Impressive clouds...

A thunderstorm developed here this morning. A few hours later, the clouds below appeared over the town, signifying the very unstable air. This picture was shot by me today (5 July 2006) at 13:00 CEST (11:00 UTC) from the Beestenmarkt, Leiden. I have tried to identify the type, and the best I can come up with is Stratocumulus opacus mamma.