Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 250320
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
820 PM PDT Thu Sep 24 2020

.SYNOPSIS...The next vigorous system will approach the region
late tonight before moving inland early Friday. This system will
bring another round of gusty winds and widespread rain to Western
Washington. Rain chances will linger into the weekend, before high
pressure aloft brings a drying and warming trend to the area early
next week.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...Active conditions are
generally winding down for the night, with only a few lingering
showers in the south King county area. Winds will increase overnight
ahead of the next system. Friday`s system will bring another round
of heavy rain and strong wind to the area. Wind will be strongest
along the coast, in the north interior and along the northern slopes
of the Olympics. The Sound will experience breezy southerlies
through mid-day, before gradually easing. Precipitation will begin
between 06-09Z along the coast before spreading further inland.
Tomorrow`s system will also contain an enhanced level of moisture,
with additional rainfall amounts of a half inch to another inch of
rain across the lowlands, with mountainous locations possibly
receiving another 2 to 4 inches. A High Surf Advisory remains in
effect for the coast through Friday afternoon. Minor erosion
impacts are possible, as well as causing dangerous conditions near
the surf zone.

Residual showers are possible on Saturday as a shortwave disturbance
traverses the region. By Sunday, the precipitation chances will
become more confined to higher terrain as a weak ridge builds in the
area. Temperatures look to be in the mid to upper 60s across the
region through the weekend.

Kristell

.LONG TERM /MONDAY THROUGH THURSDAY/...Drier and warmer conditions
will persist next week as an upper level ridge becomes the dominant
influence across the Pacific Northwest. Low level offshore flow will
develop on Monday and Tuesday, allowing for highs to warm into the
70s. The ridge axis looks to shift inland near midweek, potentially
allowing for Wednesday to be the warmest day across the region, with
afternoon highs climbing into the mid to upper 70s. 14

&&

.AVIATION...Shower activity across the region has largely
decreased this evening, with residual showers possible along the
coast. Overnight, conditions will be in IFR to LIFR criteria along
the coast as the next weather system moves in, with VFR to MVFR
criteria at inland terminals through the 10-11z timeframe. As rain
spreads inland, visibilities and ceilings are expected to decrease
by early morning. Winds will also increase at all terminals
overnight, with gusty conditions arriving at the coast between 06-
09Z. Gusts at coastal locations are expected to exceed 25 mph.
Inland locations will also be gusting by 10-12Z.

KSEA...VFR conditions expected at the terminal until roughly 10-11Z
with possible shower activity developing near the terminal.
Conditions expected to deteriorate to IFR early Friday morning as
the next system arrives. Winds expected to be elevated out of the
south overnight, gusting over 25 mph at times early in the morning.

Kristell

&&

.MARINE...A strong frontal system will move inland early Friday
bringing gales over the Coastal Waters, East Entrance and Northern
Inland Waters with Small Craft Advisory winds over remaining
waters. Strong onshore flow will follow Friday afternoon then ease
Friday night. Meanwhile, seas remain at 12 to 17 feet and will
subside on Saturday. High pressure and offshore flow will follow
early next week. 33

&&

.HYDROLOGY...A vigorous frontal system will bring another round
of heavier rainfall later tonight and Friday. River flooding is not
forecast at this time but additional rises to many rivers is
expected - particularly those draining from the Olympics and North
Cascades. An additional 2-5 inches of rain is likely over the
mountains with this frontal system tonight and Friday.

A drying trend will begin over the weekend with some light rain
lingering in spots. Dry weather will return early next week.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory from midnight tonight to 10 AM PDT Friday for
     Central Coast-North Coast-San Juan County-Western Skagit
     County-Western Whatcom County.

     High Surf Advisory until 2 PM PDT Friday for Central Coast-North
     Coast.

PZ...Small Craft Advisory until 11 AM PDT Saturday for Grays Harbor
     Bar.

     Small Craft Advisory from 11 AM Friday to 11 AM PDT Saturday 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 11 AM PDT Friday 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-East Entrance U.S. Waters Strait Of Juan De Fuca-
     Northern Inland Waters Including The San Juan Islands.

     Small Craft Advisory from 11 AM to 11 PM PDT Friday for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 5 AM PDT Saturday for West Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 11 PM PDT Friday for Admiralty Inlet-
     Puget Sound and Hood Canal.

&&

$$

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