469
FXUS66 KPQR 102153
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
253 PM PDT Mon Aug 10 2026

.SYNOPSIS...Warm and dry conditions continue through the
upcoming week as temperatures moderate towards August normals.
Onshore flow will keep smoke east of the Cascades, while
precipitation chances remain very low through the end of the
week. Temperatures trend slightly warmer towards the end of the
week as a ridge of high pressure develops offshore. Increasing
potential for afternoon convection over the central OR Cascades
Friday into the weekend.

&&

.DISCUSSION...Tonight through Sunday...Fairly typical summer
weather continues this week as near average temperatures are
expected through Tuesday. This is in part due to zonal flow
aloft and onshore flow in the lower levels. Shallow marine
stratus is expected to return overnight along the coast and push
inland along the Columbia River towards the Portland/Vancouver
Metro area. Clear and sunny skies are expected to return on
Tuesday, with a near repeat of Monday`s conditions.

For Wednesday, there is increasing confidence that an upper
level pattern change will occur as a broad upper level
trough will move southward out of British Columbia into
Washington and Oregon. Model forecast soundings are showing a
deepening of the marine layer which would allow for deeper
stratus to push into SW Washington and the northern Willamette
Valley, as well as the potential for some aggressive drizzle
along the coast. This would result in daytime highs for inland
valleys to warm into the upper 70s to low 80s, with highs in the
60s along the coast and the 70s for the Cascades.

Looking towards the latter part of this week, some uncertainty
within the models and their ensembles remain. Daytime high
temperature spread remains relatively large Thursday and
Friday as guidance is split between the mid-week trough
lingering or a return of zonal flow in the upper levels of the
atmosphere. If troughing were to linger, cooler (or near
average) temperatures would be more likely, but if the more
zonal flow pattern develops, a warming trend would be more
likely with highs returning into the mid to upper 80s, with at
least a 25% chance of reaching 90 degrees on Friday and
continuing through Sunday.

500 mb cluster analysis of the ensembles indicates the
potential for upper level ridging to build offshore with varying
degrees of troughing or upper level low pressure developing
near central California. This feature is also bringing the
potential (5-10% chance) for more convective weather developing
near the central OR Cascade crest both Friday and Saturday
afternoons with the northward push of some monsoonal moisture.
Temperatures are likely to persist near to slightly above normal
into next weekend, with warm and dry conditions likely. /42-DH

&&

.AVIATION...Through 00Z Wed...Westerly flow aloft continues as we
remain in a zonal pattern through the TAF period. As of 21Z Mon,
marine stratus has receded greatly, now well off the coastline
from KTMK southward but still lingering in the mouth of the
Columbia River. Expect continual burnoff of marine stratus,
resulting in KAST likely improving back to VFR by 22-23Z Mon
(60-80% chance of VFR by 22-23Z Mon).

Looking ahead, Willamette Valley terminals will stay VFR through
the TAF period, with the exception of potential marine stratus
bringing a 20-30% chance of MVFR CIGs between 12-18Z Tue for
terminals around the Portland Metro. Additionally, there is a
35-50% chance of MVFR CIGs at KKLS beginning around 11Z Tue. As
for coastal terminals, another marine stratus push will bring a
mix of MVFR/IFR/LIFR conditions between 03-18Z Tue. Guidance
suggests majority of this time range to consist of a 70-90% chance
of MVFR, 40-60% chance of IFR, and 20-40% chance of LIFR
conditions (highest to lowest chances from KAST to KONP).
Otherwise, expect north to northwesterly winds of 10-15 kt with
gusts up to 25 kt along the coast and up to 20 kt inland this
afternoon to weaken into late this evening. Similar winds expected
tomorrow by 18-21Z Tue.

KPDX AND APPROACHES...VFR conditions with clear skies through the
TAF period. However, there is a 20-30% chance of MVFR CIGs between
12-18Z Tue. Northwest winds around 9-12 kt with gusts up to 20 kt
this afternoon will weaken by 06-08Z Tue. Similar winds expected
tomorrow by 18-21Z Tue.
~12

&&

.MARINE...High pressure offshore will continue to support
northerly winds through much of the week. Surface pressure
gradients this afternoon may result in wind gusts up to 21 kt
south of Cape Foulweather through this evening. The Small Craft
Advisory remains in effect until 11 PM Mon. Winds will ease
on Tuesday with much 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.
~12/DH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for PZZ253.

 Small Craft Advisory until 11 PM PDT this evening for PZZ273.

&&

$$

www.weather.gov/portland

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