Weather in Australia: Negative dipole in the Indian Ocean will bring rain in December

As La Niña was only recently declared over, another key weather factor has hinted that Australia’s rainfall could drag on for another summer.

As the flood-hit areas of New South Wales and Queensland continue to recover from unprecedented levels of rain, it looks like the wet weather will continue.

Sky News chief meteorologist Thomas Saunders’ forecast that above-average rainfall is likely to last until November or December, predicting a negative Indian Ocean Dipole (IOD) year for 2022.

Describing it as “the Indian Ocean’s version of La Niña”, the Indian Ocean dipole is one of the main climatic factors affecting Australia. While the El Niño-Southern Oscillation (ENSO) system (which defines the El Niño/La Niña climate pattern) refers to winds and sea-surface temperatures in the Pacific Ocean east of Australia, the IOD refers to the Indian Ocean, which borders with Australia. west.

Although positive IOD years result in drier and less cloudy winters and springs with less rainfall in southern Australia and the Upper End, negative IOD years have the opposite effect.

Instead, the weather event will increase the likelihood of “above-average winter and spring precipitation” as well as “warmer days and nights for Northern Australia,” the Bureau of Meteorology (BOM) says.

2021 was a negative IOD year, as was 2016.

“The latest dipole value in the Indian Ocean is the lowest since September 2016. We can probably call it now, 2022 will be the year of -IOD,” Mr. Saunders said on Monday afternoon.

“The value must stay below -0.4 for 8 weeks for it to become official. Why is it important? The rain is here to stay.”

The latest BOM update also points to the possibility of a negative dipole in the Indian Ocean.

This is because the capitals on the east coast of Australia have already exceeded the average annual rainfall this year. Sydney receives an average of 1214 mm of precipitation per year, for a total of 1859 mm. Brisbane also outperformed its 1130mm average with 1627mm recorded this year.

Will La Nina repeat in 2022?

Although La Niña officially ended in 2022, the BOM has warned that, although rare, a third year of the rainy weather system is possible.

“Reciprocal La Niñas are not uncommon,” said Bureau of Meteorology long-range forecasting chief Dr. Andrew Watkins.

“In fact, we have received them about half the time since 1900.

“But the three-year-old La Niña is less common, and we’ve only seen it three times since the middle of the last century.”

BOM has now released a “tracking” update for the return of La Niña, meaning there is about a 50 percent chance that the weather will even recover. Remarkably, this is “about twice the normal probability” we see at this time of year.

US National Weather ServiceThe forecast is slightly more in favor of the third year of La Niña. The most recent reports indicate that there is a 58 to 59 percent chance that La Niña will increase in spring/summer 2022.

Originally published as Negative Indian Ocean climate dipole will lead to more rain in Australia until December