It is doubtless true that in general there is little descent round the
edges of active growing large cumulus. The received wisdom is for
pilots to steer well clear of such clouds. I found over years of
experience that you could fly with the wingtip almost brushing the
cloud and not feel a burble of turbulence. You do of course keep much
further away from active cunims but the risk here is not so much
turbulences as lightning strikes.

I expect to be taken to task for flying so close to large cumulus, but
I can't have been so wrong. 40 years as a professional (survivor)

Jack