Good evening all, could somebody please explain to me what I witnessed?
When I was on holiday in Rovinj, Croatia back in June 2000, I witnessed a strange severe weather event which I never really could explain as I have only a basic understanding of convective weather and you'd never see something like this in Britain.
It was a very warm, sunny afternoon and we were sitting in an outdoor bar at the marina, directly facing the Adriatic Sea to the West. Then, from the horizon appeared a blanket of extremely-fast-moving, dark clouds, relatively low-level, flat and seemingly shapeless. It was quite a menacing sight as I've never before (or afterwards) seen clouds moving that fast! As soon as they reached the coast, the wind immediately picked up from a soft coastal breeze to a strength at which large branches, outdoor umbrellas and even chairs and tables were broken or overturned, there were also large waves that frightened and completely soaked quite a few unsuspecting tourists spread along the rocky beaches. There was no lightning or rain, just a very powerful wind. The mini-chaos only lasted for few minutes and then it stopped as quickly as it started. It was sunny again and other than the debris around town, it was as if nothing had happened (it maybe felt little fresher but that's all). It was fine sunny weather for the rest of the afternoon and early evening, until...
...probably around 20.00, an thunderstorm arrived, it was extremely intense with the night sky almost constantly lit with flashes. I'm not even sure if it came from the same direction as the initial event as I recall seeing impressive cumulonimbus tops on the horizon from our hotel balcony, which faced inland rather than the Adriatic. The storm lasted for a while, I think until around 00.30-01.30 with a a couple short breaks of lower intensity in-between.
What I still can't get my head around is, what were the very fast-rolling clouds and if they preceded the severe thunderstorm, why was there such a long break between the two events? I'd be delighted if someone could finally solve this mystery!