|WA Seasonal Rainfall Outlook: probabilities for Summer 2003/2004, issued 14th November 2003|
Neutral odds across WA for summer rainfall
The Bureau's summer rainfall outlook provides little guidance across Western Australia, 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 from 45 to 50% in northern Western Australia to above 55% in the southwest of the state (see map). So with climate patterns like the current, about 5 seasons out of 10 are expected to be wetter than average across Western Australia, with about 5 out of 10 being drier.
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 to strong across much of WA, except in the far southeast where this relationship is weak (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 (WST) Monday to Friday by contacting the Climate and Consultancy section in the Bureau's Perth Office: (08) 9263 2222.|
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 16th DECEMBER 2003.