The latest weather bureau report predicting another summer of wild weather will force the Queensland Government to open the floodgates on major dams.
The forecast was delivered last Wednesday, but kept under wraps, it is expected to force the Government to reverse measures to keep the dams close to full before the wet season.
The Bureau of Meteorology has provided the federal and Queensland governments with the latest La Nina data, which shows the chances of extreme rainfall have doubled in the last few weeks.
Premier Anna Bligh announced on September 30 that Wivenhoe and North Pine would not be drained, the government hoping that Queensland would not be hit hard again.
The commission of Inquiry into last year's floods has been investigating the impact of the delayed release of water from full dams combined with the heavy rain.
Its interim report in August called for a reduction at Wivenhoe to 75 per cent only if another wet season threatened.
Natural Resources Minister Rachel Nolan said then that BOM had advised the Government that conditions would not be as severe, so the dams could remain at their current levels.
While north Queensland has received significant rain in the past week, experts thought the south would still be spared. But the new weather data shows climate models trending towards another La Nina event.
The Southern Oscillation Index, a key climate driver, had climbed from positive 6 to positive 12 in recent weeks. Although it was down on the positive 25 reading from a year ago, officials were still concerned it had doubled so quickly.
Weather bureau climate services manager Jeff Sabburg confirmed a new report had gone to Canberra and the State Government last week, but declined to elaborate. "It is embargoed until Tuesday," Dr Sabburg said.
However, sources said the report would raise fears that Queenslanders would be in for a repeat of the wild weather that claimed 35 lives last summer.
The US Climate Prediction Centre said last week that La Nina globally was expected to strengthen gradually into 2012, while the US National Centres for Environmental Predictions warned that the current La Nina might become as strong as last year's.
Premier Anna Bligh said that the government would reconsider draining the dams if information from the BOM indicated it would be required.
In the south east of the state last week, Wivenhoe dam was 81.5 per cent full yesterday and North Pine 97.3 per cent.