|WA Seasonal Rainfall Outlook: probabilities for April to June 2007, issued 26th March 2007|
Neutral June quarter rainfall outlook for most of WA
The Western Australian outlook for total June quarter (April to June) rainfall, shows no moderate or strong swings in the odds towards either above-normal or below-normal falls over most of the State. The one exception is in part of the Gascoyne, where there is an increased chance for a wetter than average season.
The pattern of seasonal rainfall odds across WA is a result of recent higher than average temperatures in the equatorial Pacific Ocean and also in parts of the tropical and sub-tropical Indian Ocean. More influence has come from the Pacific.
The chances of exceeding the median rainfall for the April to June period are between 60 and 65% in part of the Gascoyne near Meekatharra (see map). So in years with ocean patterns like the current, about six June quarters out of ten are wetter than average and four out of ten are drier in this region with enhanced odds. Over the rest of the State the chances of accumulating at least average rain for the coming three months are between 45 and 60%.
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 Southern Oscillation Index (SOI) has been rising recently with values of −7 in January, −3 in February and an approximate 30-day value of +5 as at 21st March.
The 2006/07 El Niño has ended, with central to eastern Pacific temperatures having cooled to near-average. There is an increased chance of a La Niña developing in 2007 - for routine updates and comprehensive discussion on any developments in this regard 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 23rd APRIL 2007