Seasonal Climate Outlook Message for May to August 2000

The bottom line

The average SOI over the previous 30 days has dropped to +5.6 . Based on the SOI, the probabilities of exceeding median rainfall during the total June to August period are little different from the 'normal' for this time of year in most of the eastern States of Australia, except for the south-eastern corner of QLD and the north-eastern corner of NSW where the probabilities are 30-40%; and parts of central NSW, western Victoria and eastern Tasmania where probabilities are 60-70%.

The full story

Based on the latest values and trends of the SOI, the probabilities of receiving above-median rainfall over the total June to August period are little different from the 'normal' for this time of year in most of the eastern States of Australia. Exceptions are the south-eastern corner of QLD and the north-eastern corner of NSW where the probabilities are 30-40%; and parts of central NSW, western Victoria and eastern Tasmania where probabilities are 60-70%.

The 'cool' sea-surface temperature (SST) anomalies that have been present since 1998 in the central and eastern equatorial Pacific Ocean have receded. However, there are still patches of cool anomalies. Atmospheric circulation parameters characteristic of the La Niña have also weakened but not to the same extent.

This recession of the La Niña is in accordance with forecasts by experimental general circulation models. Most of these forecasts are suggesting that neutral conditions will dominate at least until summer. Some early research work suggests the sub-tropical ridge may again be further north than normal this winter which may tend to reduce winter rainfall from the Goondiwindi district through to the Central Highlands. As these indicators provide some cause for concern, regular monitoring of them and the SOI is highly recommended.

Combining the rainfall outlook with current soil water and pasture condition, the probabilities of above-median pasture growth during the total May-July period are 60-100% in much of Qld; 0-40% in much of far North Qld (maximum pasture growth has already been achieved); and 0-40% in eastern areas of southern Qld due to current poor soil moisture.

The next passage of the 30- to 50-Day Oscillation over Queensland is expected mid-June.