Australians will experience more than normal rainfall over the next few months, especially those living in the southeast, according to water temperature readings taken on both sides of the tropical Indian Ocean. If the latest model is correct, the expectation that rain will continue to fall until the summer will be discouraging for many, but potentially devastating for those whose lives have been turned upside down by this year’s catastrophic floods. .
The last two times the Indian Ocean Dipole Index (IOD) recorded measurements similar to the readings being made now, Australia was hit with record levels of spring rain.
Indian Ocean dipole index readings suggest above-average rainfall in large areas of Australia over the coming months, especially in the south and south-east. (SMH / Louise Kennerley) The index, which measures differences in sea surface temperatures on both sides of the Indian Ocean, has just reached its most negative value since 2016, increasing the likelihood of climate wet in southeastern Australia in the coming months.
Australia’s last negative IOD occurred from July to December 2021, a period that included the country’s wettest November.
Prior to that, the most recent negative IOD took place in 2016, causing Australia’s wettest September.
That year also saw South Australia the fourth wettest year in history.
“The negative phases of IOD are similar to La Niña in the Pacific Ocean because they improve the flow of moisture-laden air to Australia and favor rainfall,” Weatherzone meteorologist Ben Domensino said.
Negative IOD events often cause above-average rainfall in large areas of the country, especially in the south and southeast.
It also has colder-than-average days in the southeastern continent.
A negative event is usually declared when the index is below -0.4 for at least eight consecutive weeks.
This scenario looks almost certain to develop in the coming weeks, confirmed Domensino, who explained how colder-than-average water has accumulated near the Horn of Africa and unusually warm water in northwestern Australia. .
“Most forecast models suggest that IOD will remain in a negative state for the rest of the southern hemisphere winter and into spring, likely to gain more strength in the coming weeks.”
The index has been following near or below the -0.4 threshold for the past two months. (Meteorological zone) Typical sea surface temperature patterns and rain anomalies during a negative dipole in the Indian Ocean. (weather zone)
The index has been near or below the crucial threshold for the past eight weeks.
“(With) more negative values on the horizon, it’s only a matter of time before the Meteorological Office officially declares a negative IOD underway,” Domensino added.
“It may even happen later this week.”
Sea surface temperature anomalies on July 9, in the two key IOD monitoring regions of the Indian Ocean. (weather zone / NOAA)
Experts say triple falls are so rare that it is difficult to predict whether a third of La Niña would be weaker or stronger than in the past two years, where some parts of the country have been hit by heavy rains and extreme weather. .
The La Niña event sees warmer water from the Pacific Ocean pushing into Australia and Asia, leading to more rain and more chance of cyclones in the summer.