I’m sorry to hear about this. With storm phobia, there isn’t a simple fix as all dogs are different. Some tips that you can bear in mind are to reward calm behaviour year round, give you dog a safe place to go during a storm such as a basement where the dog can’t see or hear its surroundings / an interior room with music playing, a snug garment or in the winter, play sounds of storms from a computer at a level not to frighten them, whilst also playing games and giving treats, subtly increasing the sound over time.
This last one may not be successful, as it doesn’t replicate the other factors that come from storms. It can pay off to visit your local vet as they may recommend a type of medication if they feel that this particular instance requires it. This medication could benefit your dog even if only given in the morning of a day that’s expecting a storm. Your local vet should be able to inform you of that.
Here’s a link to a vet tip article posted by Bondi Vet regarding this topic. https://bondivet.com/dogs/286-storm-stress-in-pets
Hope this helps