Seasonal Climate Outlook Message for February to May 2009

The bottom line

SOI phase remains Consistently Positive Dave McRae, Qld Climate Change Centre of Excellence, 02/02/09.

The monthly value of the SOI for December was plus 11.6 and for January was plus 8.2. This places the SOI in a Consistently Positive phase for the 5th month in a row.

Based on historical rainfall records and a Consistently Positive SOI phase at the end of January, there is a reasonable 50 to 70% chance of getting above median rainfall during February through to the end of April across most of Queensland.

For example Atherton has an 70% chance of getting above its February to April median rainfall of 595mm, Aramac has a 67% chance of getting above its February to April median rainfall of 132mm, Charters Towers has a 65% chance of getting above its February to April median rainfall of 253mm, Birdsville has a 60% chance of getting above its February to April median rainfall of 36mm, Esk has a 60% chance of getting above its February to April median rainfall of 270mm, Goondiwindi has a 60% chance of getting above its February to April median rainfall of 150mm and Roma has a 50% chance of getting above its February to April median rainfall of 155mm.

For more information on historical rainfall data for your region try Rainman Streamflow or www.bom.gov.au

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%.

SOI influence on climate varies across Australia (greatest skill is for eastern Australia) and between seasons (usually greatest skill is for winter, spring and early to mid summer). Therefore users of the SOI and any other seasonal forecasts are urged to investigate skill level for their location by using such tools as Rainman StreamFlow.

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 February to April in the following years since 1950 that have had a Consistently Positive SOI phase at the end of January; 1950, 1951, 1956, 1957, 1962, 1974, 1975, 1989, 1997, 1999, 2000, 2001 and 2008. Find out your average rainfall for February to April and see how many times rainfall was well below, well above or close to average during February to April in the listed years.

The 30 day average of the SOI as of 2 January is plus 7.7. You can receive a text message with the latest SOI values sent to your mobile phone. To subscribe to this free service, call (07) 4688 1459. For more climate related information try www.longpaddock.gov.au