain and mountain
snow. A wetter pattern returns for Monday into mid-week with
heavy rain and potentially gusty winds.

SHORT TERM /TONIGHT THROUGH TUESDAY/...We had a foggy start to
the day but now seeing dry and partly to mostly cloudy skies. The
ridge over the region will exit tonight as our next Pacific
frontal system moves inland. This fairly weak frontal system will
bring light rain and a few inches of mountain snow tonight into
Sunday. Another frontal system will clip the area mainly Sunday
afternoon through Sunday night for more rain and high elevation
mountain snow. The Cascade passes may see a wintry mix with lower
snow levels due to ease winds. It'll be windy in the usual places
as well - coast and north interior - with Wind Advisories
possible.

A wetter and more active period of weather is expected through
Tuesday under strong and moist W/SW flow. This is another AR or
Atmospheric River event where we'll see rising snow levels and
periods of heavy rain, especially over the mountains. Highest
rainfall totals will be over the south slopes of the Olympics with
rises on the rivers once again (and flooding on the Skokomish).
Rivers flowing off the west slopes of the Cascades will see rises
too and a few rivers will be close to minor flooding - a
hydrologic outlook has been issued. 33

LONG TERM /WEDNESDAY THROUGH SATURDAY/...Our AR event will
continue into early Wednesday then taper off by the afternoon or
evening as a baroclinic band exits. River flooding and gusty winds
will remain the primary impacts. Lowland 48-hour rainfall totals
ending Wednesday afternoon will range from 1-2" in the interior
to 2-3" along the coast. This may put more pressure on our already
saturated soils which leads to an increase threat for landslides.
High pressure may bring a period of dry and quiet weather toward
the end of next week, based on ensemble mean forecasts. 33

AVIATION...Southwesterly flow aloft through Sunday. Weakening
front moving through the area Sunday morning. Low level easterly
flow weakening Sunday.

Ceilings near 10000 feet lowering after 06z with the onset of rain
to 3500-5000 feet and after 09z to 1500-2500 feet. Coastal terminals
may see brief periods of IFR to LIFR cigs. Local visibility 3-5sm
with the rain. MVFR ceilings continuing into Sunday afternoon with
ceilings improving late Sunday afternoon to 3500-5000 feet.

KSEA...Ceilings near 10000 feet lowering to 4000 feet after 06z
and to near 2000 feet around 09z. Rain lowering visibility to
3-5sm at times 09z-15z. Mvfr ceilings continuing into Sunday
afternoon with ceilings improving late afternoon back up to
around 4000 feet. Light wind becoming southeasterly 4 to 8 knots
this evening. Southeast wind 4 to 8 knots continuing into Sunday.

Felton/Kristell

MARINE...A front will move through the area Sunday morning.
A series of vigorous frontal systems will affect the region
Monday through Wednesday. High pressure will build over the waters
Wednesday night and Thursday.

Gale force winds over the coastal waters tonight with small craft
advisory winds over the remainder of the waters with the exception
of the Puget Sound and Hood Canal. Winds easing slightly on
Sunday. Another round of gales for the coastal waters Sunday
night and for the coast, Northern Inland Waters and East Entrance
to the Strait of Juan de Fuca Monday night.

Seas will remain high for the next few days with swells ranging from
13 to as high as 21 feet tonight through Thursday. Highest swells
possible Sunday afternoon.

Felton/Kristell

HYDROLOGY...A series of wetter frontal systems will arrive on
Monday, with periods of heavy rain with higher snow levels into
Wednesday. This may give rise to flooding concerns once again, but
extent of river flooding will hinge on just how much
precipitation falls - this forecast is still a bit uncertain. See
ESFSEW for hydrologic outlook. The threat for landslides will
become elevated again during this period with a concern for
localized urban flooding as well.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...High Surf Advisory from 6 AM to 6 PM PST Sunday for Central
     Coast-North Coast.

PZ...Gale Watch from Sunday evening through late Sunday 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-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.

     Small Craft Advisory from 6 AM to 6 PM PST Sunday 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 6 AM PST Sunday 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.

     Small Craft Advisory until 6 AM PST Monday for Admiralty Inlet-
     Grays Harbor Bar-Northern Inland Waters Including The San
     Juan Islands-West Entrance U.S. Waters Strait Of Juan De
     Fuca.

     Small Craft Advisory until 2 PM PST Sunday for East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 6 AM PST Sunday for Central U.S.
     Waters Strait Of Juan De Fuca.

&&

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