Why does the ThunderBolt say a storm is “local” when it reaches a distance of 8 miles?
The 8-mile warning boundary is based on the length of the typical lightning stroke (6-10 miles!) and the normal pattern of lightning activity within a storm cell. Most thunderstorms produce the highest number of strokes at the leading and trailing edges of the storm cell. Very often, the strokes produced at the leading edge of the storm are thrown forward into areas that might not even be under cloud cover. This is the reason that up to 70% of all people injured or killed by lightning are struck with blue sky overhead!
