There will be little reprieve for flood-affected areas, with meteorologists forecasting significant rain and “prolific thunderstorm activity” over central and eastern Australia in the coming week.
On Tuesday, Weatherzone imaging showed a 2,000km band of thunderstorms that stretched from Northern Territory’s top end to the South Australian coast over the previous 24 hours, “giving a preview of what’s heading for eastern Australia over the next few days”.
Severe weather is expected to result in renewed or prolonged river rises and flooding, according to the Bureau of Meteorology.
Rain and severe thunderstorms are forecast to spread across Queensland, large areas of inland New South Wales and eastern South Australia on Wednesday, the BoM said, with wet weather expected through the latter half of the week.
“The storms can bring the usual heavy rain, flash flooding, damaging winds, and also some large hail,” said BoM meteorologist Dean Narramore.
Thursday is expected to bring rain and widespread thunderstorms in eastern Queensland, New South Wales, Victoria and far-eastern parts of South Australia.
“We’re kind of looking at generally 10 to 20mm [of rain daily],” Narramore said. “We could have isolated falls up to 50mm with thunderstorms.”
Total forecast rainfall for the five days from Wednesday is between 50 and 100mm, Narramore said. “That’s extending from central Queensland, all the way down through NSW and into north-eastern Victoria. Unfortunately, of course, that’s going to lead to renewed river level rises for many of our flood-affected communities.”
In addition to major flooding in inland NSW and northern Victoria, the BoM has issued flood watches for South Australia, Queensland and NSW, with the risk of “flash and riverine flooding and renewed river level rises in these areas”.
Narramore said there would be “no real break” between the current weather system, which will bring rain over the weekend, and the next, which “comes in Sunday into Monday … it continues the pattern of showers and thunderstorms across much of eastern and southeastern Australia into early next week”.
“Most people won’t even know a difference, because every afternoon and evening there’s going to be showers, storms and some severe rain areas of rain as well.”
Forecast modelling from Weatherzone anticipated more than 200mm of rain over the Queensland–NSW border over the week from Tuesday.
“Thunderstorms will be particularly dangerous over Queensland and NSW between Wednesday and Friday when daily severe storm activity is likely in both states,” Weatherzone said.
The “prolific thunderstorm activity” was the result of “moisture-laden air interacting with an upper-level low pressure system as it moved across southern and central Australia”, according to Weatherzone.
“These setups cause lots of storms because atmospheric moisture gets lifted ahead of the approaching upper-level low and converted into cloud, rain and hail when it meets much colder air aloft. The strong upper-level winds associated with the low also help thunderstorms become more organised, often allowing them to last longer and become more intense.”
Narramore said the “big drivers” of the wet spring were the combination of the negative Indian Ocean dipole and the La Niña.
“Also, the really warm waters around much of northern Australia are providing a lot more moisture,” he said.