Corvallis, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

571
FXUS66 KPQR 251013
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
313 AM PDT Wed Mar 25 2026

.SYNOPSIS...Showers return later Wednesday morning into the
evening hours. Mountain snowfall returns to the passes as well
before all lingering precipitation tapers off early Thursday
morning. High confidence in the return of dry weather
accompanied by a warming trend late week into the weekend.
Chances are increasing for another weather system late weekend
into early next week, although the exact details of this event
remain uncertain at this time.

&&

.DISCUSSION...Wednesday through Tuesday...Radar imagery early
Wednesday morning shows dry weather across NW OR and SW WA. This
dry weather won`t last long as satellite imagery shows the next
front approaching the PacNW from the eastern Pacific. This will
be a fast moving front that will bring a push of widespread
showers through the area as the front moves east late this
morning through the early evening hours. This front is looking a
bit stronger than previous guidance suggested in a few ways.
First, winds may be a bit more elevated along the coast than
previous forecasts, though not nearly as breezy as Tuesday.
Expect gusts mainly 20-25 mph with a brief period of gusts up
to 30-35 mph as the front passes. Additionally, the front is
looking a little more convective. Tie in surface heating along
with the colder air mass above, and some soundings indicate
pockets of weak instability strong enough to produce a 10-15%
chance of thunderstorms (100-250 J/kg MUCAPE), mainly along or
behind the frontal passage. This could allow for locally
heavier showers than originally anticipated, especially with
orographic forcing along the terrain. Also can`t rule out small
hail, locally gusty winds, and maybe a few lightning strikes.

Snow levels will fall throughout the day, especially behind the
cold front this afternoon. The potential for heavier showers
over the Cascades into the evening could lead to snow
accumulation of 1-4 inches down to around 3000-3500 ft,
including over Cascade passes. However, showers will likely be
becoming more scattered by this evening, which means some
locations may not receive any snow while others receive
accumulating snow. The latest NBM probabilities of at least 6
inches of snow over the Cascades (both OR and SW WA) remains
less than 5-15%, except for the highest peaks. Snow levels
continue lower to 1500-2000 ft for a brief period late tonight
into early Thursday morning as showers are ending, with a 5-10%
chance of snow levels falling near valley floor in the southwest
Washington lowlands. However, precipitation probabilities along
with amounts are so low by this point that even if some wet
snow does mix in, it would not accumulate or lead to any
impacts, especially as road surfaces would be too warm.

Although the surface front will move east of the Cascades by
late this afternoon, the associated upper level shortwave
will lag, moving east of the Cascades by Thursday morning. This
is what will keep isolated shower chances into early Thursday
morning for the coast and terrain of SW Washington. Skies will
be clearing quickly Thursday as zonal flow takes shape with
zonal flow to weak ridging continuing over the area into the
weekend over the region. Expect dry weather with a warming trend
into Saturday, possibly into Sunday. Daytime temperatures
Thursday are forecast in the upper 50s for the interior lowlands
with low to mid 60s Friday and mid 60s Saturday. The clear skies
overnight will allow for radiative cooling and low temperatures
falling back into the 30s Thursday morning through at least
Saturday morning. Expect widespread frost, which could impact
sensitive vegetation.

For Sunday into early next week, ensemble guidance continues to
indicate a deep upper trough moving through the eastern Pacific
towards the West Coast and bringing increasing chances of
precipitation Sunday into Tuesday. A significant amount of
uncertainty remains in the exact timing and amplitude of this
trough, leading to uncertainty in impacts. More ensemble members
continue to push precipitation onset into Monday, but there are
still plenty that suggest rain or at least cloud cover could
return Sunday. This is still leading to a significant spread in
the high temperature forecast on Sunday and to a lesser extent
on Monday. Latest NBM 25th-75th percentile temperature spread
shows highs ranging from the upper 50s to the low 70s for the
interior lowlands Sunday afternoon and upper 40s to mid 60s for
Monday. By Tuesday, the majority of ensemble members indicate
rain will have returned to the region with higher confidence in
cooler temperatures. -03

&&

.AVIATION...Predominately VFR conditions with pockets of MVFR cigs
continuing, mainly for both coastal and inland locations south of
KSLE. Will have to monitor for the presence of low stratus or fog
formation through 16z Wed due to the lingering moisture from the
rain along with skies clearing more than model guidance
originally suggested. Luckily, conditions behind the front will
mix, but it may not be significant enough to prevent fog. Cannot
rule out areas of patchy fog in some of the rural areas and in the
Cascade valleys with some models showing greater than a 20%
chance in these areas.

A break in the rain will be followed by a quick moving cold front
that will bring around around a 20% chance of rain showers and
thunderstorms between 16z Wed and 04z Thu. There are some
components missing in the pattern to include PROB30s for TS in the
TAFs, but cannot rule out small hail, breezy outflow winds, and
maybe a rumble of thunder here or there. Flight conditions remain
mostly VFR, though brief periods of MVFR/IFR are possible in
heavier showers or thunderstorms. Light and variable winds will
increase and turn westerly after 14-16z Wed along the coast and
15-18z Wed inland. Gusts up to 20-25 kts are possible along the
coast, but gusts should mostly remain less than 20 kts for inland
areas with sustained winds around 10-14 kts.

KPDX AND APPROACHES...Mainly VFR conditions through the next 24
hours. Around a 15-30% chance of IFR VIS in fog between 10-16Z
Wed,but if mixing remains those chances will be far lower and
may remain in the vicinity of the terminal. with isolated showers
after 18-20z Wed with a passing system 10-20% chance of TS
between 18Z Wed and 00Z Thu. -27

&&

.MARINE...Winds have decreased below 20 kts as of early Wednesday
morning. Seas have eased to around 10-12 feet at 10 seconds and
may continue to slightly lower into the morning hours. Another
cold front will quickly move through the waters later this
morning into the afternoon, increasing winds and seas again.
There`s high confidence in widespread gusts up to 25-28 kts with a
50-80% chance of peak gusts reaching 30-35 kts north of Cape
Foulweather. Although winds begin increasing after 5 AM, the peak
gusts are only expected for a brief period between 8 AM to 2 PM
with wind gusts easing below 20 kts by late afternoon to early
evening. Seas will increase in response to the winds, peaking at
10-12 ft at 10 seconds this afternoon then slowly easing below 10
ft this evening. The Small Craft Advisory has been extended
through 11 PM tonight for a combination of winds and seas.

High pressure then builds over the waters on Thursday. Northerly
winds return late Thursday into Friday as a surface thermal
trough strengthens along the coast. There`s a 70-90% chance of
widespread small craft wind gusts over 21 kts Thursday night
through Friday night. Seas generally remain around 7 to 8 ft at
10-11 seconds. -03

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until noon PDT today for PZZ210.

     Small Craft Advisory until 11 PM PDT this evening for PZZ251>253-
     271>273.
&&

$$

www.weather.gov/portland

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