253
FXUS66 KPQR 300446
AFDPQR

Area Forecast Discussion...Updated Aviation
National Weather Service Portland OR
946 PM PDT Sun Jun 29 2025

.SYNOPSIS...Hot weather continues through Tuesday. The hottest
day is expected to be Monday, with widespread highs in the low
to mid 90s across interior valleys. There is a 10-20% chance
for isolated thunderstorms over the Lane County Cascades Monday
and Tuesday. Cooling follows midweek with temperatures into the
low to mid 80s, though temperatures will remain above seasonal
norms.

&&

.DISCUSSION...Sunday afternoon through Friday...Satellite
imagery this afternoon shows mostly clear skies across NW Oregon
and SW Washington as high pressure over the Desert SW builds
northwest into the region. Temperature observations at 2pm
Sunday show inland conditions in the low to mid 80s and 70s
along the coast, except for 60s along the central Oregon coast
where stratus is lingering. Temperatures are on track to peak in
the upper 80s to near 90 in the Willamette Valley today. High
pressure continues building into Monday, allowing temperatures
to continue warming. Monday will be the hottest day of the week
with temperatures peaking in the low to mid 90s inland. NBM
indicates a 70-90% chance of daytime temperatures reaching or
exceeding 95 degrees for valley locations north of Corvallis and
a 40-60% chance for locations south of Corvallis. High pressure
begins receding somewhat on Tuesday, though temperatures are
still forecast to peak near 90 degrees again. However, morning
low temperatures through Tuesday will cool into the upper 50s to
low 60s, which will keep HeatRisk designation in the Moderate
instead of Major category except for portions of the Columbia
River Gorge where overnight temperatures remaining in the low
70s bump that area up to Major HeatRisk on Monday. Although this
heat event is brief and does not currently meet criteria for
excessive heat headlines, sensitive populations - especially
those without access to cooling or spending time outdoors - are
still at risk for heat related impacts.

Along with warming temperatures, this high pressure will pull
monsoonal moisture north from the Desert SW into Oregon Monday
into Tuesday. However, latest guidance continues indicating the
majority of this moisture will remain just south and east of the
forecast area, with a small amount possibly making it just north
enough to clip the Lane County Cascades. Soundings indicate
enough instability across the Cascades (MUCAPE > 500 J/kg) that
if enough moisture does push into the Lane County Cascades that
there`s a 10-20% chance that a thunderstorm or two may be
possible Monday evening/overnight and again Tuesday
afternoon/evening. The main impact from any thunderstorm would
be lightning and gusty winds.

By Wednesday, guidance indicates the high pressure will have
moved east of the region as a weak troughing is expected to move
into the region, continuing through the rest of the week. This
will cause a return of weak onshore flow as well as cooler
temperatures. Expect inland high temperatures in the low to mid
80s and coastal temperatures in the 60s to low 70s through the
end of the week. -HEC

&&

.AVIATION...Likely VFR conditions throughout the period, with more
or less clear skies. Coastal terminals see a 20-30% chance of some
marine clouds developing overnight, especially KONP, but most
likely scenario is VFR throughout the period. Northwest winds
gusting up to 15-20 kts still as of 5z Mon; these winds weaken and
drop below 6-8 kts by 8z Mon at latest for all terminals. Weak
winds throughout the rest of Sunday night, increasing again late
Monday morning. Northerly gusts up to 25-30 kts at the coast and
20-25 kts inland at that time.

PDX AND APPROACHES...VFR with northwesterly winds, weakening
overnight. Gusts up to 20 kt possible until 7z. Winds pick up
again late Monday morning, with gusts up to 20 kts possible at
that time. /JLiu

&&

.MARINE...High pressure over the area with a typical summer time
wind pattern. Northerly winds are beginning to really ramp up.
Gusts around buoys 46050 and 46029 are around 23 kt and will
increase slowly through the next 24-48 hours. Gusts up to 30 kt
likely south of Tillamook, especially in the far outer waters.
These wind speeds may not be observed by the local buoys. North
winds of 10-15 kt with gusts up to 25 kt within the inner waters,
especially in PZZ252 and PZZ253. Winds will maintain these speeds
through at least Tuesday. Seas will be a persistent 5-6 ft at 10
seconds except Monday night as the strongest winds kick in. Seas
will be greatly impacted by the wind waves on Monday and Tuesday
with significant wave heights rising to 7-9 ft at 9 seconds.

For the Columbia River Bar, the Small Craft Advisory has been
continued due to strong winds over the entrance to the bar. Winds
will begin to ease Monday after 5 AM with gusts of 15-20 kt. Given
the marginal nature of the decreasing winds have maintained the
advisory through Monday morning.
  -Muessle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 11 AM PDT Monday for PZZ210.

     Small Craft Advisory until 11 PM PDT Monday for PZZ251>253-
     271>273.
&&

$$

www.weather.gov/portland

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