The run of mild temperatures might seem unusual given the cool,wet summer,but Hugh McDowell,a climatologist at the bureau,said the weather systems that soaked NSW also kept temperatures moderate and drove off cold snaps.
“Although we had a cool,wet summer because of La Nina and a positive SAM(Southern Annular Mode),which drives cooler and wetter than average weather,those systems also drive warmer than average seawater in the Tasman,” McDowell said.
“We don’t see maximum temperatures as high,but they don’t go as low either because of the moist,warm surface water.”
The bureau said on Thursday there are signs an El Nino weather system,associated with hotter,drier conditions and potential bushfires,could develop in winter.
Six of the seven climate models consulted by the bureau predict that,by July,water temperatures in parts of the tropical Pacific will reach above-average levels,indicating an El Nino could be brewing.
Climatologists are also keeping an eye on a mass of warm water hundreds of metres below the surface off the Pacific that is moving east.
Once this warm subsurface water breaks onto the surface off the coast of South America,it could help drive El Nino conditions and increase the likelihood the weather system will form.
The bureau maintained its prediction that there is a 50 per cent likelihood of an El Nino event forming by the end of the year,while the US National Oceanic and Atmospheric Administration calculated an 80 per cent chance of an El Nino forming between July,August and September.
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