173
FXUS66 KPQR 022216
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
316 PM PDT Tue Jun 2 2026

.SYNOPSIS...Hot and dry conditions this afternoon as high
pressure remains overhead. Moderate HeatRisk is expected along
the I-5 Corridor north of Salem, including the Portland/Vancouver
Metro. Cooler temperatures return Wednesday to Thursday as a
weak shortwave trough swings through the region. Slight chances
for showers along the coast, Coast Range, and Cascades on
Wednesday. Cool trend continues at the end of the week as a
deeper trough arrives from the Gulf of Alaska, returning
widespread chances for rain Friday night into Saturday. Renewed
chances for precipitation early next week.

&&

.SHORT TERM...Today through Thursday night...Satellite imagery
as of early Tuesday afternoon depicts mostly sunny skies across
northwest Oregon and southwest Washington has an upper-level
ridge moves overhead. Temperatures are on track to peak in the
upper 80s to low 90s across interior valleys, with the warmest
temperatures across the Portland/Vancouver Metro Area due to
urban heat effects. There is Moderate HeatRisk today across
along the I-5 corridor from Salem to the Cowlitz Valley, as well
as the Columbia River Gorge. This level of heat affects those
who are sensitive to heat, especially those without cooling or
hydration. Everywhere else will experience Minor HeatRisk.

Other than heat, surface observations as of early Tuesday
afternoon are showing easterly winds with gusts up to 25 mph
along the Columbia River Gorge and surrounding terrain. These
easterly winds will gradually weaken this afternoon as KTTD-KDLS
pressure gradients turn more positive (onshore) and westerly
winds return.

Tonight, most places will experience overnight relief as low
temperatures  Wednesday morning fall below 60 degrees. An
exception would be the Portland/Vancouver Metro Area, where
there is moderate confidence (40-60% chance) that morning low
temperatures remain above 60 degrees. Therefore, this Metro Area
will be a little slower to cool off from today`s heat compared
to other areas.

The hot temperatures will be short lived as a negatively tilted
trough along the leading edge of a low pressure system in the
Gulf of Alaska drops down tomorrow (Wednesday). This trough will
transition the flow into a zonal onshore flow pattern and thus
usher in cooler and more moist air. There remains a chance for
light showers, but the probabilities are quite low with the
chances between 15-30% being along the coast, Coast Range and
spots within the Cascades. The rest of the interior valleys
remain predominately dry. The mass of dry air leading into this
trough will decay most of the rain that would normally reach the
ground in a more moist scenario. It is not uncommon for these
troughs to be sacrificed to weaken the ridge allowing for more
precipitation to follow. Thursday will generally be dry and
sunnier with seasonable temperatures in the mid 70s inland and
in the 60s along the coast.               -10/27

&&

.LONG TERM...Friday through Monday...Very little change in the
forecast on Friday as onshore flow persists and the low pressure
system in the Gulf of Alaska remains nearly stationary.
However, Friday night into Saturday is a different story as the
low aloft drops down over the northern Washington coast, and is
coupled with another surface. This is a very energetic system
with strong vorticity advection and climatologically abnormal
CAPE over the marine waters. With ample support, there are
increasing chances for more widespread rain. However, the most
robust portion of this system will be well to our north as we
sit on the southern edge of the low. Therefore, could see less
of a stratiform rain and trend towards a convective/showery
pattern. Due to the combination of increased instability with
cooler air aloft, there remains a 15-20% chance for
thunderstorms over southwest Washington and far northwest Oregon
Friday and Saturday afternoon/evening.

Accumulation of rainfall remains uncertain as there is a) still
ample time for this system to evolve, b) the location of the low
will come into play - if it shifts south we could see heavier
rain, and c) the convective nature of the overall pattern. 24
hour precipitation as described by the NBM continues to show
quite a large range of possibilities. The 19Z Run currently
shows the 10th-90th percentile spread of 24 hour precipitation
being between 0.10 inch to 0.80-1 inch across southwest
Washington, north Oregon coast, and north Oregon Cascades. For
all other areas, the spread is generally 0.00 inch to 0.60 inch
from Salem northward, and 0.00 to 0.40 inch south of Salem.
Overall, the rain is non-impactful.

Transitioning into Sunday and Monday there will be some
lingering showers but overall weather appears to be more
settled. One thing we will have to watch is a cut-off low that
some of the ensembles are attempting to produce on Sunday night.
This cut-off low creates almost like a double barrel low type
situation along the coast. The impacts are uncertain at this
time, but this would bring renewed chances for precipitation
heading into early next week.         -10/27

&&

.AVIATION...VFR conditions continue across the airspace as surface
high pressure moves inland and weakens ahead of a decaying front
which will approach the coast later in the period. Inland,
coverage of high clouds continues to increase, with cigs lowering
to 5-10 kft through tonight. Terrain-influenced winds out of the
southwest to northwest continue at most terminals, while the
weakening offshore pressure gradient should see gusty east winds
through and west of the Columbia River Gorge to KTTD begin to
ease this afternoon. Winds will ultimately turn southwesterly as
the weak front nears the coast tonight into Wednesday morning.
Along the coast, chances for restricted cigs increase above 50%
by 06z Wed, reaching 70% chances of IFR at KONP and 60% chances
of MVFR at KAST. There are 25-50% chances of light rain showers
early Wednesday morning at coastal sites. West to southwest winds
of 5-10 kt will persist through the period.

KPDX AND APPROACHES...VFR conditions expected throughout the
period. Coverage of high clouds will continue to increase through
this evening before cigs lower to around 10 kft tonight. West to
northwest winds of 5-10 kt will shift out of the south-southwest
tonight ahead of a weakening frontal boundary.         -36

&&

.MARINE...Northwesterly flow of 5-10 kt will veer southwesterly
this evening through much of Wednesday before a decaying front
traverses the waters tomorrow afternoon. Hourly rain shower
chances peak at 50-80% early Wednesday morning south of Cape
Falcon, with 20-40% chances otherwise lingering through midday.
Northerly to northwesterly flow returns across the waters by
Wednesday evening behind the boundary. Seas of 4-6 ft at 10-12
seconds with a dominant northwest swell continue through
Wednesday, before a more westerly swell builds behind the frontal
passage. Seas then build to 6-8 ft at 10 seconds from Wednesday
night into early Thursday morning.

Generally unsettled weather looks to persist over the Northeast
Pacific through the remainder of the forecast period with
repeated systems bringing chances for further rain showers and
elevated winds, most notably from Friday night into Saturday.
Despite the active pattern, winds and seas are favored to remain
below hazardous thresholds aside from chances for wind gusts
exceeding 20 kt when brief northerly flow redevelops Sunday
afternoon and evening.         -36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...None.

&&

$$

www.weather.gov/portland

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