237
FXUS66 KPQR 231753 AAB
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
952 AM PST Sun Nov 23 2025

Updated aviation discussion.

.SYNOPSIS...A fast moving cold front will cross over the region
through this morning. This will bring a return of light rain
across northwest OR and southwest WA. Temperatures cool down
behind this system, dropping snow levels towards 4000 ft by
Sunday night, resulting in light snow through the Cascade
passes. Expect a chilly Monday night into Tuesday morning. The
next system arrives Tuesday night into Wednesday, with wet
weather continuing through the end of the week. Looking beyond
and into the start of December, some models are hinting at
winter weather across the forecast area. However, there is a
wide range of model solutions and the forecast will change.

&&

.SHORT TERM...Today through Monday Night...The next frontal
will cross the region today, resulting in widespread light rain
for the CWA. Current observations already show light rain at the
Astoria Airport, with high resolution guidance bringing light
rain to the northern Willamette Valley by 4-7 AM Sunday, central
Willamette Valley and central OR coast around 8-11 AM Sunday
and the southern Willamette Valley around 9 AM-12 PM Sunday. 24
hour rainfall totals from 4 AM Sun to 4 AM Mon are forecast
around 0.25-0.50" along the coast and Coast Range, 0.15-0.35"
across the Willamette Valley and southwest Washington lowlands,
and 0.40-0.80" across the Cascades. Southerly winds will become
westerly behind the front tonight, but generally remain light.
Although, expect some breezy across the high Cascades and
eastern Columbia River Gorge with gusts up to 30 mph (25-45%
chance gusts exceed 30 mph).

Shower activity gradually decreases into Monday morning as the
system weakens and exits the region. Temperatures will also cool
down behind this system, making for a chillier Monday morning
across interior valleys with snow levels dropping below pass-
level (2000-3000 ft). Any lingering showers in the Cascades
tonight into Monday would fall as snow, with snow amounts
forecast around 0.5-2" through the passes, highest along Highway
26. There is currently a 10-20% chance that snow amounts exceed
4". Drier conditions return Monday afternoon as a shortwave
ridge builds over the Pacific Northwest ahead of the next system.
/42

.LONG TERM...Tuesday through Saturday...Tuesday morning will be
the chilliest night of the week, with low temperatures forecast
to drop into the low to mid 30s across interior lowland
valleys. With moist surface conditions, there will be potential
for frost development Monday night into early Tuesday morning
especially on grasses and elevated metal surfaces. By late
Tuesday afternoon and evening, the majority of ensemble members
suggest upper level ridging will build over the U.S. West Coast,
however, the Pacific Northwest appears to be right at the top
of the ridge. While 500 mb heights will climb and bring relatively
warmer temperatures, we will be far from dry.

The next system will ride the periphery of the ridge and enter
the Pacific Northwest from the northeastern Pacific. This will
bring widespread rain back into the forecast Tuesday into
Wednesday. This system is expected to be on the warm side with 850
mb temperatures around 2-4 C. As a result, snow levels will climb
above 6000 ft. Conditions remain showery through the latter
part of the week as this system moves through the region.

Chances for 48-hour liquid precipitation exceeding 1" from 4 AM
Tuesday to 4 AM Thursday are around 45-80% along the coast,
Coast Range, Willapa Hills, and Cascades, 20-50% across the
Willamette Valley, southwest WA lowlands and Upper Hood River
Valley. Similar, 48-hour liquid precipitation exceeding 1"
probabilities are forecasted from 4 AM Wednesday through 4 AM
Friday.

Ensemble members maintain wet weather through the end of
November and into the start of December. However, there is a lot
of uncertainty as to how exactly how the end of November/start
of December will greet the Pacific NW. At this time, the 06Z
deterministic GFS is bringing -8 to -17 C (18 to 1 F) 850 mb
temperatures into the CWA. Looking at the 06Z deterministic
ECMWF is bringing -2 to -7 C (25 to 19 F) 850 mb temperatures.
So, when looking at any forecast for the end of November into
the start of December, be aware that uncertainty is high. With
that in mind, now is the perfect time to make sure that your are
ready for any winter weather. /42

&&

.AVIATION...Expect a mixed bag of LIFR/IFR/MVFR/VFR flight
conditions today and tonight, with MVFR conditions being most
prevalent. A slow-moving frontal boundary will continue moving
over southwest WA and northwest OR today, bringing light rain
and/or drizzle to all terminals much of the time through 00-03z
Monday. Precipitation should end from west to east after 03z
Monday as the aforementioned front shifts over the Cascades. Note
there will likely be a brief period of improvement to either
high-end MVFR cigs or low-end VFR cigs between 04-10z Monday,
before cigs likely lover again after 10z.

KPDX AND APPROACHES...Expect periods of light rain/drizzle and
MVFR cigs to continue through approximately 04z Monday, with
surface visibilities fluctuating between 2 and 4 SM. After 04z
Monday, there is a 70% chance cigs will temporarily lift to
3500-4000 ft before lowering back to MVFR thresholds around 10z
Monday when probabilities for cigs below 2000-3000 ft increase to
60%. Cannot rule out IFR cigs below 1000 ft at that time either,
however this is not the most likely outcome. -23

&&

.MARINE...High pressure over the area is maintaining fairly stable
conditions with minimal change expected through Sunday. Seas will
remain around 10 to 14 ft through the remainder of the weekend
before falling to 8 to 9 ft Monday afternoon and then 6 to 8 ft
on Tuesday. A weak cold front will move over the waters Sunday
morning, bringing southwest becoming northwest wind gusts up to 25
kt. A relatively stronger front arrives Tuesday night into
Wednesday, bringing wind gusts up to at least 25-30 kt with a
30-50% chance for gale force wind gusts up to 35 kt. Confidence in
gale force wind gusts materializing is not high enough to issue a
Gale Watch at this time. /42-23

&&

.BEACH HAZARDS...An energetic westerly swell is expected along
the northwestern Oregon and southwestern Washington coasts through
Monday. Seas 10-14 ft at 14-16 seconds are forecast and resulting
in a high sneaker wave threat. These energetic waves can run
significantly farther up a beach than normal, including over rocks
and jetties, creating potentially life-threatening conditions in
the surf zone when beachgoers can be unexpectedly knocked off
their feet and pulled out into cold ocean waters.

A Beach Hazards Statement has therefore been issued through 10 AM
Monday. Caution should be used when in or near the water, and
beachgoers with children should be especially watchful. Never turn
your back on the ocean, and be sure to keep an eye on the waves.
Those participating in razor clam digs should additionally
exercise caution. /42

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 10 AM PST Monday for PZZ210-251>253-
     271>273.
&&

$$

www.weather.gov/portland

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