Weak La Nina increases the likelihood of wet summer in south-east Queensland

Mr Rex Falls, the Regional Director for Queensland of the Bureau of Meteorology, said today that the Bureau's rainfall outlook for the coming summer indicates no strong bias towards wetter or drier conditions than normal except in the south-east quarter of Queensland, where there is a higher likelihood of wetter than normal conditions.

He said the balance of probabilities favoured near average to above average tropical cyclone activity in the Queensland region. Mr Falls said, as in almost every summer, we must expect serious flooding somewhere in the state.

The outlook alerts us to an increased risk in the south-east, but flooding in other areas of the state is also likely on a seasonal basis. In an average year, four to six cyclones occur over our neighbouring seas, and it is very unlikely that all will avoid Queensland's coasts. The seasonal average number of cyclones impacting the east Queensland coast is between one and two; and one or two cyclones may also develop in the Gulf of Carpentaria.

Mr Falls said tropical cyclone activity and rainfall in eastern Australia are fairly strongly affected by the El Nino-La Nina climate see-saw over periods of seasons to a few years, popularly measured by the Southern Oscillation Index (SOI). Since 1878, tropical cyclones have caused an impact in eastern Australia at least 173 times. Records show the numbers of impact cyclones during the La Nina phase was about double those which had occurred during the El Nino phase.

Mr Falls said The National Climate Centre's outlook for summer favours the continuation of weak La Nina or neutral conditions. The current Sea Surface Temperature Anomaly pattern indicates cooler than normal temperatures in the tropical eastern Pacific Ocean, and warmer than normal temperature's around Australia, and the SOI has recently risen to around + 8, both indicative of the current weak La Nina pattern.

The Bureau's Tropical Cyclone and Flood Warning Systems will operate throughout the season to provide as much advance warning of these hazards as possible.

Although the outlook gives no reason for complacency, adequate preparedness can minimise the safety issues and reduce property losses. For information and advice on preparing for cyclones, severe storms and flooding, people should contact their local State Emergency Service or their local council.

Ends

For further information call Rex Falls on (07) 3239 8739 (B/H).

Key NCC products:
SOI Graph B
SST Anomalies
Summer Rainfall Prediction