The Lonely Thunder Cloud

This was one warm and sunny evening, as the golden hour had just started in Espoo, Finland. Sun was up and I went for a landscape photography trip, I turned around and saw this, a huge thunder cloud, clearly on top of Helsinki City some 20 km/12 mi away from where I was standing at the moment. Later I learned from the news that Helsinki City had experienced torrential rains, some of the worst in History, and yes, I could have guessed that, could I...