PORTLAND,Ore. -- Prepare for a winter that is colder and wetter than normal in Oregon and much of the Northwest. La Nina has returned.

Tyree Wilde is monitoring conditions in the Pacific Ocean from his National Weather Service office in Portland. He knows what La Nina means.

Probably lots of storms and it looks like as we transition to La Nina conditions -- wetter than normal conditions and colder than normal conditions, said Wilde.

Wilde says La Nina happens when strong trade winds blow the warmer surface layer of the Pacific Ocean near the equator to the west. That allows cooler water to surface. Even a change of three degrees Fahrenheit can alter weather patterns. Wilde says it shifts the jet stream into a pattern that points it directly at the northwest.

The last big La Nina event stretched from 2007 to 2008. It brought punishing wind storms to the Oregon Coast and devastating floods to the town of Vernonia. In 2008 storm systems buried the City of Portland and surrounding areas in snow and ice.

KGW TVMeteorologist Rod Hill says the La Nina of 2010 will bring a series of strong storms.

You have a high number of rain days. You have cold fronts off the pacific coming in bam, bam, bam one after another.

On the streets of Portland, many enjoyed the final day of summer. Many like Laura Isquirdo are not looking forward to winter.

Not really, said Isquirdo. And it seems like summer was way shorter this year -- so that's why it may be a nastier winter, she said.

Read or Share this story: