Seasonal Climate Outlook Message for September to December 1999

The bottom line

The average SOI over the last 30 days has fallen to -0.1 . The probabilities of exceeding median rainfall during the total October to December period are mainly around 50% in the eastern half of Australia

The full story

Review of Climatic Forecasts and Information

Based on the latest values and trends of the SOI, the probabilities of exceeding median rainfall during the total September to November period are mainly around 50% in the eastern States of Australia.

Colder than normal equatorial sea-surface temperatures are now present from around the International Dateline to the Central Pacific Ocean, and in most of the eastern Pacific. However, temperatures now are mainly normal in waters off Queensland and the Northern Territory.

Sea-surface temperatures in the Pacific Ocean indicate the remains of a weak La Nina pattern, but some experimental models suggest re-strengthening of the pattern towards the end of the year. In general terms, such a pattern means reduced rainfall for our trade competitors in south-western USA, Argentina, and central Asia.

Potential yields of late-planted crops in winter cropping areas of central and southern Queensland are slightly below average. The SOI phase at the end of May indicated that frosts (-2 degrees C in the screen) could be expected to be later than normal in the winter cropping areas of southern and central Queensland. However, the frost risk is generally very low for June plantings.

Due to the SOI being in a consistently-near-zero phase, the likelihood of above median pasture growth in September to November is high only in parts of south-eastern Queensland where good soil moisture is present following three months of above-average rainfall.

The next passage of the 30- to 50-Day Oscillation is expected about the third week of October.

It is important to obtain more detailed information for your location. We recommend combined use of the Australian RAINMAN package and the Bureau of Meteorology's Seasonal Climate Outlook. Also a lot of additional information is available on our SOI Fax Hotlines, our Internet World Wide Web service called 'The Long Paddock', and on BoM's Fax and internet information services.

Last updated: 23 September 1999