[bhw33191]

Sounds like you need a new alternator. Possibly the voltage regulator is going bad. This happened to me a few weeks ago. The reason it almost always shuts off in a storm is probably because you have a lot of things running (lights, wipers, defrost, etc) and the alternator (which is most likely failing) can't handle it. You should try having your alternator tested for free at autozone or some place like that