El Nino may step aside for La Nina, reports say

The El Nino weather phenomenon that has brought heavy rains and flooding to some parts of the world and drought to others is likely to weaken after May, the World Meteorological Organization said Friday.

Most climate models foresee conditions beginning to return to normal, but some show El Nino may be followed by a cold weather event known as La Nina, which would bring abnormal cold to the eastern Equatorial Pacific beginning from July to September, the WMO said in a report.Asian countries in the Western Pacific, subject to unusually dry conditions during El Nino, might be in for heavy rains under La Nina, said Dr. Michael Coughlan, head of WMO's world climate program.

The United Nations agency said El Nino, which stems from a warm Pacific current off South America, was the strongest on record, surpassing that of 1982-83.

But it has peaked, with the volume of its warm water pool down 40 percent since its maximum last November, WMO said. Even so, the surface area of its warm water pool in the Pacific is still about 1.5 times the size of the continental United States.

Due to its energy, the warm pool's impact will "continue to dominate world climate patterns through to mid-1998," WMO said.

California and the southern third of the United States can expect "increased storminess and wetter-than-normal conditions," with "warmer-than-normal conditions" along the northern third of the country, WMO said.

WMO predicted drier-than-normal conditions over Indonesia, eastern Australia, northern South America and southern Africa during the next few months. Residents of southern Australia should be aware of the continuing threat of fires, it added.

Tropical cyclones are expected to be more frequent in the South Pacific islands from June through August, especially in the Cook Islands and French Polynesia.

Wetter-than-normal conditions should continue over the central and eastern equatorial Pacific, along the coasts of Ecuador and northern Peru and over southeastern South America, according to the Geneva-based agency.

The El Nino update was based on information from the national meteorological and hydrological services of 185 WMO member states and territories, as of Jan. 21.

"The forecasts from most major climate prediction centers indicate that warm episode conditions will continue through March-April-May 1998, followed by a weakening of the warm episode," the WMO update said.

"Some climate models indicate a switch to a cold event (La Nina) beginning during July-September 1998," it added.

Coughlan said most climate forecast models foresaw a return to more normal conditions after May.