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La Nina May Replace Fading El Nino by Summer Storm Season

  • U.S. sees 75 percent chance La Nina will arrive by 2016's end
  • Pacific phenomenon often means more Atlantic hurricanes

A La Nina, a weather pattern marked by a cooling of the Pacific Ocean’s surface, might begin as soon as summer in the Northern Hemisphere, threatening an increase in the number of hurricanes that develop in the Atlantic.

La Nina is the inverse of the warming that characterizes an El Nino pattern. One of the strongest El Ninos on record is now weakening in the equatorial Pacific.

“We are still technically in an El Nino but we are seeing a lot of cold water bubbling up near the coast of South America,” said Michelle L’Heureux, a forecaster with the U.S. Climate Prediction Center in College Park, Maryland. “It is not widespread at this point, but it is indicative to a transition and a fairly quick one.”

Both phenomena can alter global weather patterns. More hurricanes tend to develop in the Atlantic in a La Nina year because it cuts down on wind shear across the basin that can rip budding storms apart. Strong La Ninas also threaten to bring drier conditions across agricultural areas of southern Brazil and flooding to parts of Australia.

The center isn’t making forecasts on the strength of the La Nina yet, in part because many predictive models aren’t always as accurate during spring in the Northern Hemisphere. U.S. forecasters believe there is a 75 percent chance a La Nina will form by the end of 2016, and they are favoring it to develop over the summer, L’Heureux said.

Earlier this week, Australia’s Bureau of Meteorology maintained its La Nina watch and said there was a 50 percent chance it could form by the end of the year. 

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