Storm fueled by former typhoon could bring fall’s wettest weather to western WA Saturday night

This weekend will be a stormy one and an event to be prepared for.

On Friday morning, a strengthening Pacific weather system was gearing up hundreds of miles off the coast and is expected to sweep onshore Saturday night. The storm may be the wettest of the fall season thus far and will offer strong blustery winds and rough seas, primarily along the outer coast and from about Everett northward.

What makes this Pacific weather system stronger, wetter, and more unique is that it has characteristics of an atmospheric river. The primary source of its moisture is coming from former typhoon Cempaka that recently moved northeast into the North Pacific and has become embedded in this evolving weather system.

Weekend weather

The rain with this weather system is expected to reach the coast Saturday afternoon and spread inland across western Washington by Saturday evening. Come Sunday morning, the system will have moved across the Cascades and into eastern Washington.

The rain on Saturday night is forecast to be one of the wettest delivered so far this fall season. Along the coast, up to two inches of rain is expected. In the Olympics and Cascades, this system is anticipated to dump up to four inches of rainfall with elevated snow levels of around 5,000 feet.

For the rest of western Washington, rainfall totals are expected to range from a half inch to a bit more than an inch.

Impacts

This weather system will also pack a punch. Winds along the coast are forecast to have peak wind gusts up to 60 mph Saturday night. For the North Sound, winds are expected to be 25 to 40 mph with gusts up to 50 mph mainly from Everett northward.

Elsewhere in western Washington, southerly winds of 20 to 30 mph with gusts up to 40 mph are anticipated. Local power outages are possible across the region.

Waves along the coast may reach as high as 25 feet with rapid beach run-up and sneaker waves carrying logs and other debris. For storm watchers, be on higher ground to watch the action and avoid being on a jetty.

For the rest of western Washington, wind-created wave action can impact low-lying exposed areas, particularly during high tide. Fortunately for Seattle, Olympia, and Everett, the highest high tide on Saturday is during the morning around the 9 a.m. hour and will not coincide with the strongest winds overnight.

With more tree leaves to fall and the rain runoff, storm drains can get clogged, producing ponding of water on roadways. Public works authorities ask everyone to do their best to keep local storm drains clear of leaves.

Sunday and temperatures

The recent quite mild mid-November weather will continue Saturday with highs ranging from the mid-50s to lower 60s.

Sunday will involve post-weather system showers and cooler conditions with highs in the 50s. The showers will continue Monday, with mountain snow levels dropping to near 4,000 feet, with snow likely at Stevens and White Passes, but not at Snoqualmie Pass.

Any threat of flooding?

Thanks to the overall dry weather in October and early this month, western Washington rivers remain well within their banks with the exception of the Skokomish River in Mason County.

The recent rains and this weekend’s wet weather will raise river levels, but for now, no significant flooding is anticipated heading into next week.

To keep up on the latest on western Washington rivers and the potential for landslides, monitor the National Weather Service website here. With the rainy season here, it may be worthwhile to keep an eye on the rivers if you live near or commute through any of the North Sound’s river valleys.

Historically, November is usually the wettest month of the year. After a dry start to the month, this month is well on its way to retaining its soggy reputation.

Ted Buehner is the KIRO Newsradio meteorologist. Follow him on X and Bluesky. Read more of his stories here.