Vashon Island, Washington Weather Forecast Discussion

541
FXUS66 KSEW 262202
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
302 PM PDT Fri Sep 26 2025
.SYNOPSIS...A mostly clear weekend is in store, at least until
Sunday afternoon when rain begins to fill in across Puget Sound.
Some morning clouds are expected as a result of zonal flow
continuing across western Washington. A frontal system will catch
the northern coast and portions of the north interior, with
successive systems arriving throughout the week.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY/...Mid and high level clouds
are streaming in from the northwest as onshore flow continues
across western Washington. An approaching frontal system will get
caught along the north coast and portions of the north interior
over the weekend, with mostly clear skies for the rest of the
region tomorrow and Sunday. Highs on Saturday will be in the mid
70s, dropping into the low 70s on Sunday. Morning clouds are
likely on Saturday, giving way to a mostly clear afternoon and
evening. Similar conditions are forecast on Sunday, but more
widespread rain will arrive in Puget Sound in the evening. Through
late Sunday night, rainfall totals will be around a half of an
inch along the coast and western Olympics, and a few hundredths of
an inch down in the lowlands and Cascade foothills. Rain picks up
early Monday morning into Tuesday for more appreciable totals.
Conditions along the immediate coast and through the eastern
Strait of Juan de Fuca could be breezy late Sunday night into
Monday as that frontal system moves into the area.
.LONG TERM /TUESDAY THROUGH FRIDAY/...The next system arrives
Tuesday into Wednesday and looks to be the strongest one of the
week. More widespread southerly winds are expected, with stronger
gusts along the coast. Additionally, rainfall will pick up and
linger throughout Tuesday and Wednesday. There is still a slight
chance for thunderstorms (10-15%) retained in the forecast for the
Pacific coast, and portions of King and Snohomish county on
Tuesday afternoon. Slight chances for thunder continue along the
coast into Thursday. The low pressure system responsible for the
increased weather activity will sit offshore of Vancouver Island
until moving east late in the week. Looking at the cluster
analysis, there are a few models attempting to bring in high
pressure late in the week into next weekend for a break in the
active weather. Confidence in this solution is weak at this lead
time, and will be refined into next week.
Looking at the precipitation forecast from Sunday through late
Thursday night, the lowlands could receive around 2 inches of
rain, while the western slopes of the Olympics range from 4-5
inches, and around 3-4 in the Cascades. This will bring very
appreciable benefits to area fires.
21
&&
.AVIATION...Weak high pressure over western WA will weaken today
with a frontal system approaching from the west. A jet streak ahead
of a trough associated with the low to the north will increase west
flow aloft today into Saturday, with it turning more southwesterly
Sunday. All terminals this afternoon are reporting VFR with FEW or
SCT clouds between 3-5,000 ft, and mid to high cloud decks moving
into the region. Winds remain southerly 4-8 kt through tonight -
decreasing to under 5 kt. High clouds forecasted tonight/Saturday
morning will likely keep most terminals VFR in the interior (though
some sites in the Kitsap/south interior and the coast) have an
elevated risk of seeing lower CIGs/VIS down to IFR/LIFR briefly
between 12-18Z. Additionally, some showers may pass through north
interior terminals tonight. High clouds clear out Saturday afternoon
for VFR conditions for interior terminals (coast will keep the
clouds through the day). Winds become west 4-8 kt Saturday afternoon.
KSEA...VFR expected through the TAF period with a FEW or SCT low
clouds, and more solid BKN or SCT mid/high level clouds will arrive
this evening through Saturday morning. Chances of MVFR and lower are
less than 15% Saturday morning (due to the high clouds). South winds
4-8 kt this afternoon will decrease to under 5 kt tonight, becoming
west 4-8 kt Saturday afternoon.
HPR
&&
.MARINE...Weak surface high pressure inland will weaken as a frontal
system approaches from the west this weekend. Some lower
ceilings/visibilities with the showers are possible in the coastal
waters Saturday afternoon in the warm sector. While winds decrease
going into Saturday out of the south, seas remain elevated with
coastal waters seeing seas increase 8-11 ft through the weekend. All
but the southern two inner coastal waterway zones remain in a small
craft advisory through Saturday due to high seas.
An additional frontal system will pass through Sunday into Monday.
While seas will range at 7-9 ft Sunday through Monday, there`s a 30-
50% chance that some of the southern parts of the coastal waters,
and the interior waters (particularly East Strait of Juan de Fuca
and Northern Inland Waters) could see wind gusts exceed 20 kt. A
stronger system digging southward from Alaska Tuesday and Wednesday
will likely increase seas up to 10-15 ft Tuesday into Thursday,
produce breezy south winds in the coastal waters, Strait of Juan de
Fuca and interior waters. There is a 30-40% chance that some of the
wind gusts in these areas could approach gale force.
HPR
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 6 AM to 5 PM PDT Saturday for Coastal
     Waters From Cape Flattery To James Island Out 10 Nm.
Small Craft Advisory until 11 PM PDT Saturday for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 Nm.
Small Craft Advisory from 6 AM to 11 PM PDT Saturday for Coastal
     Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.
&&
$$

NWS SEW Office Area Forecast Discussion