073
FXUS66 KPQR 170456 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
956 PM PDT Thu Oct 16 2025

Updated aviation and marine discussions.

.SYNOPSIS...This evening into Friday, the weather pattern
becomes more progressive. A weak frontal system will produce
chances for light rain showers and/or drizzle, most likely near
the coast and in SW Washington. High confidence remains in a
widespread rain event slated for for late Saturday into Sunday
thanks to the arrival of an upper- level trough followed by
unsettled post- frontal conditions. The weather trends drier by
late Monday into Tuesday morning, although some uncertainty
remains with a 20-45% chance of rain returning by mid-week.

&&

.SHORT TERM...Now through Sunday Night...Visible
satellite imagery Thursday afternoon shows upper level clouds
beginning to stream into NW Oregon and SW Washington as high
pressure begins to break down over the region and a weak
approaches. The cloud cover will continue overnight into
tomorrow morning, which will keep overnight temperatures warmer
than the previous number of nights. Expect widespread low
temperatures in the 40s except for mid to upper 30s in the
higher elevations. The weak front is expected to move through
the area late tonight through tomorrow morning, bringing a
localized chance of rain showers to the northern Oregon and
southern Washington coast and adjacent terrain. The front is
expected to continue to weaken as it makes landfall, with most
inland areas south of the Portland metro area not expected to
receive any rain and only a 15-25% chance of light showers
elsewhere inland.

Transient ridging builds again tomorrow afternoon into early
Saturday, with skies clearing by tomorrow evening. This could
lead to chilly temperatures once again for inland valleys
Friday night into Saturday morning. Will have to monitor for
the potential of another frost advisory, especially for the
Upper Hood River Valley, northern Oregon Coast Range lowlands,
and portions of the southern Willamette Valley as low
temperatures could fall into the mid 30s to low 40s.
-03


.LONG TERM...Monday through Thursday...Ensemble guidance is in
good agreement that the next weather system will slide northwest
into the region late Saturday into Sunday, though some
inconsistencies continue with the depth and timing of the upper
trough, leading to uncertainties in timing of precipitation
onset and amount of precipitation. Latest guidance narrows down
the timing of widespread precipitation to begin along the coast
sometime in the late hours Saturday night or early Sunday, then
moving inland not long after. The bigger uncertainty is still in
rain amounts, though overall model guidance remains consistent
that locations south of Highway 20 will receive less rain than
locations north. NBM`s low-end forecast (90% chance of
exceeding) is around 0.1-0.5 inch for inland valleys and 0.2-0.8
inches along the coast and terrain, whereas the high end
forecast (10% chance of exceeding) is around 1.1-1.6 inches for
inland valleys and 1.25-2.75 inches for the coast and terrain
through 5am Monday. The deterministic forecast is around
0.25-0.6 inches for inland valleys, 0.35-1.1 inches for the
coast and Coast Range, and 0.5-2 inches for the Cascades. The
other concern is a 15-25% chance of post-frontal thunderstorms
on Sunday midday through the evening, mainly for locations west
of the Cascades. Model soundings indicate some instability
behind the front as well as a 30-40 kt low level jet, which
could produce gusty winds, heavy rain, small hail, and some
lightning with stronger showers/thunderstorms. Additionally,
some breezy winds could mix down from the low level jet. NBM has
a 40-60% chance of wind gusts greater than 30 mph along the
coast north of Lincoln City and a 40-60% chance of gusts greater
than 25 mph for inland areas north of Eugene Saturday night
into Sunday. These winds would not cause significant impacts,
but they could still cause minor concerns such as causing dying
leaves to fall off of trees and clog drains and gutters.

For Monday, some showers could linger over the terrain in the
morning, but otherwise dry weather should return as LREF
clusters indicate some level of ridging returns. For Tuesday and
Wednesday, the LREF ensemble clusters show uncertainties in the
general weather pattern. There`s about a 15-20% chance of
showers returning Tuesday and/or Wednesday, increasing to 20-40%
by late Wednesday, with temperatures remaining fairly mild.
However, the period of more concern to keep an eye on is October
24-27 where CPC has indicated a moderate risk for the PacNW of
heavy precipitation, strong winds, and Cascade snow. This is out
of the main 7-day forecast period, but we will provide updates
as this moves into the period. -03


&&

.AVIATION...Satellite shows the initial stages of a weak frontal
system approaches the region this evening, returning low-end VFR
CIGs to Willamette Valley terminals. Airports have yet to respond
to the frontal system though, likely because the lower levels of
the atmosphere are dry. However, as the bulk of the system moves
in after 08Z Fri, coastal terminals will begin to fill. MVFR CIGs
spread southward into the central Oregon coast (KONP) around
12-14Z Friday as the front progresses southeastward. Models have
begun to back off of MVFR CIGs inland this morning so confidence
is much lower than previous forecasts. Have upper level MVFR CIGs
and low-end VFR CIGs in TAFs for a short period of time this
morning. Return to VFR this afternoon.

KPDX AND APPROACHES...VFR CIGs through the TAF period, with CIGs
lowering after 10-12z Fri with the frontal passage. Variable
winds under 5 kt. Lower confidence in the presence of significant
MVFR CIGs this morning but still around a 50-60% chance of CIGs
around 2500-3500 ft AGL. -27/10

&&

.MARINE...
A weak front will briefly shift winds southwesterly
across the waters tonight and remain around 10 kt or less. Winds
return to a northerly direction behind the front Friday morning
around 10-15 kt as high pressure re-builds. Seas hold around 4-6
ft at 14-15 seconds. Conditions become more active on Friday as a
northwesterly swell enters the waters due to a low pressure
system over the Gulf of Alaska. This swell will build seas to
11-13 ft at 15-16 seconds, resulting in hazardous conditions for
small craft. Small Craft Advisories go into effect across all
waters including the Columbia River Bar 5 PM Friday and last
through at least Saturday evening. At least winds stay rather tame
out of the north with gusts up to 10-15 kt into Saturday morning.

Going forward, the pattern remains rather active Saturday night
into early next week as a stronger frontal system progresses
through the waters and brings breezy southerly to westerly winds.
Marine conditions quickly amplify as a higher northwesterly swell
enters the waters, building seas above 15 ft at 15 seconds (>80%
chance) on Sunday. There is also a 15-20% chance that seas reach
20 ft or higher across the outer waters (beyond 10 NM) on Sunday
as well. Seas likely decrease later Monday into Tuesday morning
bottoming out around 8-10 ft at 13 seconds before another potent
northwesterly swell arrives Tuesday afternoon and evening pushing
seas into the 10-15 ft range again.      -10/99

&&

.BEACH HAZARDS...
A northwest swell of 10-12 ft at 16-17 seconds is expected to
enter the waters Friday evening. This increase in wave energy
will support a high threat for sneaker waves through much of
Saturday, possibly longer into Saturday night or Sunday as a
moderate threat. A Beach Hazards Statement remains in effect
across the Central and Northern Coast of Oregon and the South
Washington Coast through Saturday afternoon. Waves can run up
significantly farther on a beach than normal, including over
rocks, logs, and jetties. Sneaker waves can suddenly knock
people off of their feet and quickly pull them into the ocean
which may lead to serious injury or drowning. Caution should be
used when in or near the water. Always keep an eye on the waves,
and be especially watchful of children. Remember, never turn
your back on the ocean! -10/99

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory from 5 PM Friday to 2 PM PDT Saturday for
     PZZ210.
     Small Craft Advisory from 5 PM Friday to 8 PM PDT Saturday for
     PZZ251>253-271>273.
&&

$$

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