Lake Oswego, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

834
FXUS66 KPQR 270959
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
259 AM PDT Fri Jun 27 2025

.SYNOPSIS...Onshore flow and patchy drizzle (mainly along the
coast) continues today. Expect a pattern change tomorrow and
through the weekend as high pressure builds into the region.
There is high confidence for inland temperatures approaching or
exceeding 90 degrees in many locations on Monday and moderate
confidence for Sunday and Tuesday. Additionally, there is a growing
possibility (20-40%) of thunderstorms in the Cascades early
next week. After Monday, high temperatures will trend cooler
(low to mid 80s) through midweek.

&&

.DISCUSSION...Now through Thursday...Through Saturday, we are
expecting fairly typical early summer weather for our area. This
mornings conditions show cloud cover and some areas of light
drizzle, especially near the coast. This pattern will gradually
shift as we head into the weekend, with clouds pulling back
inland and giving way to more sunshine later in the day. By
tonight, we should see a general clearing trend, although a few
light showers may still pop up in the north Oregon Coast Range
or near the Cowlitz and Willapa Hills in southwest Washington.

As we move into Saturday, upper-level winds high above the
Pacific will start to shift. This change will help push in
warmer air from the south, causing inland temperatures to begin to
climb. While mornings might still be cool and cloudy, expect a
trend toward sunnier and warmer afternoons, especially in the
central and southern Willamette Valley. Temperatures there may
rise a few degrees, reaching the upper 70s to low 80s by
Saturday afternoon.

Sunday is where we will really notice the change. A stronger
push of warm, dry air is expected, and with winds shifting from
the east, inland valleys are likely to heat up significantly.
Forecast models are in good agreement that Monday will be the
hottest day, with high confidence that the Willamette Valley
will reach or exceed 90 degrees. There is moderate confidence
that Sunday and Tuesday could also hit similar highs, depending
on how quickly and how long the ridge stays in place. While this
will not be an extreme or record breaking heat event, it will
likely be the warmest stretch of the week. Probabilistically,
there is a 30-50% chance to exceed 90 degrees on Sunday and
Tuesday, and a 70-80% chance on Monday.

Starting Monday and into early next week, we will be watching
for possible thunderstorms in the Cascades, especially in the
afternoon. These storms could be fueled by moisture sneaking in
from the south and meeting the heat building in the region. At
this time, chances are in the 20-30% range for storms mainly
focused along the Cascade ridges. Areas like Lane County
southward may have the best chances of seeing these storms
develop (50-60% confidence). Could see thunderstorms again on
Tuesday, although with less certainty (30-40% confidence).

Temperatures will cool down a bit after Monday but still stay
warm. Highs in the Willamette Valley will likely stay in the low
to mid 80s through midweek. Overnight temperatures will also be
warmer than what we have seen recently, generally staying in
the 50s to low 60s.
~Hall

&&

.AVIATION...Onshore flow continues for the next 24 hours or so.
Generally MVFR to IFR marine stratus has returned to the coast
and is expected to persist, with MVFR being the dominant flight
category through at least 16Z-18Z Friday. There`s also a 30%
probability of IFR/LIFR conditions along the coast through around
18Z Friday. Higher probability of IFR/LIFR conditions around KONP.
Any lowered flight conditions along the coast should improve to
VFR around 18Z-20Z Friday.

Forecast for inland locations is a little more complicated
as mid-level, overcast clouds has settled over the airspace. This
could easily limit the ability of MVFR conditions developing
inland. Guidance indicates around a 40-60% probability of MVFR
conditions developing within the Willamette Valley around 10Z-12Z
Friday. Inland conditions that did lower should return to VFR
around 18Z-21Z Friday.

Winds remain light and generally less than 10 kts. The exception
will be in the Columbia Gorge east of KTTD where westerly winds
will amplify after 18Z Fri with gusts up to 25 kt.

PDX AND APPROACHES...VFR conditions likely lowering to MVFR around
10Z-12Z Friday. Conditions expected to improve back to VFR around
18Z-20Z Fri. Generally northerly winds 6 kt or less. /42

&&

.MARINE...Weak perturbations will move through the onshore flow
through the Saturday before high pressure begins to build on
Sunday. Southerly winds will slowly become more westerly today
with gusts up to 15 kt expected through Friday. By Saturday, winds
will become more northerly and increase. This will bring Small
Craft Conditions with gusts up to 25 kt through Saturday. These
conditions are expected to continue to spread northward through
Sunday. Highest winds are expected on Sunday with around a 70%
probability of gusts up to 30 kt south of Cape Falcon, OR. Seas
3-5 ft today, but will build towards 5-7 ft at 9 seconds by
Saturday afternoon and maintain these levels through at least the
start of the week. Also, expect the Small Craft Advisory to spread
northward as timing and strength of the northerly winds become
more certain.

Moving into Sunday and Monday, models have a broad, upper level
low moving over northern California. This pattern is consistent
with increasing thunderstorm chances. While this will mostly
impact areas inland, cannot rule out a strike or two on Monday
evening. /42


&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory from 8 PM Saturday to 2 PM PDT Sunday for
     PZZ252-272.

     Small Craft Advisory from 2 PM Saturday to 2 PM PDT Sunday for
     PZZ253-273.
&&


$$

www.weather.gov/portland

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