U.N. agency sees small chance of El Nino this year

GENEVA, June 24 (Reuters) - There is a small chance that an El Nino weather pattern will develop in the second half of 2008, the World Meteorological Organisation (WMO) said on Tuesday.

The El Nino phenomenon, characterised by warming of Pacific Ocean surface waters, can lead to higher temperatures worldwide and is often associated with drought in typically wet areas.

"For the second half of the year, the chance of an El Nino developing is small, but it cannot be ruled out," the WMO said.

The opposite of El Nino -- a cooling of Pacific sea surface temperatures, known as La Nina -- occurred earlier this year. That event peaked in February and has since weakened, according to the United Nations agency's latest update.

La Nina events can also trigger widespread weather changes around the world. They are said to support hurricane formation in the Atlantic basin and are widely associated with flooding.

"Climatic anomalies in specific regions are also influenced by factors other than El Nino and La Nina," WMO expert Rupa Kumar Kolli told a news briefing. "Extremes (in weather) can always occur."

El Nino or La Nina tend to take place once every two to seven years, and typically last nine to twelve months, he said.

The U.N.'s climate panel, which concluded last year that global warming was unequivocal, has not found clear evidence that the frequency or intensity of El Nino or La Nina events will change in the future, according to Kolli. (Reporting by Stephanie Nebehay; Editing by Laura MacInnis)