277
FXUS66 KPQR 091055
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
355 AM PDT Tue Jun 9 2026

.SYNOPSIS...Now that temperatures have hit "rock bottom" the
only way forward appears up, and up into the 90s towards the
triple digit mark we shall go. While shower chances linger
through Wednesday morning, starting today we embark on a
prolonged stretch of warming temperatures day to day culminating
in a multi-day heat event focused over the weekend into early
next week (June 13-16th). This time period will presents some of
the hottest temperatures we`ve seen so far this year. Don`t get
caught off guard by our recent stretch of cooler/wet weather
and start preparing for heat related impacts now. At least
there is growing confidence in a return closer to normal
temperatures (70s/80s) by Wednesday of next week.

&&

.SHORT TERM...Now through Thursday...The core of the upper-level
trough which brought widespread rain and locally breezy
conditions to much of the region has progressed inland to our
north across Washington state this morning leaving us in a post-
frontal airmass. Model guidance maintains broad WNW flow across
the region today with shower activity and slightly cooler than
normal temperatures being maintained. While this pattern can be
favorable for weak thunderstorm activity, and the NBM which
generally drives the base layer of our forecast suggests a
10-20% chance for thunderstorms this afternoon, deterministic
model soundings reveal the available 100-200 j/kg of CAPE is
rather shallow (surface to 8,000ft) and updrafts likely won`t be
deep enough for the electrification of stronger showers. Take
any thunderstorm probabilities in the forecast this morning with
a heaping pile of salt as these values are more than likely
exaggerated.

Wednesday is the start of the next major pattern change. Upper-
level troughing which has been the dominant synoptic pattern to
the start of the week will get slowly shunted eastward by an
upper-level ridge amplifying over the eastern Pacific. As this
high pressure develops, daytime highs are expected to warm into
the mid 60s to low 70s across the inland valleys. The latest
model guidance suggest any lingering showers by this point,
mainly in the Cascades and Coast/Coast Range, taper off by the
midday and early afternoon hours Wednesday. Dry weather is
anticipated from here on out through the long term period. But
before the heat alluded to in the synopsis begins to really kick
in, expect pleasant weather on Thursday with mostly sunny skies
and high temperatures in the mid to upper 70s for inland valley
locations - enjoy it while it lasts. -99

.LONG TERM...Friday through Tuesday...Hot temperatures, likely
the hottest of the year so far, are the main driver of our
weather impacts through the long term period. Friday through
early next week, models and their respective ensembles are in
good agreement depicting an upper level ridge amplifying over
the far northeastern Pacific before shifting overhead. By
Saturday, June 13th, the NBM probabilities for daytime highs
above 90 degrees F are 45-75% for the Willamette Valley. NBM
probabilities for daytime highs at or above 100 degrees F on
Sunday June 14th are 30-50% and 20-70% on Monday June 15th, with
the highest probabilities each day towards the northern
portions (Portland/Vancouver Metro) of the Willamette Valley.
Also, there is a 5-15% chance for daytime highs on June 14th and
June 15th of 105 degrees F or higher for locations between
Salem, OR and Kalama, WA.

For reference, HeatRisk levels are as follows:
Little to None, Minor, Moderate, High and Extreme.

Probabilities for a Moderate HeatRisk or higher on Saturday
June 13th are 80-95%, then on Sunday/Monday (June 14th and 15th)
90-99% across almost the entire region. For Major HeatRisk,
there is a 50-80% probability on Sunday June 14th and 25-80%
probability on June 15th (highest Portland Metro, lowest near
Eugene and along the coast). At least through this period the
probability for Extreme HeatRisk across the CWA is 5-15% or
less. Anyone who is sensitive to heat or those who have outdoor
plans should prepare for and takes steps to mitigate
potential heat impacts. For those planning to seek relief by
swimming in local area rivers and/or lakes to cool off, be
mindful of cold water temperatures and swift currents which can
become life threatening if precautions like wearing a life
preserver is not taken.

By June 16/17th (Tuesday and Wednesday of next week), ensemble
modeling systems including the newer AI based suites do hint at
the ridge finally breaking down and shifting to the east with
westerly flow and thus a noticeable decrease in temperatures
finally prevailing. However, there`s a large degree of
uncertainty as to whether this transition takes place on Tuesday
or Wednesday, but at least the majority of models do push
temperatures downward back into the 70s and 80s by the latter
day (Wed June 17th). The latest NBM only gives the inland
valleys a ~15% chance for highs to exceed 90s degrees Wednesday
afternoon so confidence is moderate to high in a return closer
to normal occurs by the middle of next week bringing the region
some much needed relief.

It`s worth noting with this upper level pattern, a thermally
induced surface trough also will establish itself somewhere west
of the Cascade Crest-line which could result in locally breezy
winds within the Cascades and/or Willamette Valley depending on
its orientation. As daytime highs increase, relative humidities
will also decrease. Therefore, with conditions drying out AND
the potential for gusty winds, there are increasing fire weather
concerns for the latter part of this week through the start of
next week. So, be aware of potential ignition sources such as
chains dragging on the pavement, hot vehicle components, as well
as cigarette butts as these could easily result in the ignition
of dry, fine fuels. Larger fuels may not have the time to dry
out, but this is a variable that is being closely monitored by
State and Federal Fire Partners. -99/42

&&

.AVIATION...A mix of MVFR to VFR conditions are in place this
morning as the region sits within a post-frontal environment.
Showers will linger through much of the day but gradually
consolidate towards terrain features during the afternoon and
evening. Visibility should stay VFR at most terminals today, but
can`t rule out brief reductions to IFR/MVFR during heavier
showers. At the coast, there is a 25-55% chance for MVFR CIGs at
any given hour through TAF period but inland sites have much
better chances to trend VFR for the afternoon hours. Southwest to
west winds stay breezy through today at most sites with gusts in
the 15-25 knot range - highest in the morning. Lighter winds
return overnight.

.KPDX AND APPROACHES...We`ll likely maintain a mix of high-end
MVFR/low-end VFR through 18-19z, then predominately VFR
afterwards. Showers decrease in frequency during the afternoon but
may still pass within the vicinity of the terminal (or overhead)
from time to time. South-southwesterly winds with gusts up to 25
kt turn more westerly during the afternoon. -99

&&

.MARINE...Early this morning broad westerly flow has returned
across the waters as our most recent frontal system begins to
depart to the east. Seas around ~9-10ft at 9-10 seconds are
expected to peak this morning before slowly decreasing the
remainder of the day while westerly winds continue to gust around
15-25 knots. Thus, conditions across both the inner and outer
waters including the Columbia River Bar likely remain under Small
Craft conditions into the evening hours after which point seas
and winds calm further. From here our focus shifts to high
pressure building offshore through the remainder of the week. West
winds of 7-15 kt on Wednesday will steadily shift out of the
north. Typical summertime northerlies lock in place from this
point forward, reaching their diurnal peaks of 15-25 kt each
afternoon and evening from Thursday through the weekend. This may
necessitate daily Small Craft Advisories, especially beyond 10 NM
south of Cape Falcon. Seas will persist at 4-8 ft at 9-11 seconds
with a continued westerly swell. -99

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for PZZ210-
     251>253-271>273.
&&

$$

www.weather.gov/portland

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