381
FXUS66 KPQR 141023
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
320 AM PDT Sat Jun 14 2025

.SYNOPSIS...Onshore flow will maintain seasonable temperatures
through the upcoming week. A weak Pacific cool front will bring a
chance of showers late Tuesday through Wednesday morning, however
rain amounts with this front look light with locations in the
central/southern Willamette Valley seeing little to no rain.
Potential for more substantial rain amounts Friday through next
Saturday when a cool upper low is expected to settle over Washington
and Oregon, resulting in widespread rain showers.

&&

.DISCUSSION...Now through next Saturday...The short term forecast
remains highlighted by onshore flow, seasonable temperatures, varying
degrees of morning cloud cover and the continuation of dry weather.
Low to mid level clouds were stubborn to clear out Friday afternoon,
with little to no clearing observed for most locations. The latest
hi-res model guidance is not handling the extent of cloud cover well.
Nudged the sky cover forecast to the NBM 90th percentile to bump up
coverage of clouds through Saturday morning. Expect at least some
clearing Saturday afternoon, however cloud cover may struggle to
clear again in some locations. If cloud cover lingers through most of
the day, high temps will only top out in the 60s rather than the
lower 70s.

Sunday is shaping up to be similar to Saturday, albeit several
degrees warmer due to more sun breaks in the afternoon and a 2-4
degree Celsius increase in 850 mb temperatures. Expect widespread
highs in the 70s, except 60s at the coast. With very little change to
the weather pattern thereafter, conditions will be nearly the same on
Monday with mostly cloudy skies in the morning becoming partly cloudy
by the mid to late afternoon. Note a weak shortwave trough is set to
move over northwest OR and southwest WA Monday morning, bringing mid
to high clouds and virga or sprinkles, but most likely virga as model
soundings show a layer of dry air from the surface up to 4000 ft.

Chances for rain actually making it to the ground increase late
Tuesday through Wednesday morning as a weak Pacific cool front moves
inland. With the airmass already primed with lingering mid-level
moisture from the aforementioned shortwave trough, this front will
likely be able to produce at least some measureable rain (under
0.1") across much of southwest WA, and a trace to 0.05" over the
Portland/Vancouver metro. Locations from Salem to Eugene only have a
10-20% chance of rain with this front, with conditions most likely
staying dry. Even if rain does occur in the central/southern
Willamette Valley, only expect a trace to 0.01".

Beyond this system, persistent onshore flow will maintain near normal
temperatures on Thursday with below normal temperatures Friday
through next Saturday. Models and their ensembles remain in good
agreement a cool upper level low will move directly over Washington
and Oregon Friday into Saturday, bringing widespread chances for
showers both days. The vast majority of ensemble guidance shows at
least some measurable rain across all of northwest OR and southwest
WA with this system (only ~5-10% of the total ensemble space from the
ENS/GEFS/GEPS is showing no rain at all). With the cool air aloft,
fairly steep mid-level lapse rates and abudant mid-level moisture,
the grand ensemble mean is showing around 200 J/kg SBCAPE during peak
heating hours on both days. If enough sunbreaks occur and surface
heating is sufficient, some showers will have the potential to
produce locally heavy rain. Note NBM thunder probabilities are
currently under 10%, but nonzero. For rain amounts, there is a 20-
40% for 0.25" or more, except 45-55% along the coast, western slopes
of the Coast Range, Willapa Hills and Cascades/foothills. If rain
amounts this high do occur, it would be the most rain the area has
seen thus far this month.  -TK

&&

.AVIATION...Broad upper level trough remains over the PacNW
through the TAF period, continuing surface level north to
northwest winds across NW Oregon and SW Washington. Winds will
remain generally less than 10 kts, except for along the coast
where winds will increase to 10-13 kts with gusts up to 20-25 kts
after 18z Saturday. Predominately VFR conditions expected to
continue through the TAF period. Marine stratus with ceilings
oscillating between FL035-FL050 across most of the area. Expecting
ceilings to become scattered at FL150-FL250 by 18-21z Saturday.
The only exception is the coast north of KTMK where there`s a
60-80% chance of MVFR ceilings from 08-20z Saturday.

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

PDX AND APPROACHES...VFR conditions expected next 24 hours. Low
end VFR CIGs around FL050 expected through much of Saturday
morning, becoming scatter FL150+ during the afternoon. North to
northwest winds less than 10 kts. -Batz/HEC

&&

.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 2 pm to 11 pm today. Seas are generally wind driven
at 3 to 5 ft. This pattern is expected to persist through the
weekend.

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 remain 7 ft or less. -Batz

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory from 2 PM this afternoon to 11 PM PDT this
     evening for PZZ252-253-272-273.
&&

$$

www.weather.gov/portland

Interact with us via social media:
www.facebook.com/NWSPortland
x.com/NWSPortland