After posting this I made a game mode that required knowing when players are in the storm. As a result I ended up creating the storm from scratch and in doing so I always know its center vector3 and also the radius and can then determine if a player is in or out of it. Then I apply a cinematic to them with a sequencer. This is the only guaranteed way of knowing they are in the storm, but if someone is reading this in the future and does not want to reinvent the wheel you can check the damage source to your players with Verse and if it is not a player or NPC then assume it is the storm. This will work for a lot of scenarios but there are obviously other non character sources of damage like fall damage for example.
If you do recreate the storm, The hardest part is getting the material right lol. If you do it also be sure to make a UV cylinder with inverted UVs (faces pointing inward). Make a thick white outline on top with a transparent center and you can get the storm circle to show on the mini-map.