What weather system controls tornadoes?

Mesoscale weather system;

In American classification and terminology, systems with a horizontal scale of 2000km ~ 2km are collectively called mesoscale weather systems, which are divided into three categories: mesoscale alpha weather systems with a horizontal scale of 200 km ~ 2000 km, including typhoons and fronts; Mesoscale β weather system of 20 ~ 200 km, including tornado and squall line; Mesoscale gamma weather system with a distance of 2-20km, including thunderstorm cell.