The national weather bureau has predicted a "wetter than usual" spring likely for eastern Australia.
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The Bureau of Meteorology took its La Nina ratings from 'La Nina watch' to 'La Nina alert', meaning the chances of La Nina forming are now three times more likely than normal, with the BoM saying a La Nina was a 70 per cent chance of forming.
With La Nina events strongly correlated with above average rainfall through eastern Australia and a Indian Ocean Dipole (IOD) negative event, also linked with above average rainfall, in place on the other side of the country the BoM says there is a very high chance of wet conditions over eastern Australian in coming months.
"Above median September to November rainfall is very likely for much of the eastern two-thirds of the mainland (chances are greater than 80 per cent)," the Bureau stated.
"Most of the eastern two-thirds of the mainland has more than double the normal chance of unusually high spring rainfall (in the wettest 20 per cent of all September to November periods over 1981 to 2018)."
Climate expert Ben Henley (of UOW's Securing Antarctica's Environmental Future research program) said the see-saw effect of La Nina and El Nino was a natural part of the climate system, but climate change had made it harder to predict what's coming next with complete accuracy.
"We are really confident in certain things - for example, a future temperature rise and the impacts of various extreme events - but other things, the forecasts of how those models say the climate's going to change don't agree with each other," he said.
Dr Henley said if a wet La Nina pattern was to return it would be for the third summer in a row - which has happened before as seen from 1998 to 2001 (which began with devastating floods).
"It's not something that anyone on the east coast wants to hear," Dr Henley said.
"It's a possibility at this stage, it's not a given, but the models are starting to appear slightly more in favour of that occurring.
"But it's still quite likely that we may have a neutral year [neither extremely wet nor dry]."
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A few more weeks of data will help forecasters, he said, and estimated experts should have a clearer understanding of our weather by the end of September.
As for the following summer? Dr Henley said it's very unlikely for a fourth dip into a wet La Nina for 2023/24 but anything could happen.
"Our models are still not very clear about what's coming, even in the next few months, let alone another year and a few months time."