|WA Seasonal Rainfall Outlook: probabilities for November 2008 to January 2009, issued 28th October 2008|
Wetter than average November to January favoured in north and west WA
The Western Australia outlook for rainfall over the November to January period shows wetter than normal conditions are likely over northern and western parts of the state.
The pattern of seasonal rainfall odds across Australia is mainly a result of continued warmth in the central and southeastern Indian Ocean, especially off the west coast of WA.
The chance of exceeding median rainfall over Australia for the November to January period is between 60 and 75% for most of the Kimberley and adjacent northern Interior, and between 60 and 65% for large parts of the Southwest Land Division (SWLD) and adjacent Gascoyne (see map). This means that for every ten years with ocean patterns like the current, about six or seven years are expected to be wetter than average in these regions, while about three or four years are expected to be drier.
For the remainder of the state, the chance of exceeding the median rainfall for the November to January period is between 50 and 60%, meaning that there are about equal chances to be wetter than average or drier than average in these regions.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During the November to January period, history shows this effect to be moderately consistent in parts of northern WA and the SWLD, but only weakly consistent for the remainder of the state. (see background information).
The tropical Pacific Ocean remains ENSO-neutral. Sea surface temperatures across most of the equatorial Pacific are near normal, however, sub-surface temperatures have recently cooled. The Southern Oscillation Index (SOI) is currently at +14 for the 30 days ending 25 October. Computer models indicate that neutral conditions are likely to continue for the rest of spring and summer. 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 (WST) 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 26th November 2008