I always found it fascinating how the jet stream pulled arctic air south to make where I live, (MN) a living polar Hell. If you look at temp averages we’re colder than most of Scandinavia and seem more like Siberia, yet we’re a much lower latitude.
The primary cause is the Rockies. The rising air causes a mean ridge over the Rockies and a mean trough in the jet over central north america. That varies due to weather but is there on average.