393
FXUS66 KPQR 180536 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1036 PM PDT Mon Aug 17 2026

Updated aviation discussion.

&&

.SYNOPSIS...Warm and dry conditions expected through much of
the week with morning clouds and afternoon clearing. Daytime
highs are expected to be in the 80s through the week. Winds
generally out of the west to northwest, strongest in the
afternoon and along the Central Columbia River Gorge and Upper
Hood River Valley. Next chances for light showers arrive Friday
into next weekend.

&&

.DISCUSSION...Tonight through Saturday...Minimal changes to the
forecast as dry and warm conditions continue through the week
with minimal weather impacts. The large-scale pattern remains
stagnant through the period as a cul looks to persist off of the
OR/WA coast within the upper levels of the atmosphere. This is
resulting in relatively calm winds and stagnant conditions.
However, this pattern is at least maintaining northerly surface
winds which will keep daytime highs near seasonal normals as
well as cool and moist air infiltrating into the region each
night. So, expect marine stratus to develop along the coast, as
well as filter into the Willamette Valley each evening before
mostly clear skies return by the afternoon through the upcoming
week. Expect light west to northwest winds, peaking each afternoon.
The strongest winds are likely to be along the Central Columbia
River Gorge and Hood River Valley, but impacts are not anticipated.

As the week progresses, a majority of ensemble members are in
agreement that upper-level ridging over the Rockies and the Great
Basin will build late in the workweek, which would favor a brief
warm-up on Thursday. However, that warm up will likely be short
lived as ensemble guidance also shows an upper-level trough
over the northeast Pacific shifting onshore Friday into the
weekend, resulting in slightly cooler temperatures and winds
coming from the south/southwest. Chances for showers also increase
to 10-25% across the region during this time, with the highest
chances over the Coast Range and Cascades. However, there is
still high uncertainty in the timing and potential rain amounts.
A weak front at the end of the week would have a hard time
counteracting the dry airmass in place, making accumulating
rainfall unlikely and keeping most places dry. It should also be
noted that with southerly flow into the region the potential for
thunderstorms also comes into the forecast. Now, while the
pattern is favorable model soundings are suggesting that
nocturnal thunderstorms could develop with ensembles suggesting
around a 5-10% probability at this time. /42-10

&&

.AVIATION...Through 06z Wednesday...VFR conditions for all inland
terminals with high level clouds moving across the area. Marine
stratus has developed along the coast, producing IFR conditions.
Sub-VFR conditions are expected to persist along the coast through
much of Tuesday morning, possibly clearing out by noon or early
afternoon for KAST and KONP. There`s a 30-50% chance of MVFR
stratus pushing east along the Columbia River and forming in the
northern Willamette Valley after 12z Tue, including KPDX, KTTD,
and KUAO. There`s a 10-30% chance of MVFR cigs forming at KSLE and
KEUG, as well. Any MVFR conditions at inland terminals should
improve to VFR by 18-20z Tue. Northwest winds around 10 kt
continue along the coast with light winds inland overnight,
increasing again from the northwest late Tuesday morning to 5-10
kt.

KPDX AND APPROACHES...VFR conditions with high clouds. Marine
stratus is expected to move east along the Columbia river,
eventually reaching the Portland metro after 10-12z. This is
expected to bring MVFR CIGs through 18-20z. Light overnight
winds, becoming northwest around 6-8 kt late Tuesday morning.
-19/03

&&

.MARINE...A largely stagnant pattern continues through much of
the week with high pressure offshore supporting northerly to
northwesterly winds of 8-15 kt and afternoon gusts up to 20 kt.
Weak low pressure moving over the northeast Pacific Friday into
the weekend will shift winds out of the south to southwest
across the waters, but chances for gusts exceeding 21 kt remain
low, only 10-20%. Seas of 3-6 ft persist through the period.
Increasing periods of 12-14 sec on Tuesday-Wednesday may result
in a moderate risk for sneaker waves along the coast. Caution
should be used when in or near the water.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

www.weather.gov/portland

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