476
FXUS66 KPQR 110347 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
847 PM PDT Thu Jul 10 2025

Updated Aviation Discussion...

.SYNOPSIS...Partly cloudy skies with seasonable temperatures
this afternoon. Temperatures warm up tomorrow into the weekend
as high pressure builds. Expect morning marine clouds along the
coast and over the waters. Temperatures cool slightly on
Monday, but still remain very warm and dry. An Extreme Heat
Watch has been issued for some interior valley locations from
Tuesday to Wednesday next week as temperatures between 95 to
105 degrees are possible with overnight lows struggling to fall
below 65 to 70 degrees.

&&

.SHORT TERM...Now through Saturday night...Satellite imagery as
of early Thursday afternoon depicts partly cloudy skies and dry
conditions across most of northwest Oregon and southwest
Washington. Afternoon highs today are forecast to peak in the
upper 70s to low 80s across interior locations, which is near or
slightly below seasonal norms. Tomorrow (Friday), an upper level
ridge begins to re-build, leading to warmer temperatures and
sunny skies. Do expect some marine fog/stratus as high pressure
aloft keeps clouds to the lowest part of the atmosphere.

Friday afternoon highs are forecast in the upper 80s across
interior valleys while the coast remains mild in the 60s to low
70s with onshore flow. Expect breezy northwesterly winds along
the coast with gusts up to 25 mph, while northerly winds gust up
to 20 mph across the Willamette Valley. The strongest winds will
be in the afternoon when pressure gradients are tightest. High
pressure persists on Saturday, maintaining similar temperatures
to Friday with generally northerly flow.        -Alviz

&&

.LONG TERM...Sunday through Wednesday...Ensemble guidance
suggests that high pressure this weekend peaks on Sunday,
leading to very warm temperatures in the low to mid 90s across
the Willamette Valley. This will lead to widespread Moderate
HeatRisk - this level of heat affects most individuals
sensitive to heat, especially those without effective cooling
and/or adequate hydration. We will continue to evaluate if a
Heat Advisory is warranted for this weekend (particularly
Sunday). On Monday, temperatures fall about 5-10 degrees as most
ensemble guidance suggests an upper level shortwave trough
dipping into the Canadian Rockies and northern Intermountain
West. Though 500 mb heights fall over our area with this
shortwave trough, they still remain above-normal and will
maintain warm temperatures with highs in the upper 80s to low
90s for interior valleys.

All eyes are on Tuesday to Wednesday as there is potential for
extreme heat. An Extreme Heat Watch has been issued from Tuesday
afternoon (July 15) to late Wednesday evening (July 16) across
the Greater Portland/Vancouver Metro, Western and Central
Columbia River Gorge, the Corbett area and the Hood River
Valley, Lower Columbia River and Cowlitz River Valleys, and
Central Willamette Valley. Dangerously hot conditions with
temperatures between 95 to 105 degrees are possible. Low
temperatures between 65 to 70 degrees are possible as well,
which would limit overnight relief especially Tuesday night.
Currently, this Watch encompasses areas where overnight low
temperatures may struggle to fall below 65 to 70 degrees. The
latest guidance suggests that there is a 40-50% chance that
Tuesday night low temperatures remain above 70 degrees. In
addition, there is also a 20-40% chance that Tuesday and
Wednesday high temperatures exceed 105 degrees across the
Willamette Valley. As a reminder, an Extreme Heat "Watch" is
issued when dangerous heat is possible. An Extreme Heat
"Warning" is issued when dangerous heat is happening or about to
happen.

Major HeatRisk is currently forecast for areas within the
Extreme Heat Watch. This level of heat would affect anyone
without effective cooling and/or adequate hydration. Heat
related illnesses increase significantly during extreme heat
events.

In addition to the upper level high pressure, models are also
indicating a thermal trough developing over the Willamette
Valley on Tuesday. If this occurs, then it would lead to more
offshore flow. Currently, the easterly winds forecast with this
thermal trough are not looking very strong, and will mainly be
through the Columbia River Gorge and Cascades. Current guidance
shows pressure gradients of -2 to -4 mb through the Gorge on
Tuesday, which would lead to wind gusts up to 20-25 mph in that
area.     -Alviz

&&

.AVIATION...Westerly flow continues across the airspace through
the TAF period, resulting in similar conditions as to what has
been observed over the past 24-48 hours. Expect coastal conditions
to redevelop around 04-06Z Friday, resulting in a mix of IFR/LIFR
conditions overnight and into early tomorrow morning. Inland will
experience mostly northerly flow, which will likely prevent any
marine stratus from pushing inland (through Coast Range gaps and
Columbia River). However, could see clouds backbuilding off the
Cascades and bringing MVFR conditions to inland terminals. While
models have been suggesting the backbuilding of MVFR clouds, each
new model run looks less likely to backbuild enough to reach
inland terminals. If these clouds build off the Cascades, expect
MVFR conditions to affect inland terminals between 13-16Z Friday.
Conditions will slowly improve across the airspace thereafter.

PDX AND APPROACHES...Expect VFR conditions and northwesterly flow
through most of the TAF period. There is the possibility of
clouds backbuilding off the Cascades between 13-16Z Friday, which
would likely result in MVFR conditions at the terminal. While low
confidence, if clouds backbuild off the Cascades and bring MVFR
conditions to the PDX terminal, expect conditions to improve back
to VFR by 17Z Friday. Expect northwesterly winds 5-10 kt becoming
08-12 kt with gusts up to 20 kt by 18Z Friday.
~Hall

&&

.MARINE...North/northwest winds across all waters will persist
through the weekend as a broad area of high pressure and a
thermally induced trough spreads northward. As the high pressure
and associated thermally induced trough mature, expect gusty
northerly winds and choppier wind driven seas. As a result have
issued a Small Craft Advisory for Zones PZZ273, PZZ253, PZZ272,
and PZZ252 starting Friday morning and continuing through at least
early Saturday morning. /42

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

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

PZ...Small Craft Advisory from 2 PM to 11 PM PDT Friday for PZZ252-
     272.

     Small Craft Advisory from 11 AM Friday to 2 AM PDT Saturday for
     PZZ253-273.
&&

$$

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