Wet weather event to soak TWO-THIRDS of Australia

The climate phenomenon behind one of Australia’s wettest winters on record is weakening slightly but that doesn’t mean there will be any reprieve to the rainy weather.

Meteorologists are warning residents in two-thirds of the country to brace for a serious soaking in spring.

New South Wales, Queensland, Victoria, South Australia, Tasmania and the Northern Territory are all expected to experience above average rainfall from September to November.

 Map of the rainfall outlook for Australia's upcoming spring (September to November). Source: Bureau of Meteorology.
With spring just over two weeks away, meteorologists are predicting a wet season for eastern parts of Australia. Source: Bureau of Meteorology.

The climate patterns causing above average rainfall

It’s due to a so-called negative phase of the Indian Ocean Dipole (IOD) which refers to the state of sea surface temperatures across the tropical Indian Ocean.

There are three phases of the IOD — positive, negative and neutral. On average, each phase lasts three to five years.

During the negative phase, water is unusually warm near Indonesia and abnormally cold near the Horn of Africa, which means increased rainfall for Australia.

It’s the first negative dipole event since 2016, when rainfall records were broken between June and August, contributing to extensive flooding including in inland NSW.

The climate pattern is also responsible for Perth’s wettest July in decades, which saw the state suffer through consecutive cold fronts, powerful storms and heavy downpours last month.

Climatologist Tamika Tihema from the Bureau of Meteorology told Yahoo News weather temperatures will also be impacted.

"A negative IOD also makes cooler days more likely across southern Australia, while the northern tropics of Australia are more likely to see warmer weather with a negative IOD," she said.

According to the weather bureau's latest Climate Driver Update, a weak La Niña-like pattern may also be contributing to the wetter-than-usual weather due to cooling of the Tropical Pacific.

A negative phase of the IOD can increase rainfall. Source: Bureau of Meteorology
A negative phase of the IOD can increase rainfall. Source: Bureau of Meteorology

Weakening system will bring temporary reprieve

Meteorologists say the IOD has weakened over the past seven days, reaching its lowest level in about six weeks.

But this retreat is expected to be short-lived, with most seasonal models suggesting that the negative conditions will persist well into spring.

The bureau will release its formal outlook for spring at the beginning of September.

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