SA Seasonal Rainfall Outlook: probabilities for Winter 2004, issued 18th May 2004

Drier Winter more likely in parts of SA

The Bureau's winter rainfall outlook shows a pattern of generally neutral odds with no strong swings towards either wetter or drier conditions. One exception is over central SA where the odds tend to favour below average falls. This outlook pattern is a result of the combined effects of above average temperatures in both the Pacific and Indian Oceans.

For the June to August period in SA, the chances of above median rain are between 35 and 40% over parts of the Western Agricultural, Northwest Pastoral, and Northern Agricultural districts (see map). This means that a drier than average winter could be expected in about six seasons out of ten in these areas with the current climate patterns. However, the outlook reliability is patchy over South Australia (see below) so these probabilities should be used with caution.

probability of exceeding median rainfall - click on the map for a larger version of the map

Across the rest of the State, the chances of a wetter than average winter are mainly between 40 and 45%.

Outlook confidence is related to the influence of Pacific and Indian Ocean temperatures on seasonal rainfall. During winter, history shows this influence to be moderately consistent in a few patches near the coast and about the centre of SA, but weakly or very weakly consistent elsewhere across the State (see background information).

Both the Indian and tropical Pacific Oceans remain mostly warmer than average, although the eastern Pacific has cooled. For more detail see the the El Niño Wrap-Up.

The Southern Oscillation Index (SOI) has been trending downwards over recent months with an April value of –15, following zero in March and +9 in February. The approximate SOI for the 30 days ending 15th May was +8.

 

Click on the map above for a larger version of the map. Use the reload/refresh button to ensure the latest forecast map is displayed.

 
More information on this outlook is available from 9.00am to 5.00pm (CDT) Monday to Friday by contacting the Climate and Consultancy section in the Bureau's Adelaide Office: (08) 8366 2664.
 

THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 17th JUNE 2004.

Corresponding temperature outlook

April 2004 rainfall in historical perspective

February to April 2004 rainfall in historical perspective

 

Background Information