|SA Seasonal Rainfall Outlook: probabilities for October to December 2004, issued 16th September 2004|
Increased risk of dry conditions in southeastern SA
There is a moderate shift in the odds towards below average rainfall for the December quarter in the far southeast of South Australia, the Bureau of Meteorology announced today. For the rest of the State, the chances of accumulating at least average rain over the last three months of 2004 are mostly close to 50%.
In the Lower Southeast district, the chances of above median rainfall for the December quarter are between 35 and 40%. So in years with ocean patterns like the current, about six October to December periods out of ten are expected to be drier than average in this part of the State, with about four out of ten being wetter.
However, when looking at the growing season (April-November) as a whole, below average falls up to the end of August mean that some parts of SA are unlikely to reach their total growing seasonal average by the end of November. In the Murray, Upper North and Northeast districts the chances of receiving the required rain are generally between 20 and 30%. For more information on the recent dry conditions, see the Drought Statement.
The current pattern of outlook probabilities is due to recent temperature patterns in both the Pacific and Indian Oceans.
Outlook confidence is related to the influence of Pacific and Indian Ocean temperatures on seasonal rainfall. During the December quarter, history shows this influence to be moderately consistent across the eastern half of SA, but only weakly consistent in the west (see background information).
The chance of a late-developing El Niño event increased over the past month, with several but not all indicators reaching their El Ni˜o thresholds. The mounting evidence includes warming of the central Pacific, reduced Trade Winds in the same area and continued negative values of the Southern Oscillation Index (SOI) which came in at 8 for August. The approximate SOI for the 30 days ending 13th September was 3.
For routine updates on the latest data relating to El Niño, together with details on what the phenomenon is and how it has affected Australia in the past, see the El Niño Wrap-Up.
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|More information on this outlook is available from 9.00am to 5.00pm (CST) Monday to Friday by contacting the Climate and Consultancy section in the Bureau's Adelaide Office: (08) 8366 2664.|
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 19th OCTOBER 2004.