Troubling 12-week forecast as wet weather continues for millions of Aussies

There's a good chance we're in for a wet Christmas this year with the rain showing no signs of abating over the summer months.

The Bureau of Meteorology released its long-range forecast on Thursday, confirming news that no one wanted to hear: It's going to keep being wet (and a little warmer).

"The Bureau’s long-range forecast for December to February shows it’s likely to be wetter than usual in the eastern states," it said. "Nights will generally be warm everywhere."

According to forecasters, Queensland, New South Wales, Victoria, and eastern Tasmania are likely to see above median rainfall from December to February. Northern Queensland has at least twice the average chance of unusually high rainfall. However the Northern Territory and WA will stay relatively dry, with below-average rain forecast.

"This wet outlook over northern and eastern Australia is consistent with several climate drivers, including La Niña, a negative Indian Ocean Dipole event, a positive phase of the Southern Annular Mode, and record waters around Australia," the BoM said.

Western and central parts of the country will be warmer than average over the period, however for the southeast of the country, it's going to be a cool summer. There is a more than 60 per cent chance that residents in south-eastern parts of Queensland, central and eastern New South Wales, and parts of Victoria will see below median temperatures in the coming weeks.

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The likelihood of higher than average rainfall comes as parts of NSW and Victoria continue to battle flooding.

According to the BoM's data, last month was the country's second wettest October since records began in 1900 while both Victoria and NSW were inundated with the most October rainfall ever recorded.

More frequent rain bursts make Sydney vulnerable to flooding: New research

Sydney is becoming more vulnerable to flash flooding as new research reveals an uptick in heavy bursts of rain over the past two decades.

Researchers from the ARC Centre of Excellence for Climate Extremes found rain bursts, which occur over a period of 10 minutes, have intensified in Sydney by 40 per cent over the past 20 years.

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The rapid rain bursts bring a large amount of water which falls rapidly over a small region, increasing the likelihood and severity of flash-flooding.

Dr Hooman Ayat, a climate data scientist at the University of Melbourne, said researchers couldn't identify the climate processes that drove the change.

"Climate change may be a factor in this shocking result," he said.

The discovery means city planners must re-evaluate how they design their infrastructure in order to withstand the wetter conditions, UNSW climate researcher Jason Evans said.

"The potential for very localised flash flooding is much higher now than it used to be," Professor Evans said.

"Instead of failing once every 20 years, now (the structures) are failing all the time."

While the flooding won't result in disasters like Lismore, it can result in things like roof leaks or gutter overflow, UNSW climate researcher Professor Steven Sherwood said.

"If you're dumping a lot of rain in a very short period of time, there's only so much that structures can get rid of."

with AAP

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