704
FXUS66 KSEW 162138
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
238 PM PDT Fri May 16 2025

.SYNOPSIS...Cloudy and showery conditions will continue across
the region through the weekend with temperatures remaining below
normal. The chance of thunderstorms will increase to around 20
percent across much of the region Saturday afternoon. Showers
continue through the start of next week as the pattern remains
somewhat active. A shift to warmer conditions is possible late
next week.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...Onshore flow prevails and
western WA remains under cloudy skies with isolated to scattered
showers. Temperatures are only in the 50s or around 5-10 degrees
cooler than average.

More showers are headed our way tonight and Saturday as an upper
level trough moves in. Showers will be enhanced during the
afternoon with the passing trough axis and a convergence zone
developing in the interior. The air mass will be slightly unstable
with a chance of thunderstorms too. Up in the mountains, snow
levels will lower from around 4500` down to 3500` Saturday night
and the Cascades may see light snowfall accumulations.

A cool upper low remains overhead on Sunday for more clouds, light
showers, and overall cool conditions. Most of she shower activity
remains over the Cascades where snow levels stay low (3500-4500`).

We`ll see a brief break in the weather with a ridge late Sunday,
then more rain on Monday with the next frontal system. Temperatures
remain cooler than average with highs around 60 degrees. 33

.LONG TERM /TUESDAY THROUGH FRIDAY/...There is broad troughing
over the Pac NW next week with ongoing onshore flow. A series of
weak upper level systems will clip the area for a chance of
showers through the period. Late in the week (and next weekend)
there are signs of warmer and drier weather with stronger ridging
over the region. The majority of the ensemble members show highs
reaching the 70s over the weekend. 33

&&

.AVIATION...Westerly flow aloft will become southwesterly tonight as
the next in a series of upper troughs and associated weak fronts
approaches Western Washington. The air mass remains moist with
widespread MVFR ceilings. Shower coverage will increase overnight
into early Saturday with ceilings dropping to low MVFR or IFR.

KSEA...Mainly MVFR ceilings expected through the evening with any
low end VFR improvement expected to be brief. Showers will increase
late tonight into Saturday with low MVFR or occasional IFR ceilings.
Surface winds S/SW 7 knots or less turning light and variable during
the overnight period then returning to S/SW and increasing to 8 to
12 knots by later Saturday afternoon. 27

&&

.MARINE...Another front will dissipate as it moves into the coastal
waters overnight. Surface high pressure will then rebuild over the
coastal waters later Saturday into Sunday. This will produce
increasing onshore flow and headlines for the coastal waters,
strait, and northern portions of the inland waters. The next frontal
system will arrive on Monday. 27

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 3 PM Saturday to 11 AM PDT Sunday for
     Coastal Waters From Cape Flattery To James Island 10 To 60
     Nm-Coastal Waters From Cape Flattery To James Island Out 10
     Nm-Coastal Waters From James Island To Point Grenville 10
     To 60 Nm-Coastal Waters From James Island To Point
     Grenville Out 10 Nm-Coastal Waters From Point Grenville To
     Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point
     Grenville To Cape Shoalwater Out 10 Nm-West Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Gale Warning from 3 PM Saturday to 5 AM PDT Sunday for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 5 PM Saturday to 11 AM PDT Sunday for
     Northern Inland Waters Including The San Juan Islands.

     Small Craft Advisory from 3 PM Saturday to 5 AM PDT Sunday for
     Admiralty Inlet.

&&

$$