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Batten down for a wild, wet winter a La Nina
5:00AM Monday April 02, 2007
El Nino is dead, but New Zealanders may get a La Nina weather pattern in its place, a climate scientist says.
"A transition to La Nina has recently become a substantial possibility," says researcher Jim Salinger of the National Institute of Water and Atmospheric Research (Niwa).
Conditions in the Pacific Ocean are neutral at the moment, but over the next couple of months New Zealand could be set up for a wet winter.
The strong El Nino of 1997-1998 was followed by a prolonged La Nina phase that extended from mid-1998 to early 2001.
A La Nina brings cold water to the tropical Pacific Ocean, but water temperatures around New Zealand are usually warmer than normal.
And there are more northerly and northeasterly winds, which tend to bring moist, rainy conditions to the northeast of the North Island and reduced rainfall to the south and southwest of the South Island.
This means that some areas, such as central Otago and South Canterbury, can experience drought in both El Nino and La Nina years. But a cloudier, wetter summer in the north of the country increases the chance of tropical storms, such as the one that hosed down Northland this week.
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