Climate experts Thursday confirmed the start of La Nina — a mild cooling of the tropical Pacific Ocean that often coincides with stronger and more numerous hurricanes, a wetter Pacific Northwest and a drier South.

La Nina will probably last through late spring and possibly through the summer, said Edward Alan O'Lenic, chief of the National Oceanic and Atmospheric Administration's Climate Prediction Center.

The center confirmed jet stream changes and lower-than-normal water temperatures in parts of the Pacific Ocean in the past three months, O'Lenic said at a meeting of the American Meteorological Society in Atlanta.

O'Lenic said that while it is too early to predict the ultimate effects of this year's La Nina — the agency has only about 50 years of data on La Nina occurrences — he expects more strong hurricane activity in the Atlantic.

Hurricane-friendly conditions are expected "for quite a while, a decade or more," he said.

Internationally, La Nina typically creates more rainfall across Indonesia and northern Australia, the Amazon basin and southeastern Africa. Places across the eastern half of the equatorial Pacific and eastern equatorial Africa experience drier weather.

La Nina is the opposite of the better-known El Nino, a Pacific warming trend. The last La Nina was in 2000-01.

La Nina updates are expected from the climate center on Feb. 9 and in mid-March. Atlantic and Pacific hurricane outlooks will be released in mid-May.