Chaos on M4 as 'grape-sized' hail hits South Wales; Pile-ups and injuries as drivers get caught in storm.
ELEVEN people were injured in a four car crash on the M4 when a freak hailstorm hit South Wales yesterday.
Rescue teams were also alerted to two other M4 crashes within 45 minutes as grape-sized hail and heavy rain made driving treacherous.
Of the 11 hurt in the pile-up, five were treated at the scene and six were taken to Morriston Hospital.
Cardiff South and Penarth MP Stephen Doughty was travelling on the M4 when the storm hit and described it on Twitter as the "biggest hail" he had ever seen in Wales.
Motorist Marc White, 45, who was driving on the M4 from Briton Ferry to Cardiff just after the storm hit, said: "The motorway was hard and white as an ice rink - there was absolute chaos.
"The hail had been compacted by the cars and I think people were caught out by it. I had to keep to 15mph, there was no way you could stop.
Mr White said he spotted seven separate incidents within a short stretch of the motorway around Bridgend.
"There were cars which had hit the hard shoulder, cars which had hit the central reservation and others which had slid off onto the embankments," he said.
"I've been driving that stretch for 25 years and I've never seen anything like it."
Mid and West Wales Fire and Rescue crews, helped by colleagues from the South Wales Fire and Rescue, were alerted to the multi-vehicle accident at 12.33pm.
It happened on the eastbound carriageway between Junction 38 at Margam and Junction 37 at Pyle, closing the motorway while emergency services helped the injured.
South Wales Police inspector Jo Williams said: "The accident happened at around the same time as the hail storm but we will have to wait and see as to the cause. Thankfully at this stage it seems there are no serious injuries."
About 30 minutes later a car careered down an embankment into trees between Junction 34 and 35, before another car slid off the motorway between Sarn and Pyle.
Both drivers were able to get out of their cars unaided by the time emergency services arrived.
The Met Office said at about the time of the crashes forecasters had been tracking towering thunder clouds which had been "funnelled" along the Bristol Channel.
Forecaster Emma Sharples said: "The clouds clipped coastal areas on both sides of the channel, with Somerset and Bristol getting really heavy downpours.
"On the Welsh side an area around Bridgend suffered a huge downpour of hail, we had thunder in that area as well."
WHAT CAUSES HAIL? HAIL forms in cumulonimbus clouds - a type of dense, towering vertical cloud associated with powerful upward air currents.
Forecaster Emma Sharples said: "A hailstone begins as a frozen raindrop or ice crystal.
"Strong updrafts of warm air and downdrafts of cool air move this frozen particle up and down through different levels of the storm cloud.
"The hailstone then attracts layers of frozen ice particles on its surface making it bigger and bigger.
"Eventually, the hailstones get so heavy they drop out of the cloud in huge storms and can cause difficult conditions for drivers."
HOW YOU RELIVED DRAMA ON TWITTER | @samofthepryce I've just passed three car accidents on the M4 due to ice and hail. Oh, dear. Living on the edge, here.
@_josh096 Passed about 5 crashes on the M4, this hail is deadly! #scary #drivesafely | @SDoughtyMP Some really bad crashes just passed near #stormydown as result of hail with @SWFireandRescue attending... Please take care if u on #m4 now. | @catgardiner M4 in chaos both ways between bridgend+port talbot-big pileup eastbound+more than 6 separate cars off road westbound due to crazy hail storm | @Mooro9 scariest experience ever in car on M4. Hail stone storm saw cars skidding 1 in front of us into ditch - walked away #drivecarefullypeople | @LilMissAshes Gnarly drive from Cardiff to Swansea on the M4 today. About 10 accidents around Bridgend. Stop rubber-necking people!!
@LydiaKate95 driving down the M4 and I've seen 5 accidents #howscary | @rachelbaker92 So many accidents on the M4 through the sudden snow storm. Literally 20 within 2 miles. Please everyone still drive super carefully!
@1SarahJayne Horrendous driving conditons M4 junction 36 and 37. At least 3 accidents on this stretch, cars pulled over and one up a hill!!! Awful.
@Sassy_1 Never seen so many accidents! #m4 #chaos #hailstones
Cars were battered with hailstones during the storm PICTURE: David Morley
Police officers attend the scene on the M4 near Pyle, Bridgend, yesterday
PICTURE: James Davies