Southern Oscillation Index
The Southern Oscillation Index (SOI) is calculated from the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin.
A strongly and consistently positive SOI pattern (e.g. consistently above about +6 over a two month period) is related to a high probability of above the long-term average (median) rainfall for many areas of Australia, especially areas of eastern Australia (including northern Tasmania) - La Niņa.
Conversely, a 'deep' and consistently negative SOI pattern (less than about minus 6 over a two month period, with little change over that period) is related to a high probability of below median rainfall for many areas of Australia at certain times of the year - El Niņo.
However, it is important to remember that the pattern of relationship between SOI and rainfall (and temperature) can vary depending on the particular season and region. Additionally, the change in SOI over a specified period can be as important in understanding relationships between SOI and rainfall as is the absolute value in SOI.
Water is flowing into outback Lake Eyre, but somewhat differently from past flooding of the remote saltpan, travel guide Rex Ellis says.
A strong and complex low is moving over New Zealand and has been generating heavy rain, isolated thunderstorms and gale force winds.
The sunrise this morning likely made the ancient sandstone formation of Uluru glow a glorious red at dawn, although cloud and rain from today should lead to more demure morning displays for the next couple of days.