or even under them if you want a 100-150kt car wash and get chucked around a fair bit.
I would be
very careful flying under a CB, Airliners have been unable to cope with some. It is not necessarily when it is raining that you get the biggest problem, this usually happens as it starts raining heavily, that is when you get the biggest downdrafts - not to mention of course the chances of a lightening strike!