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Learn about types of thunderstorms in Australia, how they form and why they can be dangerous
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Thunderstorms and severe thunderstorms
A thunderstorm is any cloud system that produces thunder and lightning. They are made up of one or more cumulonimbus clouds – very tall, puffy, dark clouds that sometimes have a distinctive anvil-shaped top.
Thunderstorms – especially severe ones – can be among nature's most dramatic sound and light shows.
A typical thunderstorm lasts for about 30 minutes to an hour. Severe thunderstorms can last many hours and travel long distances.
In northern Australia, severe thunderstorms have different characteristics to those that typically happen in southern and central Australia. Find out more about severe thunderstorms in the tropics on our Tropical severe thunderstorms page.
While we experience many types of thunderstorms in Australia, some more intense thunderstorms are referred to as severe thunderstorms.
A thunderstorm is classified as severe if it produces any of the following:
If we expect a thunderstorm to produce any of these phenomena, we issue a severe thunderstorm warning. Most thunderstorms don't reach the intensity needed to produce these dangerous phenomena.
Severe thunderstorms can happen at any time of the year.
Most severe thunderstorms happen between September and March when the supply of solar energy is greatest.
Thunderstorms need 3 main ingredients to form:
Thunderstorm clouds, called cumulonimbus, have features including a:
Diagram showing some key features of a thunderstorm
There are 3 general thunderstorm types: single-cell, multi-cell and supercell. Each has a distinct structure, circulation pattern, and set of characteristics.
A single-cell thunderstorm's life cycle is limited to the growth and collapse of a single updraft pulse.
The cloud forms, grows to maturity and produces a heavy downpour. It then decays as the cool outflow spreads out and descending air cuts off the original warm inflow.
These thunderstorms are most likely to happen on summer afternoons and usually last no more than an hour. They can produce strong wind gusts (microbursts). Developing single-cell storms can produce waterspouts or (over land) weak tornadoes.
It's rare to encounter a pure single-cell storm – almost all of them have some multi-cell characteristics.
Multi-cell thunderstorms are the most common. They consist of successive, separate updraft pulses that help maintain the system's overall strength, structure and appearance. The pulses may be:
Multi-cells can produce any of the thunderstorm phenomena but are less commonly associated with tornadoes or giant hail.
This type of thunderstorm is very strong and can produce:
They can last a long time, maintaining an almost steady state for many hours.
A supercell is distinguished by a deep and rotating updraft called a mesocyclone – a vortex within the thunderstorm.
Thunderstorms can bring a range of phenomena – heavy rain, thunder and lightning, hail, wind gusts and even tornadoes.
Lightning is electrical discharge. It happens when there are large voltage differences between:
The difference in voltage needs to be several million volts. That is, large enough to overcome the insulating effect of the air.
Lightning strikes can happen within the cloud, between clouds, or between clouds and the ground.
Thunder is the sound produced by the explosive expansion of air heated by the lightning strike to temperatures as high as 30,000 °C.
To see the annual variation in thunderstorm and lightning activity across Australia, view the average annual thunder day and lightning flash density maps.
Hail is solid precipitation, in the form of balls or pieces of ice known as hailstones.
Hailstones can form in a thunderstorm with a strong updraft. This happens when small particles of snow with a thin crust of ice (called graupel) are suspended in the updraft. They can grow rapidly by 'sweeping up' small cloud droplets which freeze onto the surface of the graupel.
Hailstone diameter can range from 5 mm to more than 100 mm (10 cm), but most are smaller than 25 mm. Hailstones larger than lawn bowls have been recorded in Australia. For example, a hailstone with a maximum diameter of 160 mm (16 cm) was recorded during a hailstorm in Yalboroo, Queensland on 19 October 2021.
Damage from hailstones may include:
Giant hailstones measuring 5 cm across
In a mature thunderstorm, the falling rain and hail drag the surrounding air downwards. Evaporation from the raindrops and melting ice cool the nearby air. This creates a cold dense bubble of air that speeds down towards the ground.
When it reaches the ground, this downdraft creates a dome of cool air. It can spread sideways very quickly, producing a cool, gusty wind that can cause damage.
The downdraft can be enhanced when there are strong winds in the lowest 2 km of the atmosphere above Earth's surface.
Tornadoes do happen in Australia and have caused significant damage.
They are the rarest and most violent of thunderstorm phenomena. Learn more about Tornadoes.
View the National warnings summary.