La Nina weather pattern seen lasting into spring 2012

La Nina, the weather phenomenon widely blamed for severe drought in the southwestern U.S. and South America, will last into the northern hemisphere’s spring of 2012, the U.S. Climate Prediction Center (CPC) said Jan. 5.

“The latest observations … suggest that La Nina will be of weak-to-moderate strength this winter, and will continue thereafter as a weak event until it likely dissipates sometime between March and May,” the CPC said in its monthly update.

The CPC is an office under the National Oceanic Atmospheric Administration (NOAA).

La Nina can last for several years. It is caused by an abnormal cooling of waters in the equatorial Pacific Ocean. El Nino leads to warming of those waters. Both conditions severely disrupt weather patterns from South and North America to India and possibly even Africa.

The CPC said La Nina means “drier-than-average conditions are more likely across the southern tier of the U.S.”