772
FXUS66 KSEW 120301
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
801 PM PDT Sun May 11 2025

.SYNOPSIS...A frontal system will cross over western Washington
resulting in widespread showers today. Lingering moisture with the
parent upper low will keep scattered showers in the forecast for
Monday. Upper level ridging will start to build into the area
midweek for the return of warm and dry conditions. Active weather
is possible later the week.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...No forecast updates this
evening.

Recent radar imagery continues to show showers across much of
western Washington as a broad low pressure system drifts to the
southeast towards OR/CA.

The aforementioned upper level low will continue to drift
southward and bring some wrap around moisture tonight into
Monday, keeping showers in the forecast. Weak upper level ridging
looks to build into Tuesday and will be the primary influence on
the weather through Wednesday, keeping the area mostly dry but a
few showers are still possible in the higher terrains such as the
Cascades during that time. Temperatures largely remaining the
same.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Ensembles are hinting at
more upper level troughing in the long term period, which would
bring more unsettled and showery weather into the weekend.
Deterministic models seem to be split on the strength of multiple
frontal systems at this time, but overall consensus looks like
more troughiness and showery weather through the long term.

Mazurkiewicz

&&

.AVIATION...Upper level trough offshore moving inland tonight and
remaining over the area Monday. Southerly flow aloft becoming
light later tonight. Light flow in the lower levels. Air mass
slightly unstable until around 06z.

Scattered to broken layer near 4000 feet with another layer
around 7000 feet. Shower activity through 06z with local ceilings
near 3000 feet in showers. MVFR ceilings developing 10z-14z Monday
morning. Ceilings improving back to VFR 18z-21z Monday.

KSEA...Scattered to broken layer near 4500 feet with broken to
overcast layer around 7000 feet. Ceilings lowering to around 2000
feet 12z Monday lifting back up to near 4000 feet around 19z.
Southerly winds 4 to 8 knots.

Slight chance of thunderstorms over the Cascades in approach
paths to the terminal through 04z. Felton

&&

.MARINE...A 1002 mb surface low over the Oregon offshore waters
will move southeast and dissipate by Monday morning. High pressure
rebuilding over the coastal waters Monday with lower pressure
inland. This pattern will remain intact through Thursday. Weak
front moving through the waters Thursday night into Friday.

Small Craft Advisory winds are likely through the Strait of Juan
de Fuca Monday night and again Tuesday night. Seas building to
around 10 ft over the outer Coastal Waters Tuesday will subside
below 10 feet Wednesday. Felton

&&

.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be included as needed.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 6 PM Monday to 2 AM PDT Tuesday for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

&&

$$