|NSW Seasonal Rainfall Outlook: probabilities for January to March 2007, issued 20th December 2006|
Decreased rainfall in March quarter for much of northern NSW
The latest seasonal rainfall outlook issued by the Bureau of Meteorology shows a moderate shift in the odds towards below-normal March quarter (January to March) rainfall for much of northern NSW. However, the confidence in the outlooks at this time of year is rather low, so this outlook should be used with caution.
The pattern of seasonal rainfall odds across Australia is mostly a result of higher than average temperatures in the Pacific Ocean (because of El Niño).
The chances of exceeding the median rainfall for the January to March period, are between 30 and 40% across eastern and northern NSW east of a line from Sydney to Wanaaring. This means that BELOW median falls have about a 60 to 70% chance of occurring. So in years with ocean patterns like the current, about six or seven March quarters out of ten are expected to be drier than average over the northeast half of the State, with about three or four out of ten being wetter.
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 approximately the eastern one-third of NSW, but only weakly or very weakly consistent elsewhere across the State (see background information).
The Southern Oscillation Index (SOI), negative for the seventh straight month as a result of the El Niño, rose from −15 in October to −1 in November. The approximate SOI for the 30 days ending 17th December was −4.
The current Pacific El Niño pattern, of which the low SOI is but one indicator, is expected to persist for most of the summer. For routine updates and comprehensive discussion 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, please see the ENSO Wrap-Up.
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|More information on this outlook is available from 9.00am to 5.00pm (EST) Monday to Friday by contacting the NSW Climate Services section in the Bureau's Sydney Office: (02) 9296 1610 or (02) 9296 1525.|
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 23rd JANUARY 2007