536
FXUS66 KPQR 151648 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
948 AM PDT Sun Jun 15 2025

Updated Aviation Discussion...

.SYNOPSIS...Onshore flow will maintain seasonable temperatures
through much of the coming week. Chances for light rain return
to the coast Monday night into Tuesday and inland Tuesday night
into Wednesday, with very little to no measurable rain expected for
most inland locations. Transitioning to a cool and showery weather
pattern Friday into Saturday as a closed upper level low settles over
the region and brings more substantial rain amounts to the area.

&&

.DISCUSSION...Now through next Saturday...Models suggest an onshore
flow regime will remain locked in place for the foreseeable future,
maintaining seasonable temperatures with highs mainly in the 70s
inland and 60s at the coast each day, except 60s inland and at the
coast on Friday and Saturday. With the mild temperatures will come
more dry weather, with two main exceptions. The first is with a pair
of slow-moving Pacific fronts that are set to move over the coastal
waters Monday night/Tuesday morning and Tuesday night/Wednesday
morning. Models suggest the first frontal boundary will decay over
the coastal waters before reaching the coast, resulting in the
continuation of dry weather for all locations. Admittedly there is a
5-10% chance for measurable rain along the south WA/north OR coast
with this front, but rain amounts would only reach 0.01-0.03" at most
if precipitation were to occur.

Despite the lack of precipitation with the first front, it will prime
mid-levels of the atmosphere with moisture ahead of a secondary front
that will move inland Tuesday night/Wednesday morning. As such, this
front is more likely to produce at least some measurable rain
along/near the coast and over most of southwest WA to the north of
Vancouver. With this system, chances for rain in a 12-hr period
increase to 40-60% over southwest WA to the north of Vancouver and
60-80% along the coast. These locations are likely to see anywhere
from a trace to 0.05" of rain.

Although the Willamette Valley, OR Cascades and Portland/Vancouver
metro will likely stay dry with this system, that will change Friday
into Saturday. This is when models and their ensembles remain in good
agreement a closed upper level low will settle directly over WA/OR
and stall for 36-48 hours. This low will bring cooler air aloft,
helping to steepen mid-level lapse rates. Abundant moisture will
accompany this low as well, resulting in a favorable environment for
widespread rain showers Friday through Saturday. If enough sun
breaks/surface heating occurs, heavier showers and isolated
thunderstorms would also be possible (NBM 12-hr thunder probabilities
peak at 10-20% Friday afternoon). Rain amounts will vary quite a bit
from location to location due to the showery nature of precipitation.
Note the probability for at least some measurable rain (0.01" or
more) is around 90-95% across all of northwest OR and southwest WA
according to the NBM, so it is now mainly a question of how much rain
will fall rather than if rain will occur or not. NBM and LREF 48-hr
QPF probabilities for at least 0.25" of rain have nearly doubled
since last night, now reaching 30-50% over the Willamette
Valley/Cowlitz Valley and Portland/Vancouver metro, 50-70% in the
Cascades/foothills, and 60-70% along the coast, coastal mountains and
western Columbia River Gorge. Probabilities range from 25% in Hood
River and Odell to 35% in Parkdale. Temps will be cooler both days
with highs most likely in the 60s due to the showery conditions in
place. -TK

&&

.AVIATION...Surface high pressure persists over the Northeast
Pacific, keeping mostly VFR conditions through the TAF period.
The only exception will be the coast, where MVFR marine stratus
will likely develop after 09-12Z Monday and continue overnight (30-50%
chance at KAST and 20-30% chance at KTMK and KONP). Light
northwesterly winds around 5 kt are expected to increase to 5-10
kt by 18-20Z Sunday for inland terminals, and to 10-15 kt with
gusts up to 20-25 kt along the coast.

*KTTD ASOS is currently INOP except for altimeter and will be AMD
 NOT SKED.

PDX AND APPROACHES...VFR conditions and clear skies are expected
through the period. Light northwesterly winds around 5 kt becoming
5-10 kt by 20Z Sunday.
~Hall

&&

.MARINE...North/northwesterly flow continues, with diurnally
driven peaks in the afternoon. Winds 15-20 kt expected with gusts
to around 25 kt south of Cape Falcon to Florence this afternoon
and evening. A short, low end Small Craft has been issued and is
in effect from 11 AM this morning to 11 PM this evening. Seas are
generally wind driven at 3 to 5 ft.

A weak disturbance is expected to cross the region on Monday,
supporting southerly winds. A westerly swell is also expected to
move into the waters late Monday, generally around 5 ft at 10
seconds. Combined seas still look to remain 7 ft or less through
next week. -Batz

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for PZZ252-253-
     272-273.
&&

$$

www.weather.gov/portland

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