Key Points
- At least two tornadoes were filmed in NSW yesterday.
- Australia records around 60-80 tornadoes a year.
- A meteorologist says while people may expect them to cause serious damage, most are "pretty brief and weak".
Tornadoes were perhaps a surprising feature of the wild weather that hit NSW.
Some Australians might not be aware tornadoes happen Down Under. But a meteorologist says the phenomenon occurs between 60-80 times annually on average in Australia, although often in places where no one lives.
A tornado was seen destroying sheds and trees as it tore through the village of Caragabal in central west NSW on Wednesday.
Another tornado was spotted near the town of Young and a suspected tornado was shared online near Cowra.
Bureau of Meteorology senior meteorologist Dean Narramore told SBS News there are many "weather ingredients" that create the conditions for tornadoes.
"We had a low-pressure system move across the state yesterday — we had warm, moist air ahead of it, then we had a cold front and trough come in that kind of lifted that warm, moist air," he said.
"We had very strong winds change direction with height, like we started north, coming in from the northeast, moving up to more of a northwesterly, or coming from the west, further up."
The warm, moist air, combined with a lifting mechanism, and that change in wind speed and direction with height allows supercell thunderstorms to form, Narramore said, which can form tornadoes in the right environment.
Narramore said that while around 60-80 tornadoes occur in Australia on average a year, the figure is about 1,200 in the United States.
However while popular films usually depict lethal, highly-destructive thunderstorms, Narramore said most that occur in Australia and the US are "pretty brief and weak".
He said that while most tornadoes occur in sparsely inhabited inland areas, they can be identified in satellite and radar data.
Tornadoes occur in two different seasons in Australia — in the winter and early spring months, strong, cold fronts typically bring tornadoes to south-west Western Australia around the Perth area, and sometimes through Adelaide and southern parts of Victoria.
In spring and summer, supercell thunderstorms and tornadoes that can be "stronger, longer, and more impressive visually, as you saw in the video yesterday, they form through much of eastern and south-eastern Australia with that warm, humid air as their main mechanism," Narramore said.
He said while droughts, floods and larger weather events are increasing as a result of climate change, it's too hard to tell whether the same applies to tornadoes because they're "only tens of metres wide".
A small online survey of 224 people by researchers at James Cook University found about 5 per cent of respondents did not know tornadoes occurred in Australia, while nearly 20 per cent did not know how to find information on disaster management.
Australia's wild weather
Australia is about to head into peak storm season from October to December and people can expect to see more severe thunderstorms, damaging winds, heavy rainfall, large hail and possibly more tornadoes in the coming months.
On Wednesday, Sydney recorded its wettest September day in 146 years.
Multiple severe weather warnings remain in place, including alerts for damaging winds and hazardous surf across NSW.
The NSW State Emergency Service has received more than 850 calls in 24 hours, mostly due to heavy rain.
— With reporting by the Australian Associated Press.
