806
FXUS66 KPQR 142259
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
259 PM PST Fri Nov 14 2025

.SYNOPSIS...Zonal flow through the weekend will transition into
a long wave trough with a closed low over northern California.
Will see a steady cool down but not a cold snap. Rain and
mountain snow expected. Another round of cold and moist air
occurs on Thursday through Friday though conditions have warmed
slightly since previous forecasts.

&&

.SHORT TERM...Now through Saturday Night...Satellite shows
generally zonal flow over the region with a broad area of low
pressure sitting within the Pacific. Westerly flow will
instigate showery conditions which are producing locally heavy
yet non-impactful accumulations. On Saturday, weak upper-level
ridging will begin to develop east of the Cascades, lowering the
chances for additional rain inland. Inland locations will see
around a 20-30% chance of accumulating rainfall (0.01" or
greater), while the coast will be closer to 50%. Daytime high
temperatures will reach their peak on Saturday. One slight shift
on Saturday night into Sunday will be the potential for fog
development. If enough clearing occurs overnight, fog within the
Coast Range valleys will form. Inland sites may remain too dry
for that to occur, however, our more fog prone areas like around
Eugene or Hillsboro may see some patchy fog. -27


.LONG TERM...Sunday through Friday...The ridging will begin to
break down on Sunday as a long wave trough associated with a
broad low pressure system to the north advects southward. The
main impacts from this system will occur on Monday through
Tuesday. Unfortunately this trough has yet to come into good
agreement and that is due to it`s split nature. Some models are
suggesting a closed low forming near the base of the trough
while others are keeping it as one "solid piece". Let`s look at
each possible solution and what the impacts would be.

If the closed low theory takes hold, the most likely track is
again over northern California. The low itself would be active
and would advect colder air over the region. The colder air and
more active pattern would promote heavier precipitation and
likely lower snow levels. If a more elongated low manifests
then the cold air intrusion will be less robust and thus snow
levels slightly lower. While the pattern may have much to be
desired for consistency, the sensible weather has not be
effected significantly. Over the last few forecasts snow levels
have continued to rise with lower and lower probability for
advisory level snow (6-12"). On Monday through Tuesday there is
less than a 10% chance of pass level advisory level snow, and
less than a 20% chance of volcano heavy snow accumulation.

On Wednesday, an inverted trough forms as the upper level low
moves into the desert southwest. Fast forward to Thursday and
Friday. This is when yet another fall system will move in. In
current ensembles there is basically no agreement in specifics
and anomaly is high in the 500 mb heights. There continues to
be a low attempting to form just off the coast but once again,
poorly realized. Currently the ECMWF is the coldest of the
modeled ensembles while the GEPS is much warmer. With that in
mind, probabilistically we are all over the place. For example,
at Willamette Pass there is around a 25% chance of 6" or more
of snow. There is high consensus in overall temperatures
lowering on Wednesday and Thursday. -27


&&

.AVIATION...Late this afternoon a frontal system continues to
slowly lumber into the region with a mix of IFR/MVFR conditions
at the coast to MVFR to VFR CIGs inland. As the evening and
overnight hours progress flight conditions are expected to degrade
(mainly inland) due to the progression of the aforementioned
front. Expect light rain already intermittently occurring in the
Portland metro through the north Oregon coast to spread northwest
to southeast across the rest of the inland and central Oregon
coastal terminals. Most likely onset times of steadier light rain
04-06z Sat Portland metro area and northern Willamette Valley
followed by the central Willamette Valley and KONP 06-12z.
However, light rain as a prevailing condition may fail to
materialize at KEUG - moderate confidence the bulk of the light
rainfall get hung up to their north. Precipitation gradually
decreases later Saturday morning first at inland sites before
finally ending around KAST near the end of the TAF period. Winds
stay breezy at most terminals tonight with occasional gusts up to
15 to 25 knots out of the south, highest at coastal sites.

KPDX AND APPROACHES...Light rain will increase this evening
(04-06z) with CIGs dropping to a prevailing MVFR the latter half
of the night. Could still see the occasional BKN025 before this
occurs however, similar to what was observed earlier this
afternoon. Light rain slowly ends 18-21z Sat before dry weather
returns although there is a ~60% chance MVFR CIGs last through he
latter half of the TAF period. -99

&&

.MARINE...A slow moving frontal system continues to progress through
the waters this evening accompanied by a lingering westerly swell
of 7 to 10 ft at ~12 seconds. Small Craft conditions today have
been rather persistent but bouy observations are finally starting
to show a gradual decrease in regards to wave height. Moderate
confidence Small Craft level waves/winds drop off across the inner
and outer waters south of Cape Foulweather late this afternoon
followed by the rest of the waters overnight into early Saturday
morning. Otherwise, seas eventually subside to 6-8 ft for
Saturday and Saturday night with gusts holding below 10-20 knots.

Them come the second half of Sunday into Monday another frontal
system will traverse the waters bringing increased southwesterly
winds with gusts to 15-21 knots before turning out of the
northwest. A westerly swell helps to increase wave heights to
12-14 ft by Monday morning as well, before falling below 10 ft
again on Tuesday. Should this forecast remain on track, an
additional round of Small Craft Advisories will be needed for the
inner and outer waters. Expect a fairly active and progressive
weather pattern to continue the rest of the week as yet another
weather system may bring hazardous winds and seas later in the
next week. Models show a 20-30% chance for wave heights to meet or
exceed 15ft late Thursday through Friday. -99

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 3 AM PST Saturday for PZZ210-251-
     252-271-272.
     Small Craft Advisory until 4 PM PST this afternoon for PZZ253-
     273.
&&

$$

www.weather.gov/portland

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