|NT Seasonal Rainfall Outlook: probabilities for October to December 2006, issued 26th September 2006|
Odds 50:50 for above average early wet season falls
Although the odds point to a drier period in northern Queensland, the chances over the NT are generally close to 50% for accumulating at least median rainfall for the first three months of the wet season (Oct-Dec).
The pattern of three-month rainfall odds across the Territory 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. In the NT, the effects from the two oceans cancel, with the warm Pacific tending to promote drier weather, while the warm Indian Ocean increases the chance of higher than normal falls,
For the total over the October to December period, the chances are mainly between 45 and 55% for above median rainfall across most of the NT (see map). So in years with ocean patterns like the current, about five October to December periods out of ten are expected to be drier than average in the NT, with about 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 much of the country (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 (CST) Monday to Friday by contacting the Climate and Consultancy section in the Bureau's Darwin Office: (08) 8920 3813.|
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 26th OCTOBER 2006