Small Craft Advisory 121, NWS Seattle, WA

Area Forecast Discussion
National Weather Service Seattle WA
200 PM PDT Thu May 31 2018

.SYNOPSIS...An upper trough is moving through the region. A weak
front will reach the coast late Friday afternoon--the front will
dissipate as it moves inland Friday night. A ridge will build
somewhat on Saturday. An upper trough will affect the area Sunday
and Monday--additional weak upper troughs will brush the region
through next Thursday.

&&

.SHORT TERM...An upper trough is over Western Washington with
scattered showers--showers are likely in a PSCZ this evening. A
weakening front will brush the area Friday afternoon and night--a
few areas of light rain are likely, mainly on the north coast, in
the Olympics, and perhaps a few other spots. The front could just
break up and give some areas of drizzle and a low overcast Friday
night. Some ridging should make for a decent Saturday afternoon.

.LONG TERM...An upper trough should bring showers into the area
Sunday and Monday. Both the 12z GFS and ECMWF show a lot of shower
activity blossoming over the area Sunday afternoon--so if that
occurs it could be quite cool Sunday. Monday is also likely to be
a cool day with some showers activity with a chance of a PSCZ late
in the day. Weaker troughs will brush the area through the rest of
next week--in a pattern that looks favorable for marine layer
cloudiness, maybe a few showers on the coast and in the north, and a
chance for some sunshine each day as the marine layer lifts and
breaks up each afternoon. Temps will probably stay near average.

&&

.AVIATION...High pressure aloft will build over the area tonight
as an upper trough moves inland. A frontal system will reach the
area on Friday. The flow aloft will be westerly. At the surface,
onshore flow will ease tonight and turn southerly on Friday ahead
of the approaching front. A Puget Sound Convergence Zone is likely
this evening. The air mass is stable. Mostly mid and high level
moisture through this evening. MVFR low clouds should increase
across the area late tonight.

KSEA...Mid and high clouds through this evening. MVFR low clouds
are likely again Friday morning. A Puget Sound Convergence Zone
is expected just north of the terminal this evening. Winds should
be southerly tonight but they could switch to northerly for a few
hours this evening if the convergence zone sags far enough south.
Schneider

&&

.MARINE...Onshore flow will ease after midnight tonight. The
Central and Eastern Strait of Juan de Fuca should reach gale this
evening although it looks marginal. There should also be small
craft advisory westerly winds tonight for the adjacent inland
waters.

A frontal system will move into the area Friday and then weaken
and move inland Friday night. Gradients will turn southerly with
the front and small craft advisory strength winds are likely for
the Coastal Waters. Onshore flow will return behind the front on
Saturday and continue into early next week. Schneider

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 AM to 5 PM PDT Friday for Coastal
     Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.

     Small Craft Advisory from 5 AM to 11 PM PDT Friday 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.

     Small Craft Advisory from 11 AM to 11 PM PDT Friday for Coastal
     Waters From Cape Flattery To James Island Out 10 Nm-Coastal
     Waters From James Island To Point Grenville Out 10 Nm.

     Small Craft Advisory from 11 AM to 5 PM PDT Friday for Coastal
     Waters From Point Grenville To Cape Shoalwater Out 10 Nm.

     Small Craft Advisory until 5 PM PDT this afternoon for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Gale Warning from 5 PM this afternoon to 2 AM 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 from 6 PM this evening to 5 AM PDT Friday
     for Admiralty Inlet-Northern Inland Waters Including The
     San Juan Islands.

     Small Craft Advisory until 6 PM PDT this evening for West
     Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 5 PM this afternoon to 11 PM PDT this
     evening for Puget Sound and Hood Canal.

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