Seasonal Climate Outlook Message for November 2010 to February 2011

Commentary on rainfall probabilities based on 'phases' of the SOI

SOI values remain very positive

Dave McRae, Queensland Climate Change Centre of Excellence, 03/11/10.

Historically, when the SOI has been in a 'Consistently Positive' phase at the end of October, 60 to 70% of the time rainfall has been above the long-term median throughout much of Queensland during November to January. The main exception to this is the far-west of Queensland where rainfall has been above the long-term median only 50 to 60% of the time.

The last time there was a Consistently Positive SOI phase at the end of October was in 2008. Other years since 1950 that have had the same SOI phase at the end of October include: 1955, 1962, 1964, 1970, 1971, 1973, 1974, 1975, 1983, 1988, 1989, 1996, 1998 and 2000. It may be useful to find out what Queensland rainfall and pasture conditions were like during November to January in each of those years.

When using a climate forecast you should remember 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.