A WARMING atmosphere is predicted to bring more intense heavy rainfall events to north-east Tasmania increasing the risk of serious flooding in the South Esk River, according to the CSIRO.
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The warming trend in the East Australia Current is also changing the marine landscape near Tasmania with marine heatwaves likely to produce conditions for further POMS outbreaks.
The Bureau of Meteorology and CSIRO released the annual State of the Climate report on Thursday, detailing the south-east Australian coast as experiencing the most intense surface ocean warming.
More instances of weather events bringing moisture from the tropics down to the south-east have also been recorded.
CSIRO Climate Science Centre senior research scientist Michael Grose said cutoff lows – which bring heavy rainfall to north-east Tasmania – would bring even greater rainfall in a warming atmosphere.
“Tasmania gets heavy rainfall from cutoff lows (the broader category of weather systems that East Coast Lows belong to), the area around St Helens and Gray regularly receive extreme rainfalls from these systems (Gray had 327 millimetres in one day in 2011), and this is linked to flooding in the South Esk River,” he said.
“In general, the intensity of rainfall at the minutes-to-hours timescale is projected to continue getting greater with a warmer atmosphere, and this is likely to increase the intensity of rainfalls from cutoff lows.
“The frequency and intensity of the systems themselves may also change.”
The warming and strengthening of the East Australia Current has brought marine species further south than before. Mr Grose said species usually only found in Victoria and New South Wales are increasingly being found in Tasmania.
While north-eastern areas are likely to experience more frequent and more intense heavy rainfall events, the overall trend for Tasmania is more heat extremes and fewer cold extremes.
Mr Grose said Tasmania is also becoming drier.
“The change in the average temperature is less than for most other regions of Australia and less than the global average, due to the moderating effect of the adjacent Southern Ocean,” he said.
“Tasmania has been getting drier, and is projected to experience further changes in annual rainfall, but perhaps more importantly a change in the seasonality of rainfall, with reductions in spring and perhaps summer but little change or an increase in winter.
“But of course these long-term changes are accompanied by substantial ongoing variability year-to-year.”
Read the State of the Climate report for 2018: