Today, I decided to investigate whether strong thunderstorms tend to cause sporadic-E clouds in the ionosphere above themselves. So I looked at the storm data for Okaloosa County, Florida and the stored ionograms for Eglin Air Force Base located in that county.
In short, no. Since 2009, a recorded thunderstorm only has about a 20% chance of being associated with a sporadic-E ionogram. In looking for short skip, the better way is to look in the morning (local) in June, July or August.
My thanks to the National Climate Data Center, The US Air Force, and Lowell Digisonde for providing the data.