Like I was thinking with your guy. I would put a leash on him when I heard a storm coming so you could keep him close, and work with him, looking to see what will work. I am positive there is a cure, you may have to figure it out.
With Diablo after the fireworks scare, which may have been the start of his fears, but his digestive problems seemed to be a cause, he would react in fear to Something New on Every walk. I mean the strangest things... Flashing lights, loud mufflers, trash cans, a white van, flags or overhead banners flapping, a wire strung from 2 buildings, and if we went under them he would go down to the ground, and each time I would talk to him, or rub him if we were sitting or stopped, but the next walk it would be something new. I was really getting tired of talking and started singing, and was thinking of a button activated tape player or chip like an answering machine has, with my voice recorded, so I could push the button and it would play, since him hearing my voice calmed him. Many have had to get used to all the noises and numbers of people they were seeing in a big city, but it usually didn't take long, and I could desensitize them. My last 2 were spooked by sunlight reflecting off car windshields that would cause a moving reflection inside the room. Me working a flashlight and doing my thing with them cured that fairly fast. A bit harder because they didn't realize that I was causing the light far from me.
Believe me, there is always a cure.