Small Craft Advisory 81, NWS Seattle, WA

Area Forecast Discussion
National Weather Service Seattle WA
255 PM PDT Fri Apr 20 2018

.SYNOPSIS...A warm front will brush the area this evening. A
trailing cold front will move through overnight with decreasing
showers behind the front Saturday. A dry upper trough will cross
the area Sunday. An upper level ridge will build in Sunday night
and remain over Western Washington through most of next week for
an extended dry and warm spell.

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.SHORT TERM...A weak warm front will move through the area this
evening with spotty light rain - mainly coast and northwest
interior. A trailing cold front will bring a quick shot of rain to
most of the area later tonight.

Showers behind the front will quickly become mostly confined to
the mountains Saturday. Moderate onshore flow will produce breezy
to locally windy conditions behind the cold front. It will be a
few degrees cooler compered to today but still close to normal. A
Puget Sound Convergence Zone will likely form during the day and
linger into Saturday night.

Sunday is looking dry with decreasing clouds. A weak upper trough
will cross the area in the morning with an upper upper ridge
building in from the west later in the day. Highs will once again
be near normal. The upper ridge will move overhead on Monday for
dry and warmer weather. Schneider

.LONG TERM...High pressure aloft will produce mostly sunny and
warm weather Tuesday through Thursday. Highs will warm into the
70s many areas. Thursday will probably be the warmest day -
possibly near 80 in spots with low level offshore flow. Onshore
flow is expected to develop Friday which should cool highs back
into the 60s. Some showers could also move into the area from the
south. Schneider

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.AVIATION...Clouds will thicken up through this evening as a weak
warm front clips the area. There are areas of rain on the coast
that will spread inland overnight. The cold front will move ashore
overnight and then the rain will turn to showers Saturday
morning. A PSCZ should develop Saturday, then shift south and
break up later in the day. The mountains will become obscured
tonight and remain mostly obscured Saturday.

KSEA...Rain will increase overnight then turn to showers
Saturday morning. It will become breezy overnight. A PSCZ will
develop Saturday morning then shift south through Seattle in the
afternoon.

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.MARINE...A warm front will clip the area this afternoon and
evening and then a stronger cold front will push through the area
overnight. Small craft advisories for the waters will give way to
Gale warnings for the Central and Eastern Strait of Juan de Fuca
behind the cold front--several hours of gales just after daybreak
seem likely at Race Rocks and in the central Strait to perhaps
Smith Island. High pressure will build into the area behind the
front and into Sunday. A thermal trough will set up along the
Oregon coast Monday and Tuesday, so we will probably see northerly
breezes develop over Western Washington Monday and Tuesday--
perhaps stronger than the current forecast and better for
afternoon sailing than the current forecast indicates which only
has north winds to 10 knots over the inland waters for now.

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.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until noon 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-Puget Sound and Hood Canal.

     Small Craft Advisory until 3 AM PDT Saturday for Central U.S.
     Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
     Strait Of Juan De Fuca.

     Gale Warning from 3 AM to noon PDT Saturday for Central U.S.
     Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
     Strait Of Juan De Fuca.

     Small Craft Advisory until 3 PM PDT Saturday for Admiralty Inlet-
     Northern Inland Waters Including The San Juan Islands-West
     Entrance U.S. Waters Strait Of Juan De Fuca.

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