FXUS66 KPQR 232125
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
225 PM PDT Sun Aug 23 2026

.SYNOPSIS...Upper level ridging and low-level offshore flow develops 
Monday, continuing into Tuesday, bringing warmer and sunnier 
conditions with high temperatures in the mid 80s to lower 90s across 
the interior lowlands, warmest on Monday. Wildfire smoke will also 
begin to increase over the Columbia River Gorge, Upper Hood River 
Valley, and the greater Portland/Vancouver metro area Monday morning 
and then linger through Tuesday; however smoke is not expected to be 
dense for most locations. Onshore flow arrives by Wednesday and 
continues thereafter, which will clear any lingering smoke out of 
the area and bring relatively cooler temperatures through the end of 
the week and into the weekend.

&&

.DISCUSSION...Tonight through Saturday Night...Water vapor satellite 
imagery reveals the upper level shortwave trough lifting across NE 
Washington into Canada this afternoon. Heights aloft will continue 
to increase through tonight allowing for clearing skies. As a ridge 
of high pressure builds aloft over the region, a surface thermal 
trough develops along the coast extending into western WA early 
Monday morning. This will allow for light offshore flow to develops, 
especially over the western slopes of the Cascades with east winds 
increasing through the Columbia River Gorge later Monday morning. 
Winds are not expected to be very strong, but gusts up to 25-30 mph 
will certainly be possible through the western gorge. Temperatures 
at 850 mb are also expected to rapidly rise to around 20C by Monday 
evening. Downsloping winds and afternoon mixing will therefore allow 
for surface temperatures to warm into the upper 80s to lower 90s 
across much of the inland lowlands, as well as through Cascade 
valleys, while temperatures at the coast will likely warm into the 
70s before winds shift as sea-breezes occur early in the afternoon. 
This offshore flow will also cause wildfire smoke to begin to filter 
back down into the valleys, including into the Portland/Vancouver 
Metro area, Columbia River Gorge and Upper Hood River Valley. 
However, smoke is not expected to be dense for most locations.   

By Monday evening, the surface thermal trough is expected to shift 
east into the Willamette Valley, and potentially to the Cascade 
crest, allowing for onshore flow to return across much of the area. 
Lingering low pressure in the valley will likely allow for very 
light offshore flow to return over the Cascade foothills Monday 
night into early Tuesday. This will likely maintain elevated 
overnight temperatures in the lower to mid-60s where the easterly 
winds persist. A moderate risk of heat related illnesses will 
therefore exist Monday into Tuesday. Wildfire smoke is also likely 
to linger into Tuesday as well for northern portions of the forecast 
area.

Early Tuesday, a shortwave trough will lift just offshore, skirting 
the coast, as a deeper upper level low in the Gulf of Alaska drops 
south. This should cause a southerly wind reversal to occur along 
the Oregon coast and into the Willamette Valley. Heights aloft still 
remain high with the axis of the upper level ridge over the 
Intermountain West, but 850 mb temps cool to around 16-17C. Still 
expecting Tuesday temperatures to warm into the mid to upper 80s 
(about 4-8 degrees above normal). By Tuesday evening, surface high 
pressure building along the coast will bring a strong marine push of 
westerly winds. Any lingering wildfire smoke should shift back east 
of the Cascades by Wednesday.   

Models and their ensembles are showing fairly good agreement that 
the upper level trough over the NE Pacific gradually pushes east 
over the Pacific NW Wednesday through Thursday, with troughing 
likely persisting over the region through the end of the week and 
into the weekend. There is high confidence that temperatures trend 
cooler to near or slightly below average. Confidence is low 
regarding precipitation, if any will occur later this week. But, if 
any rain does fall, it would most likely be very light. Best chances 
would be drizzle along the coast with a weak frontal passage 
Thursday morning; and again on Saturday, but PoP remains around 15% 
or less.  /DH

&&

.AVIATION...00Z TAFs...Widespread VFR conditions with mostly clear
skies will likely prevail from 00Z Monday through 00Z Tuesday, 
with one potential exception at the coast. By 11Z Monday, KONP has
a 50-60% chance for the return of low stratus with ceilings below
1000 ft and surface visibilities around 2 SM or lower. 
Probabilities for low stratus to return to KAST are lower at 
around 20%. Inland TAF sites have around a 10-20% chance to see a 
brief period of MVFR low stratus between 12-17Z Monday. Aside from
KONP, these probabilities are not high enough to justify a 
mention in the TAFs.

Expect breezy northerly winds along the coast through 03Z Monday,
gusting upwards of 20 kt at KONP. Winds will be relatively weaker
inland, mainly out of the north to northwest. Around 18-20Z 
Monday, easterly winds around 8-11 kt are expected to develop at 
KTTD and KPDX as offshore winds develop through the Columbia River
Gorge. This will also push some wildfire smoke into the Gorge and
greater Portland/Vancouver metro area Monday morning. Although 
dense smoke is not expected, slantwise visibilities may be 
reduced. In addition, temperatures are expected to warm into the 
lower 90s Monday afternoon at the inland TAF sites, so be aware of
high density altitude which may reduce aircraft performance.

KPDX AND APPROACHES...Expect VFR flight conditions with mostly
clear skies from 00Z Monday through 00Z Tuesday. Light winds 
should become northwest around 7-8 kt by 00Z Monday with an 
incoming sea breeze. Winds become light again by 08Z Monday,
before becoming easterly around 8-11 kt sometime between 18-20Z
Monday. Once the easterly winds begin, expect increasing wildfire
smoke at and near the terminal. Although dense smoke is not 
expected, slantwise visibilities may be reduced. Temperatures are
expected to warm into the lower 90s Monday afternoon at the
terminal, so be aware of high density altitude which may reduce 
aircraft performance. -23

&&

.MARINE...Northerly winds will gradually increase Sunday afternoon
and evening as high pressure strengthens over the northeast 
Pacific. Gusty winds will develop over the waters, increasing from
south to north from Florence to Cape Shoalwater. Wind gusts up to
25 kt are expected to develop Sunday evening over the southern 
and central waters, and over the northern waters Sunday night. 
These wind speeds will then persist through Monday afternoon/early
evening before decreasing Monday night. Small Craft Advisories 
remain in effect from 5 PM Sunday to 5 PM Monday for the coastal 
waters from Florence north to Cape Falcon and from 11 PM Sunday to
8 PM Monday for the coastal waters north of Cape Falcon to Cape 
Shoalwater. Gusty north winds up to 25 kt are also expected for 
the Columbia River Bar starting at 8 AM Monday, which also has a
Small Craft Advisory in effect.

A southerly wind reversal arrives early Tuesday morning over the 
inner waters with gusts up to 15-20 kt expected by Tuesday 
afternoon. This will also bring increasing chances for marine fog 
beginning early Tuesday morning, especially over the inner 
waters. Visibilities may fall below 1 SM at times as the southerly
winds develop and upwelling occurs. Aside from the increasing 
winds and potential marine fog, significant wave heights look to 
remain relatively low at around 3 to 5 ft through Friday. -23

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory from 8 AM to 8 PM PDT Monday for PZZ210.

     Small Craft Advisory from 11 PM this evening to 8 PM PDT Monday 
     for PZZ251-271.

     Small Craft Advisory from 5 PM this afternoon to 5 PM PDT Monday 
     for PZZ252-253-272-273.
&&

$$

www.weather.gov/portland

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