The Bureau of Meteorology has announced that its El Niño-Southern Oscillation Outlook has been lifted to La Niña Alert status.
According to the Bureau this means that the chance of a La Niña event this year has increased to 70 per cent, roughly three times the normal likelihood.
The Bureaus said La Niña impacts the global climate and disrupts normal weather patterns, which as a result can lead to intense storms in some places and droughts in others.
Manager of Climate Operations at the Bureau, Andrew Watkins said La Niña typically resulted in above-average winter-spring rainfall for Australia, particularly across eastern, central and northern regions.
“It typically also brings cooler and cloudier days, more tropical cyclones, and an earlier onset of the first rains of the wet season across the north,” Dr Watkins said.
“The cooling of surface temperatures in the tropical Pacific Ocean and an increase in the strength of the Pacific Trade Winds indicates the chance of La Niña has risen.”
He said when the two changes occurred at the same time, at this time of year, there was a greatly increased chance of a La Niña forming and persisting through spring.
“Climate models suggest that further ocean cooling and intensification of trade winds may occur over the coming months, which has triggered the Bureau to shift from a La Niña Watch, issued on 26 June, to a La Niña Alert,” Dr Watkins said.
He said the last significant La Niña event was in 2010-11, which resulted in Australia’s wettest two-year period on record beating the previous record from the La Niña years of 1973-74.
The last time the Pacific Ocean approached La Nina conditions was in late 2017, but thresholds were only briefly exceeded, Dr Watkins said.