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BOM issues warning on fading La Nina

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The Bureau of Meteorology (BOM) warned today that the La Nina weather system could go out with a bang.

A La Nina event, which increases the chances of flooding in parts of Australia, remains active in the tropical Pacific, but climate models suggest it is at or near its peak. Conditions will likely return to neutral in early autumn.

But that doesn’t mean there’s room for complacency.

“Significant weather can still occur as La Nina weakens, especially as the peak of the Australian tropical cyclone season is around February/March,” BOM said.

Other climate drivers might also play a part.

“The Madden–Julian Oscillation (MJO) is currently weak, but models indicate it may strengthen in the eastern Indian Ocean or western Maritime Continent in the coming week,” today’s update said.

“Typically, when the MJO is in the eastern Indian Ocean it may provide a boost to La Nina by encouraging strengthened trade winds in the Pacific Ocean.

“The Southern Annular Mode (SAM) index has recently risen to positive levels. It is forecast to remain positive, but gradually weaken, over the next three weeks.

“A positive SAM during summer typically brings wetter weather to eastern parts of Australia, but drier than average conditions for western Tasmania.”