A La Nina weather pattern is likely to cause a cold, wet winter, the National Oceanic and Atmospheric Administration reported Thursday, Aug. 12, 2021.

SALEM — Odds increasingly favor a La Nina weather pattern taking hold by fall, upping the chances for a cold and wet Northwest winter, the National Weather Service’s Climate Prediction Center says.

The center pegged at 60% the chances of a La Nina prevailing in November, December and January. A month ago, the center put the chances at 53%.

Since then, the Pacific Ocean has resumed a cooling trend that started last spring, but paused in June and early July, according to the center.

A cooler-than-average ocean, especially along the equator in the mid-Pacific, triggers atmospheric changes to form a La Nina.

Its opposite, El Nino, is cased by higher-than-average ocean-surface temperatures and is linked to warm Northwest winters and below-average snowpacks. 

Currently, the ocean and atmosphere temperatures are neutral, indicating neither a La Nina nor El Nino.

The center predicted a 36% chance conditions will still be neutral next winter. The center rated the chances of an El Nino forming at only 4%.

The last La Nina reigned in the winter of 2017-18. Washington’s snowpack that winter was 113% of normal.