The Bureau of Meteorology on Tuesday confirmed that a La Niña event is under way in the Pacific Ocean, increasing the likelihood of above-average rainfall during spring and summer in eastern Australia.
It’s the first time this century that La Niña has returned for three consecutive years, according to the World Meteorological Organisation, a UN agency.
In a statement, BoM head of long-range forecasts Dr Andrew Watkins said the bureau’s three-month climate outlook shows a high chance of above-average rainfall for most of the eastern half of the Australian mainland and eastern Tasmania.
“During La Niña events, waters in the eastern tropical Pacific Ocean are cooler than normal, and waters in the western tropical Pacific Ocean warmer than normal,” Dr Watkins said.
“This causes changes in wind, cloud and pressure patterns over the Pacific. When this change in the atmosphere combines with changes in ocean temperature, it can influence global weather patterns and climate, including increasing rainfall over large parts of Australia.”
BoM is encouraging communities to keep up to date with the latest forecasts and warnings on the bureau’s website and BOM weather app.
Three in a row
La Niña was in place during the past two Australian summers.
The first event occurred between late September 2020 and March 2021, followed by a second from November 2021 to June 2022.
Although it is common to see La Niña occurring over two consecutive seasons, a third event – often called a “triple-dip” – is rare.
What does this mean for Australia’s weather?
According to forecaster WeatherZone, current forecasts indicate that this episode is expected to peak during spring (most likely around November) and then weaken in early-to-mid summer.
Most forecast models suggest the Pacific will return to a neutral state early next year, meaning neither La Niña nor El Niño are occurring.
“It is worth pointing out that no two La Niña events are the same and places that experienced flooding during last season’s La Niña are not guaranteed to see more flooding in the coming months,” WeatherZone said.
“However, with La Niña in place and a negative Indian Ocean Dipole (IOD) and positive Southern Annular Mode (SAM) also under way, the risk of flooding will be one of the main concerns for the eastern half of Australia over the coming months.”
In a statement Chas Keys, former deputy director-general of the New South Wales State Emergency Service and Emergency Leaders for Climate Action member said: “A third La Niña brings increased wet weather risk to a landscape where the rivers and dams are already full, and the floodplains are saturated.
“It’s really a wake-up call for governments to stop dragging their feet on the measures needed to protect communities from increasingly intense and destructive floods.
“We know that extreme weather disasters are only going to get worse due to climate change, and policymakers know exactly how they should respond thanks to the Royal Commission into National Natural Disaster Arrangements, and the NSW Flood Inquiry.”
The announcement is not what Robert Quirk, a farmer from NSW wanted to hear.
“I’m worried about how people in Lismore will cope with a wet spring,” he said.
“These massive rain events will keep happening unless we do something urgently to cut our emissions to protect our farms in the future.”
The community of Lismore was devastated by flooding following an extreme La Niña weather event in February and March.
