Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 261530
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
830 AM PDT SUN JUN 26 2016

.SYNOPSIS...An upper ridge will build as it moves across the
region, bringing sunny warmer weather to Western Washington today
and Monday. Isolated thunderstorms are possible over the
mountains Monday afternoon and evening. Fair weather will continue
Tuesday through Saturday with light southwest flow aloft, onshore
flow at low levels, and temperatures slightly above normal.

&&

.SHORT TERM...The upper ridge will continue to build as it moves
across Western Washington today, with 500 mb heights rising to
around 5820 meters. Low level flow will remain northerly, with only
a very weak onshore component this afternoon. Morning stratus should
be limited to only the coast, with sunny skies otherwise. It will be
a warmer today with highs mainly in the 70s to lower 80s. Some
parts of the south interior will get into the mid 80s.

The ridge will build further as it moves into the Rocky Mountains
tonight and Monday, and the flow aloft over Western Washington
will back to southwest as a very weak upper shortwave reaches the
area. The shortwave could trigger isolated afternoon and evening
thunderstorms over the mountains, but otherwise it will be a
mostly sunny day. The upper heights will change little, and the
lower part of the air mass will warm slightly. Highs will be
around 1 to 3 degrees higher inland, and 1 to 3 degrees lower at
the coast as onshore flow increases there during the day.

The increase in onshore flow associated with the upper shortwave
should deepen the marine layer on the coast, and marine stratus
could move into the lower Chehalis Valley and parts of the south
interior and south Puget Sound region late Monday night and early
Tuesday morning. The morning clouds should burn off though for
sunny skies and just slightly cooler weather.

.LONG TERM...Models agree that the upper ridge position will
remain over the Rockies during the extended period Wednesday
through Saturday, with weak southwest flow aloft over Western
Washington. The 500 mb heights will be around 5820 meters, give or
take, with light to moderate onshore low level flow. Aside from
some late night and morning marine stratus, mainly at the coast,
the days should be mostly sunny. Highs will be a little above
normal, mainly in the 70s to lower 80s.

&&

.AVIATION...An upper ridge will move over the region today and
then over Eastern Washington tonight with westerly flow aloft
becoming southwest. At the surface, onshore flow will prevail with
high pressure offshore and lower pressure inland. The air mass is
dry and stable. Areas of stratus at the coast will burn off late
this morning. Otherwise, skies will be clear.

KSEA...Clear. Northerly wind 7-14 knots. Schneider/13

&&

.MARINE...Onshore flow will prevail for the next five days with
high pressure offshore and lower pressure inland. There will be
small craft advisory west winds in the Central and Eastern Strait
most evenings. Onshore gradients will gradually increase Monday and
Tuesday and gales are possible by Tuesday evening. There will also
be small craft advisory northwest winds for the coastal waters at
times the next several days. Schneider/13

&&

.SEW Watches/Warnings/Advisories...
WA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 2 AM PDT Monday
     for 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 5 PM this afternoon to 2 AM PDT Monday
     for Coastal Waters From Cape Flattery To James Island 10 To
     60 Nm.

     Small Craft Advisory from 5 PM this afternoon to 1 AM PDT Monday
     for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.

&&

$$

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