571
FXUS66 KPQR 021137 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
437 AM PDT Tue Jun 2 2026

Updated aviation discussion.

.SYNOPSIS...High pressure will maintain very warm and dry
conditions today. 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 into the weekend.

&&

.SHORT TERM...Now through Thursday Night...High pressure
remains anchored over the region which will maintain hot and dry
conditions today. Easterly flow aloft combined with
temperatures of around 15 deg C at 5000 ft will keep overnight
lows on the warm side which sets the stage for a near record
breaking high temperature forecast. Overall looking at high
temperatures today in the mid 80s from Corvallis south, and in
the 90s north of Salem in the lowlands. In the Greater
Portland/Vancouver Metro highs are forecast to be just above
record highs. Along the coast, the weak offshore flow will keep
temperatures on the warmer side as well as downsloping off of
the Coast Range will enhance warming. Could see highs in the mid
70s along the coast, especially around Tillamook which tends to
run warmer than other locations on days like today. Moderate
HeatRisk remains for today for all of Multnomah and Clark
County, much of Washington and Columbia County, and along the
Lower I-5 Corridor. More urban areas of Clackamas County are
within this category as well. Elsewhere, Minor HeatRisk
dominates.

The warm temperatures will be short lived though as a negatively
tilted trough along the leading edge of a low pressure system in
the Gulf of Alaska drops down. 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 precipitation,
but the probabilities are quite low with the only areas with
chances above 15% being along the coast, Coast Range and spots
within the Cascades. 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 with
seasonable temperatures in the mid 70s inland and in the 60s
along the coast. -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, overnight into Saturday is a different story as the low
aloft drops down over the northern Washington coast, and is
coupled with a low pressure system at the 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 is around a
15-20% chance for thunderstorms over southwest Washington and
far northwest Oregon on Saturday afternoon.

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 though the "high end"
amounts are less than in previous runs. The 07Z Run currently
shows the 10th-90th percentile spread around 0.00 inch to 0.60
inch along the coast and around the Portland area. The 90th
percentile (high end amount) is around 1.0 inch in Battle
Ground and 1.25 inch along the south Washington Cascades.
Storm total 48 hour precipitation ending 5 AM Sunday has a high
end precipitation total of around 1.0 inch along the coast,
0.25 inch in the southern Willamette Valley, around 0.75-0.9
inch in southwest Washington and northern Willamette Valley and
around 1.25 inch in the Gifford Pinchot and Mt Hood Natl
Forests. 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 unrealized at this
time but again, something to watch moving forward. -27


&&

.AVIATION...Generally VFR over the next 24 hours with light
winds becoming northerly in the early afternoon. After 00Z Wed,
a frontal system will advance towards the coast which will cause
winds to shift to the south-southwest and usher in more
moisture. Most terminals will remain VFR, but along the coast
there is around a 40-60% chance of at least MVFR CIGs after 03Z
Wed. Stratus will begin to form around KONP then move northward
through the morning. The big challenge in the forecast is wind
direction. Overall, there is not a very strong trend towards
one wind direction. However speeds will be less than 10 kt in
most inland locations so impacts should be minimal.

KPDX AND APPROACHES...VFR over the next 24 hours. Weak easterly
flow this morning will transition to the N-NW later in the
afternoon into the evening as onshore flow returns. Eventually
winds will shift to the south. -27/99

&&

.MARINE...Settled conditions as surface high pressure remains
over the waters. The high will shift inland today which will
allow for the north/south pressure gradient to decrease and thus
winds continue to ease. Looking at winds north to northwesterly
winds of 5-10 kt with gusts up to 20 kt through the early
afternoon then they shift to the west. Seas will remain around
5-7 ft at 10 seconds. Winds turn southwesterly ahead of a
decaying front tonight into Wednesday. Rain shower chances
increase to 20-45% beyond 20-30 NM Wednesday morning, before
winds back out of the northwest by Wednesday afternoon behind
the boundary. Seas of 4-7 ft at 8-10 seconds with a dominant WNW
swell continue through midweek.

Generally unsettled weather looks to remain over the Northeast
Pacific through the remainder of the week. The dominant swell
will shift out of the west, with seas rising to 6-9 ft at 10-12
seconds into the weekend. Northwest winds persist through Friday
morning, when another front may bring further rain chances into
the weekend.-27/36

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.
&&

$$

www.weather.gov/portland

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