Seasonal Climate Outlook Message for March to June 2016

The monthly value of the Southern Oscillation Index (SOI) was -21.8 in January and -19.1 in February. According to the SOI Phase system, the SOI is in a ‘Consistently Negative’ phase.

A map showing the probability of above-median rainfall for the next three-month period (March to May) is available. This map is based on previous years from 1900 to 1998 which, like 2016, had a consistently negative SOI over January and February (i.e. 1900, 1903, 1915, 1919, 1941, 1942, 1952, 1958, 1959, 1969, 1970, 1983, 1992, 1993 and 1998). This map indicates a 30 to 50 per cent probability of above-median rainfall for north-eastern Queensland, with close to normal (40 to 60 per cent) probabilities of above-median rainfall elsewhere. However, it is difficult to draw meaningful statistics from this information, as at this time of year the SOI is less reliable as an indicator of rainfall for the autumn season.

Rather than track the SOI over summer, the Department of Science, Information Technology and Innovation (DSITI) bases its monthly climate statements, over the summer period, on conditions leading up to summer, including the state of the El Niño–Southern Oscillation (ENSO) phenomenon prior to summer, and on factors which alter the impact of ENSO on Queensland rainfall (i.e. the more slowly changing extra-tropical sea surface temperature (SST) pattern in the Pacific Ocean). The DSITI Monthly Climate Statement for March 2016 is available.

When using a climate outlook it should be remembered that the probability, or per cent chance, of something occurring is just that – a probability. For example, if there is a 70 per cent probability of above-median rainfall, then there is also a 30 per cent chance of below-median rainfall. It does not mean that rainfall will be 70 per cent more than the median.

Furthermore, while climate outlook schemes cannot provide outlooks with absolute certainty, users who follow a skilful scheme should benefit from doing so in the long-term. Thus, users should consider the historical track record of any scheme, and such information is becoming increasingly available.