The metaphor is a comparison between a storm, and The Bad Plus' music.
This is the final color scheme that I decided to go with, after a spending a lot of time with different color iterations. This version has a dark background and contrasting bold colors for the important elements. One thing that I kind of struggled with was finding colors that were bold enough to convey the strong sound of their music without making the poster look like some sort of indie alternative rock band.
I fragmented the text and the instruments to hint at the nature of the music, but particularly to The Bad Plus' live shows. In their performances, they often do a lot of improv, which to be honest, can sometimes become so much that it's unbearable (at some points during listening to their music, I just wanted to take my headphones off, they were so much!). But underlying all of that chaos was a complex harmony and synthesis of contemporary music with classic jazz. So, these fragmented images were meant to show this "controlled chaos."
Visually to help with the trope, and also make sure I was making this look like a music poster, I used the indexical objects of musical staffs as lightning bolts and music notes and raindrops. As the lighting bolts twist and turn, this represents the interaction of the band members with each other (even though there are 3 band members, I had 6 bolts, as only 3 did not really fill the page enough). The music notes are small, and even with their bright red color are not immediately visible if you just glance at the poster (while driving by, given the context that the poster will be in). But I still wanted to keep them as a smaller detail, something that might be noticed upon closer inspection of the poster.