SA Seasonal Rainfall Outlook: probabilities for Spring 2004, issued 17th August 2004

Dry Spring more likely in parts of SA

There is a moderate shift in the odds towards below average spring rainfall in central to southeast SA, the Bureau of Meteorology announced today.

Across these parts of the State, the chances of above median rainfall for spring are below 40%, dropping below 35% in a region north of Port Augusta. So in years with ocean patterns like the current, about six or seven spring periods out of ten are expected to be drier than average in central to southeast SA, with about three or four out of ten being wetter.

In the remaining parts of South Australia, the chances of above average seasonal rainfall are close to 50:50.

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

The current pattern of outlook probabilities is due to recent temperature patterns in both the Pacific and Indian Oceans.

Outlook confidence is related to the influence of Pacific and Indian Ocean temperatures on seasonal rainfall. During spring, history shows this influence to be moderately consistent only in patches across SA, so the outlook probabilities should be used with caution (see background information).

The Southern Oscillation Index (SOI) has remained significantly negative for the second successive month, with a July value of –7 following the June reading of –14. The approximate SOI for the 30 days ending 14th August was –12. Consistent with the negative SOI, the central Pacific has been warming over the past few months. However, given historical precedent and the current model guidance, the triggering of an El Niño event during the second half of 2004 is less likely than the persistence of neutral conditions. For more detail see the El Niño Wrap-Up.


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 (CST) Monday to Friday by contacting the Climate and Consultancy section in the Bureau's Adelaide Office: (08) 8366 2664.


Corresponding temperature outlook

July 2004 rainfall in historical perspective

May to July 2004 rainfall in historical perspective


Background Information