Scientific Forecaster Discussion
fxus66 ksew 261521
Area forecast discussion
National Weather Service Seattle Washington
822 am PDT Tue Sep 26 2017
Synopsis...an upper ridge will build over the region. The air will
warm and dry and low level offshore flow will develop Wednesday.
A cold front will arrive Friday and an upper trough on Saturday.
Short term...areas of clouds and a patchy fog will give way to
sunshine. An upper ridge will build over the region and low level
offshore flow will develop. Except for patchy morning fog, Wednesday
will warm up with highs getting well into the 70s across the area.
Some lower 80s are possible through the Chehalis gap and in the
interior from about Shelton and Olympia southward. Thursday promises
to be the warmest day of the upcoming warm spell as the upper ridge
shifts off to the east and offshore flow continues. Most locations
in the interior will see temps rise into the upper 70s to mid
80s in the warmest spots.
Long term...onshore flow ahead of a frontal system will increase
Thursday night and a cold front will reach western Washington on
Friday. An upper trough reaches the area Saturday for showers. Cool
unsettled weather will likely persist into next week.
Aviation...areas of morning clouds and a few patches of fog will
give way to sunshine. Clear skies tonight and Wednesday--except for
patchy morning fog. The air will be dry and stable as an upper ridge
builds over the area Wed.
Ksea...some low level moisture this morning then sunshine and a
Marine...the flow will turn northerly today then offshore on
Wednesday as a thermal trough forms along the coast. Onshore flow
will increase on Friday as a cold front moves inland. Onshore flow
will persist through the weekend.