Scientific Forecaster Discussion
fxus66 ksew 260314
Area forecast discussion
National Weather Service Seattle Washington
814 PM PDT sun Jun 25 2017
Synopsis...onshore flow will bring much cooler weather and mainly
night and morning clouds for the upcoming work week.
Short term...a thermal trough currently over the Cascades will
shift inland tonight with increasing onshore flow. Low clouds will
fill in along the coast this evening and spread at least partially
inland Monday morning before burning back to the coast later in
the day. Highs will cool 15-20 degrees on Monday but still be
slightly above normal. Low level onshore flow will continue
Tuesday and Wednesday with a weak upper trough over the area.
Night and morning clouds should be fairly extensive with some
afternoon sunshine for the interior each day as clouds burn off
diurnally. Highs will be near normal. Schneider
Long term...previous discussion...medium range models remain in
good agreement with varying degrees of onshore flow lingering
through at least Friday. An upper level ridge will move into the
coastal waters Thursday then onshore into Friday ahead of a weak
upper level trough that will brush the region on Saturday. This
system looks pretty weak, with the most likely scenario being a
chance of showers over the mountains Saturday. Models starting to
hint at a more consolidated system moving into British Columbia
Sunday or Monday. This mornings European model (ecmwf) run remains more progressing
with this system, bringing precipitation into western Washington
Sunday while the GFS runs have trended a bit slower and weaker
keeping most precipitation to the north of the area over British
Columbia Sunday evening or even Monday morning. The forecast was
updated to reflect a chance of precipitation Saturday night Onward
especially for the mountains and the northern areas. High
temperatures will remain near normal.
Aviation...an upper ridge will be replaced by a weak upper
trough through Monday and Tuesday. The warm dry air mass will give
way to cooler marine air and low stratus got into Hoquiam late
this afternoon. Most of The Lowlands of western Washington should
have marine clouds by morning while the mountains will continue to
have scattered high clouds.
Ksea...a marine push giving morning low clouds is the forecast
and that looks good.
Marine....marine air will push into western Washington tonight as
the hot thermal low pressure is down around 1007mb near The Dalles
while a 1017mb high center is along the Oregon coast. Oth-sea is
over 5mb this evening. The onshore flow will ease a bit Monday night
but will still persist into the week ahead--a much more typical and
cooler weather pattern.
Washington...heat advisory until 9 PM PDT this evening for Bellevue and
vicinity-Bremerton and vicinity-east Puget Sound lowlands-
Hood Canal area-Seattle and vicinity-southwest interior-
Pz...Small Craft Advisory until 3 am PDT Monday for coastal waters
from Cape Flattery to James Island out 10 nm-coastal waters
from James Island to Point Grenville out 10 nm.
Small Craft Advisory until 6 PM PDT Monday for coastal waters
from Cape Flattery to James Island 10 to 60 nm-coastal
waters from James Island to Point Grenville 10 to 60 nm-
West Entrance U.S. Waters Strait of Juan de Fuca.
Gale Warning until 9 am PDT Monday for East Entrance U.S. Waters
Strait of Juan de Fuca.
Small Craft Advisory until 6 am PDT Monday for northern inland
waters including the San Juan Islands.
Gale Warning until 6 PM PDT Monday for central U.S. Waters
Strait of Juan de Fuca.