Question about GPI (Genesis Potential Index) : meteorology

I’m working on a D&D campaign and was wanting to figure out how the world would actually work and am simulating it. I know GPI is used to determine where storms would appear, but I don’t understand how to read the numbers to determine how likely. It’s a tidally locked planet, so if those number are super high that’s why. So how would I read this? If you need other information about the world I can get that for you. The simulation has most things.