FXUS66 KPQR 312106
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
205 PM PDT Sun May 31 2026

.SYNOPSIS...High pressure persists through Tuesday with temperatures
warming each day. Moderate HeatRisk is expected along the I-5
Corridor north of Salem, including the Portland/Vancouver Metro, as
temps potentially warm into the upper 80s to lower 90s. Temperatures
cool again to near seasonable averages by Wednesday as high pressure
is replaced with more zonal flow aloft. Chances for rain remain low
(less than 10%) through at least Thursday, except for afternoon
showers in the Cascades on Wednesday. Cooler conditions likely by
next weekend as a low pressure system in the Gulf of Alaska brings
increasing chances for rain later Friday into Saturday.

&&

.SHORT TERM...Now through Tuesday Night...Mostly sunny skies today
with dry, northerly flow as high pressure continues to build over
the northeast Pacific. Seasonable temperatures today are expected to
trend warmer Monday and Tuesday as the upper level ridge gradually
shifts east over the region.

On Monday, upper level ridging amplifies offshore while a broad cut-
off low develops east of the Cascades. This will bring dry offshore
flow aloft by Monday morning as a surface thermal trough also builds
northward along the coast. Temperatures on Monday are expected to
jump around 10-14 degrees F warmer than today's highs, reaching the
lower to mid-80s inland, while temps along the coast warm into the
mid-60s to lower 70s. Only Minor HeatRisk is expected across the
area tomorrow, except within parts of the Portland Metro area where
overnight lows dipping into the upper 50s Monday night are
suggesting the potential for Moderate HeatRisk.

High pressure continues to build on Tuesday as the upper ridge
slides east, with the axis of the ridge shifting over western Oregon
Tue afternoon. 850 mb temperatures peak at around 14-16C with plenty
of sunshine. East winds are also expected to increase out of the
Columbia River Gorge Tue morning bringing drier air. Therefore,
expect afternoon temps to warm another 3-6 degrees F from Monday,
with highs reaching at least the mid to upper 80s across the
interior lowlands, and into the 70s along the coast until moderated
by the seabreeze. Guidance continues to maintain a 45-65% chance of
exceeding 90 degrees along the I-5 corridor from Salem northward
into SW Washington. There is also a 10-20% chance that locations
within the Beaverton to Wilsonville area exceed 95 degrees. A
Moderate HeatRisk is likely (70-90% chance) for Tuesday within the
greater Portland/Vancouver Metro area, which means those without
access to sufficient cooling and hydration may be impacted by the
heat. Therefore, take precautions on Tuesday if participating in
outdoor activities, especially during peak afternoon heating. The
heat is not expected to last long, though as a decent marine push is
expected by later Tue evening ahead of an upper shortwave trough.
/DH

.LONG TERM...Wednesday through Saturday night...A negatively tilted
upper level trough is expected to swing across the Pacific NW on
Wednesday, returning seasonable temperatures with mostly dry
conditions. There remains high confidence that temperatures cool
back into the 70s on Wednesday and persist through the end of the
week. Models and their ensembles are in fairly good agreement that a
low pressure system in the NE Pacific weakens as it moves toward the
Gulf of Alaska on Wednesday. An associated frontal band well ahead
of the surface low will approach the coast, but guidance continues
to trend down with minimal, if any, precipitation spreading inland.
In fact, NBM guidance generally shows less than a 10% chance of rain
through Thursday. Except, there are around 20-30% chances for
showers in the Cascades Wed afternoon and evening as the afore-
mentioned trough lifts across the region. The timing of the trough
could make things somewhat interesting east of the Cascades.

Uncertainty increases late in the week and into the weekend
regarding the weakened low pressure system potentially dropping down
from the Gulf of Alaska toward the Washington coast. In general,
there are increasing chances for rain on Saturday, but very low
chances for any impactful weather. Ensemble guidance suggests 24-
hour rainfall accumulation could range anywhere from zero (10th and
25th percentiles) up to potentially exceeding 0.5 to 1.0 inch
(closer to the 90th percentile). Despite the potential pattern
shift, onshore flow is likely, which will usher in cooler marine air
and thus lower temperatures. The overall spread between the 10th to
90th percentile (essentially the coolest and warmest scenario)
ranges from around 61-73 deg F in the lowlands with little to no
change along the coast. /DH

&&

.AVIATION...Surface high pressure centered offshore will
maintain VFR conditions across the airspace. Diurnal north to
northwest winds continue at 15-20 kt with gusts to 30 kt along
the coast, and 10-15 kt with gusts to 20-25 kt inland. East-west
oriented gaps, such as the Columbia Gorge and including KTTD,
remain shielded from the wind and will see lighter flow below 10
kt out of the west to northwest. Winds aloft will turn offshore
tonight, while surface winds ease to 5 kt or less out of the north
to northeast. Marine stratus is favored to remain west of coastal
terminals given developing offshore flow.

KPDX AND APPROACHES...VFR conditions beneath largely clear skies
expected throughout the period. Diurnal northwest winds of 10-15
kt with gusts of 20 kt will ease below 5 kt late this evening,
after 06z Mon. -36

&&

.MARINE...High pressure building offshore will continue to
generate gusty north winds through much of Monday. A weak feature
moving overhead through tonight will support accelerated winds
today, before easing overnight and re-strengthening on Monday.
Small Craft Advisories are now in effect across all coastal waters
for gusts of up to 25-30 kt, with the strongest winds south of
Cape Foulweather and weaker flow north of Cape Falcon. The
Advisory north of Cape Falcon including the Columbia River Bar is
expected to expire late this evening, while areas south of Cape
Falcon will maintain hazardous conditions through late Monday
evening. Weakening high pressure Monday night through Tuesday will
see wind gusts across the waters ease below 20 kt. Seas continue
at 4-8 ft at 9-10 seconds with a dominant WNW swell.

A pattern change midweek will see high pressure replaced by a
trough offshore. Winds will shift southwesterly ahead of a
decaying front Wednesday morning, then turn northwesterly again
in its wake by Wednesday night. Rain shower chances will reach
30-50% beyond 30-40 NM Wednesday morning, but remain below 15-20%
elsewhere as the weakening front moves onshore. Unsettled weather
continues through the remainder of the week, with further rain
possible next weekend as another front traverses the waters. A
persistent westerly swell will support continued seas of 4-8 ft at
10-11 seconds. -36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.

WA...None.

PZ...Small Craft Advisory until 11 PM PDT this evening for PZZ210.

     Small Craft Advisory until 2 AM PDT Monday for PZZ251-271.

     Small Craft Advisory until 11 PM PDT Monday for PZZ252-253-272-
     273.

&&

$$

www.weather.gov/portland

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