UK weather - live: Thunderstorm threat to continue across weekend as drivers warned of flash flooding

Good morning, and welcome to The Independent's liveblog, where we update you on the stormy weather expected across England and Wales today.

Thunderstorm warnings cover England and Wales

(Met Office)

Most of England and the entirety of Wales is under a yellow thunderstorm warning by the Met Office until Monday.

According to the weather agency, that means heavy showers and thunderstorms are expected at times.

Residents should be aware there is a small chance of homes and businesses being hit by flooding, and there is potential for damage to some buildings due to floodwater, lightning strikes and large hailstones.

The adverse weather could result in delays and cancellations to train and bus services, as well as disruption on the roads due to flash floods.

The Met Office also warns of power cuts to some homes and businesses.

Network Rail pledges to review management of extreme weather following train derailment

Emergency services inspect the scene following the derailment of the ScotRail train which cost the lives of three people near Stonehaven (Getty)

Network Rail has pledged to review its resilience to, and management of, extreme weather following the derailment of a train earlier this week that resulted in the death of three people, including the driver.

The company is investigating the cause of the derailment, which remains unknown, but it is believed torrential rainfall and flooding contributed to the tragedy.

Chief executive Andrew Haines said there had been floods and landslips in the area due to the “appalling” weather, and Network Rail will put extra measures in place including “heightened inspections” and “medium-term work with meteorologists to improve information and forecasting”.

“Our climate is changing and it is increasingly challenging the performance and reliability of the railway, but incidents like yesterday’s devastating accident are incredibly rare, and our railway remains the safest major railway in Europe,” he said on Thursday.

“Our network was designed for a temperate climate and it’s challenged when we get extremes such as storms and floods. We are seeing this more and more and although we can address them on the ground with precautionary measures, we are acutely aware we need a long-term resolution, and we had already secured additional funding and resources to help achieve this.”

Londoners rejoice as storms hit overnight

While some parts of the country experienced torrential rain, hail and flash floods, many Londoners felt the promised rain had passed them by.

But on Thursday night, several areas in the city reported dazzling displays of lightning and - at last - the relief of rain.

M25 flash flood in pictures

A deluge of rain caused flash flooding on the M25 on Thursday evening, leaving drivers stuck in traffic for hours.

The Roads Policing Unit for Surrey Police tweeted the M25 was closed between junction six and eight to allow authorities to pump water off the road and allow those trapped on the hard shoulder to make their way through.

Screen grab from footage taken with permission from the Twitter feed of @planetmyk of flash flooding on the M25 near Redhill (Mike Purvey)

Screen grab from footage taken with permission from the Facebook page of Matt Hickmott of flash flooding on the M25, where it was also raining and hailing (Matt Hickmott/PA)

Screen grab from footage taken with permission from the Twitter feed of @Julian_HJ of flash flooding on the M25 near Junction 7 (PA)

Thunderstorm Factbox

(PA)

Spectacular thunderstorms have lit up the UK skies this week.

Here are the answers to some of the key questions around thunderstorms.

Why do thunderstorms happen during heatwaves?

The two vital ingredients for a thunderstorm are instability in the atmosphere and moisture.

Thunderstorms take place when there is more humid air in the system, which is the case at the moment during the ongoing heatwave.

They tend to develop later in the afternoon after the progressive heating during the early part of the day.

What is a thunderstorm?

A thunderstorm is a series of sudden electrical discharges resulting from atmospheric conditions. These discharges result in sudden flashes of light and trembling sound waves, commonly known as thunder and lightning.

Thunder and lightning are associated with convective clouds and are often accompanied by heavy rain or hail.

Thunder is the sound produced by the rapid heating of air by a lightning strike, and lightning is a huge electrical discharge that flows between clouds, from a cloud to air, or from a cloud to the ground.

How do thunderstorms form?

Thunderstorms are created by the intense heating of the earth's surface, and are most common in parts of the world where the weather is hot and humid.

The Met Office says thunderstorms develop when the atmosphere is unstable - when warm air exists underneath much colder air.

Are thunderstorms common?

Thunderstorms are common occurrences on Earth.

It is estimated that a lightning strike hits somewhere on the Earth's surface approximately 44 times every second, a total of nearly 1.4 billion lightning strikes every year.

In the UK, thunderstorms are most common over the East Midlands and the south east of England.

PA

Weather watches snap cloud conditions amid storms

Cloud formations can be fascinating, particularly during stormy or unsettled weather.

Here are some of the best cloud photographs in the UK, posted on Twitter, from the past week:

Thunderstorm warnings removed for some parts of England and Wales

The Met Office has updated its yellow thunderstorm warnings, removing the warning area from southern parts of northern England, parts of the Midlands and all but the southeast corner of Wales.

On Saturday, the warning covers a smaller area, as storms are unlikely to hit southwest England.

But on Sunday, the warning area expands to cover southwest England, as well as extending over the whole of Wales and England up to Manchester. Northern England remains less likely to see impacts.

The Met Office’s warning on Monday said: “Some slow moving thunderstorms may form during the afternoon before these largely die out through the evening.

“Many locations within the warning area will miss the thunderstorms altogether, but where they do occur, 30-40mm may fall in an hour with 50-70mm possible in three hours.

“Thunderstorms may be accompanied by large hail, frequent lightning and gusty winds.”

Garden floods in St Albans

Consistent rain overnight has caused a St Albans resident's garden to flood.

Conditions in the east of England are warm and humid, but further heavy showers and thunderstorms are likely to continue in places overnight, according to the Met Office's forecast.

Best umbrellas for stormy days

Need an umbrella that won't blow out on you during a storm? Heidi Srimgeour has the rundown on the best sturdy umbrellas: