Australian tropical cyclone season long-range forecast

Near average cyclone season most likely for Australia

• Near average tropical cyclone activity is most likely for the Australian region this season.
• The tropical Pacific Ocean, which affects tropical cyclone activity in Australia, is currently neutral (neither El Niño nor La Niña), meaning there is no strong shift expected in the average number or location of tropical cyclones.

The typical Australian tropical cyclone season:

• has most tropical cyclones between 1 November and 30 April;
• averages around 11 tropical cyclones;
• sees an average of four tropical cyclones cross the coast, though coastal impacts can be felt when tropical cyclones remain well offshore;
• on average has its first cyclone cross the coast in late December.

Outlook influences

This outlook is based upon the status of the El Niño-Southern Oscillation (ENSO) over the preceding July to September period. In 2013, neutral conditions were present during these months in the Pacific. Neutral conditions are also forecast to continue through the southern Summer. In the absence of El Niño or La Niña (i.e., neutral years), tropical cyclone numbers around Australia are most often close to average, though individual years can be above or below the long term mean.

Regional details

The statistical outlook indicates all regions can expect near average tropical cyclone activity this coming season (1 November and 30 April).

• Tropical cyclone activity over the full Australian region is likely to be near average during the 2013–2014 season. The outlook indicates a 57% chance of having more tropical cyclones than average over the Australia region (43% chance of having less). Such odds mean that for every ten years with similar climate patterns to those currently observed, about five years would be expected to have an above average number of tropical cyclones, while about five years would be expected to have a below average number of tropical cyclones. Past outlooks have shown that the Australian region outlook has a high level of accuracy. On average, 11 tropical cyclones occur over the full Australian region, with four crossing the coast. In neutral ENSO years, such as this, the Australian region has seen as many as 18 and as few as eight tropical cyclones throughout the cyclone season, but it is most common to have near average cyclone activity.
• The Western region experiences, on average, around seven tropical cyclones in the eastern Indian Ocean during the tropical cyclone season. This year's forecast indicates near average tropical cyclone activity is most likely with a 53% chance of an above (47% chance of below) average number of cyclones. On average, around 30% of tropical cyclones in the western region will have an impact on the coast at some stage in their life cycle. In the past, the accuracy level for forecasts in the Western region has been low.
• The North-western sub-region (the area from 105°E to 130°E, where tropical cyclones can impact upon coastal Western Australian communities) also has a near normal outlook for tropical cyclones this season (55% chance of above average). Typically, five cyclones form or pass through this area each season. Around 40% of tropical cyclones in the north-western sub-region have an impact on the coast at some stage in their life cycle. Model accuracy in this region is good
• The Northern region does not have tendency towards above or below average tropical cyclone activity this season. In an average year the northern region sees two or three named storms and one or two tropical low pressure systems that become cyclones after moving into the western or eastern regions. A relatively high number (75%) of tropical cyclones in the northern region impact the coast at some stage in their life cycle. Historically, the level of accuracy for the Northern region tropical cyclone outlook is low, though still better than chance.
• The Eastern region forecast indicates a 53% chance that an above average (47% chance of below average) number of tropical cyclones will form in this region. Historically, the level of accuracy of the model is low in this region. Around 25% of the tropical cyclones that form in the eastern region cross the coast.