The Bureau of Meteorology has today issued a La Nina alert, meaning there’s now a 70% chance that the flood-inducing climate driver will develop this year.

It would be the third La Nina in a row – something that has only happened twice since 1950 – leading to fears of more heavy rain along the already flood-hit east coast of Australia.

Before today, the bureau was on La Nina watch, with a 50% likelihood of the system developing. But the heightened state of alert reflects renewed cooling in the tropical Pacific Ocean, it said.

“Historically, when La Nina alert criteria have been met, La Nina has subsequently developed around 70% of the time; this is approximately triple the normal likelihood,” the bureau said.

“La Nina events increase the chances of above-average rainfall for northern and eastern Australia during spring and summer.”

Four of seven climate models surveyed by the bureau suggest La Nina could return by early-to-mid spring. The remaining three models maintain a neutral outlook.

Meanwhile, a negative Indian Ocean Dipole (IOD) event continues. A negative IOD is associated with above average winter-spring rainfall for much of Australia.

“All surveyed climate models indicate that negative IOD conditions are likely to continue into late spring,” the bureau said.