|National Seasonal Rainfall Outlook: probabilities for January to March 2009, issued 17th December 2008|
Mixed rainfall odds for the March quarter
The national outlook for total March quarter rainfall (January to March), shows mixed odds for exceeding the seasonal median. There is a moderate to strong shift in the odds favouring higher than normal rainfall over southwestern WA as well as for an area covering northeast NSW and southeast Queensland. Conversely, there is a moderate shift in the odds favouring lower than normal rainfall over parts of central and southwestern Queensland.
The pattern of seasonal rainfall odds across Australia is mainly a result of continued warmth in the central Indian Ocean.
The chance of exceeding median rainfall over Australia during the March quarter is between 60 and 75% over southwest WA and between 60 and 65% over northeast NSW and the far southeast of Queensland. 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.
In contrast, the odds of exceeding median rainfall over parts of central and southwestern Queensland are between 35 and 40%, which means that these areas have a 60 to 65% chance of being drier than normal.
Across the rest of the country, the chance of exceeding the median rainfall during the March quarter is between 40 and 60%, meaning that above average falls are about as equally likely as below average falls in these regions.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During the March quarter, history shows the effect to be moderately consistent through eastern parts of NSW and Queensland, large parts of the NT and over much of southern and western WA. Elsewhere the effect is only weakly or very weakly consistent (see background information).
The tropical Pacific Ocean remains ENSO-neutral. Sea surface temperatures across most of the equatorial Pacific are near normal, however, cool sub-surface temperatures persist from the dateline to the South American coast and the trade winds are now stronger than normal across most of the basin. The SOI remains positive at approximately +13 for the 30 days ending 14 December. Most international computer models indicate that neutral conditions are likely to continue through summer and autumn, however, two models predict cooling. For routine updates and comprehensive discussion on any developments please see the ENSO Wrap-Up.
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|The following climate meteorologists in the National Climate Centre can be contacted about this outlook: Lynette Bettio on (03) 9669 4165, Blair Trewin on (03) 9669 4623, Robyn Gardiner on (03) 9669 4671,|
Regional commentary is available from the Climate Services Sections in the Bureau's Regional Offices:
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 22nd January 2009