Severe weather season is a result of the winter jet stream staying strong enough as we move into the warmer months of spring. High humidity from the Gulf of Mexico gets drawn northward during the spring, and then severe thunderstorms are the violent result of clashing air masses.
Tornado Alley is supposed to be the hot spot each year, but this is just not the case, and this year is a perfect example of it not lighting up. Tornado Alley, which extends from Texas north across Oklahoma, Kansas into parts of Missouri, Nebraska and Iowa, is the result of two large geographical boundaries. Air flows over the Rocky Mountains and out into the plains. This drier air interacts with the warm and moist air, the fuel for the thunderstorms from the Gulf of Mexico.
This year, shockingly, Georgia has been the #1 state for tornadoes. Texas came in #2 and Missouri was #3 as of June 1, 2017.
So, is severe weather season over? It usually ends by mid-June as the jet stream lifts north.
It is doing that right now, and severe weather season may still have a few more moments, but it is just about done due to the retreating jet stream.