The monthly value of the Southern Oscillation Index (SOI) rose from -21.3 in October to -3.2 in November. According to the SOI Phase system, the SOI is in a ‘Rapidly Rising’ phase.
Based on previous years when the SOI has been in a ‘Rapidly Rising’ phase at the end of November, the probability of above-median rainfall for the next three-month period (December to February) is less than 50 per cent for most northern and eastern parts of Queensland. The probability of exceeding median rainfall is higher (50 to 70 per cent) for many western and some southern parts of the state.
Previous years with a ‘Rapidly Rising’ SOI phase at the end of November include 1906, 1912, 1918, 1934, 1946, 1947, 1959, 1960, 1969, 1973, 1976, 1981, 1984, 1993, 2001, 2006 and 2013. The rainfall probabilities stated above are based on the 1900 to 1998 period (that does not include 2001, 2006 and 2013).
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.
Users should note that, 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.
Further seasonal climate outlook information for Queensland is available in the monthly climate statement produced by the Department of Science, Information Technology and Innovation.