Lake Oswego, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

542
FXUS66 KPQR 230528 AAD
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
928 PM PST Mon Dec 22 2025

Evening Discussion Update

.SYNOPSIS...An unsettled and progressive weather pattern
remains in place across northwest Oregon and southwest
Washington as multiple disturbances continue rotating inland
from the Pacific. Periods of rain at lower elevations and snow
in the Cascades will persist through midweek. Increasing
attention is focused on the potential for a significant wind
event on Wednesday, as ensemble guidance continues to converge
on a solution. Details remain uncertain as the signal for
impactful winds has increased and decreased for various
ensembles. Conditions may gradually trend quieter late in the
week into the weekend as ridging attempts to build over the
region.

&&

.DISCUSSION...Evening Update...Confidence has slowly increased
over the past few model runs in regards to the potential for
strong winds to impact the forecast area on Wednesday. Current
high-resolution models continue to show a more favorable pattern
for the low tacking northward from California to bring gusty
conditions. As such, have issued a Wind Advisory for the
Willamette Valley from Wednesday morning through at least late
Wednesday afternoon. It should be noted, that there is still a
fair amount of uncertainty as to the strength, path and timing
of this system. So, this forecast could easily change over the
next 24 hours. Please stay vigilant and we will continue to
monitor this system and keep you up to date with the latest
forecast. /42


No changes after this point. Previous discussion follows...

Tonight through Sunday...Tuesday, short- term ridging should
temporarily suppress shower coverage. Precipitation will become
increasingly terrain- focused, favoring the coast, Coast Range,
and Cascades, while much of the interior lowlands experience a
relative lull in activity. This break will be brief, but it may
provide several hours of drier conditions across the Willamette
Valley.

Forecast confidence decreases notably beginning Wednesday as
the larger-scale pattern becomes more amplified and complex.
Guidance depicts the parent trough evolving into a closed low
while dropping southward, allowing additional shortwave energy
to rotate northward toward the Pacific Northwest. This pattern
introduces a wide range of possible outcomes, particularly with
regard to wind impacts.

Ensemble guidance has pivoted with the most recent update, where
the EPS now has the meso-low tracking inland rather than along
the coast, resulting in a weak pressure gradient and less
impactful winds. However, the GEFS still suggests that this low
will track northward along the coast, which would allow for
stronger winds. Additionally, high-res model guidance (WRF and
NAMnest) still suggest the possibility for strong and impactful
winds. To give more detail on this scenario, winds will
initially come out of the east (due to the pressure gradient
from the low on the coast) and then shift southerly to
southwesterly as the low tracks north. The window for potential
damaging winds (45 to 65+ mph) remains between 6 AM to 2 PM
Wednesday across most of western Oregon and southwest
Washington, including the I-5 corridor (most locations will only
observe peak wind gusts for 1-2 hours). Such winds would likely
result in widespread tree damage and power outages.

While this remains a lower-probability outcome relative to the
full ensemble envelope, the increasing consistency within
higher-resolution and select ensemble guidance warrants close
monitoring. Should upcoming model runs continue to trend in this
direction, wind-related headlines may become necessary.

Beyond midweek, ensemble guidance generally favors a gradual
eastward progression of the amplified trough, allowing shower
activity to continue at times, especially near the coast and
higher terrain. Toward late week and into the weekend, a
majority of solutions suggest at least a temporary period of
ridging, which could bring a short-lived stretch of drier and
calmer weather. Confidence in the duration and strength of this
break remains moderate at best, but it represents the most
likely window for improving conditions in the extended forecast.
~12

&&

.AVIATION...Widespread mixture of MVFR/VFR conditions with slowly
decreasing showers as a cold front continues to push eastward.
Behind the front, conditions are expected to stabilize slightly
with generally VFR conditions between FL030 and FL045. Winds
generally below 10 kt through the TAF period. A more robust system
is expected to bring yet another round of precipitation across
the airspace around 00Z Wednesday, which will bring a mixture of
VFR/MVFR conditions back into the forecast.

KPDX AND APPROACHES...MVFR/VFR conditions with slowly decreasing
showers through 10Z Tuesday. Expect generally VFR with CIGS around
FL030 to FL040. A more robust system is expected to bring yet
another round of precipitation across the airspace around 00Z
Wednesday, which will bring a mixture of VFR/MVFR conditions back
into the forecast. /42

&&

.MARINE...Current buoy obs show seas in the 10-13 ft range,
with southwesterly wind gusts up to 25 kt. Winds are expected to
slowly subside through the overnight hours with seas remaining
elevated through Tuesday. As a result, will maintain a Small
Craft Advisory across all waters and the Columbia RIver bar
through at least Tuesday night.

A very active weather pattern return to the waters by Wednesday.
A low pressure system moving northwards from California looks to
bring elevated winds and seas across all waters. The current
forecast has southerly gusts up to 45 kt across all waters and the
Columbia River Bar. Seas are also expected to build towards 11-14
ft. As a result have issued a Gale Watch starting late Tuesday
night. It should be noted, that there is a lot of uncertainty as
to the track and overall strength of this incoming low. So, please
keep an eye on the forecast as it could easily change over the
next 72 hours. /42

&&

.HYDROLOGY...Past heavy rain continues to drain into slower
responding rivers, resulting in continued minor river flooding
for the Pudding River at Aurora. Expect the Pudding River at
Aurora to fall below flood stage by late tonight into Tuesday
morning. The latest river forecasts across the region can be
found at: www.water.noaa.gov/wfo/pqr. Please be sure to never
drive through a flooded road and heed any remaining road
closure.

&&

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 10 PM PST Tuesday for PZZ210-251>253-
     271>273.

     Gale Watch from late Tuesday night through Wednesday afternoon
     for PZZ210-251>253-271>273.

&&

$$

www.weather.gov/portland

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