Seasonal Climate Outlook Message for July to October 2000

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SOI message 26th July 2000. Queensland Centre for Climate Applications

The average SOI over the last 30 days was -2.8. Based on the SOI, the probabilities of exceeding edian rainfall during the total July to September period are little different from the 'normal' for this time of year in most of the eastern States of Australia, except for the Sunshine Coast and adjacent sub-coastal districts of Qld, central coastal and adjacent sub-coastal districts in NSW, where probabilities are 60-70%; and parts of northern Tasmania where the probabilities are 30- 40%.

For more information contact your local QCCA extension officer (07 46881200)

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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 July to September period are little different from the 'normal' for this time of year in most of the eastern States of Australia. Exceptions are the Sunshine Coast and adjacent sub-coastal districts of Qld, central coastal and adjacent sub-coastal districts in NSW, where probabilities are 60-70%; and parts of northern Tasmania where the probabilities are 30- 40%.

The cooler-than-normal sea-surface temperatures in the eastern equatorial Pacific Ocean, that characterised the 1998-2000 La Niña event, have continued to recede. Ocean temperatures off the Qld and northern Australian coastline are now slightly cooler than normal. The Indian Ocean has warmed over the past couple of weeks.

In terms of the future development of climatic patterns, most forecasts from experimental general circulation models are suggesting that neutral conditions will dominate for the next 6 months. Interestingly, many of them suggest that sea -surface temperatures in the eastern equatorial Pacific Ocean may become slightly warmer than average which may have a drying effect on our summer rainfall.

Dry conditions this month may have been partially due to the subtropical ridge being further north than normal. Typically this reduces winter rainfall from the Goondiwindi district through to the Central Highlands.

There is a good probability that the frost season will finish one to two weeks earlier than normal for some towns in Queensland. However, the expected number of frosts, and the chances of getting at least one frost, are about average.

The prospects for above-median pasture growth during the July-September period vary considerably across Qld, but are highest in parts of the region running from the northern Central Highlands to the Gulf of Carpentaria. However, pasture growth during this period is generally low, but can be valuable in terms of animal nutrition.

The next passage of the 30- to 50-Day Oscillation over Qld is expected about the second week in August.