we hit a cell rising fast went from fl33 to fl39 in seconds and wild airspeed swings then back down to fl33 all three of us looked at each other and said what the hell was that?
So all you can say is the
indicated altitude/level changed (same probably goes for airspeed).
Within a CB as well as the turbulence the pressure variations will affect readings on the pressure instruments.
Hence the advice to fly attitude and set power.