


Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
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. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland