Joe Zawinul and 15tET

I was reading a friend's Introduction to Jazz History textbook last
night. It said that after Wayne Shorter left Weather Report, Joe Zawinul
renamed the group Heavy Weather and experimented with
fifteen-tone-per-octave scales. Anyone know anything about
this?!?!?!?!?!?!?!?

A few pages earlier in the book, a Joe Zawinul group called Weather
Update was mentioned. Perhaps "Heavy Weather" above, which is also the
name of a Weather Report album, is a typo and should be "Weather
Update"?

I don't see either group mentioned in an online Joe Zawinul discography.
Help!