|Northern Aust Seasonal Rainfall Outlook: probabilities for October to December 2008, issued 25th September 2008|
Wetter December quarter indicated for northeastern Australia
The outlook for rainfall over the December quarter (October to December) shows a moderate to strong shift in the odds favouring wetter than normal conditions over much of northern Australia, with the strongest signal over central Queensland.
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 chances of exceeding the median rainfall for October to December are between 65 and 75% over central Queensland (see map). Over the remainder of Queensland and the NT, the odds for exceeding the median rainfall are between 55 to 65%. This means that for every ten years with ocean patterns like the current, about six to eight years are expected to be wetter than average over these regions, while about two to four years are drier.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During the October to December period, history shows this effect to be moderately consistent over much of the region (see background information).
The tropical Pacific Ocean remains ENSO-neutral. There has been some slight cooling at the surface and slightly stronger cooling of the subsurface in the central Pacific recently. The Southern Oscillation Index (SOI) has responded to this cooling and has risen to a value of approximately +17 for the 30 days ending 22nd September. Computer models indicate that neutral conditions are likely to continue for the next few seasons. 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 Monday to Friday from 9.00am to 5.00pm local time by contacting the Bureau's Climate Services sections in Queensland and the Northern Territory at the following numbers:
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 28th October 2008