In this improvisation, I'm soloing over just two chords. Remember, it's very common to combine a major scale with the melodic minor scale built from it's 4th degree.
The first chord is Eb Major and the second is Abm6 which is equivalent to our Abm∆7 chord from Ab melodic minor. In other words we can play Abm6 in place of Abm∆7.
In order to play over this progression I'm using Eb major or Eb lydian for the Eb chord and Ab melodic minor for the Ab chord.
The purpose of this exercise is to get you used to switching between the scales smoothly and freely as I am.
A backing track is provided at the end of the tutorial so you can try your own improvisation.