The Southern Oscillation Index (SOI) remains extremely positive, with monthly values of the index falling slightly from +26.4 in December to +18.1 in January. These values currently place the SOI in a Consistently Positive Phase.
Based on previous years when the SOI has been in a 'Consistently Positive' phase at the end of January, there is a 50 to 70% probability that rainfall during February to April will be above the long-term median throughout much of Queensland.
In assessing this information, it is worth considering other years with a ‘Consistently Positive’ SOI phase at the end of January. Since 1950, these include: 1951, 1956, 1957, 1962, 1974, 1976, 1989, 1997, 1999, 2000, 2001, 2008 and 2009.
When using a climate forecast it should be remembered that the probability, or percent chance, of something occurring is just that – a probability. For example, if there is a 70% probability of above-median rainfall, then there is also a 30% chance of below-median rainfall. It does not mean that rainfall will be 70% more than the median.
From a risk management point of view, the SOI-Phase system continues to highlight the potential for further significant rainfall this summer. While this does not necessarily equate to ongoing flooding, it is a risk that should be monitored.
Users are advised not to rely on a single climate outlook alone and should consider the range of climate risk assessment information that is available. Further seasonal climate outlook information is available at www.longpaddock.qld.gov.au and www.bom.gov.au