Severe thunderstorm warning: Met Office issues amber alert for London and the south east - full list of areas

The Met Office now says the storms expected to batter east and central parts of England are now worthy of an amber, rather than yellow alert. It says that torrential rain could lead to some significant surface water flooding during Saturday morning.

What is an amber alert?

The Met Office weather warning system has three levels; yellow, amber and red. In short, red signifies a danger to life. While yellow alerts are relatively common, amber alerts - which denote the increased likelihood of severe disruption and treacherous conditions - are not.

For this weekend for the area covered by the amber alert which is London and the south east, some communities are likely to become cut off if roads flood. The Met Office says that spray and sudden flooding will probably lead to difficult driving conditions and some road closures. Power cuts likely to occur and other services to some homes and businesses could be lost.

Where does the amber alert cover?

The alert covers the following local authority areas: Bedford, Cambridgeshire, Central Bedfordshire, Essex, Hertfordshire, Luton, Southend-on-Sea, Thurrock, Bracknell Forest, Brighton and Hove, Buckinghamshire, East Sussex, Greater London, Hampshire, Kent, Medway, Oxfordshire, Portsmouth, Reading, Slough, Surrey, West Berkshire, West Sussex, Windsor and Maidenhead, Wokingham.

The alert lasts from 4am to 11am on Saturday.

What is the weekend’s forecast?

The Met Office says: “Areas of heavy rain with embedded thunderstorms will move northwards during the early hours of Saturday, with torrential downpours in places. Accumulations of 20-40 mm are possible in 1 hour, and where heavy downpours persist then as much as 70-100 mm could accumulate in just a few hours. Significant impacts are possible if this occurs over more urban areas.

“The more widespread heavy rain should clear to the north during Saturday morning, but additional scattered heavy showers and a few thunderstorms could develop during Saturday afternoon and early evening, this risk covered by the much larger yellow thunderstorm warning.”

What else does the Met Office recommend?

Its advice includes: “Being outside in high winds and/or lightning makes you more vulnerable to injury. Stay indoors as much as possible. If outside, try not to walk, or shelter, close to buildings or trees, or other structures which could be struck by lightning. If you hear thunder, and are unable to get to a safe enclosed shelter (such as a car), crouch down in a ball-like position with your head tucked in and hands over your ears making minimal contact with the ground, away from objects that conduct electricity.”