I just read this article on RT, the storm which hit the Southern Italian regions was pretty impressive with hailstones as huge as human adult palm or fist:
In the article there are some video footage taken during the storm, pretty impressive.http://www.rt.com/news/314666-hailstones-naples-italy-thunderstorms/ said:The Italian city of Naples was pounded with a storm of massive hailstones on Sunday, many of which were the size of fists. The huge chunks battered cars, smashed windows, and injured several people and animals.
The “baseball size hailstones” fell from thunderstorms at a speed of “at least 75 miles per hour,” according to Jonathan Erdman, a senior meteorologist for the Weather Channel.
“It's no wonder you can see the magnitude of smashed windshields and structural damage,” he added. The storm was caused by a southward plunge of the jet stream that carved into western Europe, sending an upper disturbance into the Italian peninsula on Saturday, according to Erdman.
...That instability stirred up a thunderstorm over the Mediterranean, which swept into Italy and caused the hailstones.
While the hailstones were certainly impressive, they weren't Europe's most destructive. Germany holds that record, with a hailstorm that caused an estimated US$2 billion in damages in 1984.