What is the relationship between the height of cloud tops in thunderstorms and the severity of those storms?

One rule is that the higher the cloud-top the greater the severity of the storm, although this is not always the case. What we call the "garden variety" of thunderstorms will usually reach 20,000 to 30,000 feet. These types of storms are afternoon thunderstorms caused by daytime heating, lake, land, and sea breezes. These storms are usually not severe.

In the Midwest though, thunderstorms typically reach much higher into the atmosphere. Radar operators have estimated storm heights from 65,000 to 70,000 feet. These storms will occasionally "punch" though the tropopause (layer between the troposphere and stratosphere) and several thousand feet into the stratosphere. This will cause a cauliflower effect on a satellite image. These types of storms usually produce large hail, damaging winds and occasionally tornadoes.