528
FXUS66 KPQR 140414
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
914 PM PDT Fri Jun 13 2025

Updated aviation discussion.

.SYNOPSIS...Onshore flow will maintain mostly dry weather and
seasonable temperatures over the next seven days. Chances for
light rain return to the forecast Monday night through Wednesday
morning with the highest chances over southwest WA and the
north OR coast/coastal mountains.

&&

.SHORT TERM...Now through Sunday Night...A deep and persistent
upper level trough centered near the Alaska Panhandle maintains
robust onshore flow across the Pacific Northwest this
afternoon. Visible satellite shows a dense blanket of stratus
west of the Cascades which has been stubborn to erode as of
early afternoon, holding temperatures down in the upper 50s
through the interior valleys of northwest Oregon and southwest
Washington. Have adjusted temperatures downward for the
remainder of the day as most locations will struggle to get
above the low 60s given the abundant cloud cover in place. A
weak upper level disturbance crossing the central OR Cascades is
supporting a few light radar echoes along and east of the
crest, but expect little if any rainfall from these through this
evening.

Expect only minor changes in conditions over the next few days
as onshore flow persists over the region and promotes dry
weather with seasonable temperatures. Highs should be closer to
the low 70s in the interior valleys on Saturday as long as
morning stratus is able to scatter out more efficiently than
today, but will have to keep an eye on forecast highs for
Saturday depending on observational trends. Have confidence in
a bit more sunshine materializing by Sunday as the marine
stratus intrusion should be a bit weaker owing to decreasing
onshore pressure gradients and a shallower marine layer. As
such, modest 500 mb height rises and 850 mb temps climbing above
10C should allow highs in the inland valleys to reach the upper
70s on Sunday afternoon, with around 40-50% chance to break 80
from Portland to Salem and a 25-30% chance in the Eugene area.
The onshore flow regime will continue to promote breezy
conditions through the Gorge this weekend, with winds gusting
as high as 25 mph in the western and central Gorge each
afternoon. /CB


.LONG TERM...Monday through Friday...Inland highs will remain
in the upper 70s to around 80 degrees for Monday and Tuesday
while onshore flow and marine layer influences keep coastal
communities in the upper 50s to mid 60s. Precipitation chances
continue to dwindle for Monday as NBM guidance now keeps the
area completely dry until Monday night, with chances then
confined to coastal areas and parts of southwest Washington
through Tuesday. Wednesday will bring the best chance for rain
inland as a shortwave trough looks to clip the northern half of
the area, The bulk of ensemble members depict at least some
measurable rainfall for Portland in this timeframe, but the
probability to reach a even a tenth of an inch remains around
10% for Portland and below 5% from Salem to Eugene. Coastal
areas and the Cowlitz Valley of SW WA will see a roughly 20-40%
chance for a tenth of an inch of rain through mid next week.
High temperatures level off into the low to mid 70s in the
interior valleys beyond Wednesday in the wake of the trough.

Models hint at better chances for more substantial rainfall
across the area late next week as ensemble clusters show decent
agreement on deeper upper level troughing shifting closer to
the Pacific Northwest by the weekend. Confidence remains low as
minor differences in the strength and position of the trough
could have large implications on the forecast, but the synoptic
pattern at least looks broadly supportive of a more showery
regime across the region late in the period. Stay tuned. /CB

&&

.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 areas except for the Coast Range and coastal
areas south of KTMK is forecast to begin dissipating after 15z
Saturday, with ceilings becoming 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, though
ceilings could drop to FL035-FL045 between 12-17z Saturday. North to
northwest winds less than 10 kts. -HEC

&&

.MARINE...North/northwesterly flow continues as a broad, upper
level trough pushes inland through today. Winds generally 10-15
kt with gusts up to 20 kt through this evening. Seas around 7 ft
at 8 seconds. This will result in steep and choppy conditions at
times across all waters through this evening. So, will maintain
the current Small Craft Advisories. Also, conditions are marginal
so SCA conditions may not be met at times. Seas subsiding to
around 3 to 5 ft by Saturday morning at 8 seconds with winds
remaining north/northwest. /42-Batz

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for
     PZZ251>253-271>273.
&&

$$

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