The pool is closed for winter,a severe storm hit. The wind was blowing and the cover started to lift. There is no electric on or around the pool.There was loud popping and flashes of light under the cover.This occurred at the deep end.Never in my life have we experienced anything like this.What possibley could this be?

If the cover is vinyl then it could be static electricity from breaking the surface of the water. The water is the grounding surface that the electricity is pulled to. That is why it was under the cover of the pool.