It was a beautiful splashy summer day on Thursday with passing showers and big puffy clouds. The showers, sometimes with a bit of thunder, were local so you could see them from a distance through clear sky. The cumulus clouds built into cumulonimbus storm clouds with lightning flickering inside them. As I was driving through the neighborhood I saw these cumuli building up in the early evening. This study is done from memory.
Photoshop, about 7 1/2" x 3", August 2, 2013.