Oregon City, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

873
FXUS66 KPQR 240444
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
844 PM PST Tue Dec 23 2025

.SYNOPSIS...An active and unsettled pattern remains across
northwest Oregon and southwest Washington as multiple Pacific
disturbances continue to rotate inland through midweek. Periods
of rain at lower elevations and snow in the Cascades persist.
Attention remains focused on Wednesday, when a developing low
pressure system may bring impactful winds depending on its
eventual track. While uncertainty remains, ensemble guidance now
suggests a modest tilt toward a coastal solution. Conditions
trend quieter later in the week as upper-level ridging attempts
to build over the region.

&&

.DISCUSSION...Now through Monday...This afternoon, the region
sits beneath a brief window of weak mid-level ridging embedded
within a much larger-scale trough over the eastern Pacific. This
has allowed precipitation to become more light and scattered in
elevated terrain, and generally a lull or lack of precipitation
in the lowlands. This pause in precipitation will be brief.
Snow levels begin to rise into tonight, bringing a halt to
winter travel conditions in the Cascades.

Conditions begin to change later tonight into early Wednesday
as the broader synoptic pattern becomes increasingly amplified.
Rain will return to the area. The parent upper-level trough
offshore continues to evolve toward a closed low configuration
while dropping southward, allowing additional shortwave energy
to rotate northward toward the Pacific Northwest. This evolution
introduces substantial forecast sensitivity, particularly with
respect to the development and track of a meso-low.

Ensemble guidance remains divided, though some clarification
has emerged since earlier cycles. The European ensemble is now
evenly split, with roughly half of its members tracking the
surface low inland and half favoring a coastal path. In
contrast, the GFS ensemble strongly favors a coastal track, with
approximately 95% of members keeping the low near the coastline
and only minimal support for an inland solution. The Canadian
ensemble leans the opposite direction, with about 60% of members
favoring an inland track and 40% along the coast. When
considering all guidance collectively, the overall signal
suggests roughly a 60% probability of a coastal track versus a
40% chance of the system moving inland.

This distinction remains critical, as a coastal track would
support stronger pressure gradients across western Oregon and
southwest Washington, increasing the potential for impactful
winds. Under this scenario, a period of strong winds would be
possible Wednesday morning into early afternoon, potentially
affecting not only coastal areas but also inland valleys,
including portions of the I-5 corridor. Gusts could exceed
advisory criteria (of 45+ mph gusts), and in the higher-end
outcomes (10-20% chance), reach levels capable of producing
scattered to widespread tree damage and power outages. Note that
while the storm system will only take about 6-12 hours to move
through the area, any given location will likely only see peak
wind gusts for 1 to 2 hours. As for an inland track, this would
substantially limit wind impacts, confining stronger gusts to
higher terrain and the immediate coast.

Given the remaining uncertainty, the forecast continues to
favor a middle-ground solution where winds remain within Wind
Advisory criteria, while advertising the low potential for a
more significant wind event (High Wind criteria of 58+ mph).
Confidence in exact timing and magnitude remains moderate at
best, and trends in upcoming model cycles will be critical in
determining whether higher-end wind headlines become necessary.

Beyond Wednesday, ensemble guidance generally supports a gradual
eastward progression of the amplified trough. This would keep
periodic chances for rain and mountain snow in the forecast,
especially along the coast and higher terrain. A weaker frontal
feature is likely to move through later Thursday, followed by
increasing support for temporary ridging aloft toward the end of
the week. Should this ridging materialize, it would provide a
brief window of drier and calmer weather heading into the
weekend, though confidence in its duration and strength remains
moderate. ~12

&&

.AVIATION...MVFR/VFR conditions will continue across the region
with areas of rain moving in from SE to NW through the TAF period.
Precipitation will continue to stream in across the airspace and
will bring rain to the majority of TAF sites by 08Z-10Z Wednesday.
A rapid pattern change in the forecast through 12Z Wednesday. The
biggest issue will be wind. For sites impacted by the Columbia
River Gorge (KTTD, KPDX and KHIO especially), the east winds will
increase into the 15 to 25 kt range between 09Z and 11Z Wednesday.
For ALL the TAF sites, look for a sudden shift in winds coming
from the south and increasing into the 25 kt to 45 kt range with a
brief period of time where gusts to 50 kts could be possible.
Expect the potential for the 50 kt gusts for about 1 to 3 hours,
which will start in the south at KEUG around 15Z Wednesday,
reaching KSLE around 18Z Wednesday and towards KPDX/KHIO/KTTD
around 22Z Wednesday-00Z Thursday. South/southwest gusts of 30 kt
or higher, for coastal locations look to start around 15Z-17Z
Wednesday with peak winds expected around 18Z-21Z Wednesday with
southern locations seeing the elevated winds first. Overall, winds
are expected to decrease rapidly after 00Z-03Z Thursday across the
airspace.

Note: Have done my best to highlight LLWS potential for TAF
locations. However, there is a general increase in both speed and
direction LLWS from around 12Z Wednesday though around 06Z
Thursday for the entire airspace as a result of the incoming
system.


KPDX AND APPROACHES...MVFR/VFR conditions will continue with rain
moving in from SE to NW through the TAF period. A rapid pattern
change in the forecast through 12Z Wednesday. East winds will
increase into the 15 to 25 kt range between 09Z and 11Z Wednesday.
Then winds will become southerly and increase significantly around
18Z Wednesday, with gusts up to 40 kt. Could see brief gusts up to
50 kt for a few hours around 17Z-22Z Wednesday. LLWS (both speed
and direction) will be a concern after 10Z Wednesday through
around 00Z Thursday. Winds drop rapidly around 00Z-03Z Thursday.
/42

&&

.MARINE...Current buoy obs continue to show elevated Small
Craft conditions across all waters. Seas in the 9 to 12 ft with
robust easterly winds. A very active weather pattern is expected
to develop across all waters through late tonight and into
Wednesday. A low moving northward along the coast from
California will bring elevated winds and seas across all waters.
The current forecast has southerly gusts up to 50 kt across all
waters and the Columbia River Bar. Isolated gusts up to 65 kt
could be possible with this system, but the probability it
relatively low at this time (10-15%). Seas are also expected to
build towards 11-14 ft. As a result have upgraded the Gale Watch
to a Gale Warning, starting late Tuesday night. A lot of
uncertainty remains with the exact track and overall strength of
this incoming low. So, please keep an eye on the forecast as it
could easily change over the next 12-36 hours. /42

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Wind Advisory from 7 AM to 4 PM PST Wednesday for ORZ104>118-
     123>125.

WA...Wind Advisory from 7 AM to 4 PM PST Wednesday for WAZ202>208.

PZ...Small Craft Advisory until 4 AM PST Wednesday for PZZ210-251>253-
     271>273.

     Gale Warning from 4 AM to 4 PM PST Wednesday for PZZ210-251>253-
     271>273.

&&

$$

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