GENEVA -- La Niña, a weather phenomenon usually linked to heavy rains and flooding in Asia-Pacific and South America and drought in Africa, has reemerged and is likely to persist into early 2012, the World Meteorological Organization (WMO) yesterday said.
However, it is “very unlikely” to reach conditions as strong as those of the 2010-2011 La Niña event that ended in May, the United Nations agency said.
“This La Niña is expected to persist through the end of this year and into early 2012, possibly strengthening to moderate intensity,” the WMO said in a statement.
La Niña, which typically cools sea surface temperatures in the tropical part of the Pacific Ocean, re-established itself in August, it said. “By the end of October, the La Niña conditions had slowly reached a weak-to-moderate level.”
Unusually for a La Niña event, warmer than normal sea surface temperatures in the western equatorial Indian Ocean have been recorded, the WMO said.
“This requires careful monitoring, along with conditions in the tropical eastern Indian Ocean, as these can influence surrounding continental climate patterns.”
La Niña periods are often associated with heavier rains across large parts of Australia, the Philippines, Indonesia and Thailand, it said. The previous event was linked to torrential rainfall, mudslides and floods in Colombia and Venezuela.
La Niña is also generally linked to increased rainfall in southern African countries and parts of West Africa, but is not the only contributing factor, it said.
“La Niña is associated with rainfall deficiency in equatorial eastern Africa and the 2011 drought in Somalia and northern Kenya was exacerbated by La Niña’s influence,” it added. A large part of Somalia is experiencing famine which the United Nations says has put 750,000 people at risk of starvation.
El Niño, its opposite weather phenomenon which warms the Pacific, has been ruled out as occurring before April 2012, according to the WMO whose assessment is based on input from climate prediction centers and experts around the world.
Both La Niña and El Niño are strongly linked to the atmospheric circulation in the tropics and are the major but not the only determinants of the seasonal and year-to-year fluctuations in climate, it said. -- Reuters
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