02. Tornado Probabilities by Day in USA
The percentage probabilities at the bottom of the map include a decimal point. So the lightest color is 0.10%, not 10%. The highest probability shown is 1.4%.
Although Tornado Alley gets all of the press, the reality is that Dixie Alley is far more dangerous. Tornado Alley is only particularly susceptible during certain times of year. The locals know it, and can prepare for it. Dixie Alley is vulnerable almost year round. On top of that, there are very few storm shelters in that region. What makes that region the most dangerous though is the fact that Tornadoes are typically day time events in Tornado Alley, but they can and do happen any time of day or night in Dixie Alley. That combined with the fact that there are more forests in Dixie Alley, impeding verification that a tornado has touched down, meaning that there are fewer intense tornadoes in Dixie Alley, but the death toll is usually much higher. Unless you live in Moore, OK. you can pretty much count on your town being leveled every couple years.
In general, the interiors of continents get more extreme weather than places close to coasts. The only place much farther from the ocean than the central United States is central Asia. Most of the parts of South America and Africa that are as far from the ocean as the central United States are pretty tropical (which also mutes extremes of weather) and low population.
North America is also the only place where there is an exposed stretch of flat land running all the way from the tropics to the polar region. Everywhere else in the world, you’ve either got mountains or water separating the two.
The geomorphic processes that cause tornados to occur more in this area the massive amounts of moist air moving north from gulf of Mexico mixing with cold fronts sweeping down the plains to the South East. This causes the right amount of wind shear at low levels required to spawn tornadoes. The moist-warm air ahead of cold front rises and tilts the vertical structures caused by shear to become the actual vortex.