Bureau of Meteorology head of long-range forecasts Andrew Watkins said the bureau's three-month climate outlook showed 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.”
Dr Watkins said while La Niña criteria had been met, most models forecast this event to be weak to moderate in strength, likely to peak during spring and ease during summer.
"La Niña is not the only driver influencing this wet outlook,“ he said.
“To our west, a significant negative Indian Ocean Dipole event is underway. We expect the IOD influence will reduce in late spring or early summer.
“The Southern Annular Mode is also in a positive phase, and likely to remain positive into summer.
“Positive SAM during summer pushes weather systems south, which increases the chance of rain in NSW, eastern Victoria and southern parts of Queensland.”
Meanwhile, flood-weary farmers and regional communities are bracing for yet another soaking.
Northern Rivers farmer Neil Baker said he and his neighbours were still mopping up the mess from torrential rains earlier in the year, which had devastated Lismore and surrounding areas.
“People are trying to rebuild and get back on top of things, but another huge rain would just be devastating for us,” Mr Baker said.
NSW Farmers Business, Economics and Trade committee chair John Lowe said another La Niña was a serious threat to farmers and regional communities.
“People just haven’t had time to prepare for more rain because it has been so wet already,” Mr Lowe said.
“While output for agriculture has been at record levels because of all the moisture, in some places it will actually be stopping people from getting onto paddocks to harvest their crops.
“Catchments are so full that there will be a chance of major floods if we get too much rain in the wrong place.
“We’re just going to have to prepare the best we can and hope for the best.”
