UK Faces 50mm Thunderstorms and Flood Risk as Temperatures Drop to 3C

Q: What hidden dangers lurk on the roads as sudden downpours mix with weeks of accumulated rubber and oil from the summer heatwave?

The main hidden danger is a thin, greasy film that forms when the first rain hits roads after a long hot, dry spell. Weeks of built-up oil, diesel, rubber dust and dirt are lifted to the surface by light or sudden rain, sharply reducing tyre grip and making the road behave more like “summer ice” than a normal wet surface. That raises the risk of skidding, longer stopping distances and loss of control, especially in the opening minutes of a downpour before heavier rain has had time to wash the surface clean. Expert road-safety guidance also points to a higher chance of aquaplaning, when tyres ride on a layer of water instead of gripping the tarmac, leaving drivers with reduced steering and braking control. The danger can be worsened by the heatwave itself. High temperatures can soften bitumen in the road surface and reduce its texture, further cutting skid resistance once rain arrives. With the ground baked hard, heavy showers can also create sudden standing water and flash flooding, particularly in dips, underpasses and poorly drained stretches. For drivers, the practical response is clear: slow down, increase following distance, avoid harsh braking or sudden steering, and do not drive through standing water if the depth is uncertain. Wet-weather crash risk is known to rise after long dry spells because both the road surface and driver expectations can be badly caught out by the first rain.

3 articles · Updated · bbc.co.uk · Aug 19

A Met Office yellow warning stays in force until 10:00 BST for northern England and north Wales, with thunderstorms then spreading south and east across Wales, the Midlands, East Anglia and southern England.
Up to 15-20mm of rain could fall in an hour and 30-50mm in six hours as low pressure and unstable air drive torrential downpours, hail and lightning.
Flooding and travel disruption are the main immediate risks, with hard-baked ground raising the chance of flash floods and RAC warning drivers about greasy roads after the long dry spell.
Temperatures are set to fall sharply, with Thursday highs at 13-23C, no UK location expected to reach 25C for the first time since 29 June, and some northern areas dropping to 3-4C overnight.
The rain is not expected to end the drought quickly, forecasters saying only sustained wet weather through coming months would replenish water stocks despite a wetter-than-normal summer in parts of the Scottish Highlands.