974
FXUS66 KPQR 120420 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
920 PM PDT Fri Jul 11 2025

Updated Aviation Discussion...

.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...Now through Sunday night...Satellite imagery as of
early Friday afternoon depicts sunny skies across northwest
Oregon and southwest Washington along with lingering marine
clouds offshore. An upper level ridge is building, leading to
warmer temperatures today. High temperatures this afternoon are
forecast in the upper 80s to low 90s across interior valleys.
Conditions along the coast remain mild in the 60s to low 70s
with onshore flow. Winds are generally northerly to
northwesterly across the area and will be strongest this
afternoon has pressure gradients tighten. The breeziest winds
are expected along the coast with gusts up to 25 mph, while
wind gusts up to 20 mph are forecast across the Willamette
Valley and southwest Washington interior lowlands. Will have
cool temps overnight with lows in the upper 50s to low 60s.

Tomorrow (Saturday), the upper ridge persists over the area,
maintaining sunny skies with temperatures forecast similar to
today. Along the coast and marine waters, high pressure aloft
will continue to support low marine stratus and fog. Any low
clouds or fog along the coast should gradually dissipate
by the late morning or early afternoon as daytime heating
progresses.

Sunday is forecast to be the hottest day of the weekend as the
upper ridge persists and the overall airmass continues to warm-
up. Warmer 850 mb temperatures will mix down to the surface on
Sunday, leading to high temperatures in the low to mid 90s for
interior valleys. Expect widespread Moderate HeatRisk, which
means that this level of heat affects most individuals sensitive
heat, especially those without effective cooling and/or
adequate hydration. As a result, a Heat Advisory has been issued
across the Willamette Valley, Portland/Vancouver Metro Area,
Columbia River Gorge, and Upper Hood River Valley from 11 AM
Sunday to 10 PM Sunday. The Lower Columbia and Cowlitz Valleys
were not included in the Heat Advisory due to the lower forecast
afternoon and overnight temperatures compared to the rest of
the interior valleys. Take necessary heat precautions as hot
temperatures may lead to heat illnesses.       -Alviz

&&

.LONG TERM...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 slightly over
our area with this shortwave trough, they still remain above-
normal and will maintain warm temperatures with highs in the mid
to upper 80s for interior valleys.

The Extreme Heat Watch remains in effect Tuesday to Wednesday;
however, the high temperature forecast has dropped a few
degrees. Ensemble guidance is showing the upper level ridge
axis being centered further west over the Pacific Ocean, making
it a bit more difficult for our area to get extreme heat. The
current forecast now calls for high temperatures in the low to
mid 90s; however, there is still potential for extreme heat. The
latest guidance suggests a 20-40% chance that temperatures
reach 100 degrees or hotter across the Willamette Valley on
Tuesday and Wednesday. Tuesday night low temperatures have also
come down a few degrees, but lows between 65 and 70 degrees are
still possible especially around the Portland/Vancouver Metro
Area and Columbia River Gorge. Guidance suggests a 50-75% chance
that Tuesday night lows remain above 65 degrees and a 15-25%
chance low temperatures remain above 70 degrees, which would
limit overnight relief. The current Watch encompasses areas
where overnight low temperatures may struggle to fall below 65
to 70 degrees. 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 the Portland/Vancouver
Metro Area on Tuesday. 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 heat, some models are also indicating a
thermal trough developing over the Willamette Valley Tuesday
night to Wednesday. 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
Tuesday and Wednesday, which would lead to wind gusts up to
20-25 mph in that area. Minimum relative humidity are also
forecast to fall Tuesday-Wednesday into the 20-30% range. Will
continue to monitor potential fire weather concerns.    -Alviz

&&

.AVIATION...Moderate northerly flow remains in place across the
region, keeping surface winds breezy into the evening with gusts
up to 25 kt. Coastal stratus has proven more persistent than
earlier forecasts indicated, especially around KONP and adjacent
terminals, where LIFR conditions continue to dominate.

Overnight, there remains about a 10-20% chance for MVFR ceilings
to develop along the mouth of the Columbia River and extending
eastward to KTTD. However, confidence in this scenario is
limited. There is moderate confidence that this stratus will
reach KKLS overnight. Conditions are expected to improve by 17-18Z
Saturday as northerly winds strengthen again in the afternoon.
Additionally, around 12Z Saturday and 06Z Sunday, northwesterly
winds aloft will gust up to 30 kt between 1000-2500 ft.

PDX AND APPROACHES...VFR conditions are expected to persist
throughout the period. A low probability (20-30%) of MVFR CIGs
developing overnight remains, but any such conditions would likely
be brief and dissipate quickly after sunrise. While elevated
winds are present between 1000-2500 ft around 12Z Saturday, the
lack of significant directional shear means LLWS is not a concern.
Could see a brief return of elevated winds around 04-06Z
Sunday.
~Hall

&&

.MARINE...Upwelling along the coast is keeping marine stratus in
place and will set the stage for another round of marine fog
overnight. Have issued a Dense Fog Advisory for the inner waters
once again. Visibility of 1 NM or less expected through the
morning.

North to northwesterly flow is keeping winds elevated throughout
the waters with gusts as high as 25 kt. This will be the trend
over the next several hours. Then, as the thermal trough begins to
shift, a wind reversal will occur and they will lessen from north
to south. May still see periodic gusts to 25 kt in the southern
waters through Saturday morning, but not expected to be widespread
enough to warrant an extension at this time.

Through the weekend, there will be a second surge of wind in the
afternoon which will exhibit similar speeds to that of today. Seas
too will build with combined heights near 10 ft in the outer
waters, and near 7 feet in the inner waters. -Muessle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

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

     Heat Advisory from 11 AM to 10 PM PDT Sunday for ORZ109-111-112-
     114>118-120>122.

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

     Heat Advisory from 11 AM to 10 PM PDT Sunday for WAZ205>207-209-
     210.

PZ...Small Craft Advisory until 11 PM PDT this evening for PZZ251-252-
     271-272.

     Dense Fog Advisory from 3 AM to 11 AM PDT Saturday for
     PZZ251>253.

     Small Craft Advisory until 2 AM PDT Saturday for PZZ253-273.
&&

$$

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