|Northern Aust Seasonal Rainfall Outlook: probabilities for May to July 2008, issued 23rd April 2008|
Higher seasonal rainfall favoured in parts of north & east Australia
The northern Australian outlook for total rainfall over the late autumn to mid-winter period (May to July), shows a moderate shift in the odds favouring a wetter than normal season over most of the NT and southern and western parts of Queensland.
The pattern of seasonal rainfall odds is largely the result of higher than average temperatures in the Indian Ocean, with some influence from the cooler than average waters across the equatorial Pacific in association with La Niña.
The chances of exceeding the median rainfall over May to July are between 60 and 70% in a broad band covering most of the NT and western and southern Queensland (see map). So for every ten years with ocean patterns like the current, about six or seven May to July periods are expected to be wetter than average in these parts of eastern and northern Australia, while about three or four are drier. It should be noted, however, that this is a seasonally dry time of year over some northern parts.
Over the northeast part of Queensland, the chances of exceeding the three-month median rainfall are mainly between 50 and 60%. So the chances of being wetter than normal are about the same as the chances of being drier.
Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall. During the May-July period, history shows this effect to be moderately consistent in a band from the central Northern Territory across most of the southern two-thirds of Queensland (see background information). Elsewhere the effects are only weakly consistent.
The La Niña event in the Pacific Basin is weakening: computer models indicate a return to neutral conditions over the outlook period of May to July. The 30-day value of the Southern Oscillation Index (SOI) was +5 as at 20th April. 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 information on this outlook is available Monday to Friday from 9.00am to 5.00pm local time 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 27th May 2008