Bill,
Us 'oldies' will remember the non-synthetic monochrome radars such as the Ecko 170/190 series where the term 'Iso echo' was used for the facility which 'inverted' returns over a preset value which had the effect of creating a 'hole' in the middle of the cloud return - through which one should not go!
Nowadays, we have happily moved on to synthetic colour radars which can give much more information about the strength of any return using colour.
So the answer to your question is no, but some radars such as those mentioned above did have a facility which was called 'Iso Echo Contouring' - probably still going in HS748 etc.
Cheers,
mcdhu