Tornadoes in Australia
Tornadoes happen in Australia more often than many people realise.
How many tornadoes in Australia each year?
Based on historical records, 30–80 tornadoes are observed in Australia each year. It's likely more, as tornadoes in remote regions may not be reported.
No such thing as 'mini' tornadoes
A common term in Australia is 'mini tornado'. This has no meaning. A tornado is a tornado, regardless of size, intensity or where it occurs.
Tornado outbreaks
Tornado outbreaks can also happen in Australia, though rare. An outbreak is multiple tornadoes associated with a single weather system. For example, on 28 September 2016 at least 7 tornadoes affected South Australia, leading to a state-wide power outage.
Warning about tornadoes
Warnings about tornadoes are issued as part of a severe thunderstorm warning:
- if a tornado is likely to form
- when there is strong radar evidence that a tornado may be occurring, or
- after a confirmed observation.
Learn more about our severe weather and coastal hazard warning services.
Video: How we warn about tornadoes
While not as numerous or powerful as those seen overseas, Australia will see around 50 tornadoes every year and they can cause extremely strong winds in a localised area, which can cause major structural and property damage.
What is a tornado?
A tornado is a violently rotating column of air that extends from a cloud to touch the ground. To be classified as a tornado, the rotating column must be in contact with the ground and the parent cloud at the same time.
A tornado is usually associated with:
- swirling clouds of debris or dust near the ground
- a funnel-shaped cloud that extends down from the base of the parent cloud.
The parent cloud is either a:
- cumulus – a tall, puffy cloud, or
- cumulonimbus – a thunderstorm cloud.
Tornadoes may last from less than a minute to more than an hour. They can range in size from just a few tens of metres to more than a kilometre wide.
Winds inside a tornado can exceed 300 km/h, making them one of the most destructive phenomena in nature.
How tornadoes form
Tornadoes form when weakly rotating air near the surface is rapidly drawn upwards into a cumulus or cumulonimbus cloud.
As the air column rises it stretches, increasing the speed of rotation – like an ice skater spinning faster as they draw in their arms.
There are two main types of tornadoes, which form in different ways.
Supercell tornadoes
Most strong tornadoes are associated with supercell thunderstorms. These thunderstorms form when there is a large change in wind speed and direction with height (vertical wind shear). Learn more about supercell thunderstorms on our Thunderstorms page.
All thunderstorms feature a column of rapidly rising warm air, called an updraft. In a supercell thunderstorm, the updraft itself rotates, though much more slowly than a tornado. This rotating updraft is known as a mesocyclone.
The mesocyclone creates an area of low pressure under the storm. This draws air from the surface upward, creating the stretching needed to form a tornado.
Scientists are still investigating exactly how supercell tornadoes form. However, we know that they are more likely when there is high humidity and strong vertical wind shear in the lowest 1 km of the atmosphere.
In Australia, supercell tornadoes are most common in:
- central and eastern parts of New South Wales
- south-east Queensland
- north-east Victoria.
They are more likely in late spring and early summer, when conditions are most favourable for intense thunderstorms.
Supercell tornadoes can also occur in the outer spiral rainbands of tropical cyclones.
Non-supercell tornadoes
These tornadoes typically form along boundaries between different air masses. For example, cold fronts and sea breeze fronts.
At the boundary, sharp changes in wind direction – horizontal wind shear – can lead to pockets of air rotation. These are called misocyclones.
Above the boundary, fast-growing cumulus clouds create an updraft. This can turn a misocyclone into a fully-fledged tornado.
More than one misocyclone may become a tornado along the same boundary. Sometimes several non-supercell tornadoes form at the same time, at regular intervals along the boundary.
Non-supercell tornadoes can occasionally form along strong cold fronts or squall lines, where lifting of air along the front may help the tornado form. For example, in the cooler months, strong cold fronts moving over southern Austalia can produce supercell tornadoes. They develop quickly and move fast. This makes them difficult to forecast and detect.
Small tornado showing the well-known funnel shape
Measuring tornado intensity
The destructive nature of a tornado makes it extremely difficult to measure the associated winds.
For this reason, we estimate wind speeds based on the amount of damage caused to trees, buildings, and other structures built by humans. It's likely that tornado intensity is underestimated in areas with few damage indicators, such as open fields or grassland.
To measure tornadoes, we use the Enhanced Fujita scale, which ranges from EF0 to EF5. Tornadoes rated EF2 and above are referred to as significant tornadoes.
Waterspouts and landspouts
Technically, the term waterspout refers only to a non-supercell tornado that occurs over water. However, it can be difficult for an observer to know how the tornado formed. For this reason, waterspout generally refers to any tornado over water.
Waterspouts are commonly observed along the east coast of Australia and the coast around Darwin (Top End), particularly during the warmer months. Learn more about marine weather.
A non-supercell tornado over land is called a landspout.
Gustnadoes and dust devils
Gustnadoes and dust devils are not tornadoes.
A gustnado is a short-lived, shallow vortex that forms along thunderstorm outflows. Unlike tornadoes, gustnadoes are usually not connected to the overlying cloud.
Dust devils (willy-willies) are rapidly rotating columns of dust-filled air. They form on clear days over hot and dry surfaces. As very hot air in contact with the surface accelerates upward, the rotating column stretches and intensifies.