378 FXUS66 KPQR 092105 AFDPQRArea 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.
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.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
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.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
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.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
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.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None. WA...None. PZ...Small Craft Advisory until 9 PM PDT this evening for PZZ210.
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NWS PQR Office Area Forecast Discussion