153
FXUS66 KSEW 011000
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
300 AM PDT Wed May 1 2024

.SYNOPSIS...Clearing skies and cooler temperatures will allow for
areas of frost across much of western Washington this morning.
Another weak system will slide to the south late Wednesday into
Thursday, bringing in light shower activity. Drier and warmer
conditions are expected Thursday and Friday before more
precipitation arrives in time for the weekend and beyond.

&&

.SHORT TERM /TODAY THROUGH FRIDAY/...As an upper trough axis
shifts eastward, cool northwest flow over western Washington will
continue to bring in drier air. Clearing skies this morning will
allow for areas to cool into the low to mid 30s, allowing for
areas of frost development. A Frost Advisory remains in effect
through the late morning across the Chehalis Valley, Hood Canal
and Kitsap Peninsula, south Puget Sound lowlands, and King and
Snohomish foothills.

Dry conditions will continue on into the afternoon for much of the
region as weak ridging builds inland ahead of an approaching low.
A weak shortwave will cross the region Wednesday afternoon, which
may stir up scattered showers mainly over the Olympic Peninsula.
Temperatures for much of the lowlands will peak in the mid to
upper 50s.

A weak low pressure system will slide south of the region late
Wednesday into Thursday, bringing more light precipitation over
the Olympic Peninsula and Chehalis Valley. Showers will linger
over southwest Washington into Thursday morning with some wrap-
around moisture triggering light showers over the Cascades
Thursday afternoon. Continued warming will allow temperatures to
return to normal for early May, with highs in the mid 60s.

A deeper low pressure system will drop along the Pacific Coast on
Friday, lifting a warm front across the region and allowing
temperatures to continue to warm. While ensembles continue to show
disagreement in the evolution of this storm system, models
continue to highlight the potential for highs near 70 degrees on
Friday. Uncertainty also remains over the intensity of
precipitation that enters the region Friday afternoon and evening
with this system. Ensembles focus the bulk of the incoming
moisture over the Olympic Peninsula, with widespread precipitation
continuing into the weekend and snow levels above 4000-5000 ft.

.LONG TERM /SATURDAY THROUGH TUESDAY/...While uncertainty remains
throughout the extended forecast period, a wetter and cooler
pattern is favored to continue through the weekend and into next
week. Ensemble members continue to show different solutions over
the path of the low along the coast, with some members pulling the
system southward through the weekend and other members bringing
the low across Washington which would result in heavier
precipitation. Moist zonal flow is favored to develop by the end
of the weekend and into next week, maintaining showery conditions
with below-normal temperatures.

Lindeman

&&

.AVIATION...An upper level trough will continue to shift eastward
into Wednesday as upper level ridging resides across the northeast
Pacific. An upper level low will then sink into the area along the
periphery of the ridge tonight. Northerly flow will continue
aloft and low level flow has shifted back to the south overnight.
Most terminals are VFR this morning, except for those in the
vicinity of patchy fog. With ample moisture still present in the
low levels, can expect fog development to briefly drop conditions
down to MVFR to IFR for terminals within its vicinity at times
this morning. Latest guidance shows fog mainly persisting across
areas of the south Sound and southwest interior. Low clouds and
fog look to scatter by 18Z, allowing for more widespread return to VFR
conditions. Otherwise, expect for streaming mid level clouds
likely to increase after 15Z Wednesday. Winds in the low levels
will generally persist from the south at 3-7 kt through the day,
before shifting to the north tonight.

KSEA...VFR conditions with a few clouds at 2500 ft. Winds
will persist out of the southeast at 3-6 kt. Increasing middle
level clouds expected after 14Z, but VFR conditions are likely to
continue. Winds look to transition to the north tonight, but look
to remain light at 6 kt or less into Thursday. 14

&&

.MARINE...Small craft westerly winds along the central and eastern
Strait will gradually ease through the early morning hours today.
Onshore flow will continue through the day with high pressure
residing over the coastal waters. A low pressure system offshore
will then move southeast tonight and move into northern Oregon on
Thursday morning, allowing for southerly winds over the outer
coastal waters to pick up tonight. Weak high pressure will then
rebuild over the area waters Thursday night into Friday, keeping
conditions calm across the area waters. The next system will then
move into the waters Friday night into Saturday, likely bringing
another round of area headlines. This will then be followed by
another frontal system that looks to arrive late in the weekend.

Seas generally hovering between 6-8 ft this morning will continue
to subside towards 3-5 ft throughout the day today. Seas look to
persist at this range into Friday, before building back over the
weekend as systems move across the area. 14

&&

.HYDROLOGY...No river flooding is expected over the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Frost Advisory until 10 AM PDT this morning for East Puget Sound
     Lowlands-Everett and Vicinity-Hood Canal Area-Lower
     Chehalis Valley Area-Southwest Interior-Tacoma Area.

PZ...Small Craft Advisory until 5 AM PDT early this morning for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

&&

$$