Gresham, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

102
FXUS66 KPQR 122145
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
245 PM PDT Tue Aug 12 2025

.SYNOPSIS...
Today remains hot, with afternoon highs approaching 100 degrees
across the interior valleys. Coastal areas continue to
experience mild conditions. A stronger onshore flow will develop
from Wednesday through Thursday, bringing a significant cooldown
of approximately 10 to 15 degrees. By Friday and into the
weekend, an approaching low pressure system in the northeast
Pacific is expected to deliver widespread rainfall and much
cooler temperatures across the region.

&&

.SHORT TERM...Now through Thursday Night...
Currently, a high pressure ridge anchored over the northeast
Pacific continues to dominate, sustaining another day of
intense heat paired with clear skies across northwest Oregon
and southwest Washington. Along the coast, onshore flow keeps
temperatures mild, with some marine stratus lingering just over
the waters. Extreme Heat Warnings and Heat Advisories remain
active until 10PM this evening, particularly affecting the
Willamette Valley, southwest Washington lowlands, the Columbia
River Gorge, and Upper Hood River Valley. With areas struggling
to dip below 70 degrees this morning, relief from yesterday was
limited. Peak afternoon temperatures within the warning areas
are forecast to range between 97 and 101 degrees. It is crucial
to stay well hydrated, take frequent breaks from the heat, and
check on vulnerable individuals. Fortunately, as onshore flow
strengthens overnight, temperatures will drop more
substantially, providing relief heading into Wednesday.

Wednesday ushers in noticeable cooling as the upper-level ridge
weakens due to an approaching trough descending from western
Canada. This will enhance onshore flow, shifting winds to a
west-northwesterly direction and deepening the marine layer
along the coast. While temperatures will fall 10 to 15 degrees,
conditions remain warm, with afternoon highs expected in the
mid to upper 80s within interior valleys. The northern areas
will experience the most pronounced cooling. The HeatRisk will
decrease to a "Minor" level throughout the region, and overnight
lows will become more comfortable, generally ranging from the
upper 50s to low 60s.

By Thursday, the initial trough will continue its eastward
movement, while a new upper-level trough originating from the
Gulf of Alaska begins moving into the Pacific Northwest. This
will maintain strong onshore flow with winds turning more
westerly. Afternoon highs on Thursday are projected to align
with or fall slightly below seasonal averages, reaching the
upper 70s to low 80s inland and the 60s near the coast. Rain
chances return late Thursday evening, with coastal areas from
northern Oregon into southern Washington possibly seeing light
rainfall accumulations around 0.05 to 0.10 inches, with a 10-30%
chance of exceeding those values.

.LONG TERM...Friday through Monday...
Rain chances increase beginning Friday as a weather system
approaches from the Gulf of Alaska, bringing cooler temperatures
and widespread precipitation across the region. This system
will likely persist through Saturday, with showers tapering off
into Sunday. Temperatures are expected to remain below normal
during this period. While widespread rain is probable, the exact
amounts and timing remain somewhat uncertain due to variations
in model forecasts. Thunderstorm activity is not favored but
cannot be completely ruled out, especially along the higher
terrain of the Cascades. By Sunday into Monday, the system will
weaken and move eastward, allowing drier and warmer conditions
to return.
~Hall

&&

.AVIATION...This afternoon VFR conditions reside at all terminals
with a broken fog/stratus layer lurking just off the coast. It`ll
be this cloud feature which likely results in degrading flight
conditions along the coast this evening with a 70-80% chance for
IFR CIGs/VIS or lower after 03-06z at KAST and KONP. Expect these
conditions to last through Wednesday morning followed by some
improvement midday into the afternoon. That said, confidence
regarding the timing of said improvement is only low to moderate.
Willamette Valley terminals will maintain VFR conditions with
clear skies through the entire TAF period. Still, we`ll need to
keep an eye on a finger of the marine stratus layer trying to work
down the Columbia River near sunrise towards the Portland metro.
For now it appears to hold to the northwest. Most locations
maintain westerly to northwesterly winds around 5-10 kt.

PDX AND APPROACHES...VFR with clear skies through the TAF period.
It`s worth noting there is a 20-30% chance for MVFR CIGS
associated with marine stratus working into the terminal between
14-17z Wednesday morning. More than likely this cloud layer gets
hung up near Ridgefield to the north. Otherwise high confidence
VFR conditions prevail. -Schuldt

&&

.MARINE...Expect high pressure near the surface to maintain
northerly winds across the waters through Wednesday, breeziest
during the afternoon/evening hours and across the out waters -
gusts to 15-25 knots. Seas around 7-9 ft at 9-10 seconds likely
persists through Wednesday as well with a fairly prominent
northwesterly swell. Given the choppy seas and aforementioned
winds, Small Craft Advisories will remain in effect across the
outer waters through 1100 Wednesday.

Come Thursday we`ll see a noticeable pattern change as a low
pressure system in the northeast Pacific shifts winds more
southwesterly. The latest NBM guidance projects a 40-60% chance
for Small Craft conditions during a frontal passage during this
period, with the highest chances across the inner waters north of
Cape Foulweather and Columbia River Bar. Fortunately winds likely
lighten the latter half of the weekend into early next week as a
ridge to high pressure to attempt to rebuild overhead. -Schuldt

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Heat Advisory until 10 PM PDT this evening for ORZ104-105-108.

     Extreme Heat Warning until 10 PM PDT this evening for ORZ109>125.

WA...Heat Advisory until 10 PM PDT this evening for WAZ202-204-208.

     Extreme Heat Warning until 10 PM PDT this evening for WAZ205>207-
     209-210.

PZ...Dense Fog Advisory until 11 AM PDT this morning for PZZ210-
     251>253.

     Small Craft Advisory until 11 AM PDT Wednesday for PZZ271>273.
&&

$$

www.weather.gov/portland

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