Flash floods that have destroyed homes and businesses, and caused travel chaos across Britain could be down to a weather phenomenon known as the "Spanish plume", meteorologists say.
Hailstones the size of golf balls rained down on the streets of Leicestershire as a unique combination of rare weather conditions led to the creation of "supercell" thunderstorms.
Paul Knightley, senior forecaster at MeteoGroup, said the freak circumstances were created by warm, moist and "unstable" air sweeping up from the south being lifted by a cold weather front and bringing unusually intense downpours.
"What tends to happen is that warm dry air from the Spanish plateau sits on top of more warm, humid air and acts like a lid," he said.
Air is unable to rise through this hot lid, but as the sun heated the ground below and a cold front came in from the west, "the humid air exploded up into the atmosphere. We also had the winds changing direction, and that can help make the storms even more powerful, creating supercell thunderstorms.
This combination is quite rare".
The storms in the Midlands eased yesterday, but not before killing a man in Shropshire. Retired maths teacher Mike Ellis was walking across fields in Bitterley, near Ludlow, when he was knocked off his feet by a brook that had burst its banks.
In North Tyneside, residents were evacuated by boat as the region was hit by thunderstorms. Twice the average rainfall for June fell in less than four hours.