|Northern Aust Seasonal Rainfall Outlook: probabilities for Spring 2009, issued 26th August 2009|
Dry spring outlook for north Queensland
The northern Australian outlook for total spring (September to November) rainfall, shows moderate to strong shifts in the odds favouring a drier than normal season across much of north Queensland.
The pattern of seasonal rainfall odds across Australia is a result of recent warm conditions in the Pacific Ocean, and is consistent with a developing El Niño event.
For the September to November period, the chance of exceeding median rainfall is below 40% across much of the northern half of Queensland (see map). Within this area, the chances drop to below 30% in parts. This means that for every ten years with ocean patterns like the current, about three or four years would be expected to be wetter than average in these parts of northeastern Australia during spring, with about six or seven being drier.
Over most remaining parts of northern Australia, the chance of a wetter than average season is between 40 and 50%. In other words the chances of above normal falls are about the same as the chances of below normal.
New: An expanded set of seasonal rainfall outlook maps and tables, including the probabilities of seasonal rainfall exceeding given totals (e.g. 200 mm), is available on the "Water and the Land" (WATL) part of the Bureau's website.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect north Australian rainfall. During spring, history shows this effect to be moderately consistent across most of the region (see background information).
An El Niño event looks to be developing across the Pacific: the latest outputs from computer models indicate it will reach peak intensity late in the year. El Niño events are usually (but not always) associated with below normal rainfall in the second half of the year across large parts of southern and inland eastern Australia. The SOI is approximately −7 for the 30 days ending 23 August. For routine updates and comprehensive discussion on any developments 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 detailed forecast maps, including the probabilities of seasonal rainfall exceeding given totals, can be found here.
More information on this outlook is available by contacting the Bureau's Climate Services sections in Queensland and the Northern Territory at the following numbers:
THE NEXT ISSUE OF THE SEASONAL OUTLOOK IS EXPECTED BY 22nd September 2009