943
FXUS66 KPQR 121816 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1116 AM PDT Sun Oct 12 2025

Updated aviation discussion.

&&

.SYNOPSIS...A cool and unsettled pattern continues across the
Pacific Northwest through Monday as a series of broad upper-
level troughs move through the region. Periodic 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...Now through Friday...Early morning satellite
imagery shows the main upper-level low now centered well east of
the Cascades, while a secondary trough drops southward from
western Canada. This setup will maintain cool and showery
conditions across the area through Monday. Radar trends show
scattered light showers continuing to shift eastward, with
occasional heavier bursts along the Cascade foothills.

Cold air aloft associated with these systems will support
convective showers today, with roughly a 15% chance for
isolated thunderstorms through this afternoon - most likely
along the coast and Coast Range, but a few could extend inland
where breaks in cloud cover allow for localized surface heating.
With the current sky forecast, there is low confidence for breaks
in cloud cover inland.

In the higher terrain, snow levels hover near 4000-5000 ft,
allowing for 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 6 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 about a 60-80% chance
of exceeding 12 inches north of the Three Sisters. This heavier
band could impact travel on unmaintained or high-elevation
roads.

As these systems move through, daytime highs remain below
seasonal averages, generally in the mid-50s to low 60s across
the lowlands and upper 30s to 40s in the Cascades. Overnight
lows trend colder as the post-frontal air mass settles in.

Focusing on the Upper Hood River Valley, confidence continues to
increase that cloud cover will keep lows above freezing through
tonight, but clearing skies Monday night will allow for strong
radiational cooling. Temperatures in the Odell to Parkdale
corridor are forecast to drop between 28 to 32 degrees, with a
50-90% probability of sub-freezing temperatures and 10-50%
probability of dropping to 28 degrees or colder, highest around
Parkdale. A Freeze Watch have been issued 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 the development of a broad ridge over the
region beginning Tuesday. This will bring a warming and drying
trend, with highs climbing into the low to upper 60s across the
lowlands and reduced shower activity. Nighttime lows will
remain cool, especially in valley locations prone to radiational
cooling under clear skies.

Beyond Thursday, forecast confidence decreases as ensemble
solutions diverge. Roughly half of ensemble members rebuild a
weak offshore shortwave trough, which could nudge inland
between Thursday and Friday. If realized, this pattern would
bring increasing cloud cover and a return of light rain,
especially along the coast. Otherwise, a stronger ridge would
keep conditions dry and mild into the weekend. At this time,
forecast PoPs range from 10-20% midweek, increasing to around
30-50% late week under the wetter scenario.
~12

&&

.AVIATION...Light to moderate rain has increased across the area
as a shortwave trough continues to dig southward through the
PacNW. Rain is supporting mainly MVFR/IFR conditions with VIS
dropping to 2-4 SM and CIGs to 1-3 kft. Rain is expected to
continue into the afternoon then become more scattered in the
evening. There is a slight chance (15-25%) for thunderstorms for
most of the are through the afternoon with the threat shifting to
southwest to just the central Oregon coast and coast range this
evening. Conditions are expected to improve during the latter half
of Monday as the trough shifts south of the area and drier air
begins to filter in from the north. Winds expected to be westerly
today, shifting northwesterly this evening and even gaining an
offshore component Monday morning as the surface low drops south
of Lane county.

KPDX AND APPROACHES...Light to moderate rain continue through the
afternoon, bringing brief drops to MVFR VIS/CIGs. Rain becomes
more scattered this evening. Slight chance (15-20%) for
thunderstorms through the afternoon. Conditions expected to
improve late Monday morning. Winds southwesterly, turning
southeasterly then northerly Monday morning as a surface low
crosses the area. /19

&&

.MARINE...Currently as of 4 AM Sunday, seas remain around 10-12
ft and northeasterly winds around 15-20 kt with gusts up to 25
kt persist over the waters. The highest seas and strongest winds
are located over the northern outer waters while the lowest
seas and weakest winds are located over the southern inner
waters off the central coast of Oregon. As the trough shifts
eastward through today, Small Craft northwesterly winds and seas
will weaken.

A weak low pressure will then 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. High pressure then looks to
build back across the northeastern Pacific during the middle of
this week. This looks to allow seas to drop down to around 5 to 6
ft.

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.
~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 9 PM PDT this evening for PZZ210.
     Small Craft Advisory until 5 PM PDT Monday for PZZ251>253-272-
     273.
     Hazardous Seas Warning until 5 PM PDT this afternoon for
     PZZ271.
     Small Craft Advisory from 5 PM this afternoon to 5 PM PDT
     Monday for PZZ271.
&&

$$

www.weather.gov/portland

Interact with us via social media:
www.facebook.com/NWSPortland
x.com/NWSPortland