549 
FXUS66 KPQR 160435 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
935 PM PDT Wed Oct 15 2025

Updated aviation and marine discussions. 

.SYNOPSIS...A ridge of high pressure continues to facilitate 
dry conditions though much of Thursday across the interior 
valleys. Beginning later Thursday into Friday the pattern become
more progressive starting with a weak frontal system ushering 
in chances for light rain or drizzle, more likely near the 
coast. Then high confidence of widespread rain for late Saturday
into Sunday thanks to an upper-level trough. Likely drier 
conditions for the first part of next week, although some 
uncertainty remains with a 20-40% chance of rain returning by 
mid-week.

&&

.SHORT TERM...Now through Saturday night...An upper level ridge
over the NE Pacific extending into western Canada will slide 
south, dropping over the Pacific NW on Thursday. Generally clear
skies combined with light winds will cause temperatures to fall
once again with patchy frost developing across rural valleys. 
Have issued a Frost Advisory for many of these locations once 
again through early Thu morning. 

A strong jet stream to the north will flatten out the upper ridge 
later Thursday, while increasing onshore northwesterly flow brings 
increasing clouds to the area by Thu afternoon. A weak front at the 
tail end of the system to the north will push onshore Thu evening, 
bringing potential for some light rain or drizzle across the area 
Thu night into early Friday morning. Overnight temperatures not 
expected to be as chilly. Should see mostly sunny skies returning by 
late afternoon with dry conditions expected through Fri night. 

Seasonable temperatures with afternoon highs in the lower to mid-60s 
continues into the weekend as broad upper level ridging transitions 
over the Pacific NW on Saturday. A more robust frontal system is 
expected to approach the region later Saturday. This system will 
bring increasing chances for rain to the coast by Saturday 
afternoon, with rain likely spreading inland later Sat evening 
through Sat night. More details in the long term discussion below. 
				  											-02

.LONG TERM...Sunday through Wednesday...An upper level trough is 
expected to move over the region on Sunday, though there is still 
uncertainty how deep this trough will be. This maintains a 
relatively large spread of potential rainfall accumulation amounts 
through Sunday night, though there is high confidence that higher 
amounts are more likely on the northern end of the forecast area 
than the southern ends. According to NBM guidance, the lower end 
rainfall amounts range between 0.2 to 0.8 inch (90% chance of 
exceeding), while the higher end amounts show anywhere from 1.5 
inches inland to 3.5 inches along the coast possible (10% chance). 
Showers likely behind a cold front that pushes across the area on 
Sunday. Latest guidance shows around a 15-20% chance of thunder at 
the coast Sunday afternoon. A few lingering showers possible into 
early next week as onshore flow persists. Active weather likely 
remains to the north through mid-week. But, long range models are 
indicating potential for this active weather to slide farther south, 
bringing a moderate risk of hazardous weather to western Washington 
and Oregon later next week. 								-02


&&

.AVIATION...High pressure over region will slowly fade late in the
forecast period as a frontal system approaches. VFR through a
majority of the TAF package except in the later half when the
coastal sites see increased chances for persistent MVFR and even 
IFR CIGs, and precipitation. Some models suggest a period of MVFR
CIGs through 17Z Thu along the coast though confidence is low due
to a lack of moisture within the upper atmosphere. Have include
high-end MVFR CIGs though it is right around a 50% chance. 
Overnight temperatures will still be cold enough to form frost in 
some interior valleys though it will be less widespread than 
previous days. In general looking at mainly our cold spots within 
southwest Washington valleys and from KCVO southward. As the front
moves in late in the forecast precipitation is expected. There 
continues to be inconsistencies in the timing of rain though so it
could fall just outside of the 24-hr TAF period. The north 
coastal runways will see any rain first. 

KPDX AND APPROACHES...VFR through the next 24-hrs. Frost will be
possible within the area but low probability at KPDX.		-27

&&

.MARINE...Expect north to northwest winds to persist through 
Thursday morning while seas hold around 4-6 ft with a dominate 
period of 14-15 seconds. Conditions become more active Friday and
into the weekend as a large west to northwest swell enters the
waters. Wave heights are expected to increase to 10-12 feet Friday
evening with a period of 16-17 seconds, leading to steep seas and
dangerous conditions for Small Craft. As such, a Small Craft
Advisory for steep seas has been issued for all waters and the
Columbia River Bar starting at 5 pm Friday. Winds are not 
expected to be an issue with north to northwest winds 5-10 kt. The
pattern remains rather active through the latter half of the 
weekend into early next week as another, albeit stronger, frontal 
system progresses into the coast waters. Conditions will quickly 
amplify as a result with a 40-70% chance of seas greater than 15 
ft late Sunday into early Monday and a 30-50% chance for seas to 
exceed 18 ft across the outer waters during the same time frame. 
															-19/99

&&

.BEACH HAZARDS...A large north to northwest swell of 10-12 ft at 
16-17 seconds is expected to enter the waters Friday afternoon. 
This 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 has been issued for the
Central and Northern Coast of Oregon and the South Washington 
Coast. 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 frigid 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! 		-19


&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Frost Advisory from 1 AM to 9 AM PDT Thursday for ORZ104-109-
     116>118-121.
WA...Frost Advisory from 1 AM to 9 AM PDT Thursday for WAZ205-208.
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.
&&

$$

www.weather.gov/portland

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