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

Dry Spring more likely in far southwest NSW

There is a moderate shift in the odds towards below average spring rainfall in far southwest NSW, the Bureau of Meteorology announced today.

However, due to the poor or very poor start to the southern growing season (April-November), many parts of NSW have a less than 20% chance of reaching the total growing seasonal average by the end of November. Along the coast, the chances drop below 10%. For more information on the recent dry conditions, see the Drought Statement.

Across the far southwest of NSW, the chances of above median rainfall for spring are between 35 and 40%, but across the remainder of the State they're between 40 and 55%. So in years with ocean patterns like the current, about six spring periods out of ten are expected to be drier than average in far southwest NSW, with about four out of ten being wetter.

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 across most of NSW (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 (EST) Monday to Friday by contacting the Climate and Consultancy section in the Bureau's Sydney Office: (02) 9296 1522.
 

THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 16th SEPTEMBER 2004.

Corresponding temperature outlook

July 2004 rainfall in historical perspective

May to July 2004 rainfall in historical perspective

 

Background Information