Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 262110
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
222 PM PDT Wed Jul 26 2017

.SYNOPSIS...Coastal marine layer clouds will push into Western
Washington overnight, then burn off Thursday afternoon. Friday
and Saturday will likely see fewer morning low clouds, and then
Sunday and Monday will probably have a bit more marine air. But
no significant weather systems will affect the area.


&&

.SHORT TERM...Onshore flow tonight will give Western Washington
deeper marine layer clouds and cooler temps on Thursday--but the
clouds should burn off in the afternoon. We might see a few spots
get a couple hundredths of drizzle--the best chance of that is
where the clouds bank up against the Olympics. There will be less
marine air for the end of the week and max temps should be warmer
for a couple days. Marine layer clouds Friday and Saturday might
be confined to the coast in the morning hours. Maybe some fog will
squirt down the Strait and into the Chehalis gap a bit.

.LONG TERM...The dry weather pattern where morning low clouds
is the extent of the moisture for the area will continue. Marine
stratus looks like it will increase for the morning hours Sunday
and Monday, and then maybe it will back off again. Sunny afternoons
and temps seasonably warm are still a good bet for the interior
of Western Washington, and cool weather with morning clouds is
usually a good bet on the coast anyway. Around the middle of next
week we may see a hot spell develop for a few days, but it is
a little early to make any big bets on that--the ECMWF shows
some rather warm weather, but the GFS has another one of these
troughs moving through British Columbia that would bring some
cooler marine air into Western Washington.

&&

.AVIATION...Southwest flow aloft will prevail tonight and
Thursday with a broad upper trough over the area. At the surface,
onshore flow will continue with high pressure offshore and lower
pressure inland. The air mass is stable.

Stratus is expected to fill in at the coast this evening and
spread inland overnight. By morning, most of the area should be
covered in low clouds. The low clouds should partially burn off
over the interior in the afternoon.

KSEA...Clear this evening. Low clouds will reach the terminal
early Thursday morning and then burn off in the afternoon. West
wind 4-8 knots will become south tonight. Schneider

&&

.MARINE...Onshore flow will continue for the next several days
with high pressure offshore and lower pressure inland. Gale
force west winds are expected over the Central and Eastern Strait
of Juan De Fuca tonight. Small craft advisory strength west winds
are likely each night in the Strait for the rest of the week.
Schneider

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Gale Warning until 5 AM PDT Thursday for Central U.S. Waters
     Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of
     Juan De Fuca.

     Small Craft Advisory from 5 PM this afternoon to 5 AM PDT
     Thursday for Admiralty Inlet-Northern Inland Waters
     Including The San Juan Islands.

&&

$$

www.weather.gov/seattle

You can see an illustrated version of this discussion at
www.wrh.noaa.gov/sew/gafd/latest_webafd.html



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