MILLIONS of Brits are bracing for travel chaos and power cuts today as experts issue flood warnings with residents warned to "be ready" to leave their homes.
An "incredible deluge" wreaked havoc on homes and businesses yesterday with the Met Office warning fast-flowing water could pose a "danger to life".
Yellow thunderstorm warnings were in place for England and Wales yesterday by the Met Office and will remain in place for southern England today.
Forecasters have warned of more dangerous flash floods to come which could cause travel chaos and power cuts.
And the Environment Agency estimated that more than three million homes in England are vulnerable to floods as the downpour hits.
Experts urged families living in low-lying properties to place valuable items up high and pack emergency “grab bags” with phones, important documents, chargers and cash in case they need to be evacuated quickly.
Read more UK news
Those in low-lying properties should make sure their valuable items are "ready to go", or "on a higher level" due to the risk, forecasters say.
And according to experts, flash-flooding is the "wrong sort of rain" to help drought-affected areas from last week's warm spell, as dry conditions make soil like "concrete" and incapable of absorbing anything.
Flash floods have already caused damage to thousands of homes and businesses, with the Met Office warning fast-flowing water poses “danger to life” and can cut entire communities off.
The agency yesterday issued 19 flood alerts for areas of South London, Surrey, Derbyshire, Nottinghamshire, Leicestershire and Norfolk.
Most read in The Sun
A more serious amber thunderstorm warning was already in place for areas of Cornwall, Devon and Somerset, which have seen the worst of the flooding.
In Cornwall, up to three inches of rain came down in just a few hours. Parts of Truro town centre were under water while nearby Bodmin was pelted by hail “the size of £1 coins”.
Staff at The Milky Way adventure park in Devon had to clear out floodwater as their premises were deluged.
Met Office spokesman Grahame Madge told the : "If people know that properties may have flooded before it might be the time just to be ready – have a clear up, put any valuables at a higher level.
"It could be as simple and as fundamental as that, so that if you do have to move quickly you are already halfway prepared.
"It’s incredibly challenging to identify where you are going to get the most extreme events."
Met Office forecasters have predicted "thundery showers" for much of the UK today - with thunderstorms "popping up anywhere".
Thunderstorms are set to continue in the early hours of the morning with a waterspout spotted off the coast in Fowey Harbour, Cornwall, yesterday.
Stefan Laeger, flood duty manager at the Environment Agency, said they are "closely monitoring the situation, with our teams out on the ground and ready to support local authorities in responding to surface water flooding.
"We urge people not to drive though flood water - it is often deeper than it looks and just 30cm of flowing water is enough to float your car.
"However this rainfall will not correct weeks of dry weather so we are continuing to respond to the environmental impacts of drought and working with water companies to make sure they are following their drought plans."
Roads had already turned into rivers overnight, with the Met Office warning of the risk of power cuts.
Meanwhile thunderstorms developed in east-coast counties like Essex, Suffolk and Lincolnshire.
And today, hail, frequent lightning and flash flooding is possible in areas further south, with heavy rain predicted across England and Wales.
The rain will likely later become more concentrated in southern parts of England.
But despite the rain, temperatures will remain in the 20s in parts - but it will feel far cooler than last month's record-breaking heat.
July was the driest on record since 1935, scorching grass areas across the UK, starting wildfires and drying up our reservoirs as a result.
And yesterday Yorkshire became the latest region to declare a drought after eight other areas changed status last week.
Yet the unsettled weather forecast for this week might not bring enough rain to replenish the crisp ground.
Professor Hannah Cloke, an expert in hydrology at the University of Reading, explained why drought-hit areas could be more at risk of flooding.
She said: "The ground is really dry and when it is so dry it acts a little bit like concrete and that water can't get in so it drains straight off.
"There is the damage to homes and businesses these floods can cause, and inconvenience with transport disruptions, but if it is very heavy in one place it can also be very dangerous."
READ MORE SUN STORIES
Read More on The Sun
Explaining why this heavy rain will not alleviate drought-hit areas, she said: "It's a drop in the ocean really. It is not soaking into the soil which is how we really need it. We need it back into the system where it can be stored.
"We really need a long winter of rain to replenish this."