925
FXUS66 KPQR 292119
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
219 PM PDT Fri May 29 2026

.SYNOPSIS...Cooler temperatures through Saturday before building
high pressure brings a warming trend Sunday through Tuesday.
Warmest day will be Tuesday with Moderate HeatRisk in the
lowlands north of Salem. Dry weather persists through Tuesday.
Cooler temperatures return Wednesday with a slight chance of
rain.

&&

.SHORT TERM...Friday afternoon through Sunday night...Radar
imagery Friday afternoon shows the band of showers that moved
east through NW OR and SW WA this morning has moved east of the
Cascades. A trough over the northeastern Pacific has lowered
upper heights over the PacNW, bringing fairly zonal and onshore
flow to the region through Saturday. This general pattern has
brought cooler temperatures to the region with interior lowland
high temperatures today and Saturday expected to peak below
normal for late May in the mid to upper 60s with 50s along the
coast. Normal high temperatures for interior lowland locations
are around 70-71 degrees this time of year. A weak shortwave
along the flow this morning interacting with lingering moisture
from last night`s storms initiated this morning`s showers and is
producing locally breezy westerly winds along the coast,
terrain, and for inland locations along and north of the
Columbia River. Another shortwave on Saturday will keep similar
conditions, though winds will be slightly less breezy.

Sunday however will be a day of transition as upper level high
pressure begins building over the northeast Pacific. This will
bring a gradual increase in temperatures, and the overall
weather will dry through all layers of the atmosphere as
northeasterly flow aloft ushers in warmer and drier air. Even
with the warmer air filtering in, we are still expecting
seasonable temperatures with interior lowland temperatures in
the low to mid 70s. Due to clear skies, overnight temperatures
will be favorable for cooling with lows on Sunday night into
Monday morning being in the upper 40s. -03/27

.LONG TERM...Monday through Thursday...Monday starts the first
of two days of drastically increasing temperatures. Ensemble
models are in good agreement of the ridge of high pressure
intensifying, and the ridge axis shifting closer to the shore.
In fact, the differences between 500 mb ensemble clusters is
minimal. This ridging is combined with widespread east flow
aloft will bring significantly warmer temperatures in the
midlevels. 850 mb temperatures will rise to around 12-14 deg C.
This pattern will cause temperatures to spike once again by
about 10-15 deg F with highs forecast to be in the low to mid
80s for the interior lowlands, in the upper 60s to low 70s
along the coast, and the Cascades in the 60s. There is currently
around a 25-45% chance of the greater Portland-Vancouver Metro
area seeing highs of 90 deg F or more on Monday, with the
central Willamette Valley sitting closer to 15-25%. Elsewhere,
chances are less than 5%. The big component to consider on
Monday is the urban heat island effect and thus why Portland
will be warmer. Overnight temperatures will still cool, but
there`s a 25-35% chance they remain above 60 degrees in the
greater Portland metro area. This is due to the easterly flow
aloft causing a weak downslope feature which will cause warming
from compression within the lower elevations.

Tuesday is marked to be the hottest day of the week. There is a
60-75% chance that the Portland-Vancouver area will see highs
of 90 deg F or higher, around 40-50% in Salem, 45-55% in
Longview, and 15-20% in Eugene. If we were to bump up that
temperature to 95 deg F or greater, the Portland area remains
the highest around 20-35% chance while other urban areas and
along the I-5 corridor have less than a 10% chance. There`s a
25-35% chance low temperatures remain above 60 degrees in the
Portland-Vancouver metro area, increasing to 40-60% chance in
the Columbia River Gorge. Elsewhere, lows of 50-55 deg F are
expected. There is currently Moderate HeatRisk for the greater
Portland-Vancouver metro area, lower Cowlitz and Columbia
Valley, and Columbia River Gorge. However, the chance of Major
HeatRisk in the greater Portland- Vancouver Metro has lowered to
less than 10% due to a combination of high temperature
probabilities lowering slightly and low temperatures remaining
below 60 degrees. Moderate HeatRisk means that 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 in the
afternoons during peak heating.

Luckily this heat will be short lived as a low pressure system
from the Gulf of Alaska deepens in the northeastern Pacific and
pushes the high pressure east. Guidance indicates a weak upper
shortwave and surface front will push through the region late
Tuesday into early Wednesday, which will usher in cooler
temperatures for Wednesday and Thursday. There`s 70-90% that
interior lowland temperatures will fall below 80 degrees into
the low to mid 70s. Some uncertainty in the exact pattern leaves
that 10-20% chance of temperatures remaining in the 80s. There
are slight chances of light precipitation late Tuesday into
Wednesday morning, mainly limited to the coast and Coast Range
as the dry airmass in place will likely cause the front to
weaken as it approaches land. On Thursday, the shortwave moves
east and 500 mb clusters are in pretty good agreement that zonal
flow takes over briefly with dry weather and similar
temperatures to Wednesday. -03/27

&&

.AVIATION...Satellite imagery and surface observations continue to
show marine stratus, resulting in generally VFR conditions with
pockets of MVFR conditions across the airspace. Persistent
onshore flow will likely result in coastal locations returning to
a VFR/MVFR mixture around 04Z Saturday, with inland locations
maintaining VFR conditions above FL040 through the remainder of
the TAF period. However, some clearing is expected overnight and
could result in pockets of MVFR to LIFR conditions. As to the
timing, duration and location of these lowered flight conditions,
confidence remains low at this time. Gusty, north/northwesterly
winds up to 25 kt expected along the coast through around 04Z
Saturday. Also, expect gusts up to 20 kt for inland locations
through 03Z Saturday.

KPDX AND APPROACHES...VFR conditions above FL040 expected through
the TAF period. North/northwest gusts up to 20 kt expected after
00Z Friday through 06Z Friday. /42

&&

.MARINE...High pressure remains over the area with a persistent
northwesterly swell and north/northwest winds. North/northwest
winds 10-13 kt with gusts up to 20 kt through Sunday morning.
Winds expected to increase on Sunday with gusts up to 25 kt across
all waters as high pressure strengthens and results in a more
summer like pattern. Cannot rule out gusts as high as 30 kt in the
waters south of Lincoln City, OR on Sunday. As Monday approaches,
winds are expected to fall below Small Craft Advisory Criteria.
Seas 9 to 11 ft will gradually subside to 6 to 8 feet by late this
afternoon/tonight and look to hold through at least the start of
next week.

A series of strong ebbs will take place on the Columbia River Bar
each evening through at least Sunday. /42

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory from 1 AM to 7 AM PDT Saturday for PZZ210.

&&

$$

www.weather.gov/portland

Interact with us via social media:
www.facebook.com/NWSPortland
x.com/NWSPortland