“Sound travels at about 1,088 feet per second, or about 0.2 miles per second (depending on air temperature and humidity). That means it'll take the sound of thunder about 5 seconds to travel 1 mile. So, the “flash to bang” distance can be calculated as follows: (seconds between flash and bang) divided by 5. Five seconds is one mile, 10 seconds is two miles, and so on”
Source: https://www.offgridweb.com/preparation/estimate-lightning-distance-with-the-flash-to-bang-method/#google_vignette
There are temperature gradients in the atmosphere. There could be a sinuous wake travelling through the air so that all of the caluculations become moot.