452
FXUS66 KPQR 121106
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
406 AM PDT Sun Oct 12 2025

.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...Showers continue as the trough moves out of the
region. A low pressure system currently located over British
Columbia begins to strengthen and dig south along the West Coast,
bringing continues showers through at least 12Z Monday. A mix of
VFR and MVFR conditions are expected through most of the TAF
period; 20-40% chance for MVFR conditions between 12Z Sunday and
06Z Monday throughout the airspace (lowest to highest chances from
north to south).

The next round of showers are expected to arrive around 12-15Z
Sunday, contributed to the aforementioned probabilities for MVFR
conditions. With passing showers, CIGs could lower further,
influencing model guidance suggesting a 10% chance for IFR
conditions at most terminals. Otherwise, expect southerly to
southwesterly winds around 5-10 kt through the TAF period.

KPDX AND APPROACHES...Showers continue as the trough moves out of the
region. A low pressure system currently located over British
Columbia begins to strengthen and dig south along the West Coast,
bringing continues showers through at least 12Z Monday. The next
round of showers arrives around 12-15Z Sunday. There is a 20-40%
probability for MVFR conditions between 12Z Sunday and 06Z
Monday, with the lowest conditions expected to occur with passing
showers.
~12

&&

.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 from 8 AM this morning to 11 AM PDT
     Monday for ORZ126>128.

WA...Winter Weather Advisory from 8 AM this morning to 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.
&&

$$

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