231
FXUS66 KSEW 071051
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
251 AM PST Thu Nov 7 2024

.SYNOPSIS...An upper level ridge will bring one more dry day to
the area. A series of systems will then bring unsettled weather
starting on Friday and throughout the weekend, consisting of
lowland rain, mountain snow, chances of thunder, and breezy
conditions.

.SHORT TERM /TODAY THROUGH SATURDAY/...Recent satellite imagery
shows pretty much clear skies over western Washington early this
morning, the exception being some patchy fog in the Chehalis
valley. An upper level ridge continues to remain over our area,
which will result in generally quiet conditions throughout the
day. High temperatures will warm into the mid to upper 50s, with
some high level clouds streaming in this evening ahead of an
approaching series of systems.

Generally quiet weather will come to an end as a first system in
a series of systems approaches the area later tonight into
Friday as broad troughing takes over. Latest guidance shows that
this frontal system looks to stall over the northern coast, with
some light precipitation starting over coastal areas by early
Friday morning. Rain will gradually then move over the interior
through late Saturday. Snow levels continue to remain around 5000
to 6000 feet during this time, with any snow accumulations in the
mountains limited more so to the higher elevations. This system
looks to be the weakest out of the systems in the forecast period,
with more frontal systems impacting the area late into the
weekend and into the first half of next week.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Moving into Sunday, a more
robust upper level trough with a associated upper level low will
push a front through the area, resulting in lowland rain, mountain
snow, and breezy winds. Ensemble guidance continues to suggest
some uncertainty with the precipitation amounts and timing with
this system, but, the bulk of the precipitation right now is
centered over the coast and the mountains Sunday night into
Monday. As the trough moves over the area Monday into Tuesday,
snow levels look to lower down to around 3500 to 4000 feet, with
some significant accumulations in the higher elevations possible.
A few inches of snow looks likely, especially at pass levels at
Snoqualmie and Stevens Pass.

Another system looks to then move through the area Tuesday into
Wednesday, with another round of rain, mountain snow, and breezy
conditions through the region. Once again, most of the
precipitation looks to be focused over the coastal regions and the
mountains. With compounding systems bringing decent QPF numbers,
refer to the .Hydrology section below for information on
potential river flooding. Snow levels look to rise slightly above
4000 feet with this system, but again there is some uncertainty
with the snowfall amounts at this time. This system looks a little
bit breezy, especially throughout the interior. Active weather
looks to continue through midweek.

Mazurkiewicz

&&

.AVIATION...A weak upper level ridge remains over the region
with westerly flow aloft continuing. The low level flow is light
offshore. Areas of LIFR/IFR fog and/or stratus around Puget Sound
and across the Southwest Interior will dissipate by 18Z-19Z.

KSEA...Confidence in low cloud development has decreased overnight
as light low level offshore flow keeps the temperature/dew point
spread at a comfortable gap. Some Lake Washington stratus may still
sneak into the vicinity of the terminal, but this may be short-lived
at best. Otherwise, VFR expected the remainder of the day. Surface
winds light easterly early, becoming light/variable this afternoon,
then backing to light S/SE tonight.  27

&&

.MARINE...Surface ridging remains centered east of the Cascades
producing light offshore flow. A warm front will stall out over the
offshore waters tonight. A weak cold front will move across the
waters on Saturday before a much stronger frontal system follows
Sunday night into Monday.

Seas will gradually build over the coastal waters beginning tonight.
Seas at or above 10 feet are expected later Friday through the
weekend before increasing sharply following Monday`s front to 17 to
20 feet.  27

&&

.HYDROLOGY...The next chance of significant precipitation is
forecasted to arrive Sunday through Tuesday. At this time, the
Skokomish River is the only river forecasted to rise above flood
stage, in the minor flood stage. For other rivers, significant
rises are expected and flooding could be possible, but at this
time is not forecasted. The amount of flooding will depend on
rainfall rates, temperatures and snow levels with precipitation
that falls with these systems, which we will continue to monitor.

HPR/Bower/Mazurkiewicz

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&

$$