|NSW Seasonal Rainfall Outlook: probabilities for November 2006 to January 2007, issued 26th October 2006|
Increased risk of dry season for eastern NSW
The latest seasonal rainfall outlook issued by the Bureau of Meteorology, shows a moderate to strong shift in the odds towards drier than normal conditions across the eastern half of NSW over the late spring to mid-summer period (November-January). The pattern of seasonal rainfall odds in NSW is mostly a result of higher than average temperatures in the Pacific Ocean.
The chances of exceeding the median rainfall for the November to January period, are between 30 and 40% over the eastern half of NSW, with a few areas having 25 to 30% chances. These probabilities mean that BELOW median falls have about a 60 to 75% chance of occurring. Across the rest of the State, the chances of exceeding the median are between 40 and 55%.
So in years with ocean patterns like the current, about six or seven November to January periods out of ten are expected to be drier than average over the eastern half of NSW, 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 November to January period, history shows this effect to be moderately consistent across much of NSW (see background information).
The Southern Oscillation Index (SOI), negative for the fifth straight month, rose from −16 in August to −5 in September. The approximate SOI for the 30 days ending 23rd October was −14.
The current El Niño conditions, of which the low SOI is but one indicator, are very likely to persist for the rest of 2006, which would qualify it as an official El Niño event. 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.
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 23rd NOVEMBER 2006