306
FXUS66 KSEW 150336
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
836 PM PDT Sun Jul 14 2024

.SYNOPSIS...An upper level ridge will remain in control over
Western Washington through the first half of the week 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. A subtle shortwave entering
the area on Wednesday may bring an increased risk of convection
over the Cascades.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...Broad upper level
ridging remains in place over western Washington. Satellite
imagery shows clear skies prevailing across the interior, while
stratus along the coast has already started to push inland into
the far southwestern portions of Mason County this evening. Onshore
flow will continue to strengthen this evening, which may allow
for the marine stratus to move a bit further inland overnight than
the previous couple of mornings. The remainder of the previous
discussion follows below. 14

High temperatures on Monday will still remain above average, but
be a touch cooler, in the lower 80s for the interior, and low to
mid 60s for coastal locations, with clear skies prevailing once
again. Temperatures on Tuesday will warm as a thermally induced
trough expands along the coast, with interior temps ranging from
the upper 80s to even low 90s. Areas along the coast will warm
into the mid to upper 70s.

Latest ensemble guidance has been keying in on a negative tilted
trough riding up along the west coast Tuesday night into
Wednesday, pushing a weak shortwave sliding over the region with
southerly flow aloft. This may open the door for elevated
instability which could lead to increased convection over the
Cascades. At this time, model guidance is a bit shaky on
specifics, but it is worth noting for recreation and fire weather
concerns. See the fire weather section for more details.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Upper level ridging looks
to amplify through Saturday, which would result in once again
above average temperatures through the region and minor
fluctuations in onshore flow. There is disagreement heading into
Sunday, where ensembles are showing a weak trough moving onshore
into the beginning of next week. This would mean potentially some
precipitation for the area, but, considering how far out it is,
the most likely scenario is the continuation of warm and dry
conditions for now.

Mazurkiewicz

&&

.AVIATION...Westerly flow aloft becoming more southwest on Monday as
upper ridging builds further into the area. Clear skies for interior
areas this evening with stratus along the coast and spreading inland
into the Southwest Interior. Stratus will continue spreading
eastward into Puget Sound tonight into Monday morning. LIFR cigs are
likely along the coast tonight and perhaps briefly near KPWT, with
MVFR/IFR cigs for portions of Puget Sound, with the eastern extent
expected to reach BFI/SEA/PAE by early Monday morning. Cigs will
clear for Puget Sound generally between 18-19z with lower cigs
lingering along the coast into early Monday afternoon. S/SW winds
into Monday morning with a more W/NW component by Monday afternoon.

KSEA...Clear skies this evening. Stratus is expected to spread into
southern Puget Sound tonight, with expected MVFR/IFR cigs by 12-13z
Monday morning. Cigs will improve generally around 18z for clear
skies Monday afternoon. S/SW winds into Monday morning will become
more NW around 23z. JD

&&

.MARINE...High pressure situated offshore will continue into the
early week, allowing for diurnally driven pushes through the Strait
of Juan de Fuca and marine stratus along the coast. Westerly SCA
winds will be driven through the Strait of Juan de Fuca tonight into
the early morning Monday. Northerly winds are expected through early
Wednesday for the Coastal Waters.

A surface front will slide northward across the region Wednesday
with a transition to southerly winds through Thursday. Seas of 5 to
7 feet tonight will generally become 4 to 6 feet for much of the
week. 15/JD

&&

.FIRE WEATHER...High pressure will persist over the Pacific
Northwest for continued warm and dry conditions, with low level onshore
flow providing excellent relative humidity recoveries each night.
Flow will start to turn southerly Tuesday night into Wednesday,
with an increased potential for convection in the Cascades, with
RH values remaining in the mid to upper 30s during this time.

It is worth noting that especially with a pattern like this, with
our fuels already being so receptive, all it takes is a rogue
lightning strike from a thunderstorm to light these fuels.
Will continue to monitor this threat as latest model guidance is
not latching on to any specifics. For now, will monitor for the
potential of thunderstorms and elevated instability.

Mazurkiewicz

&&

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

&&

$$