Second La Nina in a row brings rain but does that mean floods?

Oct 27, 2011

Climate experts have predicted a colder and wetter than normal winter on the way for Washington, thanks to a second year in a row of La Nina’s effects. 

While some people in the area will be happy about a surge in showers, a lot more are probably disappointed or worried.

Snowboarders and skiers are probably rejoicing at the news of back-to-back La Nina winters. The periodic cooling of the Pacific Ocean typically results in deep snow on the slopes.

It also means more rain at lower elevations. 

That’s not only a bummer for people looking forward to a milder winter than last year, it’s also a concern for those who live near rivers. 

Brent Bauer of the National Weather Service in Seattle says it shouldn’t be, though:

“When you see it raining day after day, that’s not a signal that, ‘oh, we better watch out, it’s going to horrendous flooding,’" he says. “While we can have big floods, it doesn’t tie one-to-one with a wetter than normal season.”

He says La Nina’s influence is more of an indicator of increased landslide activity, especially on steep slopes and coastal bluffs:

“When you have those long periods of rain, the ground keeps soaking it up and gets wetter and wetter,” he says. “Then, a heavy rainfall on top of that is the prime trigger for getting landslides in Western Washington.”

Areas particularly prone to landslides include parts of West Seattle and railway lines near Edmonds, Mukilteo and Tacoma. Bauer says it’s “highly possible” that will lead to commute delays and disruptions of Amtrak service. Last year, Amtrak Cascades cancelled dozens of trains because of landslides during the La Nina winter.