In recent years there has been a lull in early season tropical cyclones in the Coral Sea but TC Freda did move into the Australian area of responsibility in December 2012. Perhaps one of the most well known early season Coral Sea tropical cyclones was the somewhat ironically named Tropical Cyclone Joy in 1990. TC Joy brought anything but Joy during the Christmas of 1990 as it sat close to Cairns as a destructive category 4 system. Fortunately, Joy quickly weakened and eventually crossed the coastline near Townsville as a weak category 1 system.
For the last few months, sea surface temperatures in the Coral Sea have largely been above average but a recent analysis shows that temperatures have cooled (relative to their averages) slightly over the Coral Sea. One of the contributing factors to the development of Tropical Cyclone Owen is likely to be due to the unusual shift of systems across the country. During November and December, a typical pattern is for a heat trough to establish itself through inland Queensland/NSW generating showers and storms here. Instead, we’ve seen the Queensland/NSW trough sit largely offshore for the last 2 weeks (hence the Queensland heatwave in November). The increase in convergence is thanks to the offshore trough converging with the trade easterlies (that should normally lie over eastern Australia). These unusual patterns also explain the rare lack of storms for this time of year over NSW and Queensland. Typically the high pressure system (that’s been sitting 1000km offshore), should be sitting much closer to the east Australian coastline.
Other factors have also had to come together to help generate this early tropical cyclone, but the unusual weather patterns of late are a likely contributor to this system.