‘Hybrid’ cyclone expected to bring at least 100mm of rain to areas across south-eastern Australia
Australia’s already drenched east is set for more heavy rain and some flooding as a hybrid cyclone forms off the coast of Victoria.
On Tuesday, two distinct low pressure systems that had already caused heavy rain across Australia over the past few days began moving towards one another to combine and create a hybrid.
While most of the intense weather activity would occur over the ocean, where the cyclone is centred, heavy rain was forecast for parts of the NSW south coast, Victoria’s Gippsland region and the east coast of Tasmania until Thursday.
One of the low pressure systems was affecting the junction of the NSW, Victoria and SA borders on Monday, while the other was centred over the western Tasman Sea, off NSW’s north coast.
The first system caused the highest daily rainfall on record for Renmark, in SA’s Riverland region, which recorded 95.6mm of rain, while the latter saw Alstonville in north-east NSW become inundated by 233mm of rain. Meanwhile, the nearby town of Ballina recorded 126.4mm of rain – more than a month’s worth of rainfall in a single day.
“What we’re seeing today is two low pressure systems … coming together and causing a hybrid low pressure system, or a hybrid cyclone,” Ben Domensino, a meteorologist with Weatherzone, said.
“That’s because we’ve got a warm-core low pressure coming down from the Tasman Sea and a cold-core low pressure system coming over southeastern Australia, and they’re meeting together to the east of Victoria.”
Sign up for our free morning newsletter and afternoon email to get your daily news roundup According to modelling from Weatherzone, areas between south-east NSW and eastern Tasmania could see rainfalls of 100 to 200mm over the next few days.
“As this system was developing we already saw over 100mm of rain falling in south-eastern NSW overnight and this morning,” Domensino said, adding that flash flooding had occurred in Cooma overnight.
“That rain is now moving farther south towards Tasmania.
“A severe weather warning and a flood watch has been issued for parts of northern and eastern Tasmania and I think that’s probably where we will see the heaviest rain and the strongest wind from this system in the next one to two days.”
Domensino added that conditions are expected to weaken in Tasmania late Wednesday and into Thursday.
Hundreds of flood warnings remain in place across NSW; however, sunny conditions could return to some parts of the state before the end of the week as a westerly wind travels up from Tasmania and creates a drying effect.
The westerly wind change would also cause wet weather to continue in Victoria, with heavy rains not expected to ease at all this week.
In Queensland, afternoon thunderstorms are forecast for Tuesday, particularly south of Townsville. Heatwave warnings are in place in the northern tropics, where some areas are expected to surpass 40C.