075
FXUS66 KPQR 260445
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
945 PM PDT Fri Jul 25 2025

.SYNOPSIS...More seasonal temps expected today through Sunday
as onshore flow is enhanced by increased upper level troughing.
Another warm up is expected early to mid next week, with
thunderstorms looking possible along the Cascades during the
evening hours each day.

&&

.SHORT TERM...Now through Sunday Night...Little to no change to
the forecast through the weekend. Closer to seasonable
conditions expected this afternoon through Sunday as a large
upper level trough crosses the region. This will equate to
inland highs closer to seasonal norms in the upper 70s to low
80s through Sunday. Coastal areas will continue to be impacted
by abundant marine stratus through the period, with diurnal
intrusions into the inland valleys becoming increasing likely as
the marine layer deepens and onshore pressure gradients
increase. Expect another solid marine layer to push into the
coastal areas late this evening into the overnight. HREF
guidance is suggesting another decent chance (40-70%) that
stratus will develop along the Cascade foothills and backbuild
into the Willamette Valley between 3-6 AM Saturday. Any clouds
that develop inland are expected to dissipate by late Saturday
morning. -Batz

.LONG TERM...Monday through Friday...Guidance continues to
suggest temperatures rebound back into the upper 80s to low
90s Monday through Wednesday as ridging builds across the Great
Basin and into the PacNW. Probabilities for inland valleys to
reach 90F on Monday are modest at 10-40% but increase Tuesday
and Wednesday to 50-80% for most locations. A significant heat
event is unlikely at this time given the relatively small
temperature spread heading into next week.

A deepening upper level low is also likely to set up off the
British Columbia coast, though there is disagreement among the
models where exactly the center of the low sets up. Depending
on its location, south to southeast flow could develop across
the area or at least a portion of the area, bringing monsoonal
moisture and potential for thunderstorms. Persistent southerly
flow will help increase PWAT values to 1.0-1.2 inches east of
the coast range. These values are 120-160% of normal for this
time of year with the larger anomalies across the Cascades of
Lane and Linn Counties. Disturbances embedded within the upper
level flow will help support destabilization across central
Oregon and to a lesser extent over the Cascade crest. For now,
have introduced a 15-20% chance for the far eastern portions of
Lane and Linn Counties Monday and Tuesday evenings. Agreement
and exact details become murkier into the middle of next week
but the threat for thunderstorms along the crest remains. A
stronger embedded shortwave is expected to move through the
upper levels across northern California and Oregon which would
bring better large-scale accent and possibly greater
thunderstorm coverage Wednesday and Thursday evenings. Models
also show potentially weak steering flow which could lead to
slow storm motion and localized heavy rains. -Batz

&&

.AVIATION...Along the coast, marine stratus has redeveloped,
bringing mixed MVFR/IFR conditions to coastal terminals. Low cigs
are likely to continue through the overnight period until 18-20z
Sat when conditions may improve as increased mixing lowers cloud
cover while raising cloud bases. Brief periods of restricted vis
within mist cannot be ruled out near dawn, especially at KONP.
North to northwest winds at 5 kt or less continue through tonight,
building to 5-10 kt out of the northwest after 18-20z Sat.

Inland, VFR conditions beneath largely clear skies are likely to
continue through at least 12z Sat, after which chances for MVFR
cigs increase. Guidance remains divided on how far inland low
clouds encroach, but given large-scale support for a stronger
marine push, have maintained a bullish outlook at Portland-area
and southern Willamette Valley terminals for MVFR cigs from 13-14z
through 16-18z Sat. Meanwhile, central and northern Willamette
Valley terminals (KHIO/KUAO/KSLE/KMMV) remain less likely to see
sufficient coverage of low clouds to yield MVFR cigs. Light winds
of less than 5 kt through much of the overnight period will build
out of the northwest at 5-10 kt after 18-21z Sat.

PDX AND APPROACHES...VFR conditions likely to continue through at
least 12z Sat. Chances increase by 13-14z Sat for MVFR cigs as
marine stratus surges up the Columbia River, although confidence
in low cigs is only moderate. Have continued to lean slightly more
aggressive on cloud coverage given large-scale support for a
marine push similar to or stronger than Friday morning, which saw
MVFR cigs from 12-16z. Any low clouds will mix out by 16-18z Sat,
returning to VFR by midday. Northwest flow continues at 5 kt or
less overnight, building to 5-10 kt after 16-18z Sat. -Picard

&&

.MARINE...Fairly benign conditions are expected through the
weekend into early next week as high pressure near the surface
persists overhead. This`ll keep winds predominately out of the
north to northwest with afternoon/evening gusts around 10-15
knots through Sunday before increasing a touch into the 15-20
knot range by the middle of next week. Background swells remain
unimpressive through the weekend into the middle of next week as
well. Thus, the likelihood for Small Craft advisory conditions
going forward a low. It`s is again worth mentioning there will
be some strong ebb currents through the Columbia River bar at
times through the weekend (e.g. Saturday 6-7am) which may lead
to locally choppy seas. -Schuldt

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...None.

&&

$$

www.weather.gov/portland

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