Oregon City, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

558
FXUS66 KPQR 091110
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
410 AM PDT Wed Apr 9 2025

.SYNOPSIS...Drier and warmer weather are expected across the
region into Thursday, before a frontal system brings the next
chances for rain and mountain snow late Thursday into Saturday.
The pendulum then swings back to warmer and drier conditions
Sunday into next week.

&&

.SHORT TERM...Now through Saturday...Incipient ridging across
the West has begun to yield rising heights aloft and diminishing
coverage of showers early this morning, with the drying trend
expected to continue through today. Temperatures throughout the
column have begun to rise, and afternoon highs will reach above
normal into the 50s to mid 60s across the region. Despite low
and mid-level clouds decreasing through the afternoon, high
cloud cover will increase on the upstream flank of upper ridging
ahead of an approaching trough, so expect at least filtered sun
even when low clouds are able to break through today. Conditions
will remain fairly mild through tonight beneath the overcast
cirrus deck, with temperatures falling to lows only in the 40s
across much of the region aside from the high Cascades. Dry
weather then continues into Thursday morning before the next
frontal system arrives from the Northeast Pacific.

Mid-range guidance has begun to lean earlier with the arrival
of rain on Thursday, reaching coastal communities by midday and
inland areas by the mid-afternoon. This trend has also affected
the temperature forecast on Thursday, which is still expected to
be above normal, but may fall a few degrees short of Wednesday.
While the chances for highs reaching the low 70s has decreased
slightly, some 10-20% throughout inland valleys, downsloping
southerly winds in the southern Willamette Valley may help push
low elevations in interior Lane County toward that mark. Rain
will otherwise spread across the region from the west through
the afternoon, producing up to 0.25 inches of rainfall along the
I-5 corridor, and 0.25-0.75 inches in the western slopes of the
Coast Range, Willapa Hills, and Cascades. Snow levels around
7000 ft will see accumulating snow only well above pass level.

Cooler temperatures will arrive behind the departing cold front,
with the freezing level falling below 2500 ft through Friday
night. With this colder air in place, an upper-level trough
passing overhead Friday afternoon through Saturday will produce
a round of light precipitation including accumulating snow at
pass level in the Cascades. At this point, liquid precipitation
amounts look to be light, up to only 0.5 inches on the western
slopes of the Cascades, meaning snowfall of less than 6 inches
is favored at elevations above 3000 ft through early Sunday. At
lower elevations, scattered light rain showers are expected with
high temperatures back in the 40s to mid 50s. -Picard


.LONG TERM...Sunday through Tuesday...Dry weather will return in
the latter half of the weekend as transient but high-amplitude
ridging replaces the departing trough. The temperature pendulum
will therefore swing warmer again beneath mostly sunny skies
Sunday through much of Monday, with afternoon highs pushing
back up into the 50s and 60s across the region. Monday may be
the next best opportunity to see low 70s within interior valleys
before the ridge begins to weaken into Tuesday. Weak troughing
may bring increased cloud cover and additional precipitation
chances on Tuesday, however there is substantial spread among
long-range ensemble members in the amplitude of troughing over
the Northeast Pacific, with European ensemble members tending
to favor a weaker trough and lower precipitation, while the
Canadian and particularly the American ensembles favor a deeper
trough and higher precipitation amounts. -Picard

&&

.AVIATION...MVFR conditions along the coast as a broken cloud
deck lingers around 2000-3000 ft which is expected to improve to
VFR between 15-18z though some guidance hints at KONP remaining
MVFR into the afternoon. Mainly VFR conditions inland with the
exception of KEUG which has maintained an MVFR cloud deck due to
residual low level moisture. The HREF hints at a brief period
of sub-VFR CIGs inland as a stratus deck develops over the next
couple of hours and dissipates by 18z. Winds are expected to be
light and variable through the period.

Note: The KAST anemometer remains inoperative. Therefore, KAST
TAF amendments are limited to CIG and VIS.

PDX AND APPROACHES...HREF indicates a stratus deck
developing over the next couple of hours and dissipating by 18z.
40-60% chance for MVFR/IFR CIGs to develop over the next couple
of hours. KHIO has already dropped below VFR so this seems
reasonable. Winds remain light and variable today. -Batz

&&

.MARINE...Benign conditions expected today as weak high pressure
builds over the region. The next impactful system will be a
strengthening low pressure that will approach the PacNW before
turning more north toward the central British Columbia coast and
northern Vancouver Island late tonight into Thursday morning.
Expecting southerly winds to increase to between 25-30 kt with
gusts between 35-40 kt during the 5am through 2pm timeframe.
While Small Craft Advisory conditions are essentially a slam
dunk, Gale conditions a 50/50 chance of occurring based on model
guidance. For now have issued a Gale watch for the 5am to 2 pm
timeframe for all zones, including the Columbia river bar.

Westerly swell will continue to drop in height through the day
to between 4 and 6 feet at 10 seconds. With winds increasing
overnight, expect wind waves to be the primary driver of wave
heights on Thursday with peak heights of 7 to 9 ft at 7 to 9
seconds. Westerly swell will again move into the waters behind
the cold front on Friday, bringing waves peaking in the 6 to 8
ft range at 10 to 12 seconds. -Batz

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Gale Watch from late tonight through Thursday afternoon for
     PZZ210-251>253-271>273.

&&

$$

www.weather.gov/portland

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