Churning Morning Sky

I had heard some muffled thunder and had just stepped outside to take the recycling out when I saw this view of the sky-- a churning, swirling mass of clouds that included some mammatus in the mix. The heavier clouds were even creating bow shocks (upper right) into the less dense leading edge of clouds. This view looks west over Bowman Woods Park in Cedar Rapids, Iowa just before 6:30 AM, Thursday, June 2, 2011. In about another five minutes the spectacle was over. The clouds were part of an approaching thin and rather weak line of thundershowers.