La Niña may be currently on leave, but the Indian Ocean Dipole (IOD) has subbed in to keep the wet weather coming throughout winter. And now the Bureau of Meteorology (BOM) has said that all climate model outlooks predict it will continue well into late spring.
While it doesn't have the high profile of La Niña, the IOD is one of the country’s most powerful climate drivers, and can have a significant influence on our picnic plans through its influence on both the daily weather and the winter growing season for agriculture.
BOM's head of long-range forecasting Dr Andrew Watkins, said much of Australia will be impacted, particularly the central and eastern states.
Gift them their favourite dining experience. The Broadsheet Gift Card can be used at thousands of restaurants around the country.SHOP NOW
The IOD has been skirting around the threshold indicators for about the last eight weeks, according to the BOM, and that is predicted to continue. This is typical of a negative IOD event: they usually begin in May or June before rapidly dissolving with the onset of the monsoon season at the end of spring.
“Westerly winds intensify along the equator, allowing warmer waters to concentrate near Australia. This sets up a temperature difference across the tropical Indian Ocean, with warmer than normal water in the east and cooler than normal water in the west,” the BOM says.
But the end of the negative IOD event might not signal the end of the wet weather. There are worrying signs that La Niña may be back for a hat-trick appearance in the next few months. The BOM says there’s a 50 per cent chance of it returning for a third year in a row come summer, which is about double the normal likelihood.
Three out of the seven models suggest that will happen in early spring; a fourth says it might come around as the IOD eases; and the remaining three are holding out hope that the sodden maiden will leave us alone altogether for this year.
The BOM says that while there has been a 10-20 per cent reduction in overall rainfall between April and October across Australia in recent decades, there is a continuing trend for high-intensity, short-duration events.