I feel myself wanting to type an essay. Must resist.
I am well versed in the formation of storms, the inflow, the outflow etc.
I have also stood both in the middle of death valley and fields in the midwest as a storm blows in. I had always assumed the smell was wet vegetation from upwind of my position as the outflow blows to me. Much stronger in the desert as tumbleweed and desert flora are much more pungent when wet.
Without getting too technical, the downflow of cool air in a storm column could conceivably carry air from the ozone layer and when it hits the earth and flattens out, it becomes the outflow.
I am not convinced yet. Your theory is sound and its conceivable, but I am still skeptical. What I will do is, in Aug, when I return to school, I will corner my weather instructor. I aced his class so he can entertain my question, he owes me that. My question would be, "If ozone had a distinct odor, could I smell it in the outflow of a storm before the precipitation begins?"
One of my boring hobbies is to photograph storm cloud formations around my farm at sunset. Sunsets are cool, even more so when a storm cloud silhouette is captured.
I think the scent of coffin wood is easier to comprehend as it leaves it to our imagination and less thought provoking than ozone.