News In Depth
'Plume' blamed for freak weather
Fierce storms bringing torrential rain and even massive hailstones to some parts of Britain have been caused by a weather phenomenon known as the Spanish plume, forecasters said.
Warm moist air sweeping up from the south - known as the Spanish plume - was lifted by a cold weather front from the west bringing prolonged and exceptionally intense downpours.
Paul Knightley, senior forecaster at MeteoGroup, the weather forecasting arm of the Press Association, said: "The whole weather pattern of the last day or so over the UK was down to a phenomenon called the Spanish plume.
"Put simply, it is warm, humid and unstable air that comes from the south - usually from the Spain area.
"It is a pattern that when it sets up in the correct fashion will produce spectacular thunder storms.
"There is a lot of energy in the area and it is released in a spectacular way.
"There was a cold front coming in from the west which helped to lift the warm mass of air. With lots of energy in the atmosphere that translates into powerful storms."
The Spanish plume was behind three rare "super cell" thunderstorms that swept across the Midlands on Thursday bringing massive hailstones in some areas.
People in parts of Leicestershire posted pictures to Twitter of large balls of ice that had fallen during the weather on Thursday afternoon.
Super cell thunderstorms are common in areas like the plains of the US Midwest but make up just 1% of storms in the UK, according to Mr Knightley.
They can do "disproportionate damage" by bringing with them large hailstones, tornados, heavy rain and and high winds, he said.