The chance of more rain falling across large parts of Australia over the next three months remains high, according to long-term climate forecaster Roger Stone.
Professor Stone told Beef Central yesterday that 'reasonably high probabilities of rainfall' remained across the country through until the end of April.
“The whole wet season process is running a little bit later this season compared to last, however the La Nina pattern is still well and truly with us, and while that is there we always have this potential for above normal rain,” Dr Stone said.
The ‘climate year’ tends to operate from June to May, primarily because of the way the Pacific Ocean – the world’s prime ‘climate driver’ – behaves.
Most climate models work on 12 month cycles, and commence in autumn when the pattern for the new year emerges, usually in late May, early June.
However a handful of longer-term climate models are used to “see through” the autumn period changeover. In April 2010, for example, models from UK and US Government agencies identified the big wet that drenched Australia in 2010-11.
Dr Stone said the same longer-term models currently suggest the climate situation will come back to normal around the Southern hemisphere winter.
“They are showing a return to what might be termed normal conditions around winter at this stage, but everyone knows that this autumn period is fairly fickle, so things tend to change over quite quickly, certainly towards the end of autumn so it is good to do a re-assessment then.”
The chances of a La Nina developing in the 2012-13 summer at this point were impossible to rate, however a pattern of three consecutive La Ninas was not without precedent.
La Nina events spanning three summer periods occurred in 1954 to 1956 and 1973 to 1975.
Dr Stone said the current weather pattern, characterised by a start to the main wet season in late January, was similar to the patterns of early 1975.
Dr Stone is a professor in Climatology and Water Resources and the director of the Australian Centre for Sustainable Catchments based at the University of Southern Queensland in Toowoomba.
Flood-inducing trough over Qld and NSW weakens
The rain that has brought severe flooding to large parts of southern Queensland and NSW has started to ease.
Flood warnings are still current for rivers in northern New South Wales and southern Queensland, a severe weather warning for heavy rain is current for parts of Queensland and as conditions ease, a severe weather warning for flash flooding has been cancelled for parts of New South Wales.
The Weather Channel says the rainfall that has caused the flooding will alleviate over the course of today, with rain reducing to showers in southern Queensland and rain abating to isolated showers in northern New South Wales.
“We have seen classic La Niña weather this week with a near stationary trough bringing continuous heavy rain to southern Queensland and northern New South Wales,” Tom Saunders, senior meteorologist at The Weather Channel, said.
Mr Saunders said the trough was now finally weakening and only isolated showers were expected over the flood affected region by tonight.