A combination of dire weather events could see millions of Australians hit with heavy rainfall and make sunny days sparse over the next five months.
Sydney has battled through its wettest start to the year, and the downpours are set to continue thanks to weather systems on both sides of the country.
The La Niña event, which drove the rain and floods across NSW at the end of February, is “struggling” to break down in the Pacific Ocean, which suggests it may last longer than anticipated, according to Weatherzone meteorologist Ben Domensino.
Modelling from US forecasters predicts a 50 to 55 per cent chance La Niña may persist through spring – though Weatherzone stressed computer models have “less accuracy” during the Southern Hemisphere’s autumn months.
Climate phenomenon in Indian Ocean to bring more wet weather
Andrew Schmidt, another meteorologist for Weatherzone, said while he thought a third La Niña event was unlikely, another phenomenon in the Indian Ocean could trigger further rainfall for most of Australia.
Similar to La Niña, a negative Indian Ocean Dipole [IOD] influences rainfall patterns but impacts areas around the Indian Ocean, including Australia.
“A negative IOD can indicate a broad-scale above average winter-spring rainfall for many parts of Australia,” Mr Schmidt told Yahoo News Australia, saying the most “intense” falls will occur across Victoria, southern South Australia and NSW.
Temperatures are also likely to drop, and increased cloud coverage will result in fewer sunny days.
Seasonal forecast models suggest that a negative Indian Ocean Dipole (IOD) could emerge this winter. Off the back of La Niña, this would increase the likelihood of above average rain over large parts of the country.
More details here > https://t.co/j3uQ3dwFgH
📷: @BOM_au pic.twitter.com/pyPTNrpYVx
— Ben Domensino (@Ben_Domensino) April 13, 2022
“With this increased rainfall we will see increased cloud cover so we could expect above average days with increased cloud cover and slightly below average maximum temperatures,” he said.
“I would say we would still see sunny days pop through here and there.”
Mr Schmidt said the negative IOD could last until “at least” September, and there is a possibility of flooding returning to areas that were already impacted by devastating floods in northern NSW.
If a third La Niña event were to occur at the same time as the negative IOD, Mr Schmidt said there could be higher rainfall, along with an increased likelihood of flooding and cyclones.
Last year, Perth recorded its wettest July in decades before the Bureau of Meteorology [BOM] declared there was a negative IOD.
Five out of five international climate models surveyed by BOM predict a negative IOD will be in place by June.
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