South Pacific tropical cyclone season outlook
About the outlooks
This outlook uses the statistical relationships between tropical cyclone numbers and two indicators: the Southern Oscillation Index (SOI) and the Niño3.4 sea surface temperature anomaly. These two indicators provide a measure of the atmospheric and oceanic state, respectively, of El Niño-Southern Oscillation (ENSO).
The July, August and September SOI and NINO3.4 values were used in making the tropical cyclone season outlook.
Interpreting the outlook
Percentages such as a 10% chance of having more tropical cyclones than average (90% chance of having fewer) mean that for every ten years with similar climate patterns to those currently observed, one year would be expected to have an above-average number of tropical cyclones and nine years would be expected to have a below-average number of tropical cyclones.
On average, eleven tropical cyclones occur over the Australian region each season, with four making landfall. Seasons during El Niño typically have less tropical cyclones than average, while more occur during La Niña. As always, it is essential that all stakeholders and local communities prepare for the cyclone season.
South Pacific countries
This Outlook provides general guidance for the South Pacific region. For specific guidance for an individual country, please contact their National Meteorological and Hydrologic Service.
South Pacific region outlook accuracy
The statistical model used for this outlook has a high level of accuracy predicting cyclone numbers in the western region, but a very low level of accuracy for the eastern region.
South Pacific tropical tropical cyclone outlook region bounds
|Whole South Pacific region||5° S||40° S||142.5° E||120° W|
|Western region||5° S||40° S||142.5° E||165° E|
|Eastern region||5° S||40° S||165° E||120° W|
- Weekly tropical climate note
- Southern Oscillation Index (SOI)
- Niño3.4 sea surface temperature index (NINO3.4 SST)
- Tropical cyclone climatology maps
Model: Kuleshov, Y., L. Qi, R. Fawcett and D. Jones, 2008: Improving preparedness to natural hazards: Tropical cyclone prediction for the Southern Hemisphere, in Advances in Geosciences, 12 Ocean Science, (Ed. Gan, J.), World Scientific Publishing, Singapore, 127-143.
Data: Kuleshov, Y., R. Fawcett, L. Qi, B. Trewin, D. Jones, J. McBride and H. Ramsay, 2010: Trends in tropical cyclones in the South Indian Ocean and the South Pacific Ocean, Journal of Geophysical Research 115, D01101, doi:10.1029/2009JD012372.
More cyclones than average likely in the western Pacific Ocean
- Neutral to weak La Niña conditions in the tropical Pacific Ocean increases the odds of above-average number of tropical cyclones for the western South Pacific region.
- Climate models indicate that neutral conditions are likely to persist into 2017.
- Near-average cyclone numbers are likely for the eastern South Pacific but model accuracy is very low
The South Pacific tropical cyclone season has most cyclones between 1 November and 30 April and averages around seven tropical cyclones in the western region and ten in the eastern region. Tropical cyclones impact Pacific island countries in most years and coastal impacts can still be felt when tropical cyclones remain well offshore.
* Long-term average number of tropical cyclones, calculated using data from 1969–2015, may change slightly from one year to the next as a new season of data is added to the calculation.
This outlook is based upon the status of the El Niño–Southern Oscillation (ENSO) during the preceding July to September period. Eastern tropical Pacific Ocean sea surface temperatures were slightly cooler than average during this time but within neutral thresholds. The Southern Oscillation Index, a measure of the atmospheric component of ENSO, has been positive through this period and has recently exceeded La Niña levels. Climate models suggest that neutral conditions will persist into early 2016. Nevertheless, warmer than average sea surface temperatures in the western Pacific ocean are favourable for tropical cyclone development. This increases the chances of an above-average number tropical cyclones forming in the western region of the South Pacific Ocean.
The statistical model used for this outlook has a high level of accuracy predicting cyclone numbers in the western region, but a very low level of accuracy for the eastern region. This outlook is for the southern hemisphere tropical cyclone season which runs between 1 November and 30 April.
Product code: IDCKSPTCSO