SOI in Rising Phase
Based on the SOI and historical rainfall records, for December through to the end of February there is a 50 to 70% chance of getting median rainfall for south west Queensland, a 20 to 40% chance of getting median rainfall for central and northern Queensland and a 40 to 60% chance of getting median rainfall across the rest of the state.
It's worth noting the difference in median rainfall levels between different locations at this time of year. For example Ingham has a December to February median rainfall of 1020 mm, Toowoomba 329 mm, St George 165 mm and Wyandra 135 mm.
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%.
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 December to February in the following years that have had a 'Rapidly Rising' SOI phase at the end of November; 2001, 1993, 1984, 1981, 1976, 1973, 1969, 1960, 1959, 1947, 1946, 1934, 1918, 1912 and 1906.
For example at Kilcoy, below average rainfall for December to February in those years was recorded 3 times, close to average rainfall was recorded 9 times with above average rainfall recorded 3 times. Therefore rainfall during December to February at Kilcoy is more likely to be close to average than well below or well above average. For more information refer to Rainman StreamFlow.
The Bureau of Meteorology has released another Special Climate Statement which reviews conditions over the last 10 years. It makes interesting reading especially with statements such as: for the last 10 years rainfall has been the lowest on record for a number of locations including Toowoomba, Gayndah and Rockhampton. For example Rockhampton has a long term average rainfall of 818 mm. Average rainfall for the last 10 years is 606 mm which is a deficit of 212 mm per year.
The 30day average of the SOI Has remained relatively stable over the last couple of weeks and as Monday the 11 December is minus 1.6. The latest rainfall probability maps are at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au and daily updates on the SOI are available on
(07) 46881439. For more on rainfall probabilities for your location refer to Rainman StreamFlow or contact 132523 or (07) 3404 6999.