637
FXUS66 KPQR 130439 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
939 PM PDT Sun Oct 12 2025

Updated aviation discussion and PQR WATCHES/WARNINGS/ADVISORIES.

.SYNOPSIS...A cool and unsettled pattern continues across the
Pacific Northwest through Monday as a broad upper-level trough
move eastward over the region. Rain, mountain snow, and below-
normal temperatures will persist into early next week. A gradual
transition toward warmer and drier weather begins midweek as a
ridge builds overhead, though model guidance diverges toward the
end of the week regarding another potential low near the coast.

&&

.DISCUSSION...Tonight through Saturday...Afternoon satellite
imagery shows a broad, upper level trough axis continuing to run
more or less parallel to the coast as the base of the trough
continues to slowly plunge southward towards the OR/CA border.
This setup will maintain cool and showery conditions across the
area through Monday. Radar currently shows scattered showers
continuing to shift eastward, with occasional heavier bursts
along the Cascade foothills. As the base of this trough moves
southward, colder 850 mb temperatures will also be introduced
to the Pac NW. This will result in snow levels falling towards
4000-5000 ft and as a result, will bring accumulating snow
across the Cascades. A Winter Weather Advisory remains in effect
for elevations above 4000 ft through Monday morning, where
there is a 50-80% probability of 2 to 7 inches of wet snow for
the Cascade passes. Highway 26 near Government Camp carries a
similar probability for a trace to 3 inches of wet snow. At
elevations above 5000 ft, snow totals of 5 to 17 inches are
likely, with a 10-30% chance of exceeding 15 inches. Overall,
there remains a 50% chance of at least 12 inches of snow,
primarily for locations north of The Three Sisters and this
scenario could result in vehicles becoming stranded along
unmaintained roads.

Monday, the aforementioned trough/low is expected to start
making an easterly trek and as such will result in clearing
skies and cooler, overnight temperatures. Focusing on the Upper
Hood River Valley, receding cloud cover Monday night will allow
for strong radiational cooling. Probabilities for temperatures
at or below 32 degrees range between 50-90%. Probabilities for
temperatures of 28 degrees or colder range between 5-35%. These
probabilities are highest in the Parkdale area and lowest in
Odell. Therefore, will maintain the current Freeze Watch from 12
AM to 9 AM Tuesday for the Upper Hood River Valley, where
sensitive vegetation and unprotected plumbing could be affected.

Tuesday through Thursday, ensemble and deterministic models
continue to favor a broad ridge over the Pac NW. This will
bring a warming and drying trend, with daytime highs into the
mid to upper 60s across the lowlands, coast and Coastal Range.
As for the Cascades, expect daytime highs in the upper 40s to
upper 50s.

Thursday into the start of next weekend, forecast confidence
remains low as model solutions diverge. However, models are
starting to trend towards a cooler and wetter solution as models
bring a shortwave trough into the region, which could push
inland between Thursday and Friday. This scenario would result
in increasing cloud cover and a return of light rain. /42~12

&&

.AVIATION...At 0430z Monday, scattered rain showers continued over
northwest Oregon and southwest Washington, with mainly VFR cigs
and visibilities in place. Expect showers to continue through
Monday morning, before decreasing in coverage Monday afternoon.
Expect cigs to begin fluctuate between VFR/MVFR thresholds between
06-15z Monday, with VFR cigs occurring more often than MVFR cigs.
Cigs should lower to MVFR mainly with passing showers. The
probability for cigs below 3000 ft ranges between 30-50% for all
inland TAF sites through 15z Monday, and 20-30% for coastal TAF
sites. Clouds will begin to clear out Monday afternoon as offshore
flow develops, bringing breezy east to northeast winds with gusts
up to 20-25 kt for all TAF sites.

KPDX AND APPROACHES...Expect cigs to fluctuate between MVFR/VFR
thresholds between 06-15z Monday, with VFR cigs occurring more
often than MVFR cigs. MVFR cigs are most likely to occur with
passing rain showers. There is a 30-50% chance for cigs below 3000
ft at any time between 06-15z Monday. VFR conditions expected
after 18z Monday as offshore flow develops and brings clearing
skies and breezy east winds with gusts up to 20-25 kt. -23

&&

.MARINE...A shortwave trough continues to pass over the region
with the axis of the trough east of the marine zones. Rain has
transitioned to scattered showers across the waters. Winds remain
westerly and have decreased to around 10 kt and gusts to around 15
kt. Wave heights peaked earlier this morning around 12-14 ft and
have slowly dropped back to between 8-10 ft at 10-11 seconds.

A weak area of low pressure developing over the Olympic peninsula
is expected to drop southward across the waters tonight into
early Monday. This will usher in a reinforcing shot of gusty north
to northeasterly winds during this period. Seas will remain
elevated as a result. Small Craft Advisory conditions are expected
to persist through 5 pm Monday. An offshore pressure gradient will
maintain northeasterly winds into Tuesday, shifting back to
onshore flow late Tuesday. Seas will drop to 5-6 ft at 8-9 seconds
late Monday.

There remains quite a bit of uncertainty surrounding the weather
pattern next weekend, with an 80% chance that significant wave
heights will climb and end up somewhere between 10 and 19 ft by
next Saturday/Sunday. /19/12

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Freeze Watch from late Monday night through Tuesday morning for
     ORZ121.

     Winter Weather Advisory until 11 AM PDT Monday for ORZ126>128.

WA...Winter Weather Advisory until 11 AM PDT Monday for WAZ211.

PZ...Small Craft Advisory until 5 PM PDT Monday for PZZ251>253-
     271>273.
&&

$$

www.weather.gov/portland

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