What happens to mass outbreaks if your clock rolls over while you're in an area with no spawns and no biome?

Question

Since mass outbreaks can be partially manipulated by the 3×3 grid where your character is at when a wave of outbreaks are generated, what pool does the game pull from if none of those tiles has Pokémon spawns?

Examples might include the boundary break from the cave near Alfornada allowing you to travel to some places otherwise inaccessible (like the unconfirmed yet speculated DLC area), the outskirts of the map where no Pokémon spawn and maybe some places you can get to with the glide speed glitch.

Answer 1

(Self Answer after finally figuring out a way to test it myself) - It uses the biome data and draws the affected outbreaks from there.