691
FXUS66 KSEW 140908
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
208 AM PDT Sun Jul 14 2024

.SYNOPSIS...An upper level ridge will remain in control over
Western Washington through the week ahead for continued dry
conditions and above normal temperatures. Minor day to day
variations in onshore flow will bring the marine layer locally
inland each night and morning.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...Clear skies prevail across
Western Washington early this morning with the exception of a
shallow marine layer over Grays Harbor county. Onshore gradients
are relatively weak so stratus along the coast will make little
progress inland this morning. In the synoptic picture, broad upper
ridging remains in control and this will continue to be the case
through much of the week ahead. High temperatures, especially
across the interior, will remain several degrees above average
today. We`ll see a minor uptick in onshore flow this evening. This
will likely pull some marine stratus further inland early
Monday...perhaps as far as Puget Sound before it burns back to
the coastline. High temperatures will cool a few degrees on
Monday, but will remain at or above normal for interior areas. On
Tuesday, thermally induced low pressure expands northward and the
low level onshore flow weakens. This will give high temperatures
another boost across the area...with 70s coast and upper 70s to
near 90 across the interior lowlands.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Models are beginning to
hint at the possibility of a weak upper level disturbance ejecting
from an upper trough offshore on Wednesday. Typically, at this
time of year, these little ripples in the atmosphere tend
to increase the possibility of some elevated instability and
possible convection over the Cascades. It`s too early to latch on
to any specifics, but it`s worth monitoring for both fire weather
and backcountry hiking interests. Aside from that feature,
relatively quiet conditions prevail through the end of the week
with 500 millibar heights remaining north of 580 decameters and
minor day to day fluctuations in low level onshore flow.
Operational runs of the GFS and Euro are attempting to bring a
weak trough onshore toward next weekend, but it would be hard to
bet against climatology as we`re entering the driest and warmest
portion of the year. Mostly dry conditions and above normal
temperatures are likely to continue.   27

&&


.AVIATION...West-southwest flow will continue aloft with ridging
over the Pacific Northwest. Marine stratus has developed along the
coast, bringing IFR to LIFR conditions to HQM. Stratus may develop
as far east as SHN, but looks to retreat through the morning. Clear
skies continue elsewhere. HQM may not clear out today; any clearing
will be short lived as a stronger onshore push late tonight into
tomorrow morning will push the marine layer well inland, with lower
ceilings moving in by the end of the TAF period. Light winds early
this morning will pick up into this afternoon with a push of
stronger onshore flow reaching 8 to 15 kt.

KSEA...VFR conditions through most of the TAF period. The marine
push early Monday morning may bring MVFR to IFR ceilings as early as
12-15Z Monday. Light N winds will become W/SW at around 8 to 12 kt
later this morning.

LH

&&

.MARINE...Little change in the weather pattern with high pressure
situated offshore and a thermal trough over eastern Washington.
Northwest winds over the coastal waters will slowly ease throughout
the beginning of next week as the high pressure ridge gently
weakens. The Small Craft Advisory over the coastal waters has been
allowed to expire. Onshore flow will increase tomorrow, with a push
of westerlies down the Strait of Juan de Fuca, permitting a Small
Craft Advisory for the Central and East Strait this evening.
Additional diurnally-driven westerly pushes will continue throughout
the week with additional headlines possible at times.

Seas 6 to 8 ft across the coastal waters will decrease Sunday night
into Monday to around 4 to 6 ft through next week.

LH

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 PM this afternoon to 2 AM PDT Monday
     for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.

&&

$$