711
FXUS66 KPQR 172155
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
255 PM PDT Thu Sep 17 2026

.SYNOPSIS...Temperatures trend toward normal on Friday with a
slight increase through the weekend. Heading into next week, the
pattern is expected tor trend cooler as troughing drops
southward from the Gulf of Alaska. Dry conditions are heavily
favored through the next week with a possible pattern shift
toward cooler, wetter conditions by the end of next week.

&&

.DISCUSSION..Now through Wednesday...A closed upper level low
covering northern California to eastern Oregon continues to
slowly shift northeast as ridging builds in from the west. Warm
conditions peak today before returning to near normal tomorrow
as onshore flow returns and marine stratus is expected to be in
place to start the next few mornings. Weak offshore flow that
was in place across the western slopes of the higher terrain
have shifted to light west to southwest flow while winds across
the interior lowlands are northerly. The vast majority of the
forecast area is expected to remain dry with the only exception
being the far southeastern portions of Lane and Linn counties
which could see light showers or a brief thunderstorm through
the evening.

Increasing onshore flow is expected to help marine stratus develop
along the coast later this evening, eventually spreading eastward up
the Columbia River into the Portland metro and through the gaps in
the Coast range and into the Willamette Valley later tonight. This
means Friday likely begins with cloudy skies for much of the area
which will impact overall high temperatures. Cloud cover is expected
to dissipate by late morning across the interior and may not
completely dissipate along the coast. Highs are expected to peak
closer to normal in the mid to upper 70s across the interior
lowlands and 60s for the coast and higher terrain.

Confidence remains high heading into the weekend for a slight warm
up into the upper 70s to low 80s across the interior and no
precipitation. Beyond the weekend, the pattern trends toward cooler
temperatures as troughing drops southward from the Gulf of Alaska.
Details at this time are unclear regarding exact temperatures and
precipitation. As of right now, conditions expected to be near or
slightly below average for highs and mostly dry. Most ensemble
members are showing dry conditions through next Wednesday with a
minority of ~10% of members showing measurable rain inland Tue-Thu.
Uncertainty increases substantially beyond this time frame but there
are possible signals for a pattern shift to a cooler, wetter pattern
by the end of next week. -19

&&

.AVIATION...Through 00Z Saturday...Satellite imagery and terminal
observations as of late Thursday morning depicts predominately
VFR conditions with mostly sunny skies across the northern Oregon
coast and Willamette Valley. An exception is the central Oregon
coast including KONP, where marine stratus continues to move in
and bring LIFR CIGs. High confidence (>80% chance) that marine
stratus will gradually make its way northward and reach KAST by
03-05z Fri. Some shower/thunderstorm activity over central Oregon
this afternoon may bring some thin high level clouds over the
Valley, but thunderstorms are not expected west of the Cascade
crest (5% chance or less).

By early Friday morning around 10-12z Fri, marine stratus will
move up the Lower Columbia River Valley and gaps through the Coast
Range and enter the Willamette Valley. There is a 40-60% chance
at any given hour between 12-18z Fri for MVFR CIGs (2-3 kft)
across Valley terminals, with the highest chances at KEUG. Stratus
will gradually dissipate after 18z Fri across the Valley as
daytime heating progresses. West/southwest winds generally under
10 kt for most locations this afternoon except 9-11 kt at KEUG
between 00-06z Fri.

KPDX AND APPROACHES...VFR conditions with mostly clear skies
through late tonight. 40-60% chance for MVFR CIGs at any given
hour between 12-18z Fri. Northwest winds 4-5 kt through this
evening turning southeast under 5 kt overnight.       -10

&&

.MARINE...High pressure will maintain light northerly winds
through this evening. Tonight into Friday, weak low pressure will
turn winds more southerly to southwesterly but remain below 15 kt.
High pressure re-builds over the waters Friday night into
Saturday, returning northerly winds through next week. This
weekend, there is a 40-70% chance for brief and isolated wind
gusts up to 25 kt across the waters, with the highest chances
Sunday afternoon across the inner waters out to 10 NM offshore.
Given that wind gusts up to 25 kt are not expected to be
widespread or frequent, Small Craft Advisories are not
anticipated. Seas around 4-6 ft at 8-10 sec expected through next
week with a persistent northwesterly swell.      -10

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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