SOI in Falling Phase Dave McRae, Qld Climate Change Centre of Excellence, 03/11/09.
Based on a Rapidly Falling SOI phase at the end of October and historical rainfall records, there is a 30 to 60% chance of getting above median rainfall throughout southern and western Queensland for November through to the end of January. However, the chance of getting above median rainfall throughout central and northern Queensland is lower and varies between 20 to 40%.
For example Ayr has an 25% chance of getting above its November to January median rainfall of 360mm, Mackay has a 33% chance of getting above its November to January median rainfall of 510mm, Wyandra has a 50% chance of getting above its November to January median rainfall of 105mm, Gatton-Lawes has a 50% chance of getting above its November to January median rainfall of 270 mm, Mount Isa has a 50% chance of getting above its November to January median rainfall of 160mm and Talwood has a 58% chance of getting its November to January median rainfall of 185mm.
It is worth noting that even for those areas with a lower chance of getting above median rainfall, that as we are entering our spring/summer rainfall season there is still a reasonable chance of getting some useful relief rain.
For those who like to follow the relationship between the SOI and rainfall patterns in more detail have a look at what happened in your area during November to January in the following years that have had a 'Rapidly Falling' SOI phase at the end of October; 1915, 1920, 1925, 1941, 1944, 1947, 1963, 1978, 1981, 1992 and 2006.
It can be useful to find out what rainfall and farming conditions where like in your area for September to November in those years. Information on what rainfall patterns where like in those years is available at www.longpaddock.qld.gov.au or in Rainman StreamFlow.
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% chance of recording more than 100 mm there is also a 30% chance of recording less than 100 mm i.e. 70-30; 30-70. It does not mean that you will get 70% more than 100 mm or 100 mm plus another 70%.
The 30day average of the SOI as of the 3rd November is minus 16.4. You can receive a text message with the latest SOI values sent to your mobile phone. To subscribe to this free service, e-mail firstname.lastname@example.org The latest rainfall probability maps are available at www.longpaddock.qld.gov.au