Seasonal Climate Outlook Message for September to December 2009

The bottom line

Winter was dry and hot Dave McRae, Qld Climate Change Centre of Excellence, 07/09/09.

According to the Bureau of Meteorology (www.bom.gov.au) seasonal climate summary for Queensland, below average rainfall was recorded throughout most of the state during winter. While low rainfall is normal between July and September throughout Queensland, July and August this year was particularly dry with a state-wide averaged rainfall of 2.0mm for those 2 months. This breaks the previous record of 2.8mm set in 1946.

As well as being drier than normal, temperatures experienced throughout winter across Queensland where also generally warmer than normal. For example, the average daily temperature experienced during winter was the second highest on record. These warmer than average conditions were also reflected by the state-averaged winter maximum temperature being the warmest on record. August 2009 was also Australia's warmest on record.

This trend is likely to continue as there is a 70 to 85% chance of getting above median maximum temperatures throughout Queensland during spring (September to November).

An analysis of a Consistently Near Zero SOI phase at the end of August and rainfall records for September to November indicate a 30 to 50% chance of getting above the long term median rainfall across northern, central and western Queensland. Throughout the south east quarter of the state, the chance of getting above the long term median rainfall for the same period is marginally higher at 50 to 60%.

Based on these probabilities, this forecast would not be regarded as indicating a high chance of getting well above average rain during September to November. It's also worth remembering that we are still in our "traditional dry season" of August and September. The latest rainfall probability maps are available at www.longpaddock.qld.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%.

In the mean time the 30-day average of the SOI as of the 7th September is minus 0.6. It will be interesting to see what the SOI does over the next few weeks. If it remains in a "Near Zero" phase through to the end of the September, there is an increase in the likelihood or chance of severe storm activity across the southern half of Queensland and northern New South Wales. You can receive a text message with the latest SOI values sent to your mobile phone. To subscribe to this free service, call me on (07) 4688 1459 or e-mail david.mcrae@climatechange.qld.gov.au