In the event of a storm/hurricane, etc, there are set guidelines for when/if any attractions, or even the parks, are shut down (& that usually only occurs for a maybe 24-ish hour period of an actual hurricane). Disney is very good about taking care of their guests, and will make it clear if the weather gets bad enough to close the parks. In that case, they make sure everyone knows, and are taken care of until the weather clears and the fun resumes!
They are also amazingly fast at clearing up any damage or debris. I've even read that some locals get rooms at Disney resorts if a hurricane is expected because of how well they handle storms, and how well their buildings are built.
Sorry, that went beyond your question, but I hope it helps you to be less stressed about being there if the storm does affect the area. We will be there too, and I don't love the rain, but we plan to have a great time, wet or dry!
I hope you are able to have a great trip, rain or shine, and make some Magical memories!!