NSW Seasonal Rainfall Outlook: probabilities for Summer 2003/2004, issued 14th November 2003

Neutral odds for summer rainfall across NSW

The Bureau's summer rainfall outlook shows that above average seasonal falls are generally a 50:50 prospect across NSW with no strong swing towards either wetter or drier conditions. This outlook is largely the result of recent temperature patterns and trends in the Indian Ocean.

For the December to February period, the chances of above median rainfall range between 45% in the far northwest of NSW to over 55% in the east (see map). So with climate patterns like the current, about 5 seasons out of 10 are expected to be wetter than average across NSW, with about 5 out of 10 being drier.

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

Outlook confidence is related to the influence of Pacific and Indian Ocean temperatures on seasonal rainfall. During summer, history shows this influence to be moderate across central and eastern NSW, but weak to very weak in the western part of the state (see background information).

The tropical Indian Ocean has been cooling strongly over recent months and temperatures there are currently close to average. The Pacific on the other hand, is generally warmer than average, particularly in the west. For more detail see the El Niño Wrap-Up. The recent temperature changes in the Indian Ocean are the dominant influence on the overall pattern of probabilities.

October's value of the Southern Oscillation Index (SOI) was –2, the same as that recorded in September and August. The approximate SOI for the 30 days ending 11th November was –3.


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 (EDT) Monday to Friday by contacting the Climate and Consultancy section in the Bureau's Sydney Office: (02) 9296 1522.


Corresponding temperature outlook

October 2003 rainfall in historical perspective

August to October 2003 rainfall in historical perspective


Background Information