000
FXUS66 KSEW 092133
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
233 PM PDT Thu Jul 9 2020

.SYNOPSIS...Dry weather and slightly warmer temperatures return
for Friday into much of Saturday before another weak system brings
a chance for showers on Sunday. The start of next work week is
looking dry.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...This morning`s cold front
has shifted east of the Cascades this afternoon with just a few
post frontal showers lingering across the southwest interior and
Kitsap Peninsula. Expect these to continue to diminish this
evening. Behind the front, weak high pressure will build into the
area for Friday with more zonal flow. After morning clouds,
sunshine should return for Friday afternoon and evening with
temperatures warming back into the 70s. Dry weather will continue
into Saturday with increasing clouds during the day in advance of
the next system.

Next trough, associated with an upper level low across the Gulf of
Alaska, will swing through Western Washington late Saturday into
Sunday. The cold front will weaken substantially as it moves
onshore, much like today`s front, so shower activity may not be
widespread. At this point, looks like highest chances across the
Olympic Peninsula and in the interior north of Seattle.
Temperatures will cool back down several degrees.

CEO

.LONG TERM /MONDAY THROUGH THURSDAY/...Trough departs on Monday
with area remaining under the influence of weak high pressure
through Tuesday night. This should allow for mostly dry weather
but temperatures will remain a few degrees below normal. Ridge
breaks down by Wednesday or Thursday with shower chances
returning. Still some model differences in timing and strength of
additional systems but ensembles agree in overall troughing
pattern. This will lead to periodic chances for showers, increased
cloud cover, and slightly cooler temperatures.

CEO

&&

.AVIATION...All terminals are in a post-frontal airmass this
afternoon, with ceilings slowly recovering back towards VFR. Most
sites should achieve this by the evening before lowering back down
to MVFR overnight as onshore flow brings the next round of marine
stratus inland. Stratus should lift by Friday afternoon, yielding
mostly sunny skies for the remainder of the day. Winds will be out
of the S at 10kts or less thru the period, except W at HQM and CLM
10-15kts and a brief shift to the N at PAE as westerly winds push
down the Strait into Puget Sound.

KSEA...VFR thru the evening and into the overnight hours, with a
gradual lowering back to MVFR as onshore flow pushes marine stratus
inland early Friday. MVFR ceilings will then give way to generally
clear skies Friday afternoon. Winds S/SW 10kts or less.

Kovacik

&&

.MARINE...All waters lie in the wake of a weak frontal boundary this
afternoon, with a few light showers still passing across the area,
mostly across Puget Sound and into the Northern Inland Waters.
Expect most of this activity to wind down this evening, with both
winds and waves remaining rather benign into Friday. The only
exception will be across the Central and Eastern Strait of Juan de
Fuca where gradients behind the front are suggestive of westerly
winds meeting small craft advisory level criteria this evening and
into the overnight hours with wind waves building to 2-4 ft. This
advisory will remain in effect from 5PM this evening thru 3AM Friday.

Onshore flow will continue Friday and through much of next week with
the overnight development of marine stratus, especially across the
offshore waters. Another frontal system will pass across the area on
Sunday, bringing the next round of showers. Winds and waves remain
unimpressive overall (less than 20kts, 5ft or less, respectively),
with the continued exception of the Central and Eastern Strait where
evening/overnight small craft advisory events will remain likely.

Kovacik

&&

.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed
until then.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 3 AM PDT Friday for Central U.S.
     Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
     Strait Of Juan De Fuca.

&&

$$

www.weather.gov/seattle

NWS SEW Office Area Forecast Discussion

Discussion Script by Ken True at Saratoga Weather - WFO Script by SE Lincoln Weather