Corvallis, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

815
FXUS66 KPQR 232153
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
153 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.
Some of the rain will become steadier at the TAF sites between
03-10z bringing in more steady MVFR conditions. The biggest issue
is the wind. For sites impacted by the Columbia River Gorge (KTTD,
KPDX especially), the east winds will increase into the 15 to 25
kt range between 11z and 17z. For ALL the TAF sites, look for a
sudden shift in winds coming from the south and increasing into
the 25kt to 35 kt range with gusts to 50 kts for about 1 to 3
hours. That will start at KEUG area around 15z and shift
northward to KPDX/KHIO/KTTD around 18z.

KPDX AND APPROACHES...Look for rainfall to come into the area
around 04z and continue until 09z with lingering showers during
the day on Wednesday. Called PDX ops and the tower to update them
on the wind forecast tomorrow with timing and speeds. Look for
east winds 10-15kts by 11z, increasing to 15-25kt by 16z. The very
strong south winds should hit around 18z from the south at 25 to
35 kts gusting to 50 kts. There is a 10% probability of greater
than 55 kts. /91

&&

.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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