Floods across the UK have brought misery to drivers and commuters on Monday, as the Met Office extended its amber thunderstorm warning of heavy rain, lightning, hail and strong winds. Homes and businesses are likely to be flooded quickly in north-west England, the forecaster said, with damage to buildings expected as a result of the storm. Some communities are also likely to become temporarily cut off by flooded roads, with power cuts likely to occur along with difficult driving conditions and road closures. The London fire brigade said it had been called to several reports of flooding across the capital after thunderstorms affected both roads and properties. It said: “Never drive through flood water – a foot of moving water at just 6mph is enough to float a car.” North of the capital, Watford Junction station was shut for an hour this afternoon, with trains cancelled and roads closed. Drivers also struggled to drive along the north circular road, after a burst water main exacerbated the heavy rain. In Staffordshire, the Meir tunnel was shut after a flash flood, causing a buildup of traffic between Uttoxeter and Stoke-on-Trent. In Lincolnshire, shoppers at a Morrisons supermarket in Stamford had to be evacuated during a thunderstorm when water poured through from light fittings and parts of the shop’s ceiling reportedly collapsed. A school was closed in Wantage, Oxfordshire, because of flooding. People were told to avoid the A&E department at Luton and Dunstable university hospital “due to a localised flooding issue” in the building. The Environment Agency has issued 14 flood alerts across the Midlands, saying heavy, thundery showers could produce large amounts of surface water. The Scottish Environment Agency has also issued flood alerts for 16 areas in Scotland. The amber thunderstorm warning covering parts of the West Midlands, north-west England and Wales is in place until 10pm. A yellow thunderstorm warning is also in place for thunderstorms and rain until 9pm on Monday, covering parts of Scotland, Northern Ireland, much of southern England, Wales, and the Midlands – and includes London, Manchester and Bristol. Further thunderstorms are forecast on Tuesday in Northern Ireland and parts of Scotland. Meteorologist Grahame Madge urged people in warning areas to prepare themselves. He told PA News: “Within the area we are advising that people might want to think about how suddenly they can be subjected to flash flooding or a power cut. Are people prepared? Make sure mobile phones are charged and that sort of thing. “Because when you get these storms they can change your circumstances quite dramatically within almost a matter of minutes.” Madge said heat rising from freshly ploughed fields or over a city area could trigger thunderstorms even when nearby areas remain dry. Higher temperatures are concentrated in the north, with Manchester, Leeds and Keswick in Cumbria between 30C (86F) and 31C, while south-central England remains in the high 20s, with London and Cambridge both reaching between 27C and 28C. Temperatures are going to decrease slightly towards Thursday and Friday but it will remain sunny and above 24C and 25C throughout the week, potentially reaching 29C in Bristol and Birmingham on Wednesday and Thursday. Cooler air from the North Sea will reach parts of the UK on Thursday and Friday, particularly areas along the north-east coast and the east of England.