010
FXUS66 KPQR 221012
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
312 AM PDT Mon Jun 22 2026

.SYNOPSIS...The hottest days of the week are expected today and
Tuesday as high pressure builds over the area, bringing
widespread Moderate HeatRisk across interior valleys. Onshore
flow will increase Tuesday night into Wednesday, bringing a
slight cool down, but still remaining hot. A pattern change
occurs Thursday through the weekend as an upper-level trough
approaches the Pacific Northwest and returns cooler and wetter
weather.

&&

.DISCUSSION...Today through Sunday...Satellite imagery and
surface observations as of early Monday morning depicts marine
stratus along the coast and mostly clear skies elsewhere. As
daytime heating progresses today, we`ll see increased mixing and
stratus breaking out by late morning.

Upper-level ridging will move overhead today, warming
temperatures into the upper 80s to low 90s across interior
valleys which is about 15-20 degrees above normal. Diurnal
northerly winds will increase this afternoon, with gusts between
15-20 mph along the coast and I-5 corridor. The warm-up we`re
experiencing today will result in widespread Moderate HeatRisk
across all interior valleys. This level of heat will affect
those who are sensitive to heat, especially those without
adequate cooling/hydration. Tonight into early Tuesday morning,
overnight lows in the mid to upper 50s for most areas will
provide some relief from the heat. However, an exception is from
Salem to the Portland/Vancouver Metro Area where Tuesday
morning lows between 60 to 65 degrees will result in limited
overnight relief. Chances for Tuesday morning lows exceeding 65
degrees across the Portland/Vancouver Metro are around 10-20%,
possible due to urban heat island effects. Therefore, there is
also a 20-40% chance for Major HeatRisk across the
Portland/Vancouver Metro Area today.

The Tuesday high temperature forecast has trended a few degrees
cooler, but still hot with interior valleys forecast to peak in
the low to mid 90s. We`ll have another day of widespread
Moderate HeatRisk across interior valleys, with a 30-50% chance
for Major HeatRisk across the Portland/Vancouver Metro Area. A
Heat Advisory is in effect from 11 AM today to 11 PM Tuesday for
the I-5 corridor from Salem to the Cowlitz Valley, along with
the Columbia River Gorge and Upper Hood River Valley. Make sure
to stay hydrated, wear light-colored and loose-fitted clothing,
wear sun protection, and take frequent breaks from the heat. If
possible, schedule outdoor plans during the early morning or
late evening when temperatures will be less intense.

One note about Tuesday`s forecast is that deterministic and
ensemble guidance is beginning to show some weak troughing
moving into the area as well. It`s a dry trough, so rain is not
expected but it will increase onshore flow. Winds on Tuesday
shift more west-northwesterly, breeziest in the evening. Tuesday
night into Wednesday morning, overnight lows cool down a few
degrees compared to tonight due to the increased onshore flow.
However, the Portland/Vancouver Metro Area will still have
limited overnight relief as it remains warmer than most
locations due to urban heat islands effects. Chances for
Wednesday morning lows exceeding 65 degrees across the
Portland/Vancouver Metro Area are around 15-30%.

On Wednesday, the vast majority of ensemble members kick
the broader upper-level ridge axis east of the Cascade crest-
line during the daytime hours. This should allow for high
temperatures to drop a few degrees into the upper 80s to low 90s
across interior valleys although the greatest day the day
temperature change will likely be felt along the coast and in
the some of the coast range valleys as westerly flow continues
to increase. The latest NBM gives a 15-35% chance for high
temperatures exceeding 95 degrees Wednesday afternoon from Salem
to the Portland/Vancouver Metro. At least confidence is very
high temperatures begin a noticeable descent back to normal,
then below normal, the remainder of the week as the upper-level
pattern undergoes a significant shift.

Thursday through the start of the weekend the majority of
deterministic and ensemble guidance are depicting a upper-level
trough of low pressure moving into the Pacific Northwest
ushering in a cooler and wetter pattern. There still remains
some uncertainty with the exact timing, placement, and magnitude
of the trough, and thus there is uncertainty regarding exact
precipitation amounts. The latest ensembles, including the NBM,
are highlighting late Thursday night into Friday morning as best
chance (70-95%) for rainfall during this late week period,
mainly focused along the coast, Coast Range, Portland/Vancouver
Metro through SW Washington, and in the Cascades. Should the
core of the upper-level trough/low track overhead Friday and
Saturday, post-frontal thunderstorms are another concern we`ll
have to watch. At the end of the day, any precipitation be can
get this time of year is largely beneficial and we`ll take what
we can get during this late week/early weekend period.  -10/99

&&

.AVIATION...Satellite imagery as of early Monday morning depicts
marine stratus along the coast bringing LIFR/IFR CIGs to KAST
and KONP. Expect this stratus deck to linger throughout the
morning, before scattering out and pushing back offshore around
17-18z Monday as daytime heating increases mixing. However,
there is low chance (15-25%) that low clouds will fail to clear
out at KONP on Monday.

Meanwhile, inland areas will remain clear with VFR conditions.
Light winds under 5 kt this morning will increase out of the
north late Monday morning into Monday afternoon to 7-11 kt. Winds
may occasionally gusts as high as 15-18 kt between 22z Mon-03z
Tue, except up to 20 kt at KONP.

KPDX AND APPROACHES...VFR through the TAF period with a few high
clouds. Light winds under 5 kt through 17-18z Mon becoming
northwest and increasing to 8-11 kt with gusts up to 18 kt after
21z Mon.        -10/23

&&

.MARINE...Northwesterly winds will generally stay under 20 kt
through this morning. High pressure strengthens this afternoon
into Tuesday, tightening pressure gradients and increasing
north-northwesterly winds with gusts up to 25 kt. Small Craft
Advisories remain in effect for the waters south of Cape Falcon
and beyond 10 NM offshore through 5 AM Tuesday. Thursday to
Friday, an approaching frontal system will shift winds more
southwesterly, however, there is only a 5-10% chance for
widespread and frequent small craft wind gusts of 21 kt or
greater. High pressure rebuilds over the weekend, returning
northwesterly winds. Seas remain steep and choppy around 5-7 ft
through Wednesday, subsiding to 4-5 ft Thursday and Friday. -10

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Heat Advisory from 11 AM this morning to 11 PM PDT Tuesday for
     ORZ108>115-119>123.

WA...Heat Advisory from 11 AM this morning to 11 PM PDT Tuesday for
     WAZ204>210.

PZ...Small Craft Advisory until 5 AM PDT Tuesday for PZZ272-273.

&&

$$

www.weather.gov/portland

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