Petersburg is expected to be in for a cooler than normal winter as La Niña conditions return for an unusual third consecutive winter.

The weather patterns in Southeast brought on by La Niña can be traced all the way back to trade winds off the Pacific coast of South America according to Rick Fritsch, a meteorologist with the National Weather Service in Juneau.

Enhanced easterly trade winds coming off of the Pacific coast of South America blow the warmer water at the surface of the ocean westward and promote upwelling, where deeper, cooler water is brought up to the surface.

As warmer wate...