never to go closer than 10 nm to an active CB cloud
Good advice, but remember the life cycle of a Cb. Starts with a towering Cu which matures into the Cb, with it's associated thunder/lightning/turbulence, and finally the dissipating stage. If there is little wind shear (turbulence), the storm will rapidly enter the dissipating stage and 'rain itself out'. Perhaps you saw the dissipating stage.