Port Stanley, Washington Weather Forecast Discussion

410
FXUS66 KSEW 031037
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
335 AM PDT Fri Oct 3 2025
.SYNOPSIS...Generally dry conditions through late this afternoon
before a weak system brushes past the area, allowing for a chance of
showers tonight and Saturday. Upper level ridging builds in starting
Sunday, warming temperatures and returning dry conditions to the
area for at least the first half of next week. Additional systems
are possible late in the week, but confidence remains low.
&&
.SHORT TERM /TODAY THROUGH SUNDAY/...Generally dry conditions this
early morning as the upper level low continues to move
southward...albeit a little slower than models had progged. This
slow trekking is still allowing for some isolated showers to pop up
over southern portions of the CWA, but these are trivial with little
in the way of precip expected.
Current generally dry conditions are expected to persist throughout
much of the day before a weak shortwave dips into the area along the
leading edge of a building upper level ridge out over the Pacific.
While this feature has been persistent in model solutions for the
past few days, NBM seems to have really ramped up the PoPs over the
area for tonight and much of Saturday in the latest solutions.
Consulting both deterministic and ensemble models, this system looks
paltry at best...perhaps a high PoP/low QPF sort of event...but
confidence in PoPs higher than 60 pct just simply is not there aside
from in the Cascades where the terrain may prove to be of assistance
when it comes to shower development. That said, did make some cuts
to the forecast, keeping PoPs at most high-end Chance wording /50-60
pct/ thus maintaining collaboration with surrounding offices as well
as splitting the difference between forecaster and model
expectations.
Sunday sees W WA under the full thrall of the upper ridge off to the
west, with a return to dry conditions as early as late Saturday
night. This will also be the first day of a warming trend, bringing
daytime highs into the mid 60s for interior lowland locations, just
a few degrees warmer than seasonal averages.
18
.LONG TERM /MONDAY THROUGH THURSDAY/...The aforementioned upper
level ridge will remain the main driver for W WA weather for at
least Monday and Tuesday as the feature moves eastward, broadening
as it does so. Beyond this point, confidence drops off fast as
models continue to offer differing solutions. Deterministic GFS
keeps the ridge strong enough to keep the next upper level trough
out over the Pacific waters while deterministic ECMWF has said
trough push the ridge further eastward, bringing rain back to the
Pac NW. Ensembles appear to favor the ECMWF solution to varying
degrees and the NBM has latched onto that. The amount of moisture in
play however continues to be the dividing point and as such keeps
confidence low as the track of said trough will make a significant
difference in how much precip the area receives...if it gets any at
all.
The long term period will start of with continued warming
temperatures, with lower 70s expected each day for interior
lowlands. The switch to a more troughy pattern will allow conditions
to cool closer to seasonal normals for the remainder of the forecast
period, lower to mid 60s. Of course, hewing closer to normal may
also be indicative of the lower confidence in this portion of the
forecast...but likely the best route to take at this time.
18
&&
.AVIATION...A mix of ceilings and visibilities early this morning
across the terminals. Stratus has developed along the coast. Light
winds and residual moisture has also promoted fog development along
the southern Puget Sound and Kitsap Peninsula. Guidance has the
stratus pushing further, with the stratus reaching Puget Sound
terminals after 10z-12z and ceilings likely going down to IFR/LIFR.
May also see additional fog formation around central Puget Sound. In
fact, latest satellite imagery shows fog along the Cascades trying
to spread west towards SEA and BFI. Improvement into VFR expected by
Friday afternoon for all terminals. A decaying frontal system will
push through the terminals Friday night into Saturday morning. It
will bring light rain and widespread MVFR ceilings. Light to calm
winds early this morning will become more SW later this morning into
the afternoon at 3-5 kt.
KSEA...VFR early this morning, but expecting a push of stratus to
make it to the terminal after 12z. May see some fog formation before
the stratus makes it to the terminal. Latest guidance shows the
potential for seeing IFR and LIFR ceilings at the terminal, with a
30% and 20% chance, respectively. Improvement expected after 18z
into VFR. A weakening frontal system will likely bring MVFR ceilings
Friday night into Saturday morning. It is possible ceilings may
lower into IFR (45% chance) and LIFR (20% chance). Rain will be
light. Light S/SE winds early this morning will become more SW by
Friday early afternoon at 5-6 kt. Winds then shift more WSW Friday
evening.
29
&&
.MARINE...A weakening frontal system will move over the waters
Friday into Saturday. Broad surface high pressure will continue
building over area waters into the weekend and into early next week,
maintaining northerly surface winds over area waters. Benign marine
conditions likely to continue into Monday. A surface trough will
move over the coastal waters on Tuesday evening, bringing increased
winds to the coastal waters. Latest guidance suggests sustained
winds have a 25-40% chance of exceeding 21 kt. Combined seas
generally 4-6 ft into the weekend. Seas will build Tuesday evening
to 6-8 ft.
29
$$
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$

NWS sew Office Area Forecast Discussion