New Bureau of Meteorology (BOM) data suggests this summer could see another La Nina event develop, leading to higher than average rainfall across northern and eastern Australia.

An updated bureau forecast was delivered last week to the Federal and Queensland governments, but will not be released to the public until tomorrow.

Brisbane’s Sunday Mail newspaper says the new forecast indicates that the Southern Oscillation Index, a key climate indicator, has climbed from +6 to +12 in recent weeks, although this is lower than the +25 reading recorded during the La Nina event last year.

The most recent public update from the bureau, released on October 12, says conditions in the tropical Pacific Ocean “are consistent with the early stages of a late-forming La Nina event”.

It adds: “If the current cooling persists, as is expected, then 2011/12 will be recorded as the second La Nina in as many years. Current observations and model predictions indicate that this La Nina is likely to be weaker than the strong 2010/11 event.”

The report comes after the Queensland Government last month decided not to lower water levels in the Wivenhoe or North Pine dams in preparation for the imminent wet season, after advice from several agencies that the season would be less severe than last year.

Wivenhoe Dam is currently 81.5% full while North Pine Dam is 97.3% full. The Queensland Floods Commission of Inquiry’s interim report in August called for a reduction at Wivenhoe to 75% – but only if another strong wet season threatened.

Queensland Premier Anna Bligh told the Sunday Mail yesterday that a decision surrounding the dam levels could be reviewed.

“If a new forecast shows a greater danger of flooding and cyclones this year than previously thought, of course we will look at lowering the level of the dams,” she said. “We will rely on the advice of BOM and follow the recommendations of the commission of inquiry to the letter.

“But the Government’s priority will always be protecting lives and protecting property.”