248
FXUS66 KPQR 122208
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
308 PM PDT Sat Jul 12 2025

.SYNOPSIS...High pressure maintains warm and dry conditions this
weekend, with a Heat Advisory on Sunday for most interior valleys.
Expect sunny skies across the area with morning marine stratus/fog
along the coast. Temperatures cool slightly on Monday, but still
remain warm and dry. An Extreme Heat Watch continues for some
interior valley locations from Tuesday to Wednesday, as afternoon
temperatures between 90 to 100 degrees and low temperatures between
65 and 70 degrees are possible.

&&

.SHORT TERM...Tonight through Monday night...A broad upper level
ridge of high pressure remains over the western US through the
weekend. This will maintain our summer weather pattern of hot and
dry conditions through Sunday. 850 mb temps rise to around 20-22 C
on Sunday, allowing temperatures for Sunday afternoon across the
lowland valleys to warm into the 90s, likely around 5 degrees F
warmer than today`s (Saturday) highs. Hottest temps into the upper
90s likely through the southern and central Willamette Valley, where
there is a 20-30% chance of reaching 100 degrees. Therefore, the
Heat Advisory remains in effect from 11 AM to 10 PM Sunday for the
Willamette Valley, Portland/Vancouver metro, Columbia Gorge and
Upper Hood River Valley, as well as the lower Columbia-Cowlitz
County lowlands.

Onshore northwest to northerly winds will again increase Sunday
afternoon as surface high pressure offshore and low pressure east of
the Cascades increases the pressure gradient. Expect wind gusts up
to 25-30 mph inland, while gusts up to 35 mph will be possible along
the central Oregon coast.

The upper ridge axis retrogrades over the Pacific as an upper level
trough drops out of British Columbia into Washington on Monday. This
will likely push 850 mb temps back down into the mid-teens,
resulting in surface temperatures cooling around 10 degrees, toward
near normal values for July. Could also deepen the marine layer
along the coast enough to push up the lower Columbia into the
Portland metro by Monday morning. /DH

.LONG TERM...Tuesday through Saturday...Temperatures are expected to
trend warmer Tuesday and Wednesday next week, with Wednesday likely
being the warmest day. There is still a bit of model spread in the
temperature outlook for Tuesday, though narrowing in on highs in the
upper 80s to mid 90s. High temperatures on Wednesday are more likely
to warm into the mid-90s, with around a 30-50% chance of reaching
100 degrees across the Willamette Valley. Will continue the Extreme
Heat Watch for now, though NWS HeatRisk continues to trend toward
widespread Moderate Risk rather than Major Risk. Should also see
morning temperatures remain somewhat elevated Tuesday night,
especially around the urban areas, as a surface thermal trough
develops, bringing light offshore flow through the Columbia Gorge
and downsloping across the Cascades. But, the probability that
overnight temperatures don`t drop below 70 degrees remains at around
10%.

More uncertainy arises in the forecast Thursday and Friday of next
week. Ensembles continue to struggle with the overall pattern, as
guidance shows a bimodal solution of either cooler weather and upper
level troughing, or high pressure ridging and continued heat, with
nearly a 50/50 split. Guidance does show higher confidence of
temperatures trending into the mid-80s by next Saturday with dry
conditions persisting.  /DH

&&

.AVIATION...High pressure with increasing daytime heating.
Overnight expect conditions inland to remain VFR over the next 24
hours. Upwelling continues along the coast which will promote
cooler temperatures along the immediate terminals. Overnight,
there is around a 50% chance of fog returning from KTMK southward,
however, given the persistent pattern leaning towards another IFR
night along the main coastal airports. VFR elsewhere. Gusty north
winds this afternoon will ease overnight before increasing once
again in the afternoon. Probability for gusts greater than 25 kt
is around 25-30% in the Willamette Valley and greater than 60%
along the coast.

PDX AND APPROACHES...VFR CIGs and VIS. Northerly winds. Generally
northerly winds aloft up to 30 kt between 02-10Z Sunday at 2000
ft. For higher approaches around FL040 northeast gusts up to 35 kt
during that time. There is a chance (around 30% chance) that these
winds mix down. -Muessle

&&

.MARINE...Strong high pressure over the waters for the next week
or so. Tonight, there is around a 25% chance of dense fog for the
inner waters due to upwelling along the shore. Due to drier
conditions today, confidence is low as to whether or not it will
develop. Therefore have not issued any dense fog products. Slight
fluctuations in small scale features will cause increased wind
speeds through early next week. Tomorrow (Sunday) winds will
increase higher than previously thought due to a strengthening
thermal trough. Gusts up to 30 kt possible, though higher
probability between 25-30 kt. These conditions will likely last
through Monday, and even through Tuesday in some locations.

Seas will increase slightly but remain in the 7-9 ft at 10 seconds
range. However, on Tuesday, with an increased wind wave, seas will
rise closer to 10 ft. -Muessle


&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Heat Advisory from 11 AM to 10 PM PDT Sunday for ORZ108-109-111-
     112-114>118-120>122.

     Extreme Heat Watch from Tuesday afternoon through Wednesday
     evening for ORZ108>115-119>122.

WA...Heat Advisory from 11 AM to 10 PM PDT Sunday for WAZ204>207-209-
     210.

     Extreme Heat Watch from Tuesday afternoon through Wednesday
     evening for WAZ204>207-209-210.

PZ...Small Craft Advisory from 11 PM this evening to 5 AM PDT Monday
     for PZZ251-271.

     Small Craft Advisory until 5 PM PDT Sunday for PZZ252-253-272-
     273.
&&

$$

www.weather.gov/portland

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