Australia Weather News

Contrary to popular belief, tornadoes do occur in Australia. The United States receives an average of around 1200 tornadoes annually. The actual number of tornadoes in Australia is unknown because many either go unseen due to the low population, or incorrectly reported – but conservatively it's likely that Australia experiences at least 100 tornadoes a year.

Fortunately Australian tornadoes tend to be weaker and more short-lived than the tornadoes in the US, however there are a few notable exceptions. Tornadoes are rated on the "Enhanced Fujita Scale" from EF0 to EF5. The recent tornado at Kurnell, Sydney appears to have a preliminary rating of an EF2. There has never been an official F5 or EF5 tornado in Australia, though both the Buladelah tornado of 1970 (Mid North Coast, NSW) and reports of a tornado in Beenleigh back in the 1920s (now a suburb of Brisbane) have been flagged as potential candidates.

Tornadoes require unstable air to form – while very unstable conditions are preferred, there are actually two other ingredients that are more important. The second ingredient is the presence of strong winds close to the surface that change direction with height. In Australia, this may be NE winds at ground level, but swinging to NW or W winds 1-2km above this. This actually occurs fairly regularly in Australia along with strong instability and this helps produce many supercells (rotating thunderstorms which most tornadoes form from). However we often lack the third ingredient which are low cloud bases.

Typically Australian thunderstorms occur when it's quite hot, and even though conditions are humid it does mean that the cloud bases remain quite high. The Kurnell tornado was a supercellular tornado – it developed when the strong rear flank downdraft (RFD) pushed ahead of the storm and interacted with the NE inflow. This caused additional vorticity between the inflow and the RFD helping to spin the tornado up. Amazingly, the wind gust of 213km/h was most likely caused by the RFD – meaning the tornado itself probably had stronger winds than this!