Welcome aboard.

A few things you can work with:
1) When you are home, sit with him during a storm. Pet and talk softly to him to comfort him. If you work, make sure he is in a kennel when you expect a storm. This way he doesn't hurt himself and he is in his "safe" palce.

2) Give him benedryl to take the edge off the storm. Get with your vet on the dosage.

If you consistantly work with him during a storm, the less the edge.

Good luck and keep us posted.