Yellow warnings as thunderstorms could bring flash floods

Yellow weather warnings for thunderstorms and heavy rain are in place for much of the UK, bringing potential for flash flooding.

Most of England falls under the alert which runs until 21:00 BST and may cause disruption to travel, fast-flowing water and power cuts, the Met Office says.

A separate yellow rain warning covers eastern Scotland from the Borders up to Aberdeen, running from 16:00 on Saturday until noon on Sunday.

It follows the agency issuing a more severe amber thunderstorm warning for London and south-east England which ended at 11:00 on Saturday, though the “torrential downpours” forecast were not as bad as feared.

The wet weekend comes after a third heatwave of the year that parched swathes of the UK and led to several hosepipe bans being declared.

The recent warm spell has made flooding more likely and severe as the dry ground is unable to absorb as much water.

While the more severe warning is now over, the yellow thunderstorm warning in place for Saturday afternoon covers all of England except for the south west.

All of Cornwall and much of Devon fall under a separate yellow warning for rain from midday on Sunday until the early hours of Monday.

This is alongside the rain warning in eastern and central Scotland, which runs overnight on Saturday.

Wales and Northern Ireland have escaped the alerts.

Yellow alerts indicate a “slight chance” of power cuts, flooding for roads and businesses and some delays and cancellations to train and bus services, according to the Met Office.

Thunderstorms develop when warm and humid air exists below much colder air in the atmosphere. This destabilises the air, allowing clouds to form and produce heavy rain – and storms.

They have developed over northern France but they will be allowed to “grow” as they move north over the eastern half of the UK on Saturday.

Last week’s heatwave brought travel disruption, a number of water-related deaths and hosepipe bans being declared for millions living in Yorkshire, Kent and Sussex.

One might think a heavy dose of rainfall would help reduce these drought conditions, but because the rain will be very heavy in localised areas, it will run off the dry, baked earth rapidly, perhaps overwhelming local sewers and waterways.

A substantial recovery in reservoir and groundwater aquifer levels would require a more sustained spell of wet weather.

Yorkshire’s hosepipe ban is expected to last until winter.

Thunderstorms following a heatwave in the summer of 2022 brought flash flooding to London and the surrounding areas, flooding roads and Tube stations.

The rainfall also caused cancellations and delays at Gatwick Airport.