I second the post that said the most important thing is to TIE THINGS DOWN. If there is any question about whether your coop may blow over/apart/away, you might even consider taking the chickens into a safer structure (e.g. your garage or house) if you have enough cages or dog carriers or what-have-you.
If the structure is very well anchored to the ground, it is not too late to go out and apply some extra wood or metal strapping/fasteners or screws to help keep it together. Places to watch are where the wind can catch the edge of the roofing (like at the edge/overhang), where the rafters or trusses attach to the tops of the walls, and any slightly loose bits of siding or roofing you may have. Now would be a good time to put in some extra screws
Also make sure you have removed from your yard all objects lighter than, say, a car... a lot of damage during high winds comes from things being blown into other things. If some things can't be taken indoors, you may be able to at least take steps to encourage them to stay put e.g. chain picnic table to tree type of thing.
And fill a buncha jugs with clean drinking water right before the storm hits, not just for you but for the animals.
Good luck, take care,
Pat, who used to live in various Atlantic seaboard states