Which East Coast Lows are the rainiest?

What is it about?

East Coast Lows are low pressure systems near south-east Australia. East coast lows can cause heavy rainfall, strong winds, large waves, widespread flooding and coastal erosion on the east coast of Australia. But not all lows on the east coast cause the same massive impacts. Many Australians will be familiar with a weather map, which shows the pressure of the atmosphere at sea level. Areas of low pressure, also called cyclones, are typically associated with rainfall. But the weather doesn’t just happen at the surface, it extends well up into the atmosphere. When studying east coast lows, scientists often look at a single level of the atmosphere, often either the surface or 5km above the surface. This paper shows that ‘deeper’ east coast lows, that can be seen throughout the atmosphere, are much more likely to have heavy rainfall than those that are just seen in one or two layers of the atmosphere. In comparison, shallower cyclones typically only produce heavy rainfall when they have thunderstorms within them.

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Why is it important?

By better understanding and identifying deep east coast lows and the heavy rainfall associated with their occurrence, we can increase knowledge on the east coast lows most likely to have important impacts in eastern Australia. This will allow us to better understand how intense east coast lows are changing over time and how they will change in the future, providing valuable information for increasing Australia’s ability to plan for these events and improve our preparedness and resilience.