Seasonal Climate Outlook October - December 2006
The Seasonal Outlook released by the Bureau of Meteorology on 26 September 2006, for the October to December period indicates increased odds of drier and warmer conditions over the next three months.
The chances of above median rainfall are 30-40% across most of Victoria, decreasing to 25-30% over most of the coastal area along the west and south-central coast. Chances rise to 40-50% in the far east of the State. Chances of exceeding median maximum temperatures are over 80% across the State.
The Southern Oscillation Index (SOI), negative for the fourth straight month, rose from −16 in August to -4.6 in September. In addition to the negative SOI, the equatorial Pacific has been warming and the Trade Winds have been weak. These indicators are all typical for the development phase of an El Niño event, the likelihood of which has risen strongly in the past month.
The observed below average rainfall since late autumn across Australia's southern half, especially in the southeast and southwest, is also consistent with the early stages of an El Niño event.
Even if El Niño thresholds are not maintained across the range of indicators, a warming Pacific and a low SOI bias the climate towards being drier and warmer than average across eastern Australia for the remainder of 2006. This is reflected in the latest outlook.