system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why are tornadoes so rare outside of the US?
gpt
The US has a perfect breeding ground for them.  Cold, dry air comes down from Canada and meets up with the warm, most air from the Gulf of Mexico. 

Mix in some instability from a warm spring/summer day, and you’ve got the makings of a hellfire and brimstone tornado producing thunderstorm.