This is one of the most quotes you hear in the media after any major storm event where there’s been significant damage. It’s also a term that storm chasers really hate to hear. It’s really just a misnomer caused by people not really knowing what to call this sort of weather scenario. It’s often an assumption that we don’t get tornadoes in Australia. So what’s really going on in these weather events?
Straight Line Winds
Thunderstorms can produce very strong straight line winds. These can be winds blowing into a storm, known as inflow, or winds blowing out of a storm know as outflow. Many storms in South East Queensland produce gust fronts with strong outflow. Depending on local topography and other factors, they can cause major damage.
A microburst, also sometimes called a downburst, is another way damage can be produced. A microburst is where a large mass of air is moving downwards at high speed within a thunderstorm. When this airmass hits the ground it spreads out radially in all directions around the microburst. On the ground they will usually seem to be straight line winds to an observer and can exceed 100km/h in some cases. Most of the severe weather events called “mini-tornadoes” are caused by microbursts. The Gap Supercell in 2008 produced multiple microbursts in The Gap suburb of Brisbane with the results of severe damage.
It’s only been in the last few years that many Queenslanders have started to realise that Australia does get tornadoes. In fact there are several confirmed tornadoes each season in the South East Queensland area. There have even been BOM Warnings issued noting the presence of tornadoes. In January 2013 there were 6 tornadoes in Bagara. Most tornadoes in Australia are in remote and regional areas with sparse populations so go unseen. They are also frequently rain-wrapped, that is hidden in heavy rain.