Scene is set for a seventies-style wet

THE Bureau of Meteorology’s regional chief, Jim Davidson, briefed State Cabinet last week on the key weather issues for the upcoming summer.
He apparently made it clear that floods and cyclones are on the radar for Queensland for the next six months.
Davidson highlighted that the BOM seasonal outlook was for six cyclones and monsoonal rain for Queensland, and “not since the 1970s” had there been such a prognosis.
Most farmers probably agree after “the out of season wet” most of us have experienced in the last two months.
By early October virtually all of Queensland has passed annual rainfall averages, many places by a large margin, and the normally wetter months are still ahead of us.
Of course, exceptional rain can be just as frustrating as exceptional dry. It takes considerable skill to manage both the peaks and troughs of Queensland’s climate and the weather extremes that come with it.
This challenge was clearly seen in early October when we witnessed the unusual event of the partial emptying of Wivenhoe Dam so that it could serve its flood mitigation role for Brisbane.
This is the same dam that just three years ago was down to 12 percent of its capacity and Brisbane residents were looking for alternate sources of water for its ever growing population.
Most would agree that ahead of the wet season it is a good idea for Wivenhoe to have capacity to absorb some heavy falls, otherwise a repeat of the 1974 floods would be a distinct possibility.
When it comes to rainfall, Queensland farmers know they have to deal with the most variable climate of any place on the planet. That is why you see so many farmers and their advisors trying to identify cycles, trends and patterns in our weather.
All the better if the climate scientists like Jim Davidson can add some precision to the weather observations and predictions.
Most farmers are aware that for this year we have a 60 to 80 percent chance of above average summer rain.
This is mainly because of the La Nina influence in eastern Pacific Ocean as measured by the positive Southern Oscillation Index (SOI) published on the back page of this newspaper. This year there is the added presence of rising temperatures in the northern Indian Ocean and this boosts the odds for a prolonged wet season in north eastern Australia.
But what of the chances of twice or three times normal rain, like the past two months? That is more for sages than scientists.
One guide that farmers use is the so called hundred “analogous years” series. The Queensland government Long Paddock web site has provided this data and analysis for many years, and while it has a pasture growth focus for the cattle industry, most Queensland farmers know it’s the place to go when the SOI is outside “neutral territory” and pointing strongly to a wet or dry season.
The last three years have been La Nina years, but none as clear-cut as this one, so it is prudent to be prepared.
Whether we get three or six cyclones, or five or nine Natural Disaster Relief and Recovery Arrangement (NDRRA) events, and which localities will be in their path, will only be revealed with time.
But just as the 2002-2007 drought may be a lingering memory, it is timely to remember what 1998 to 2000, and 1973 to 1976 was like in your locality.
We will not get an exact repeat, but the signals are there for all Queenslanders to prepare for a long, wet and stormy summer.
For their part, Queensland farmers will remain optimistic that there are good stretches of sunny weather in between the many rain events predicted for the months ahead.
I also feel that Jim Davidson’s warnings provide a timely reminder to the experts trying to calculate what are “sustainable flows” for key river systems in Australia.
For a continent with such variable intra and inter seasonal rainfall patterns, perhaps all stakeholders need to acknowledge “natural flows” are as highly variable as the weather itself.