GENEVA, July 20: The UN's weather agency on Friday said a disruptive La Nina climate pattern was taking shape in the Pacific, raising the prospect of an active Atlantic hurricane season and strong monsoons in Asia.

The World Meteorological Organisation (WMO) said in a statement that the development of La Nina in the second half of 2007 was now “more likely than not” after an initial hesitation in the past two months.

The combination of tropical wind patterns over the Pacific Ocean and cooler than normal sea temperatures off the Pacific seaboard of Latin America generally has an impact “of planetary scale,” WMO scientist Rupa Kumar Kolli said.

“La Nina conditions are frequently associated with stronger monsoon rainfall and flooding in Asia and... higher frequency of hurricanes in the Atlantic,” he told journalists.

“Now things seem to be on track for the development of La Nina, but it is likely to be a weak La Nina event rather than a strong one.” However, the WMO highlighted other unusual climatic conditions in the Atlantic and Indian Ocean which could reinforce the disruption to local weather in the coming months.

They included warmer than usual sea surface temperatures in the North Atlantic, an unusually warm sea current off the Atlantic coast of southern Africa, and similar warm conditions in the western Indian Ocean.

The nine to 12 month La Nina traditionally causes heavy rainfall in Indonesia, Malaysia and Australia, droughts in parts of South America, an increased number of storms in the tropical Atlantic, cold snaps in North America and wetter conditions in south-eastern Africa.

The Atlantic hurricane season is at its most active in August and September. US experts have predicted that a total of about nine to 10 Atlantic hurricanes could form in the course of 2007 after a relative lull last year.

In 2005, record hurricanes struck the US city of New Orleans and the southern US seaboard, on top of the Caribbean, killing about 1,500 people in the United States alone and causing massive flooding and economic disruption.

Monsoon rains generally sweep south Asia until September, causing flooding and hundreds of deaths every year in some of the world's most densely populated areas. South-western Pakistan has suffered harsh monsoons so far this season.

However, they also bring most of the annual rainfall to some areas and are vital for local farming.

La Nina brings the reverse pattern of extremes to the equally disruptive El Nino phenomenon, which was blamed for the worst droughts in a century in Australia, a record warm winter in South Korea, and floods in Bolivia and East Africa in 2006 and early 2007.—AFP