Weathercatch: It’s warm now, but here’s what the ‘triple dip’ La Nina could mean for the Northwest

As the Pacific Northwest basks in an unusually warm start to October, La Niña is gaining strength in the tropical Pacific Ocean. Although the meteorological phenomenon is thousands of miles away, it could be a significant driver of our region’s weather conditions this winter.

La Niña is the intermittent cooling off of surface ocean waters near the equator that can alter weather patterns around the world. Meteorologists believe a moderate-to-strong La Niña may be in place in late fall through January.

This would mark the third La Niña winter in a row, which is unusual.

“It is exceptional to have three consecutive years with a La Niña event,” secretary-general Petteri Taalas of the World Meteorological Organization said in a statement, adding that it would be the “first triple dip” La Niña of the century.

Depending on how much strength La Niña gains and for how long, it could significantly impact the United States, bringing cooler and wetter weather to portions of the northern U.S. and abnormally dry conditions to much of the southern tier. Here in the Pacific Northwest, historical patterns suggest colder and stormier conditions, including more snow in the mountains. For the Southwest and the lower half of California, it could mean another year of drought.

The last strong La Niña occurred during 2010-11, one of the most intense ones recorded. In the Pacific Northwest, it triggered abnormally cool, wet weather that began in late fall and persisted through winter. On Nov. 22, blizzard conditions in the Spokane area buried roads, canceled flights and closed schools. By the end of the season, Spokane received nearly 70 inches of snow, compared to its average of 42 inches.

Although there’s a statistically significant correlation between La Niña and increased wintry conditions in our region, it’s not a guarantee. Its current presence in the Pacific Ocean “tilts the odds” for the weather pattern to occur, according to the National Oceanic Atmospheric Administration. What’s known for certain is that the La Niña phenomenon is under way for the third year in a row – a rare meteorological event.

Nic Loyd is a meteorologist in Washington state. Linda Weiford is a writer in Moscow, Idaho, who’s also a weather geek.