Seasonal Climate Outlook Message for January to April 2000

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SOI Message 5th January 2000

The average SOI over the previous 30 days has risen to +10.5. Based on the SOI, the probabilities of exceeding median rainfall during the total period from January to March range mainly between 50 and 80% for much of Queensland including the Central Highlands, the central coast, and parts of the northern inland.

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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 January-March period are relatively high for many regions of Queensland especially the Central Highlands, central coast, and parts of the northern inland.

Probabilities of exceeding median rainfall are 60-80% in the Central Highlands and central coast of Queensland, southern coastal regions of NSW and the far north-west of NSW. Conversely, there is only a 20-40% chance of exceeding median rainfall in south-western Victoria and south-western Tasmania. Remaining areas of eastern Australia have a rainfall probability little different from the 'normal' for this time of year.

The continuing 'cool' sea-surface temperature (SST) anomalies in the eastern equatorial Pacific Ocean combined with 'warm' SST anomalies around Western Australia suggest a continuing 'weak' La Nina pattern.

There is no clear message coming from the experimental models regarding the development of the La Nina over the next 6 months. The forecasts of ocean conditions six months from now (June 2000) range from La Nina through Neutral to El Nino conditions. By September 2000 the majority of models suggest Neutral conditions are most likely.

Combining the rainfall outlook with current soil water and pasture condition, the probabilities of above-median pasture growth during the total December-February period are 70-100% over Queensland except for the far central west.

The 30- to 50-Day Oscillation was very inconsistent during 1999. It appears that the "shadow wave" passed through the region during the last week of December and the main wave is next expected around the third week of January.

Last updated: 4 January 2000