Not sure of the accuracy of this technique, but you may like to try it some day...
When approaching a CB buildup on your track...
Adjust the tilt/range to just see the very top of the buildup, then...
calculate:
(Selected range x 100) multiplied by (Tilt reading in degrees(-1.5 deg)) = height in feet the top of the CB is above your level.
Might be handy to know, if it can proven accurate in known conditions.