|WA Seasonal Rainfall Outlook: probabilities for April to June 2008, issued 28th March 2008|
Neutral outlook for WA June quarter rainfall
The Western Australian outlook for total rainfall over the June quarter (April to June), does not show any moderate to strong shifts in the odds favouring either a wetter or drier than normal season. The chances of above average rainfall are about the same as the chances of below average falls.
The pattern of seasonal rainfall odds across WA is a result of continuing higher than average temperatures in the southeastern Indian Ocean, and cooler than average waters across the equatorial Pacific in association with La Niña.
The chances of exceeding the median rainfall over April to June are between 40 and 55% over Western Australia (see map). So for every ten years with ocean patterns like the current, about five June quarters are expected to be wetter than average across the State, while about five are drier.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During the June quarter, history shows this effect to be moderately consistent in a broad band stretching from the Pilbara to the southeast and far eastern interior. Elsewhere in WA the effect is only weakly or very weakly consistent (see background information).
The La Niña event in the Pacific Basin is showing signs of weakening, although computer models indicate it is likely to persist until about the end of autumn. The 30-day value of the Southern Oscillation Index (SOI) was +15 as at 25th March. For routine updates and comprehensive discussion on any developments 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 8.30am to 4.30pm (WDST) Monday to Friday by contacting the Climate Services Centre in the Bureau's Perth Office: (08) 9263 2222.|
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 23rd April 2008