444
FXUS66 KPQR 152247
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
247 PM PST Sat Nov 15 2025

.SYNOPSIS...A relatively drier pattern with upper-level ridging
atop a closed upper low over California will give way to a
progressive and active pattern early next week. Repeated systems
will bring cooler temperatures along with multiple chances for
lowland rain and mountain snow to the region.

&&

.SHORT TERM...Now through Sunday night...Mostly dry conditions are
expected to persist until late tonight. A broad upper level
cut-off low continues to spin just off the central California
coast. Cloud cover across the region has started to dissipate
from southeast to northwest for much of Lane County and into the
Willamette Valley. This is due to the position of the upper low
bringing drier air from the Great Basin westward. Clearing is
expected to persist over the central and southern Willamette
Valley, eastward over the Cascades and south of the Columbia
River Gorge. Sufficient low level moisture in areas under clear
skies will have a decent chance of fog developing overnight,
mainly in the central and southern Willamette Valley. NBM
probabilities for visibility less than 3 miles peaks between
40-50% from Aurora southward overnight while probabilities for
less than 1 mile of visibility are between 20-30%. Elsewhere,
conditions are expected to remain mostly cloudy overnight.

The next round of rain is expected to reach the coast late
tonight into Sunday morning. A trough over the Gulf of Alaska
will dig southeast toward the PacNW, sending a cold front toward
the region. Rain is expected to move inland late Sunday
morning. The best moisture with this system splits the area,
with better moisture associated with the surface low that will
come onshore around Vancouver Island and another surface low
over southern Oregon and northern California. As such, rainfall
totals associated with this system are expected to be on the
lighter side generally 0.2-0.3 inches inland and 0.4-0.75 along
the coast and higher terrain. Minimum snow levels are expected
to remain above 4000-5000 feet with this system until the cold
front passes through and drops closer to 3000 feet. Not
expecting substantial snow at pass level with this system. /19

.LONG TERM...Monday through Saturday...The beginning of next
week remains active as the trough that brought Sunday`s rain
pinches of and develops into a cut-off low centered over the
Great Basin by late Monday. Residual moisture and the proximity
of the upper low is expected to support showery conditions.
Expect just rain below 3000 feet while some flakes may mix in
above this level in the Cascade Foothills and mainly snow on the
Cascade crest.

A brief period of dry conditions under shortwave ridging will keep
the latter half of Tuesday through Wednesday benign. The next
potentially impactful system is expected to impact the region
late Wednesday night into Thursday, though there is substantial
differences among the models and their ensembles. Cluster
analysis is split between solutions with around 35% showing a
weak trough, 34% showing a much deeper trough with an amplified
pattern, 16% close to zonal, and the last 15% with a deeper
trough but well offshore. Depending on what happens with this
late week system, could see impactful snow around the mountain
passes through, NBM spread is quite large with some showing no
snow and others showing 6 inches or more. Will need to keep an
eye on this system as it approaches late next week. /19

&&

.AVIATION...Conditions have largely returned to VFR at inland
sites this afternoon with ample clearing of lingering mid to high
level cloud cover underway. This will likely set the stage for
fog development overnight, especially in the Willamette Valley,
leading to a widespread degradation of flight conditions to
IFR/LIFR. However, confidence in the timing of fog formation is
only moderate at this time with the onset of fog most likely
around 04-08z Sun at KEUG, KSLE, and KUAO. Lower confidence
comparatively for Portland Metro sites where fog/low stratus and
accompanying IFR/LIFR conditions may hold off closer to 09-14z
Sun - this is further complicated at KTTD by light east winds out
of the Gorge working against fog and stratus formation. At the
coast a mix of MVFR to IFR conditions trend towards IFR with a
40-50% chance for LIFR CIGs after 9-12z Sunday.

Another frontal systems is expected to push inland during the
Sunday as well with light rain beginning at the coast 15-17z
before the band of light rain advances eastward into the
Willamette Valley and Portland metro by 20-22z Sun. This will aid
in keeping conditions sub-VFR the latter half of the TAF period.

KPDX AND APPROACHES...Expect VFR conditions to persist into the
evening and early overnight hours. Will have to be on the lookout
for fog and/or low stratus formation in the 10-14z time period
which would quickly push conditions to IFR or LIFR at KPDX. High
resolution models project a 80% chance for IFR or lower CIGs/VIS
by 14-16z Sunday. -99

&&

.MARINE...Expect the coastal waters to remain in a brief lull
between weather disturbances tonight into early Sunday as seas
hold around 6-8ft. However, this break is short lived as another
frontal system traverses the waters the second half of Sunday
into Monday, leading to increased southwesterly winds initially
quickly switching northwesterly - gusts up to 20-23 knots mainly
outer waters. Behind the front, a building westerly swell will
increase wave heights to 12-15 ft by Monday morning, before
falling below 10 ft again on Tuesday. Given the high confidence in
wave heights increasing above 10 ft during this late Sunday
through Monday time-period, a Small Craft Advisory was issued for
the inner and outer waters including the Columbia River Bar. The fairly
active and progressive weather pattern likely ushers in a
slightly stronger weather disturbance late week bringing
increasing chances for hazardous winds and seas at or above 15 ft
focused Thursday into Friday. -99

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.

WA...None.

PZ...Small Craft Advisory from 7 PM Sunday to 7 PM PST Monday for
     PZZ210.

     Small Craft Advisory from 4 PM Sunday to 10 PM PST Monday for
     PZZ251>253-271>273.

&&

$$

www.weather.gov/portland

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