Storms can be a useful tool when creating atmospheric environments, when you want lighting to illuminate your scene.
Storm keyframes are added to the cloud layer, to create structures representing thunderstorms. Just like with cloud keyframes, you can get and set their properties via scripting or blueprints as well as in the sequencer. Don’t forget, to produce a storm, you need clouds!
We have a youtube overview documenting these settings and how to use them here: