|WA Seasonal Rainfall Outlook: probabilities for April to June 2005, issued 18th March 2005|
Neutral outlook for WA seasonal rainfall
There are no strong shifts in the odds towards either above or below average rainfall for the June quarter (April-June) in Western Australia, the Bureau of Meteorology announced today.
For the April to June period, the chances of above median rainfall are between 50 and 60% across the State (see map). So in years with ocean patterns like the current, about five or six June quarters out of 10 are expected to be wetter than average over WA, with about four or five out of ten being drier.
Outlook confidence is related to the influence of Pacific and Indian Ocean temperatures on seasonal rainfall. During the June quarter, history shows this influence to be moderately consistent in a broad band stretching from the Pilbara to the southeast and far eastern interior. Elsewhere in WA the influence is only weakly or very weakly consistent (see background information).
After reaching +2 in January, the Southern Oscillation Index (SOI) fell strongly in February to a value of 29, the lowest for any month since February 1983 (33). The approximate SOI for the 30 days ending 15th March was 20.
Recent low SOI values have caused some speculation regarding a possible El Niño developing in 2005. While the risk has increased it is too early at this stage to predict what might happen in the Pacific, with any confidence. For routine updates and comprehensive discussion on the latest data relating to El Niño, together with details on what the phenomenon is and how it has affected Australia in the past, 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 15th APRIL 2005