Further warning issued as thunderstorm likely to cause flooding and damage

The Met Office previously issued a yellow warning which covered North Wales, and warned that floodwater, lightning strikes, hail and strong winds could damage property.

The thunderstorm warning is expected to come into force from 4am on Saturday until 11.59pm the same day.

Heavy rain is also expected from Friday.

What to expect

There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater.

Spray and sudden flooding could lead to difficult driving conditions and some road closures

Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services

Met Office advice on how to stay safe in a thunderstorm:

There are many myths surrounding lightning - such as lightning never strikes the same place twice or it always strikes the tallest object. Both are false, as lightning strikes the best conductor on the ground - whether it has been struck before or not.

Thunderstorms can occur at any time of the year but it is during the summer months when thunderstorms in the UK are most likely to produce large hail, gusty winds and torrential downpours that can cause disruption to transport networks and damage property.

Before the thunderstorm

Lightning can cause power surges, unplug any non-essential appliances if not already using a surge protector.

Seek shelter if possible. When you hear thunder you are already within range of where the next ground flash may occur, lightning can strike as far as 10 miles away from the centre of a storm.

During the thunderstorm

Telephone lines can conduct electricity so try to avoid using the landline, unless in an emergency

If outside avoid water and find a low-lying open place that is a safe distance from trees, poles or metal objects

Avoid activities such as golf, rod fishing or boating on a lake

Be aware of metal objects that can conduct or attract lightning, including golf clubs, golf buggies, fishing rods, umbrellas, motorbikes, bicycles, wheelchairs, mobility scooters, pushchairs, wire fencing and rails. If you are in a tent, try to stay away from the metal poles

If you find yourself in an exposed location it may be advisable to squat close to the ground, with hands on knees and with head tucked between them. Try to touch as little of the ground with your body as possible, do not lie down on the ground

If you feel your hair stand on end, drop to the above position immediately

After the thunderstorm

Avoid downed power lines or broken cables

If someone is struck by lightning, they often suffer severe burns. The strike also affects the heart, so check if they have a pulse.

Driving in a thunderstorm

If you are caught out in thunder and lightning it is advised that you wind up the windows and stay inside your car. This is because in the vast majority of cars with a metal roof and frame, the frame will act as a conductive Faraday cage, passing the current around the passengers inside and on to the ground.

Soft-top convertibles, with their fabric roofs, are the most at risk and could catch fire if struck by lightning

Be aware that current can travel through other parts of many modern cars, including GPS and radio systems. Cars with metal interior handles, foot pedals and steering wheels can also carry current

Cars can be damaged both internally and externally by lightning strikes

Thunderstorms can also bring a risk of sudden gusty winds, those most at risk would include cyclists, motorcyclists and high sided vehicles.

Remember to give vulnerable road users including cyclists, motorcyclists and pedestrians more room than usual. They are more likely to be blown around by side winds – always keep a safe distance.

Keep your speed down, lowering your speed will lower the distance you travel when buffeted around by the wind.

Hail storms can be extremely dangerous to drive in reducing your ability to see and be seen, as well as causing damage to your vehicle. If hail is severe, stop and pull over to a safe place and remain inside the vehicle