917
FXUS66 KSEW 160308
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
808 PM PDT Sat Jun 15 2024

.SYNOPSIS...Unsettled, cool conditions will persist over Western
Washington into Sunday as an upper level trough remains over the
region. The trough will shift east of the region on Monday and a
trend toward warmer and drier conditions will commence Tuesday
through the end of the week as higher pressure aloft gradually
rebuilds into the region.


&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...Showers remain across
much of western Washington this evening, although the thunderstorm
threat is largely over for the night. Rain that is approaching the
burn scars is continually being monitored for any potential debris
flow or flooding threat. This too should taper off heading into
the late evening. Otherwise, no major updates have been made to
the forecast. The rest of the previous discussion can be found
below, with an update to the aviation and marine sections.

The upper trough axis gradually shifts southeastward during the
day on Sunday. The keeps a chance of showers in the forecast,
though the instability indices decrease with time. The trough axis
shifts east of the Cascades Sunday night into Monday with north to
northwest flow aloft developing. Drier conditions are expected on
Monday with residual showers mostly focused over the higher
terrain of the Cascades. Heights continue to rise on Tuesday, but
only modestly so with weak troughing aloft and low level onshore
flow still in place. Nonetheless, plentiful sunshine is slated to
return on Tuesday with temperatures bouncing back to near
seasonal norms.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Looking ahead to the
second half of the coming week, ensembles generally support the
return of flat to low amplitude upper ridging with 500 millibar
heights back into the 570s dam. With onshore flow continuing, some
of the guidance might be a little overzealous with some interior
locations getting into the 80s. Nonetheless, a return to seasonal
temperatures and generally dry conditions during the extended
period looks like a reasonable forecast at this time.  27


&&

.AVIATION...A broad upper level trough remains over the Pac NW with
a cool and slightly unstable air mass over western WA. Showers are
still continuing across a couple of the Puget Sound terminals (which
may reduce visibilities and cause temporary wind shifts on the
ground). Otherwise, the threat for thunder will diminish by dusk.
Onshore flow will keep the low level air mass moist overnight with
low-end VFR/MVFR clouds by morning. More showers are possible Sunday
as the cool upper low tracks overhead. Surface winds south/westerly
at 8 to 12 kt will become northerly by Sunday afternoon at 4 to 8
kt.

KSEA...Showers are moving out of the vicinity of the terminal this
evening (convection threat has ended). Gusty S/SW to 25 kt Saturday
evening will ease after 03z to 8-12 kt sustained. Low clouds at low-
end VFR or MVFR conditions possible by 12-15z Sunday. Chance of
showers Sunday, but no thunder expected.

33/HPR


&&

.MARINE...Onshore flow prevails tonight with highest wind and
waves through the Strait of Juan de Fuca - a Small Craft Advisory
remains in effect. High pressure over the NE Pacific will maintain
light to moderate onshore flow moving through next week. 33


&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.

&&

$$