Tornadoes happen in lots places across Australia. This tornado swept by east of Perth in 2012. (Supplied: Mary Wilson)
While reports of tornadoes in Australia can be met with surprise, there are dozens of reports of tornadoes in the country every year, according to the Bureau of Meteorology.
Yesterday afternoon the bureau confirmed a tornado had ripped through the small Queensland town of Tansey, near Kingaroy.
Meteorologist Diana Eadie said public awareness of tornadoes had increased in recent years, particularly through social media.
She said farmers with camera phones and storm chasers were bringing tornadoes into the public consciousness.
Ms Eadie does not think tornadoes are becoming more common, but we are hearing about them more.
“We’re seeing a lot of videos and things pop up of tornadoes, and that sort of footage was just never shared in the past,” she said.
“But the reality is it certainly is something that occurs in Australia. It’s not unprecedented.”
The bureau’s Severe Storms Archive has records of 1,204 tornadoes since 1900, which may not sound like many, but they are just the ones that have made it to the record.
So they exist here, but what are tornadoes exactly?
Seen the movie Twister?
Basically, tornadoes are violently rotating columns of air. They can be from a few to hundreds of metres wide and they have an intense updraft in the centre.
They generate ferocious winds and can lift heavy objects.
Ms Eadie said their lifespans were variable.
“It can be anywhere between a couple of minutes and some of the biggest and most long-lived ones can be up to a couple of hours,” she said.
“It just basically depends on the thunderstorm that it’s accompanying and how long it can sustain that sort of low-level rotation.”
How do tornadoes form?
Ms Eadie said most tornadoes in Australia were associated with supercell thunderstorms.
“[Supercell thunderstorms are] really big, significant thunderstorms that last for a period of anywhere between an hour or so to a number of hours and cause significant damage,” she said.
Along with the potential for tornadoes, supercells are typically damaging with destructive winds, large to giant hail and possibly localised flash flooding.
“What makes a tornado potentially develop is just that little bit more,” Ms Eadie said.
“Particularly humid air below the cloud base … a really low cloud base, and the main ingredient is really strong wind shear.”
America’s National Oceanic and Atmospheric Administration’s diagram describing tornado formation. (Supplied: NOAA)
She said wind shear was essentially a change in the wind in the low levels of the atmosphere.
“You can imagine that if you’ve got wind coming from one direction at the surface, slightly different direction just above. It encourages the atmosphere to rotate and create these little vortices that we call tornadoes.”
Picture it like your drain.
“When you pull out the plug from the bottom of your bathtub and you start to see the water drain and really increase in speed as it goes down towards the bottom of the drain,” Ms Eadie said.
“It’s essentially just different directions, encourage that turning and it sort of helps the cell or the thunderstorm really become more long lived as well.”
Cyclones can cause tornadoes
But supercells are not the only triggers for tornadoes — cyclones can also mix things up.
“As you can imagine with tropical cyclones there’s a lot of wind going around, massive changes in direction,” Ms Eadie said.
She said there had even been cyclone-triggered tornadoes in the same region as Thursday’s tornado.
“When we saw Cyclone Oswald come down the coast back in 2013, we saw a number of reported tornadoes in and around the Bundaberg area. So once again, the sort of Wide Bay Burnett area.”
Do we have our own Tornado Alley?
Despite the recent events, Ms Eadie said the Wide Bay region of Queensland did not necessarily hold the title of being a tornado alley (a term for an area in the United States where tornadoes are most frequent).
“I have heard people talk about the South Burnett and Wide Bay area in the past as being sort of a bit of a tornado alley … but when you look at Queensland and then in Australia in a more general sense, in fact we see a lot more reports coming through from the Darling Downs and the south-east coast.”
Tornadoes do not just happen in Queensland.
“We saw a number of tornadoes developing back in 2016 around Adelaide. They contributed to what we now call the Adelaide blackout back in 2016,” Ms Eadie said.
In Sydney there were the Kurnell tornadoes in 2015, and there are five tornadoes reported in Western Australia a year on average.
“Even in north-east Victoria, talking to some of the Victorian forecasters, they have what they call a tornado triangle up in north-eastern parts of Victoria,” Ms Eadie said.
“Maybe as we start to get more observations in a more dense network and tornado reports, we’ll start to see a trend developing in the future.
“But at this stage I’d say much of Australia could potentially experience a tornado and there’s no one favourable spot.”
There is not a particular season for tornadoes in Australia either.
The bureau’s website said they were more common in late spring to early summer, but winter tornadoes are regular occurrences on the southern Australian coastlines.
Are our tornadoes different to those in the US?
We hear more about tornadoes in the US, so are they different to ours? Ms Eadie said essentially not.
“They’re still coming out of these big thunderstorms that we experience in Australia,” she said.
“But I think the main difference for the US is first of all, you have that density of population through what they call Tornado Alley.”
The tornadoes in the US are bigger, stronger and there are more of them.
“If you can imagine in North America you’re getting really cool air coming in off the Rockies and over Canada meeting with this really warm and moist air from the Gulf of Mexico,” Ms Eadie said.
“They’re getting a real contrast, completely different air masses.
“So much sharper, more defined features and much bigger and more frequent storms as a result.
“I think as a consequence you just see a lot more of them. You see much bigger ones as well.”