Flooding fears for Wales as heavy rain set to hit dry ground on Monday

The Met Office have warned that there could be floods in Wales as downpours look set to follow on from scorching weather early next week.

A yellow warning for Monday follows on from days of amber weather warnings for “extreme heat” across parts of the country.

Floods are a danger after dry weather as the water hits dry, hard ground rather than softer ground that can absorb a large volume of water at once.

The Met Office said that “thunderstorms are likely to develop during Monday, bringing locally heavy rain and possible disruption”.

“There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds.”

They are also warning that:

• Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services
• Spray and sudden flooding could lead to difficult driving conditions and some road closures
• There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost

Thunderstorms are likely to develop “increasingly widely” in Wales by “late morning and into the afternoon,” they said.

“Storms should begin to ease from the west later. Very locally 20-30 mm of rain is possible in an hour, and up to around 50 mm in three to six hours. Hail and frequent lightning are also possible.”

The yellow weather warning is in place between 6am and midnight on Monday.

‘Careful’

A university professor has warned that people should “be careful” about wishing for heavy rain to cool down temperatures as a downpour could lead to flash floods.

Rob Thompson, who is part of the University of Reading’s meteorology department, posted a video of an experiment on Twitter which used three glasses of water on different grass surfaces to demonstrate what happens when it rains after a drought.

In this experiment Dr Rob Thompson of @UniRdg_Met shows just how long it takes water to soak into parched ground, illustrating why heavy rainfall after a #drought can be dangerous and might lead to flashfloods. @R0b1et @UniRdg_water pic.twitter.com/zbb3xLTXdK

— Uni of Reading (@UniofReading) August 10, 2022

In the first experiment, a glass of water is put on top of wet grass and rapidly soaks into the ground, with the second experiment highlighting that water soaks into grass during a normal summer at a slower pace.

In the final experiment, the water is placed on to what appears to be dry grass and does not seem to budge, highlighting the potential for flash floods to occur if heavy rain follows a heatwave.

Dr Thompson told the PA news agency: “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 the post and added: “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.”

Drought

Meanwhile, a drought has been declared for parts of England following the driest summer for 50 years.

The conditions, which have almost completely deprived some areas of rainfall all summer, have prompted the National Drought Group to move parts of the South West, parts of southern and central England, and the East of England into official drought status.

The change could lead to more measures such as hosepipe bans, however, the Environment Agency has reassured the public that essential water supplies are safe.

The NDG is made up of representatives from the Department for Environment Food and Rural Affairs (Defra), water companies, the Environment Agency, the National Farmers’ Union, Natural England, Consumer Council for Water, water services regulator Ofwat, Water UK and the Drinking Water Inspectorate, as well as the Angling Trust and the Rivers Trust.

At a meeting earlier this summer, it moved most of England into “prolonged dry weather” status, the first of four stages used to describe it’s response. It has now moved to “drought”, the second stage.

Water Minister Steve Double said action was already being taken by the Government, the EA and others to manage the impacts.

“All water companies have reassured us that essential supplies are still safe, and we have made it clear it is their duty to maintain those supplies”, he said.

“We are better prepared than ever before for periods of dry weather, but we will continue to closely monitor the situation, including impacts on farmers and the environment, and take further action as needed.”

The most recent EA data showed rainfall totals for August have ranged from 12% of the long-term average in north east England to 0% in south east and south west England.

Meanwhile, river flow data revealed almost 90% of measuring sites were showing below normal readings, with 29% classed as “exceptionally low”.

‘Tinder dry’

It comes after the driest July on record for some areas and the driest first half of the year since 1976.

Four water companies, Welsh Water, Southern Water, Thames Water, and South East Water have all imposed hosepipe bans, while Yorkshire Water has announced a ban will start on August 26.

The heat and dry conditions have also taken their toll on agriculture.

According to the NFU, crops such as sugar beet and maize are showing signs of stress from a lack of rain, while crops relying on irrigation, such as field vegetables and potatoes, are also facing problems.

NFU deputy president Tom Bradshaw said the situation was “hugely challenging” for farmers who were facing running out of irrigation water and having to use winter feed for animals because of a lack of grass.

The NFU also said “tinder dry” standing crops and parched grass posed a huge risk of fires spreading.

Mark Hardingham, chair of the National Fire Chiefs Council, said: “While we are likely to see more wildfires due to the current conditions, it is impossible to say whether this will be more than when the country experienced 40-degree temperatures.

“The bigger risk at the moment is a combination of temperature and wind speed, which will contribute to fire spread and makes incidents harder to manage and extinguish.”

However, he added brigades were “well prepared and have plans in place” to respond.