UK weather: Flash flooding warning if ‘wrong type of rain’ falls after heatwave

‘Be careful what you wish for,’ warns professor as heavy downpours after long dry spell may create problems

Heavy downpours following an extremely dry heatwave may result in flash floods, experts have warned.

The UK is currently scorching in a blisteringly dry four-day heatwave which has seen water shortages and wildfires.

However, an onslaught of rain may not be the answer, according to scientists.

It comes as a drought is expected to be declared for some parts of England on Friday (PA Wire)

Dr Rob Thompson, from the University of Reading’s meteorology department, posted a video on Twitter showing how different grass surfaces absorb rain.

The drier the grass surface, the less water is absorbed which stresses the likelihood of flash floods if a downpour follows the heatwave.

Dr Thompson said: “Britain desperately needs rain to break this drought. But we should be careful what we wish for.

“Experience around the world has shown what can happen when heavy rain follows a very dry and hot period that has baked the soil hard.

“The water can’t soak in easily, most of it just runs straight off the surface, which can quickly turn into flash floods.

“If you’re praying for rain, you should pray for two days of drizzle, as dreadful as that sounds.”

The Met Office retweeted his post, writing: “Dry ground takes more time to soak up water following a #heatwave than if it were during a normal summer. This experiment shows how heavy rainfall following an extended period of extreme heat could lead to flooding.”

The National Drought Group - made up of government and agency officials, water companies and other groups such as the National Farmers’ Union - is set to meet on Friday to discuss the prolonged dry weather.

A drought could be declared for the most affected areas of England in the south and east, after the driest July on record for some areas and the driest first half of the year since 1976.

Parched fields have become the norm after this summer’s series of heatwaves (Copyright 2022 The Associated Press. All rights reserved)

“Drought will not disappear in a matter of days — it’s going to take a long period of sustained rainfall,” Professor Liz Bentley, chief executive of the Royal Meteorological Society, said.

The threat of a drought has led water companies to impose hosepipe bans in areas across England, with Yorkshire Water being the latest company to announce a ban.

However, the water companies have come under fire by the public after reports of widespread wastage through leaking pipes.

Professor Hannah Cloke, Professor of Hydrology, University of Reading, said:“Water companies need to get their act together in fixing leaks faster, and showing that they are making progress, or they will face issues similar to those of the UK government in enforcing lockdown rules during the pandemic.

“It is hard to ask people to make sacrifices when the authorities look profligate.”