901
FXUS66 KPQR 050854
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
154 AM PDT Sat Jul 5 2025

.SYNOPSIS...High pressure builds through the next week with
general onshore flow. Increasing temperatures through Tuesday
with low elevation inland temperatures near 90 degrees F on
Monday and Tuesday. Cooler on Wednesday and Thursday before
heating back up on Friday. Breezy onshore winds on Wednesday due
to an increasing pressure/temperature gradient.


&&

.SHORT TERM...Now through Tuesday...The shortwave troughs that
brought cooler weather the last two days have exited the region
and high pressure builds through early next week. A low aloft
will park over northern California through Monday which will
contribute to the amplification of the ridge. Each day
temperatures will rise by a few degrees, except along the coast
where temperatures will be moderated. Because the flow will be
onshore, humidity is not expected to drop considerably.

On Monday, winds aloft will transition to the northeast. This
switch will usher in warmer and drier air. 850 mb temperatures,
which will mix down, will be around 15-18 deg C. Even at night
these temperatures will be elevated so overnight relief will be
less, especially in the Greater Portland/Vancouver Metro and
Columbia River Gorge. On Tuesday, this ridge will reach it`s
peak intensity as the low aloft shifts over the OR/CA border.
Winds will slowly shift back to the northwest and increase
slightly.

On both Monday and Tuesday Moderate HeatRisk is present within
the Willamette Valley, Clark County lowlands and the Gorge.
Those sensitive to heat should take precautions. -Muessle


.LONG TERM...Tuesday night through Friday...Transitioning into
Wednesday, the low will continue to trek eastward into Idaho.
This will result in increasing northwesterly flow and bring in
cooler, moister air. There continues to be shifts from model run
to model run trending a bit cooler each day on Wednesday and
Thursday. Overall, looking at the upper level of seasonable
temperatures with onshore flow on Wednesday and Thursday.

Late Thursday, a developing ridge will shift eastward increasing
north to northeasterly flow and once again, warmer temperatures.
Confidence at this point is low though due to a) a mixed bag of
clustered max temperatures with a near 50/50 chance of above or
the multi-model mean, and b) yet another newly forming shortwave
trough aloft moving over northern California. If this pattern
does manifest, could easily a rinse and repeat temperature
forecast of Tuesday`s highs.-Muessle


&&

.AVIATION...Largely tranquil conditions continue across the region
as a weak upper-level low exits eastward through the period. Areas
of marine stratus along the coast look to bring mixed VFR/MVFR
cigs to coastal terminals and inland to KKLS through 16-18z Sat.
IFR cigs remain possible through 15z Sat at KONP, but are unlikely
farther to the north at KTMK/KAST. Inland, high cirrus coverage
left over from earlier convection east of the Cascades continues
to diminish. Early morning stratus is expected to develop along
the Cascade foothills, but MVFR cigs remain unlikely, with only a
15-25% chance along the Willamette and Lower Columbia Valleys.
Any low stratus will mix out by 16-18z Sat. Diurnal winds remain
out of the north to northwest throughout the period, rising to
10-15 kt gusting to 20-25 kt in the afternoon and evening, then
easing to 5 kt or less tonight.

PDX AND APPROACHES...VFR conditions favored through the period,
with diminishing cirrus coverage at 20-25 kft. There remain low
chances, 15-20%, of stratus yielding MVFR cigs through 16-17z Sat.
Diurnal northwest winds rise to 8-12 kt gusting 15-20 kt after
21-24z Sat, then ease to 5 kt or less after 09z Sun. -Picard

&&

.MARINE...Surface high pressure offshore will maintain north to
northwest winds across the coastal waters through midweek. The
pressure gradient over the waters will increase today into Sunday
and Monday as the thermal trough strengthens over the south
Oregon coast, bringing stronger northerly winds with diurnal gusts
up to 20-25 kt each afternoon and evening. Seas will remain fairly
steady at around 3-6 ft through Sunday, building slightly to 4-8
ft Sunday night through Monday. -DH/Picard

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.
&&

$$

www.weather.gov/portland

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