If you dog is alone during the day and you know there are thunderstorms coming through....Kennel them. Kenneling for 8-10 hours is not a bad thing. It is actually helpful in situations like this and can prevent injuries.

In the meantime, if you hear a thunderstorm coming, sit outside with your pet, pet her until she is comfortable. When she begins to stress take her inside. You will have to do this continuosly until she begins to feel safe. It will take some time.

If this doesn't work, ask your vet about benedryl tablets. It takes the edge off and mellows them out a little.

Good luck