Does storm get on with your other cats? Its normally stress that causes overgrooming.
Have you tried feliway plug in's?
Is he neutered?
How old is he? If hes maturing into an adult he may be struggling to find his place in the heiracy.
If hes desperate to get outdoors, maybe you could look into a cat run or securing your garden (if you have one) so he can go out.
If hes overgrooming from boredom, you could try making your home more cat friendly with scratching posts of different heights,shelves, fish tank to watch and hidey holes etc