Positive values of the SOI are associated with stronger Pacific trade winds and warmer sea temperatures to the north of Australia. Together these give a high probability that eastern and northern Australia will be wetter than normal. There is then a high probability that eastern and northern Australia will be drier than normal. The area of warm water usually over the western tropical Pacific cools and the warmest water is displaced eastward to the central Pacific. The Southern Oscillation Index remains negative.
Enhanced cloudiness develops over the central equatorial Pacific.
When the Southern Oscillation Index sustains high positive values, the Walker circulation intensifies, and the eastern Pacific cools. These led to the National Climate Centre's launch of the Seasonal Climate Outlook Service in 1989. Useful predictions of seasonal rainfall have the potential to contribute to the goals of sustainable development in the rural sector. A large proportion of Australia's natural environment is farmed, harvested or managed by farmers. Many renewable resources, from topsoil to wildlife, are broadly under rural sector management.