El Niño weather pattern now likely into 2007, UN meteorological agency forecasts

27 September 2006

A weak to moderate El Niño is now likely, persisting into early next year, according to the latest United Nations forecast on the weather pattern that periodically disrupts the Pacific area with consequences that can range from increased rainfall and floods in the United States and Peru to drought and brush fires in Australia.

But the UN World Meteorological Organization (WMO) warned against trying to predict any possible impact at this early stage from the phenomenon, which is caused in part by a warming of the waters of the tropical Pacific and its effect on the trade winds.

“Climate patterns across the equatorial Pacific over the last one to two months have developed a notable tendency toward El Niño conditions,” WMO said in its update bulletin, although it cautioned that at this stage there is a small possibility that it might not materialize.

“However, it may be noted that El Niño conditions, once established at this time of the year, almost always persist until early the following year,” WMO added.

It called for additional caution, in view of the evolving situation, in forecasting the impact in those regions typically affected by El Niño, with the situation expected to become clearer in the next month or two.

It noted that although sea-surface temperatures (SSTs) are not yet at uniformly warm levels typical of El Niño across the whole central and eastern equatorial Pacific, conditions in the eastern equatorial Pacific close to the South American coast became warm toward the end of July.

During August, oceanic and atmospheric patterns in the central and western equatorial Pacific also began to resemble conditions typical of an early stage of El Niño. In the central equatorial Pacific, SSTs became more than one degree Celsius warmer than normal, while at the same time there was a weakening of the trade winds.

It is very likely that sea-surface temperatures in the central and eastern equatorial Pacific will in general be warmer than normal through the remainder of the year and into early 2007, the bulletin said.

“The development of a basin-wide El Niño event is considered likely based on expert interpretation of the prevailing situation and the general consistency of forecast models,” it added.

 

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