|WA Seasonal Rainfall Outlook: probabilities for August to October 2006, issued 25th July 2006|
50:50 chances for above average seasonal rainfall
The current seasonal rainfall odds do not strongly favour either wetter or drier than average conditions across Western Australia. The chances of accumulating at least median rain during the late winter to mid-spring period (August-October) are close to 50% across the State, the Bureau of Meteorology announced today.
For the August to October period, the chances of above median rainfall are mainly between 40 and 50% in WA (see map). So in years with ocean patterns like the current, about four or five August to October periods out of 10 are expected to be wetter than average over the State, with about five or six out of ten being drier.
However, it should be remembered that it in terms of average conditions, it is a rather dry time of year in northern WA, with heavy rain being uncommon.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During August to October, history shows this effect to be mostly weakly or very weakly consistent across WA (see background information).
After falling to −10 in May, the Southern Oscillation Index (SOI) rose slightly in June to a value of −6. The approximate SOI for the 30 days ending 22nd July was −9.
Although the chances of an El Niño have risen somewhat in the past month, continued neutral ENSO conditions is the most likely outcome for the remainder of 2006. For routine updates and comprehensive discussion on the latest data relating to ENSO, together with details on what the phenomenon is and how it has affected Australia in the past, please see the ENSO 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 (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 24th AUGUST 2006