You might recall an image we posted on our Facebook blog that shows how a small change in movement could have a massive shift in where the system actually moves? And that’s exactly what happened – and this actually touches on a complex part of mathematics known as ‘chaos theory’ where a small change in initial conditions can create very different outcomes. A common part of chaos theory might be planning your route to work each day. Sometimes leaving 5 or 10 minutes earlier or later could have a significant impact on your commute time due to the unpredictable nature of traffic or accidents.
If we look at TC Owen’s path, it relied on the upper low to its south moving as expected (and upper lows are also notoriously difficult to predict). So when you combine the interaction between tropical cyclones and upper lows then you have a highly dynamic system that is likely to change and evolve rapidly over time providing different outcomes. TC Owen still produced a lot of rain down the east coast, even if it wasn’t a direct impact. Rather, the moisture from Owen fed down into an unstable and cold upper atmosphere allowing for heavy storm activity and this saw floods and severe storms in Tasmania, Victoria, NSW and much of eastern Queensland!
It also shows the importance meteorologists can have too as they can use their experience to interpret the data. In the case of Weatherwatch, while we acknowledged it as a potential outcome, we didn’t suggest it to be a likely outcome in our forecasts because there was too much variability at play.