Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Seattle Washington
900 PM PDT Monday Jul 28 2014
Synopsis...high pressure aloft will bring warm sunny days to
western Washington through early next week at least.
Short term...southwest flow aloft continues over western
Washington...as a strong upper ridge dominates the western part of
the United States. At the surface...thermally induced low pressure
east of the Cascades is maintaining weak onshore flow. Skies
remained generally clear across western Washington this evening...
with marine stratus hugging the coast.
The large scale pattern will change little through Thursday. The
ridge will remain strong with weak low level onshore flow. Marine
stratus will push weakly inland from the coast each night --
probably just reaching Whidbey Island and the San Juans through the
Strait of Juan Delaware fuca...and just to the south end of Puget Sound sound
and Hood Canal through the Chehalis gap. The stratus will burn off
quickly each morning...for sunny days with highs in the 70s at the
coast and mainly in the 80s inland.
Moisture rotating around the upper high is producing some
thunderstorms over the Oregon Cascades this evening. These storms
will occur Tuesday through Thursday as well...peaking each day
during the late afternoon and evening. They could reach the border
of Oregon and Washington some days...but we are expecting them to
remain just to the south and east of our forecast area. Mcdonnal
Long term...here is the long term section from the afternoon
forecast discussion -- an upper ridge will remain the dominant
feature over the western USA through early next week. The primary
differences in the medium range solutions were in the details. As
stated in the short term section...will need to keep a close eye on
disturbances rotating around the upper high centered over the Desert
Aviation...an upper ridge is over the western U.S. And it will persist.
Southwest flow aloft. Surface high pressure offshore with thermal
low pressure east of the Cascades. Some areas of fog and low clouds
along the coast will push into the Strait of Juan Delaware fuca during the
late night and morning hours...otherwise the air is dry and stable.
Ksea...clear with a northerly breeze.
Marine...high pressure offshore with thermal low pressure inland
will result in varying degrees of onshore flow for the next week.
The strongest wind will occur in the central and eastern Strait of
Juan Delaware fuca and over the coastal waters during the late afternoon
and evening hours. Areas of late night and morning fog can be
expected over the coastal waters and in the Strait of Juan Delaware fuca.
Pz...Small Craft Advisory in effect for the coastal waters and
central/eastern Strait of Juan Delaware fuca.
You can see an illustrated version of the forecast discussion at