|NSW Seasonal Rainfall Outlook: probabilities for October to December 2006, issued 26th September 2006|
Odds 50:50 for a wetter than average season in NSW
Although parts of Queensland and southeastern Australia have increased chances of below average December quarter (October to December) rainfall, the odds for a wetter than average season are close to 50:50 over most NSW, the Bureau of Meteorology announced today.
The pattern of seasonal rainfall odds across Australia is a result of higher than average temperatures in both the Pacific and Indian Oceans, the former of which has been warming strongly in the past few months.
For the total over the October to December period, the chances are between 40 and 55% for above median rainfall across most of New South Wales, except around Albury where the chances are a little below 40% (see map). So in years with ocean patterns like the current, about five or six December quarters out of ten are expected to be drier than average in NSW, with about four or five out of ten being wetter.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During the December quarter, history shows this effect to be moderately consistent across the western half of NSW, but generally only weakly consistent in the east (see background information).
The Southern Oscillation Index (SOI), negative for the fourth straight month, dropped from −9 in July to a low −16 in August. The approximate SOI for the 30 days ending 19th September was −4.
In addition to the low SOI, the equatorial Pacific has been warming and the Trade Winds have been weak. These ENSO indicators are all consistent with the development phase of an El Niño event, the likelihood of which has risen strongly in the past month. For routine updates and comprehensive discussion on the latest data relating to ENSO, together with details on what the phenomenon is and how it has affected Australia in the past, 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 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 26th OCTOBER 2006