Edit: Unfortunately it was not supercell, only storm shelf.
Seč reservoir has many faces, but the wildest one is when a thunderstorm is close here. What a surprise in late evening on 25th June, 2016, when perfectly shaped supercell showed in front of me over the calm water. This is not that usual for Czech Republic. And it was so fast – just a few minutes after the storm hit not so far Čáslav city and moved further north. Used Canon 6D, Sigma 15 mm, f4.5, ISO 2500, 8x20s panorama from tripod.The