A patch of warm water off the coast of northeast Australia could play havoc with our autumn weather, turning what should be a wet, even drought-breaking season into one that’s dry and parched in some places.
Moisture dragged to northern Australia by the monsoon that should fall on the east coast between April and June could instead being sucked out to sea, meteorologists have said.
The Bureau of Meteorology (BOM) has released a series of long-range forecasts for the next three months.
In the BOM’s recently released climate and water outlook for the next three months, senior climatologist Dr Andrew Watkins said while some areas would get more rain, Queensland could be deficient over the next three months.
And he said there were “high odds” of hotter than average temperatures across the country’s north and down into New South Wales and even Tasmania.
Looking back, it has been one of Australia’s most tumultuous summers.
Tinder-dry conditions led to bushfires that spread further and lasted longer than usual due, in part, to the monsoon that was at least three weeks late.
Then it all changed with huge deluges of rain.
In February, Sydney was drenched with more than 400mm of rain – 3½ times its average monthly rainfall.
Most of that fell in just a couple of very soggy days. The city’s dams have gone from less than half full to four-fifths full.
Autumn should be a lot less dramatic, with close to average conditions in some places.
It’s still extremely dry across large parts of the country, though. As a whole, 30 per cent of Australia hasn’t had enough rainfall. That rises to 90 per cent for NSW, with just the populated coastal strip receiving adequate moisture.
The big climate drivers that steer Australia’s weather – El Nino/La Nina in the east and the Indian Ocean Dipole to the west – are in neutral and are likely to stay that way all autumn.
Dr Watkins said that would usually give the monsoon more free rein to dump lots of rain on Northern Australia.
“We’re all hoping to see a bit more rainfall, but at the moment there is a warm patch in the tropical Pacific Ocean near the date line,” he said.
“Unfortunately, that would normally draw moisture away from Australia.”
That piece of hot sea is located west of Papua New Guinea and Nauru and north of Fiji close to the Marshall Islands.
However, its effects are being counteracted to a certain extent by warm ocean temperatures in the north of Australia and the eastern Indian Ocean.
That could mean above-average rainfall is the isolated northern half of Western Australia, in WA’s far south and through the centre of Australia touching parts of South Australia and Victoria.
However, the influence of that warmer body of water hovering about the date line will mean the Queensland coast, and parts of the NSW coast, will likely have below-average rainfall this autumn.
The central Queensland coast could be particularly dry.
Inland Queensland and much of NSW are forecast to have more average rainfall.
In terms of temperatures, this autumn the country will split itself in two.
“Across northern Australia there are high odds of having above-normal temperatures during the daytime,” Dr Watkins said.
That band of hotter temperatures could also extend down the east coast, meaning warmer days and nights for Brisbane, Sydney and Canberra and as far south as eastern Tasmania.
Elsewhere, expect more average temperatures including in Melbourne, Adelaide and Perth. It could even be slightly cooler than average in the southwest of WA.
So, hotter and drier in Australia’s northeast and east and wetter in the southwest but more average over much of the rest of the continent.
And to be honest, after all the drama of summer, a run-of-the-mill and utterly average autumn of weather might be just what we all need.
Originally published as Patch of ocean that could change weather