Mixed seasonal outlook for Queensland Dave McRae, Qld Climate Change Centre of Excellence, 06/04/10
Based on the shift in monthly SOI value from the end of February (minus 18.2) to the end of March (minus 10.8) the SOI has remained in a "Consistently Negative" phase. Interestingly the upward trend of the 30day average of the SOI has continued and is minus 1.1 as of Tuesday 6th April. This is the highest value the 30day average of the SOI has been since October 2009. I expect this trend to continue during the rest of autumn.
Despite the "Consistently Negative" SOI phase at the end of March there is a somewhat mixed seasonal outlook for April through to the end of June across Queensland.
For example, throughout the far north west and peninsular region of Queensland along with isolated pockets of the far south east and far south west of the state, there is a lower 20 to 40% chance of getting above the long term April to June median rainfall. This is in contrast to the rest of the state where there is a higher 50 to 70% chance of getting above median rainfall during April to June.
As always when dealing with any probability based climate forecast system it is important to consider the alternate view. For example, currently there is a 70% chance of getting above the long term April to June medium rainfall of 90mm at Taroom. This also means there is a 30% chance of not getting above 90mm.
Another way of looking at this is that in around 7 years out of 10 (or slightly less than three quarters) with the current SOI pattern, Taroom has received more than 90mm during April to June. Therefore in 3 years out of 10 (or around one quarter) with the current SOI phase, less than 90mm has been recorded at Taroom.
For those who like to follow the relationship between the SOI and rainfall patterns in more detail for their location have a look at what happened in your area during April to June in following years: 2003, 1998, 1993, 1992, 1987, 1983, 1978, 1941, 1926, 1919, 1915, 1912, 1906 and 1905. It can be useful to find out what rainfall patterns and seasonal conditions where like during April to June in your area for those years. Work out your long term average rainfall for April to June and see how many times rainfall was well below, well above or close to average.
Daily updates on the SOI are available at www.longpaddock.qld.gov.au or to receive the latest SOI values sent to your mobile phone call me on (07) 4688 1459