SCIENTISTS have been “severely underestimating” our short thunderstorms which are actually set to get worse.

The latest rainfall research on Australia reveals how heavy and quick rain storms are intensifying more rapidly than expected.

This means more flash floods, severe water surges in urban areas and bigger dry and wet extremes in general.

A team of international scientists, led by Newcastle University in the UK and involving the University of Adelaide, studied intense rain storms in Australia over the past 50 years and discovered they were substantially larger than anticipated under climate change.

They found the amount of water falling in thunderstorms is increasing at a rate two to three times higher than expected, with the most extreme events showing the biggest increases.

Associate Professor Seth Westra, of the University of Adelaide, warned this meant we were poised for worse problems.

“This large increase has implications for the frequency and severity of flash floods, particularly if the rate stays the same into the future,” Associate Professor Westra said.

“It seems counter intuitive when large parts of Australia are now in drought, but we need to remember Australian droughts are often broken by severe floods.

“We have always been a country of weather extremes, and it seems that climate change is causing both the dry and wet extremes to intensify.”

A devastating dry spell is affecting 99 per cent of New South Wales.

Below average rainfall since April 2017 has been exacerbated by warm, dry weather, according to the Bureau of Meteorology.

September 2017 was the driest September on record, compared with the previous year, which was the wettest September.

Two-thirds of Queensland and farmers in parts of Victoria, South Australia and Western Australia are also suffering.

Experts have warned shoppers could soon feel the pinch at the checkout as our drought crisis deepens.

While daily extremes can cause river flooding, hourly and multi-hourly extremes often cause urban flooding in small, steep rivers, and landslides.

The study in Nature Climate Change showed that the situation was worse in the tropical north where researchers expected an increase in severity of seven per cent but returned a “highly concerning” 20 per cent.

Lead author Dr Selma Guerreiro, of the UK, said scientists believed there was a limit on how much more rain could fall during extreme events because of rising temperatures but now that upper limit had been broken.

“The important thing now is to understand why rainfall is becoming so much more intense in Australia and to look at changes in other places around the world,” Dr Guerreiro said.

“How these rainfall events will change in the future will vary from place to place and depend on local conditions besides temperature increases.”

Associate Professor Westra said the changes were well above what engineers currently took into account when determining Australia’s flood planning levels or designing stormwater management and flood defence infrastructure.

“If we keep seeing this rate of change, we risk committing future generations to levels of flood risk that are unacceptable by today’s standards,” he said.

The analysis was based on looking at rainfall extremes between 1990-2013 and 1966-1989, from 107 weather stations from all over Australia.