I grew up in Norman...local myth has it that Norman proper is protected by the So. Canadian River. Some kind of natural power source that forces tornadoes to veer away or dissipate. Some attributed the myth to Indians who lived in the area pre-land run days. City leaders apparently didn't buy into that and in the early '70s built tornado-safe schools to serve also as public shelters (Whittier, Longfellow, & Irving middle schools). They would herd us kids into the gym during storm drills only to have an expert come along and say that the open span of the gym wouldn't protect us after all.