La Niña over and out: Australia versus US predictions explained

The Bureau of Meteorology has declared the La Niña climate event officially over, countering earlier US forecasts that would see the cold, wet weather stick around for months.

Australia’s Bureau of Meteorology has declared the La Niña climate event which lashed the east with cold and wet weather for months is officially over, countering earlier US forecasts.

The latest predictions from the BOM put the country on a La Niña “watch”, with the majority of indicators at neutral levels.

“La Niña WATCH means there is around a 50 per cent chance of La Niña forming later in 2022,” the BOM wrote.

“This is approximately double the normal likelihood.”

However, data from the US Climate Prediction Centre and The International Research Institute for Climate and Society at Columbia University suggested that the now very familiar climate pattern, which first started in November 2021, is set to continue until the end of August, with a 55 per cent to 60 per cent chance of hanging around until spring.

A wetter-than-average season is likely for most of Australia from July to September. As the 2021-22 #LaNiña slowly weakens, a negative Indian Ocean Dipole (IOD) is likely to develop. Learn more in our #Climate and Water Outlook: https://t.co/rmGKfMfch5pic.twitter.com/4oOrO395j0

— Bureau of Meteorology, Australia (@BOM_au) June 16, 2022

Weatherzone meteorologist Ben Domensino said: “the US Climate Prediction Centre has had some model data come out showing that there is about a 60 per cent chance of La Niña continuing into the Southern Hemisphere’s spring.”

“Their forecast suggests that this would decay during our summer next year,” he said.

Mr Domensino says there’s a reason for these “seemingly disagreeing” predictions, being the different thresholds to declare La Niña held by the US and Australia.

Sunrise on the shortest day of the year, the winter solstice, at Bondi Beach. Picture John Grainger

“They (BOM) do point out that even if it returns to a neutral phase, the Pacific will most likely stay in a La Niña like pattern, just below the threshold,” he said.

“The thresholds are different for the Bureau and the CPC.”

The meteorologist said these thresholds are based on impact and that the impacts of La Nina for Australia “are more aligned to a sea surface temp value of -0.8 degrees” whereas the US have a threshold of – 0.5 degrees.”

“Even though there are slight differences in wording, they are both agreeing that the Pacific Ocean will stay in a La Niña state or like phase during spring,” he said.

The latest model-based ENSO forecast from the @climatesociety / @NWSCPC shows La Niña holding on through the Southern Hemisphere's winter and spring before decaying early next year. pic.twitter.com/0evuV8ClFH

— Ben Domensino (@Ben_Domensino) June 20, 2022

Sunrise on the shortest day of the year, the winter solstice, at Bondi Beach. Picture John Grainger

Mr Domensino said Australians particularly in northern and eastern Australia could continue to see above average rain during winter and spring below average day time temperatures and “generally more rain and cooler days over large parts of Australia.”

The Weatherzone meteorologist also pointed out that on the other side of the country, the Indian Ocean is in a neutral state also but it is moving towards a Negative Indian Ocean Dipole, where patterns of sea surface temperatures cause more moisture.

“The outlook is for a Negative Indian Ocean Dipole to develop and persist into spring, which causes more moisture and cloud to move towards Australia from the northwest” and above average rain over southern and southeastern Australia in winter and spring.

Sunrise on the shortest day of the year, the winter solstice, at Bondi Beach. Picture John Grainger

In the next few days, Sydney’s weather is expected to remain largely fine with tops of 18C and a lows around 9C on Wednesday.

Temperatures will increase slightly heading into the weekend, with a top of 21C predicted for Saturday.

Bureau of Meteorology duty forecaster Stephen Stefanac said the current temperatures were very close to the June average.

Sunrise on the shortest day of the year, the winter solstice, at Bondi Beach. Picture John Grainger

“Mornings will be quite cold but days we will have average wintertime temperatures,” he said.

In other parts of the state, he said, it was colder with snow falling over parts of the alpine region.

“Over the ­coming days, they will continue with westerly winds, the occasional snow shower on and off,” Mr Stefanac said.

“On Friday, a cold front comes through, which might just improve the amount of snow falling over the alps.

But he said the cold front would not mean much for temperatures in lower lying areas of the state, where the mercury would remain at 19C.

On Tuesday the mercury hit a high of 18C on the shortest day of the calendar year, with just under 10 hours of daylight after the sun rose at 7am and went down at 4.54pm.