084
FXUS66 KSEW 162157
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
257 PM PDT Mon Sep 16 2024

.SYNOPSIS...Weak ridging over the area today for general benign
conditions. A upper level trough and associated front will push
through the region late Tuesday for some rain showers into
Wednesday. Drier conditions into Thursday before unsettled weather
likely returns to the area through the weekend.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...Recent satellite imagery
shows dissipating stratus clouds from this morning leading to
mostly clear skies this afternoon. High temperatures this
afternoon will remain near normal, in the mid 60s to lower 70s
across the area. Clear skies will continue to trend into tonight
with some high level clouds moving ahead of an approaching system,
with some patchy fog likely in the lower prone areas.

An upper level trough and associated front will start to approach
the coastal areas by Tuesday morning and will start to spread rain
showers inland by the afternoon. Latest ensembles show a strong
jet jet digging southward which could slow down and weaken the
front as it approaches western Washington. Regardless, there will
be plenty of cloud cover around with light rain showers across
the area. Low temperatures Tuesday night will hover in the 50s.

The front will dissipate over the area into Wednesday with
lingering showers, as weak northerly flow will keep our region
somewhat dry into Thursday. High temperatures will continue to
remain in the low to mid 60s.

.LONG TERM /FRIDAY THROUGH MONDAY/...Confidence in the long term
continues to wobble as ensembles attempt to agree on a solution.
Latest guidance indicates a weak disturbance passing through the
area on Friday which would keep showers in the forecast. The GFS
continues to highlight an upper level ridge into the weekend,
meanwhile the ECMWF highlights multiple systems with plentiful
moisture into the beginning of next week. The latest trends have
been pushing more towards the more wet solution, of multiple
systems transversing across the Pacific Northwest, which could
really open up the door to fall. Will keep chance of showers in
the forecast for now and will see how the models evolve.

Mazurkiewicz

&&

.AVIATION...Light east to northeast flow aloft will become westerly
late tonight as another upper trough and associated frontal system
approach the region. At low levels, increasing onshore flow will
result in widespread low MVFR to IFR ceilings along the coast by
07Z then spreading across Western Washington by 14z Tuesday morning.

KSEA...VFR conditions will linger though the evening with stratus
and MVFR ceilings expected to develop by 14Z. NW surface winds 5 to
7 knots this afternoon will become light NE during the late evening
before backing to south/southwesterly late tonight.

&&

.MARINE...A broad surface ridge remains centered well offshore with
lower pressure over the interior. Onshore flow will increase
somewhat this evening. Strongest winds expected in the central/east
strait tonight, with high resolution ensembles continuing to show
only a 15-20% chance of reaching small craft criteria. The surface
ridge over the offshore waters will weaken tonight and a trough and
associated front will shift into the coastal waters on Tuesday. This
system is unlikely to generate any headlines. The trough will weaken
as it gradually shifts southward into the Oregon coastal waters on
Wednesday. High pressure rebuilds offshore late in the week before
another front is expected over the upcoming weekend.

27/cook

&&

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

$$