Corvallis, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

279
FXUS66 KPQR 160430
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
930 PM PDT Fri May 15 2026

.UPDATE...This evening, model guidance has trended towards
greater amounts of total snow accumulation in the Cascades and
at the Cascade passes tonight through Saturday night. There is
now a 50-70% chance for 6+ inches of total snow accumulation
from 11 PM tonight to 11 PM Saturday for elevations above 4000
ft. As a result, a Winter Weather Advisory has been issued for
the South Washington Cascades and the Northern and Central
Cascades of Oregon above 4000 feet from 11 PM tonight to 11 PM
Saturday. Total snow accumulations between 4 to 8 inches,
highest amounts at Government Camp. 12 to 18 inches of snow
expected above 5000 to 5500 feet.~12

&&

.SYNOPSIS...Showers continue through this evening as a weak
frontal system moves across the area. Upper level troughing
will maintain showers with seasonably cool temperatures through
Saturday, as well as a 10-25% chance of afternoon thunderstorms.
Cooler temps will also bring snow levels down to 3500-4000 feet,
allowing for light snow along the Cascade passes tonight through
Saturday night. Drier and warmer weather returns Sunday through
next week as high pressure re-builds.

&&

.DISCUSSION...Today through Thursday...Radar imagery and surface
observations as of early Friday afternoon depicts widespread
rain moving through southwest Washington and far northwest
Oregon (mainly from Lincoln City/Salem northward) as an upper-
level shortwave trough and associated surface front swings
through the Pacific Northwest. West-southwesterly winds have
also picked up with this system with gusts up to 20-25 mph along
the I-5 corridor and 25-40 mph across higher terrain and
exposed ridgetops.

Looking at satellite imagery, it appears we`ll transition post-
frontal conditions by the late afternoon as cloud cover appears
the break up behind the front just offshore. Colder air aloft
behind the front and potential surface heating from cloud breaks
will increase atmospheric instability this afternoon and
evening. Therefore, there is a 10-25% chance for thunderstorms
through 11 PM this evening across northwest Oregon and southwest
Washington, with the highest chances along the south Washington
coast and Willapa Hills. Any passing thunderstorms may produce
lightning, heavy downpours, erratic winds, and/or small hail.

Showery conditions continue through Saturday as broad upper-
level troughing progresses through the Pacific Northwest.
Another impact from this system will be snow levels falling to
3500-4500 feet (lowest across the southwest Washington
Cascades). Orographics of the Coast Range and Cascades will
likely enhance precipitation as west to northwesterly flow
persists. This may lead to some accumulating snow, especially
above 3500 feet including the Cascade passes. Latest guidance
suggests there is anywhere from a 30-50% chance of exceeding 6
inches of snow in a 24-hr period ending 5 AM Sunday along the
Cascade passes, highest near Government Camp. If planning on
traveling to the Cascades, make sure to check the latest
forecast, refer to ODOT/WSDOT for the latest road conditions,
and pack an emergency supply kit. Considering many of the forest
roads are free of snow from the early melt-out and access to
unmaintained roads is growing, the lower snow levels may catch
people off guard if they are unprepared for cold, wet, and even
snowy conditions.

After seasonably cool temperatures today and Saturday, expect a
warming trend to return Sunday through early next week. As the
upper level trough shifts east, expect high pressure to return
back over the region. Ensemble guidance is is general agreement
that upper level ridging builds into the NE Pacific. But, there
remains uncertainty with how far east the ridge progresses
toward the PacNW. The farther east the ridge does shift over the
Pacific NW, temperatures are more likely to see higher end
amounts, mid to upper 70s by the middle of next week. If the
region stays under more northwesterly flow aloft, afternoon
temps would be more likely to remain in the upper 60s to lower
70s. The majority of ensemble guidance does return to mostly dry
conditions for next week.        -10/DH


&&

.AVIATION...As of 04Z Sat, VFR conditions at most terminals,
rain showers linger mostly north of KSLE, and southwesterly to
southeasterly winds generally under 8 kt. Through the TAF
period, expect rain showers and mostly VFR conditions, with
a 10-20% chance of MVFR conditions.

For coastal terminals, expect generally westerly winds around
8-10 kt through 16-18Z Sat, then shifting northwesterly and
increasing to around 10-14 kt. Winds will likely gust to 20 kt
through the TAF period, with weakened gusts possible between
12-18Z Sat.

For inland terminals, expect southwesterly winds around 6-8 kt
through 16-18Z Sat, then increasing to around 9-12 kt and
gradually shifting northwesterly towards 00Z Sun. Wind gusts up
to 20 kt will become possible beginning around 18-22Z Sat for
most terminals.

KPDX AND APPROACHES...VFR conditions and rain showers will
continue through at least 06Z Sun, with a 10-20% chance of MVFR
conditions. Southwest winds around 6-8 kt will increase to 9-12
kt by 18Z Sat and then shift northwesterly towards 00Z Sun. Wind
gusts up to 20 kt possible beginning around 19-21Z Sat.
~12

&&

.MARINE...
An upper level trough continues to move across the
area, supporting low pressure offshore along with a weak cold
front. Westerly flow with scattered rain showers expected to
persist through Saturday. Winds expected to increase with the
approaching front, supporting gusts up to 25 kt across all of
the waters from Cape Shoalwater WA to Florence OR, including
the Columbia River Bar. A Small Craft Advisory remains in effect
for all the waters until 2 AM Sunday. A westerly swell will
increase seas to 10-12 feet at 11-13 seconds tonight. Very
strong ebb currents across the Columbia River Bar early Saturday
morning will shorten the wave period and result in steeper
seas.

Northerly to northwesterly winds return Sunday into early next
week while seas ease to around 4 to 8 ft as high pressure builds
offshore. Strong currents during morning ebb tides will continue
daily through Thursday, potentially yielding steep and
hazardous seas for small craft crossing area bars through much
of the week. ~12/19/DH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 11 PM PDT Saturday for
     ORZ126>128.
WA...Winter Weather Advisory until 11 PM PDT Saturday for WAZ211.
PZ...Small Craft Advisory until 2 AM PDT Sunday for PZZ210-251>253-
     271>273.
&&

$$

www.weather.gov/portland

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