816 
FXUS66 KPQR 181801 AAB
AFDPQR

Area Forecast Discussion...UPDATED 
National Weather Service Portland OR 
1058 AM PDT Sat Oct 18 2025

...Updated aviation discussion and watches/warnings/advisories 
section...

.SYNOPSIS...A robust frontal system arrives late Saturday into 
Sunday, bringing widespread soaking rain to the area with gusty 
southerly winds. Trending drier Sunday night into early next week, 
aside from the south WA/north OR coast where light rain appears 
increasingly likely Monday night into Tuesday morning. A stronger 
weather system is possible late next week, bringing heavier rain and 
the potential for impactful wind gusts. However, uncertainty remains 
high for exact wind gusts and rain amounts.

&&

.SHORT TERM...Now through Sunday Night...Not much change to the short
term forecast with today's update. The forecast is generally on 
track as high pressure remains in place Saturday morning, bringing 
mostly clear skies and light winds aside from some patchy fog and 
low clouds in the Cascade and Coast Range valleys. As expected, the 
coldest areas this morning are generally over the Upper Hood River 
Valley, south WA Cascade foothills, and Battle Ground area where 
temps have dipped into the 30s. Frost or freeze headlines remain in 
effect for these areas through 9 AM Saturday. Elsewhere, 
temperatures are generally in the low to mid 40s.

Despite the chilly temperatures in place Saturday morning, 
temperatures will rebound nicely in the afternoon with highs in the 
60s, except near 70 degrees in Eugene-Springfield, Creswell, Blue 
River, Lowell and Oakridge. These areas will see sunny skies 
throughout the day aside from patchy morning fog, however northern 
areas will see clouds begin to increase ahead of the next frontal 
system. Models remain in good agreement on the timing of this front, 
bringing stratiform rain to southwest Washington and the north 
Oregon coast Saturday evening and then the rest of northwest Oregon 
from Lane County northward Saturday night into Sunday morning. 

Persistent stratiform rain will transition to post-frontal showers 
by mid Sunday morning. This is when forecast soundings show 850 mb 
temperatures cooling to +1 to +2 degrees Celsius, with SBCAPE values 
increasing to 100-200 J/kg and equilibrium levels generally below -
10 degrees Celsius. However, 0-3 km AGL bulk shear values are fairly 
high at 30-35 kt (have opted to use 0-3 km AGL bulk shear values 
instead of 0-6 km as cloud tops generally look to stay near or below 
3 km). Both speed shear and directional shear are in place, as the 
wind direction will veer with height for a few hours or so as the 
upper level trough axis moves overhead late Sunday morning/early 
afternoon. The limited instability and shallow nature of Sunday's 
convection suggests overall lightning activity will most likely be 
limited (which helps explain why NBM thunder probabilities only peak 
around 15-25%). However, whether lightning occurs or not, stronger 
showers will have the potential to produce a funnel cloud, 
landspout, or gusty outflow winds up to 45 mph given the 
environmental wind profile in place, meaning highly localized wind 
damage is possible.
Note southerly winds will be breezy in general Saturday night and 
Sunday, even away from showers and thunderstorms. Currently 
expecting southerly wind gusts up to 25-30 mph for inland areas and 
up to 30-40 mph for the south WA/north OR coast. Gusts up to 40-50 
mph appear likely in the high Cascades. Now would be a good time to 
secure any loose outdoor objects you may have. Winds will weaken 
Sunday night while any lingering showers begin to dissipate. -23/03

&&

.LONG TERM...Monday through next Saturday...Most model guidance
suggests mainly dry weather with seasonable temperatures, relatively 
light winds and a mix of clouds and sun Monday and Tuesday. The main 
exception to that will be the south WA/north OR coast where there is 
a 30-50% chance of light rain. The highest chance of rain is Monday 
night and Tuesday morning. Inland areas have a 10-20% chance of 
light rain Tuesday.

Chances for more substantial rain gradually increase late Wednesday 
through Friday, peaking near 80-90% by early Friday morning. This is 
when a moisture-rich frontal boundary with an axis of heavier rain 
will take aim at western WA/OR, bringing widespread rain and gusty 
southerly winds to the region. Although confidence is high 
conditions will trend much wetter and breezier Friday into next 
Saturday, confidence remains low for exact wind speeds, rain 
amounts, and associated impacts. Given the relatively low river 
levels heading into this system, river flooding is not expected 
despite river rises and forecast uncertainty on rain amounts. What 
appears to be more concerning is the potential for damaging wind 
gusts late Friday into next Saturday, but only if a deep surface low 
winds up tracking towards the coast like some ensemble members from 
the ENS show.
Ensemble low locations vary significantly both spatially and 
temporally, with some ensemble guidance suggesting a fairly weak low 
with minimal impacts, while other members suggest a very strong low 
capable of wind damage somewhere along the Washington, Oregon, or 
northern California coast. That said, the ENS has begun showing more 
ensemble clustering for a strong low with a central pressure 
somewhere between 960-980 mb moving near Astoria.
This scenario would result in impactful wind damage. On the 
contrary, there are still a relatively larger number of ensemble 
members that show either a weaker low and/or a different low 
position that remains further offshore. In addition, the GEFS also 
suggests a weaker low with a central pressure around 990-1000 mb, 
with only one or two members pushing a stronger low inland. In other 
words, we have a low probability for a moderate to high impact wind 
event that bears watching over the coming days. There is currently a 
15-30% chance for max wind gusts of 45 mph or stronger across all of 
northwest Oregon and southwest Washington, except for a 40-60% 
chance at the coast and on exposed ridges in the Coast Range and 
Cascades. Probabilities for max wind gusts over 55 mph range between 
5-15%, except 20-30% at the coast and over higher terrain. If wind 
speeds of this magnitude were to occur, extensive tree damage and 
power outages would be expected, especially given how many trees 
still have foliage on them. -23

&&

.AVIATION...Satellite imagery and terminal observations as of late
Saturday morning show low stratus/fog beginning to dissipate, 
returning widespread VFR conditions with high clouds. Some lingering 
stratus remains in the southern Willamette Valley (KEUG), but should 
lift by 19-20z Sat. VFR conditions with increasing high clouds 
persist through this afternoon. Winds generally remain variable 
around 5 kt or less today.

Attention then turns to Saturday evening/night. Low-end VFR CIGs 
will develop from northwest to southeast across the area after 00z 
Sun in response to an incoming frontal system. Moderate to high 
confidence (60-80% chance) that this system will bring MVFR CIGs and 
rain to all terminals by 03-06z Sun along the coast and 06-09z Sun 
inland. Cannot rule out a brief period of IFR cigs at the coast 
between 04-09z Sunday as the front pushes inland, especially at KONP 
where chances for cigs below 1000 ft peak around 80% during that 
time. Chances for IFR cigs for inland TAF sites range between 10-
20%. Visibility may also briefly drop to IFR/MVFR thresholds with 
heavier rain. Gusty south to southwest winds will also accompany the 
frontal passage, with gusts up 30 kt expected at the coast. Winds 
will increase inland as well, with gusts up to 25 kt likely for all 
inland TAF sites between 06-12z Sun.

KPDX AND APPROACHES...VFR conditions with increasing high clouds 
ahead of the next frontal system. MVFR CIGs/VIS and rain return 
tonight around 06-08z Sun as the front pushes inland. Expect 
southeasterly winds around 5 kt or less today. Winds turn more 
southerly to southwesterly tonight with the front with gusts up to 
25 kt.      -10/23

&&

.MARINE...Seas have increased to 10-12 ft at 15-16 seconds as a 
northwesterly swell arrives from a dying low pressure system over 
the Gulf of Alaska. This will be hazardous to small craft, so Small 
Craft Advisories remain in effect across all waters including the 
Columbia River Bar Saturday night, before hazardous seas up to 20 ft 
develop Sunday behind a frontal system.

The weather pattern remains 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, with seas 
peaking somewhere between 15 to 20 ft. Chances for seas above 20 ft 
remain less than 10%, except over the northern outer waters from 40 
to 60 NM offshore where there is a 30-50% chance for seas over 20 
ft. In addition to increasing seas, winds will likely gust up to 25-
30 kt. Brief and isolated gale forced wind gusts up to 35 kt are 
possible over the northern and central inner waters (Cape Shoalwater 
to Cape Foulweather) including the Columbia River Bar during the 
frontal passage Saturday evening into Saturday night.

Seas will decrease later Monday into Tuesday morning, bottoming out 
around 7-9 ft at 12-13 seconds before another potent northwesterly 
swell arrives Tuesday afternoon and evening pushing seas up to 
around 15 ft range again. An active weather pattern is then expected 
to continue late Wednesday through Friday night with a period of 
storm force wind gusts of 48 kt or stronger possible (20-40%, except 
for a 50% chance over the northern inner waters, including the 
Columbia River Bar).      -23/10

&&

.BEACH HAZARDS...A northwest swell of 10-12 ft at 15-16 seconds 
seconds has entered the coastal waters as expected. This increase in 
wave energy will support a high threat for sneaker waves through 
this weekend. A Beach Hazards Statement remains in effect across the 
central and northern Oregon coast and the south Washington coast 
through Sunday evening. Sneaker 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 and pets. Remember, never turn your back on the ocean! 
                                            -10/23

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until 8 AM PDT Sunday for PZZ210-251>253- 
     271>273.

     Hazardous Seas Warning from 8 AM Sunday to 5 AM PDT Monday for 
     PZZ251>253-271>273.
&&

$$

www.weather.gov/portland

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