Seasonal Climate Outlook Message for May to August 2000
The bottom line
SOI message 24th May 2000 The average SOI over the previous 30 days has dropped to +9.7 . Based on the SOI, the probabilities of exceeding median rainfall during the total May to July period are little different from the 'normal' for this time of year in most of the eastern States of Australia, except for parts of southern NSW, western Victoria and eastern Tasmania where the probabilities are 60-70%.
The full story
Review of Climatic Forecasts and Information
Based on the latest values and trends of the SOI, the probabilities of receiving above-median rainfall over the total May-July period are little different from the 'normal' for this time of year in most of the eastern States of Australia. Exceptions are parts of southern NSW, western Victoria and eastern Tasmania where the 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 Ni¤a have also weakened but not to the same extent.
This recession of the La Ni¤a is in accordance with forecasts by experimental general circulation models. Most of these forecasts are suggest that neutral conditions will dominate at least until summer. However, sub-surface sea temperatures to the east of Australia are still significantly warmer than normal, which is a classic `pre-El Nino' mode. In addition, 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
