UK weather: flash flooding fears as thunderstorms hit southern England after Met Office warning

Heavy rain for much of southern England could lead to flash flooding, leaving businesses and homes at risk of damage, forecasters have warned.

A yellow warning has been put in place for thunder for much of southern and eastern England, including Bath, Brighton, Norwich and London, until 2am on Monday (24 October).

A warning on the Met Office’s website states: “There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds.”

When is the warning in place?

The yellow weather warning has been issued by the Met Office for between 4am on Sunday (23 October) and 2am on Monday (24 October). Forecasters are concerned about a band of heavy rain and thunder which is expected to roll in across a large part of southern England.

What does the Met Office warning say?

Met Office meteorologist Alex Burkill warned that England still has some heavy thunderstorms to come this weekend.

“We still have some heavy thunderstorms to come as you go through the next 15 hours or so,” he said.

He added that storms could lead to 20 to 30 millimetres of rainfall in one hour, causing flash flooding.

He said: “It is because of the risk of some heavy thunderstorms coming through, talk of 20 to 30 millimetres perhaps in just an hour, and for some 40 to 60 (millimetres) in two to three hours.

“So, whilst the totals won’t be that high, we’re talking flash flooding, surface water flooding, just because of intense rates in a short period of time.”

The warning on its website adds: “Spray and sudden flooding could lead to difficult driving conditions and some road closures. There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds.

“Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services. There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost.

“Earlier thundery rain is now in the process of clearing northeastwards, but following a brief brighter interlude (albeit with scattered heavy showers and isolated thunderstorms), further heavy rain and thunderstorms are expected to spread northwards later this afternoon and evening, particularly across southern and then eastern parts of England, easing through the early hours of Monday morning.

“A few locations could see 20-30 mm falling within an hour and as much as 40 to 60 mm in 2-3 hours. Frequent lightning, squally winds and hail are also possible, these thundery hazards probably focused across southeastern parts of England.”

What is a flash flood?

The Met Office describes a flash flood as happening “when rain falls so fast that the underlying ground cannot cope, or drain it away fast enough”. Roads can “become like rivers and if there is a lot of water, it can flood buildings and carry cars away”.

Where the weather warning in place?

The Met Office’s yellow alert for between Sunday and Monday is in place for the following areas:

East Midlands

• Leicestershire
• Lincolnshire
• Northamptonshire
• Rutland

East of England

• Bedford
• Cambridgeshire
• Central Bedfordshire
• Essex
• Hertfordshire
• Luton
• Norfolk
• Peterborough
• Southend-on-Sea
• Suffolk
• Thurrock

London & South East England

• Bracknell Forest
• Brighton and Hove
• Buckinghamshire
• East Sussex
• Greater London
• Hampshire
• Isle of Wight
• Kent
• Medway
• Milton Keynes
• Oxfordshire
• Portsmouth
• Reading
• Slough
• Southampton
• Surrey
• West Berkshire
• West Sussex
• Windsor and Maidenhead
• Wokingham

South West England

• Bath and North East Somerset
• Bournemouth Christchurch and Poole
• Bristol
• Devon
• Dorset
• Gloucestershire
• North Somerset
• Somerset
• South Gloucestershire
• Swindon
• Wiltshire

West Midlands

• Warwickshire

What could the weather be like next week?

However desite the storms over the weekend, people could see some sunny spells next week once the storms are out of the way.

Mr Burkill said: “The theme through the next few days through this week is temperatures rising. So, with that in mind, by the middle of the week, we could be in the low 20s in some places, possibly 21, but probably only 20.”

He added that the only concern could be some further heavy rain on Tuesday night.

“The only slight cause for concern is a system that comes through Tuesday night into Wednesday,” he said. “That could bring some heavy rain, particularly for western parts.”