There's a temperature inversion in the stratosphere ... a thunderhead might push the troposphere up into spaces that are normally stratosphere ... but the thunderhead itself is strictly tropospheric ... jet airliners fly around these events ...
More heat in the atmosphere won't do this, we need the extra heat in the lower parts, which make the lower air more buoyant and this air will rise in the atmospheric column ... we want "cold tops" for added convection ...
No location in the OP ... but the closest airport should have hourly rainfall data from the past 100 years ... my hunch the phenomena is normal, even common ... copy/paste the data into a spreadsheet and see what the statistics say ...