There are two scientific theories as to how tornadoes could be prevented, but neither have been tested and both have attracted scientific criticism. One theory proposes building giant walls in tornado alley to block the air currents that cause tornadoes. Another theory says that using satellites to zap thunderstorms that look like potential tornadoes with microwaves will dissipate their abilities to form funnels.
Rongjia Tao is the scientist who proposed the wall-building plan. Tao proposes building three walls, one stretching from the east to west in North Dakota, another on the border between Kansas and Oklahoma, and a third stretching across the southern part of Texas and into Louisiana. These walls would have to be 1,000 feet high and 150 feet wide. The idea behind these walls is to block the clashes of warm air from the south and cold air from the north that start thunderstorms and tornadoes. Other scientists doubt the efficacy of this plan, pointing out that we have mountain ranges of similar size that do not perform that function.
Bernard Eastlund is a physicist who supports zapping thunderstorms with microwaves sent from satellites so that the air that would normally turn into funnels is warmed and cannot form a tornado. However, Eastlund himself concedes that scientists do not have enough knowledge at present to be able to use the technology he envisions and to know that it is safe.