049
FXUS66 KPQR 110953
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
253 AM PDT Tue Aug 11 2026

.SYNOPSIS...Warm and dry conditions expected to continue through the
week, with a brief cooldown likely on Wednesday as clouds and
onshore flow increase. Precipitation chances remain low through the
weekend, but there are indications of increasing chances for rain
early next week (though chances remain low at this time).

&&

.DISCUSSION...Today through Monday...Onshore flow continues with
another day of near average temperatures expected. A few morning
clouds will give way to mostly sunny skies as highs warm back into
the lower to mid-80s across the interior lowlands. Slightly cooler
conditions are expected on Wednesday as the upper level pattern
shifts from zonal flow to more troughing. Broad upper level
troughing over British Columbia this evening becomes a bit more
organized as it drops south into Washington and Oregon. This pattern
typically corresponds with a deepening of the marine layer allowing
for marine stratus to push inland by Wed morning. Would not be
surprised for the coast to see some drizzle Wed morning as well.
With the deeper cloud layer lingering into the afternoon,
temperatures will be slower to warm resulting in highs reaching into
the mid to upper 70s in southwest WA and Portland metro area, while
temps in the southern Willamette Valley are more likely to warm into
the lower 80s. Any rain or thunderstorm chances are likely to stay
across portions of the northern half of WA.

Beginning to see a bit more agreement among the models and their
ensembles for later in the week as the upper level pattern is
trending toward broad upper level troughing. The potential range of
afternoon high temperatures from the NBM for Thursday and Friday has
generally consolidated into the lower to mid-80s, retuning the
likelihood of near to slightly above average conditions for mid-
August. More uncertainty into the weekend, but ensembles are
suggesting weak upper level ridging may nudge back into the Pacific
NW as low pressure deepens the upper trough offshore. This could
result in a slight warming trend, though models suggest there is
only around a 10% or less chance of exceeding 90 degrees. Shortwave
troughs within the more southwesterly flow aloft along with some
increasing monsoonal moisture will bring chances for convection
along the Cascade crests for Saturday afternoon.

The question then turns to the possibility of rain early next week.
But, the probability for measurable precipitation remains low (20%
or less) across the area next Monday. Cluster analysis of 500 mb
heights shows a wide range of the strength and depth to the upper
level trough offshore, while around 10-15% of ensembles show the
potential for any substantial rainfall across the area.  /DH

&&

.AVIATION...Through 12Z Wed...Westerly flow aloft continues with
predominately VFR conditions expected inland. Marine stratus
continues to fill in along the coast early this morning returning
low-end MVFR to IFR CIGs. Stratus is expected to persist at
coastal terminals through 18-21z, lingering longest near KAST.
Onshore flow may also push stratus up the lower Columbia River
Valley, with lower chances (10-20%) of reaching the Portland
Metro area today. VFR conditions with clear skies prevail for
Willamette Valley terminals through at least 06-08z Wednesday. A
stronger marine push will be possible for Wed morning as upper
level troughing allows for deepening of the marine layer. North to
northwest winds continue across the area, increasing to around
8-12 kt in the afternoon.

KPDX AND APPROACHES...Predominately VFR with clear skies through
at least 06-08z Wed. There is a 10-20% chance for MVFR CIGs at
any given hour between 12-17z Tue. Northwest winds increase to
8-10 kt after 18z Tue. /DH

&&

.MARINE...High pressure offshore will continue to support
northerly winds and fairly benign conditions across the coastal
waters through the week and into the weekend. Winds are expected
to ease today, trending toward lower chances (less than 10%) of
wind gusts exceeding 21 kt. Similar conditions persist through
late in the week. Wind driven seas are expected to remain around 3
to 6 ft through the week. /DH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...None.

&&

$$

www.weather.gov/portland

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