The Climate Central post Shifting Tornado Zones (4/24/19) provides a map of changes in the number of tornadoes since 1979 (copied here).
Let’s be clear, tornadoes are not going away in the Plains and Upper Midwest, but more have been recorded east of the Mississippi. While there are connections to climate variability modes like ENSO, these overall trends are consistent with an eastward shift in the drier climate zone of the western U.S. and with climate change projections indicating that severe storm environments will become more common in the eastern U.S.
The number of tornadoes in large tornado outbreaks is also on the rise.
In addition to the changing geography and number of tornadoes, there is a shift in the time of year they occur.