I live in northeastern Nebraska, and I had seen more than enough of tornadoes in my lifetime. So in an alternate Earth, it is my hope to make some changes that would save my home from being another potential target for that spinning Reaper's scythe.
Marked here in red is a vast plateau that varies in elevation above sea level between 3600 and 15,000 feet. To the west are the Pacific lowlands (that peninsula in Alaska shouldn't be there). To the east are the Rocky Mountains, which, in this alternate Earth, is a singular spine of Tetons no taller than Denali (20,308 feet above sea level). The brown Y on the Atlantic coast are the Appalachians, which hadn't changed much except that its tallest point is now 9,931 feet above sea level, the height of Yosemite's Cloud Rest.
The Great Lakes Area has its own set of differences.
Imagine that the entire basin has been flooded off into one megalake, Lake Agassiz, 1500 feet at the deepest.
Are these differences the key I needed to bar off Tornado Alley, or have I created something as bad, if not worse? Will the Midwest still be prairie?