Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Seattle Washington
900 am PDT Sat Jul 4 2015
Synopsis...the warm spell will continue through the middle of next
week. Cooler weather will arrive late next week as an upper trough
nears the area and onshore flow increases.
Short term...well above average temperatures will continue into the first
half of next week. Even the coast will warm up on Sunday as the
surface thermal trough expands westward over the coastal waters. A heat
advisory is in effect through Sunday evening for inland areas
Seattle southward. Weak onshore flow will return Monday. Highs will
cool 10-15 degrees at the coast and there will likely be some
morning low clouds and fog for the coast again but the interior of
western Washington will remain rather warm.
Long term...the warmth will continue through at least Wednesday as
low level onshore flow is likely to remain weak. A cooling trend
should start Thursday and Friday as an upper trough nears the area.
The upper low that has been off calif is shown shifting over northern
calif Thursday and Friday...with showers spreading across Oregon. There are
also showers shown over b.C. Associated with a northern upper trough
Friday and Sat...but western Washington is mainly dry.
Aviation...strong high pressure remains offshore while an upper
level low spins over northern Alberta. The flow aloft over western
Washington is W/NW. The air mass is dry. Skies are clear except for patchy
low level stratus clouds along the central coast...but these clouds
will erode late this morning. High pressure and offshore flow will keep
skies clear tonight and sun for VFR conditions.
Ksea...VFR conditions. Light north winds at the surface. 33
Marine...northerly flow will prevail over the waters today with
surface high pressure over b.C. Models show north/northwest winds of 15 to 25 knots
over the outer coastal waters - a Small Craft Advisory is in effect
through noon today.
Offshore flow will develop tonight and sun as a thermal trough of
low pressure forms along the coast. The flow will flip back to onshore
Monday and Tuesday as low pressure shifts inland. 33
Washington...a heat advisory is in effect until midnight Sunday night for
parts of the Puget Sound sound region.
Pz...Small Craft Advisory in effect for the coastal waters from Cape
Flattery to Cape Shoalwater from 10 nm out to 60 nm until noon