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The Word on the Weather

El Niņo... The Southern Oscillation Index (SOI) is calculated from the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin.
Sustained negative values of the SOI often indicate El Niņo episodes. These negative values are usually accompanied by sustained warming of the central and eastern tropical Pacific Ocean, a decrease in the strength of the Pacific Trade Winds, and a reduction in rainfall over eastern and northern Australia.

AUSTRALIA  has a 90 per cent chance of experiencing an El Niņo weather pattern this year, the Bureau of Meteorology has said. In a blow to farmers, the bureau said it appeared the main factors that contributed to an El Nino phenomenon would lock themselves in for the rest of the year. An El Nino is normally associated with drought conditions in eastern Australia. The phenomenon refers to a warming of the eastern and central Pacific Ocean, which generally reduces rainfall in eastern Australia, Indonesia and other parts of south-east Asia. Rain and storms increase in intensity and number on the west coast of North and South America. The bureau said sea surface temperatures were staying above long-term averages, with a marked warming in the central and eastern Pacific. "The chance of these conditions persisting for the remainder of the year, thereby constituting an El Nino event, is probably about 80 per cent or 90 per cent," it said. "The sea temperatures are now sufficiently high that should they persist for several months - 2002 could be called an El Nino year." Easterly trade winds have weakened to such an extent that some have actually reversed in the western Pacific.
El Niņo translates from Spanish as 'the boy-child'. Peruvian fisherman originally used the term - a reference to the Christ child - to describe the appearance, around Christmas, of a warm ocean current off the South American coast.
Nowadays, the term El Niņo refers to the extensive warming of the central and eastern Pacific that leads to a major shift in weather patterns across the Pacific. In Australia (particularly eastern Australia), El Niņo events are associated with an increased probability of drier conditions.

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