Forecasting tropical cyclone paths
Tropical cyclones can follow erratic paths and predicting their movement is complicated. Scientific understanding of these complex weather systems is still developing.
We use sophisticated computer weather models to do this, but there can be:
- limits to how well we can observe the current state of the atmosphere
- small changes in the atmosphere that can result in large changes to the track or intensity of the tropical cyclone.
Our ability to predict cyclone movement has greatly improved over the past few decades. We have better science, faster computers and a huge increase in satellite observations.
The key is understanding the flow of the winds in the surrounding environment. These winds guide the speed and direction of the overall movement of the cyclone.
As the cyclone moves, it can encounter different conditions. This can make it stronger or weaker. For example, it may weaken if it moves over land or cooler waters, or into regions where the winds vary greatly with height (wind shear).
How weather models over the decades would have forecast tropical cyclone Tracy's path, showing how these models have improved over time
Tropical cyclone tracks in the Australian region
Tropical cyclones can have unusual tracks or erratic movement. Each cyclone is unique.
In our region, it's typical for a tropical cyclone to form in the deep tropics and track west-south-west.
As it gets further away from the equator, the tropical cyclone encounters changing winds. These winds steer it south and then south-east. This is why many cyclone tracks in the Australian region are shaped a little like the letter C.
On the west coast, this means cyclones usually head out into the Indian Ocean before turning back toward the coast. This is why Australia's north-west coast sees a lot of cyclone action.
How far south can tropical cyclones go?
Our tropics are most prone to direct impact. But tropical cyclones or their effects can be felt:
- as far south as Perth on the west coast
- into northern New South Wales on the east coast.
The most common effects are heavy rain and associated flooding after a cyclone has weakened. A former tropical cyclone can still have big impacts. For more about the effects cyclones can have, see Tropical cyclone categories.
Some cyclones that remain over water can produce gale-force winds when they move outside the tropics (become extra-tropical), even though they lose their tropical cloud patterns.
Tropical cyclone track maps
We issue maps that show a cyclone's predicted path for all tropical cyclones in our region. To learn more about cyclone forecast track maps, view our Tropical cyclone warning services page.
Predicting tropical cyclone activity
We are constantly researching and improving how we predict high impact weather such as tropical cyclones, thunderstorms, heavy rain and aviation hazards.
To do this, we use:
- numerical modelling and data from radars, satellites and other observing platforms
- statistical methods to increase the value of information from the model.
To learn more about this work, view our Weather prediction research page.
When predicting future cyclone activity, we take into account influences. This includes climate change and climate drivers such as the El Niño–Southern Oscillation and Indian Ocean Dipole.
El Niño–Southern Oscillation influence
In the Australian region, there has historically been a significant relationship between cyclone frequency and the El Niño–Southern Oscillation (ENSO) phase – El Niño, La Niña or neutral.
During El Niño years, the number of tropical cyclones was typically below average.
During La Niña years, numbers were typically above average.
These patterns now appear to be changing but more data is needed to confirm this shift.
Find out more about ENSO on our El Niño and La Niño page.
Indian Ocean Dipole influence
The influence of the Indian Ocean Dipole (IOD) is most pronounced in the early part of the tropical cyclone season – November and December.
Years with a positive IOD typically see below average tropical cyclone numbers. The relationship is not particularly strong in negative IOD years.
Climate change
Climate models suggest there could be a future shift towards fewer, but more intense, tropical cyclones.
There could be greater rainfall in areas nearer the storms than previously observed for similar systems.
Storm surges and extreme sea levels are also likely to increase, as sea levels rise due to global warming. Learn more about storm surge, types of tides and sea level on our Tides and sea level page.
Learn more about Climate change in Australia.