378
FXUS66 KPQR 092105
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
205 PM PDT Thu Oct 9 2025

.SYNOPSIS...Cooler and cloudier weather continues through early
next week. Low pressure system offshore will bring persistent
chances for rain through the remainder of the week and into the
weekend. Another low pressure system will bring continued rain
chances through at least early next week. Light snow accumulations
possible over the Cascades Saturday night into early next week
with minimal impacts expected.

&&

.DISCUSSION...Tonight through Wednesday...Overall, the remainder
of this week through the start of next week will be cloudy, cool
and wet. Precipitation remains in the forecast with most areas
seeing at least 0.50-1.25 inches of rain and most likely more
than that. Late Sunday into Monday, colder air arrives and will
bring an elevated potential of light snow accumulations to
elevations above 4000 ft in the Cascades. Expect a trace to 1
inch of wet snow around the passes over the Cascades with elevations
above 5000 feet likely picking up 3 to 6 inches of snow. Expect
daytime highs in the low 60s and cooling towards the mid to
upper 50s by Sunday and Monday. Afterwards, a slight warming and
drying trend is on deck, but there is a high level if uncertainty
at this time. More detailed information about the forecast can
be found below.

Satellite IR and Water Vapor imagery has the center of an upper
level, closed low pressure system west of the Oregon coast
around 43.10 N/-131.55 W this afternoon. This closed low will
continue spinning off of the coast through Friday and will send
a robust shortwave, that will bring a more widespread round of
showers to the region tonight through Friday, generally
spreading across the area from the southwest to the northeast.
This round of precipitation looks to bring around 0.20-0.50
inches for the interior lowlands and 0.30-0.75 inches to the
coast, Coast Range, and Cascades.

As Saturday approaches, precipitation remains in the forecast,
as the closed low will continue deepening along the coast and
push eastward. Expect widespread rain for the start of Saturday,
with showers developing by Sunday. Precipitation totals for
Saturday through Sunday, look to bring an additional 0.40-0.80
inches of rain in the lowlands, 0.60-1.25 inches along the
coast and Coast Range, and 0.60-1.75 inches over the Cascades.

As Sunday comes to a close and we push into Monday, colder air
will infiltrate the area behind this low. Daytime temperatures
will fall into the low to mid 50s on Sunday and Monday. Temperatures
over the Cascades and portions of the upper Hood River Valley
will also fall into the 30s, and frost advisories may be needed
for some of the low lying Cascade areas and the upper Hood
River Valley. So, if you have any sensitive plants outside, now
would be a good time to start thinking about how to protect
them.

Additionally, this will also lower snow levels to around
4000-5000 feet early Sunday morning through Monday, increasing
snow chances to the high Cascades and a rain/snow mix to around
3500-4000 feet. Expect a trace to 1 inch of wet snow around the
passes over the Cascades. It should also be noted that there is
a 10-25% probability for more significant snow accumulations of
2 to 6 inches along the passes and if that were to occur, greater
travel impacts would be expected. Given that roads above 5000
ft that are currently open will be most impacted, likely picking
up 3 to 6 inches of snow. There is a 10-25% probability elevations
above 5000 ft having 8-12 inches of snow accumulation. If this
were to happen, this scenario could result in vehicles becoming
stranded along unmaintained roads.

Model ensemble guidance remains in very good agreement that
another upper level low will drop southward from Canada late
Sunday into Monday, with rain and Cascade snow continuing
through at least Monday. As the middle of next week approaches,
models remain fairly confident in that the low will continue to
deepen around the OR/CA border. This likely bring slightly
warmer and drier conditions to the region, but if the low
remains further north, it will help to bolster a cooler and
wetter scenario. Ultimately, a 15-30% chance of showers for
most of the area, though some clusters suggest dry and warmer
conditions could return by Wednesday. /42

&&

.AVIATION...Low pressure offshore will maintain southerly flow
aloft and increasing moisture through Friday. Expect predominately
VFR conditions with mid to high level clouds across the area
through at least this afternoon. A frontal band is expected to set
up near the coast from KEUG to KAST and lift NNE across the area
overnight. Conditions are likely to deteriorate during the
heavier rain showers. Along with these showers comes a 10-20%
chance of thunderstorms. Surface winds expected to generally be
variable less than 10 kt.

KPDX AND APPROACHES...VFR conditions expected to prevail through
at least 10z Friday with mid to high level clouds streaming north
across the area. Chances for rain showers increase after 10z with
around a 30% chance of CIGs falling to MVFR between 11-18z Fri.
Northwest winds expected around 5 kt becoming variable tonight.
/02

&&

.MARINE...An area of weak low pressure continues to spin off the
southern Oregon coast near 130W. This will maintain generally
southeast offshore winds through Friday morning. Winds are easing
this afternoon and expected to remain 15 kt or less. There is
potential for some stronger southerly winds to develop Friday
afternoon, dependent on any meso-lows that form, with gusts
possibly up to 25 kt. The low weakens further into Friday night
as it moves onshore by Saturday. Southwesterly winds Saturday
morning turn northwest later in the day. These northwest winds are
expected to increase to 15-25 kt, with gusts potentially up to 30
kt, strongest across the northern coastal waters.

Seas around 7 to 8 ft are expected to subside to around 4 to 6 ft
by Friday morning. An incoming northwest swell will likely push
seas up to around 10 to 12 ft late Saturday into Sunday. Another
weak low pressure system approaches the coastal waters from the
north late Sunday into Monday. This low is expected to quickly
drop south through the waters early next week, with northerly
winds returning by Tuesday. /02

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for PZZ210.

&&

$$

www.weather.gov/portland

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