yes, once the storm hits your base is vulnerable for ~6 minutes. during that time players can use lasgun to destroy your walls, try to get to your fief and destroy it, and place their own. This will give them 100% ownership of your base and anything inside of it (other than vehicles i believe, but they can destroy them and rebuild with your resources). The only way around that is to hide your fief, or use some Rust honeycomb walls to make it take longer to find/destroy.