588
FXUS66 KSEW 020913
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
213 AM PDT Thu May 2 2024

.SYNOPSIS...Dry and mostly clear conditions paired with warmer
temperatures through Friday morning. A cooler and wetter storm
system will move into western Washington on Friday, and unsettled
conditions will continue through the weekend and beyond.

&&

.SHORT TERM /TODAY THROUGH SATURDAY/...Showers over southwest
Washington will continue to shift southward early this morning as
a surface low slides inland over Oregon. Wrap-around moisture poses
a slight chance for showers over the Cascades this afternoon as
the trough exits to the southeast. Otherwise, dry conditions and
mostly clear skies will prevail today across western Washington as
a ridge builds in overhead with a return to near- normal
temperatures in the mid 60s.

The next weather maker will move into the Pacific Northwest Friday
morning as a trough deepens offshore. A front will swing inland
throughout the day, bringing in widespread precipitation with snow
levels near 4500-5000 ft. Temperatures ahead of the front will
peak in the upper 60s with some areas seeing a good shot at 70
degrees, but temperatures behind the front will cool off roughly
10-15 degrees. Steady precipitation will continue on into Saturday
as the trough shifts inland with little break in shower activity.
A majority of the moisture with this system will fall over the
Olympic Peninsula, with roughly 1 to 2 inches of rainfall. The
lowlands and Cascades will see between half an inch and an inch,
with lesser amounts northward towards the Canada border.
Temperatures Saturday will be limited to the mid 50s.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Forecast models have come
into better agreement through the long-term, with cooler and wet
conditions continuing into next week. The broad upper level low
over the Pacific Northwest will continue to shift eastward
towards the end of the weekend, spreading more wrap-around
moisture across the region as another wet system approaches from
the northwest. Snow levels are forecast to stay above pass level,
and cool onshore flow under zonal flow will help maintain showers
into Monday and Tuesday. Onshore flow will ease by mid-week, which
may provide some brief relief to the rainy weather and allow
temperatures to return into the 60s.

Lindeman

&&

.AVIATION...An upper level low will continue to sink southeastward
across the Pacific Northwest today, while upper level ridging
nudges into the northeastern Pacific. This will maintain northerly
flow aloft. VFR conditions remain in place across the region early
this morning. Satellite imagery shows some mid to high level cloud
cover continuing to stream over portions of SW WA as a surface
low offshore makes its way towards OR. Clearing across the region
will continue from north to south through the morning hours.
Expect cloud cover to keep lower cigs and fog out of KOLM this
morning, however cannot rule out some fog development and brief
reductions to IFR conditions at KPWT as conditions have already
cleared. Latest NBM probabilistic guidance has a 15-20 percent
chance of IFR conditions developing at KPWT between 12-15Z.
Elsewhere, expect conditions to remain VFR through the TAF period.
Surface winds will generally persist out of the north at 5 to 10
knots through the day, shifting to the south late tonight into
early Friday.

KSEA...VFR conditions through the TAF period. Clearing skies
expected by mid morning. Northerly winds will see a slight uptick
to 5-10 kt by mid morning and look to persist through the afternoon.
Winds will ease again by the evening hours and look to transition
back to the south between 06-09Z Friday. 14

&&

.MARINE...A low pressure system offshore will continue to move
southeast and push into Oregon later this morning. Weak high
pressure will then rebuild over the area waters today for overall
calm conditions. The next frontal system will move into the area
waters Friday into Saturday, likely bringing small craft
southerlies to portions of the area waters and gusty westerly
pushes down the Strait of Juan de Fuca in its wake on Saturday.
Another system looks to arrive in the region late in the weekend
and into early next week.

Combined seas across the coastal waters will generally hover
between 3-5 ft through Friday, before increasing towards 6-8 ft
over the weekend. Latest probabilistic guidance hints at a 50-60
percent chance of seas approaching 9-10 ft Monday night into
Tuesday. 14

&&

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

&&

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

$$