Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 272237
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
237 PM PST Mon Jan 27 2020

.SYNOPSIS...A front will move through Western Washington this
evening. Additional precipitation will fall through Tuesday as the
associated low pressure system weakens and moves ashore.
Additional frontal systems will affect the region Wednesday
through Saturday.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...A front will move through
the area this evening. A few periods of fairly organized shower
activity will follow the front tonight through Tuesday. The passes
ought to pick up about a foot of snow from this system but travel
probably wont be impacted a great deal since it hasn`t been cold
--although it will probably get slushy at Snoqualmie Pass tonight.
 Tuesday night will see a break in the weather, and then a couple
 of warmer fronts ought to reach the area Wednesday and Thursday.
 The low pressure centers associated with these two fronts are
 nowhere near Western Washington and a little breezy weather is
 about all we will see with these fronts.

.LONG TERM /FRIDAY THROUGH MONDAY/...The frontal system slated for
Friday and Saturday will be wet and mild, although the heavy rain
in the 12z GFS ends up over Vancouver Island and southwest
British Columbia Friday night and Saturday. The ECMWF has more
rain for Western Washington with less of a tendency to lift the
precip north of here--although for Friday afternoon and evening
only the Olympics and North Cascades have the heavy precip. Behind
that frontal system cooler drier air will arrive for Sunday and
Monday. 19



&&

.AVIATION...RA beginning to spread eastward across Western
Washington at this hour. Expect this to move over all TAF sites by
lat afternoon, lowering CIGS to around high end MVFR levels through
the remainder of the period. Prevailing winds out of the south-
southeast between 5 and 15kts with an occasional higher gust to 25
kts along coastal and northern interior TAF sites.

KSEA...RA expected to move over the terminal by 23Z, bringing CIGS
down to MVFR levels through the remainder of the period.
Southeasterly winds generally AOB 10 kts will prevail through much
of the period, becoming southerly overnight into Tuesday morning.
Pullin

&&

.MARINE...A frontal system will continue to move through the coastal
waters tonight, yielding gale force winds into the overnight hours.
Small Craft Advisory winds will spread through the Strait and into
the interior waters this evening. Conditions will relax briefly
before additional systems push through later in the week. Additional
headlines will be needed from mid week onward.

&&

.HYDROLOGY...With the exception of the Skokomish river, flooding
is not expected through Thursday. The Skokomish will remain above
flood stage through the week. A possible atmospheric river
scenario could set up beginning later Thursday and continue into
Saturday. This event has the potential to create another round of
flooding on area rivers.

&&

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until 10 AM PST Tuesday for Cascades of
     Pierce and Lewis Counties-Cascades of Snohomish and King
     Counties-Cascades of Whatcom and Skagit Counties-Olympics.

PZ...Small Craft Advisory until 10 PM PST Tuesday for Grays Harbor
     Bar.

     Small Craft Advisory from 10 PM this evening to 10 PM 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 10 PM PST this evening 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 Tuesday for Admiralty Inlet-
     East Entrance U.S. Waters Strait Of Juan De Fuca-Northern
     Inland Waters Including The San Juan Islands.

     Small Craft Advisory until 6 AM PST Tuesday for West Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until midnight PST tonight for Central U.S.
     Waters Strait Of Juan De Fuca.

&&

$$

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