Tornado aftermath: The science behind the twisters

They are the most destructive storms on the planet, but tornadoes like the twin twisters that struck Ottawa and Gatineau on Friday are also among the most limited, capable of flattening one home and leaving the neighbour next door virtually unscathed.
Southern Ontario and the Prairies are the parts of Canada most prone to tornadoes, but, because the twisters tend to be short-lived and very localized, many go unseen and unreported in low population areas. Canada averages about 60 tornadoes a year