Why tornado sightings are creeping east 

Tornadoes have long been a hallmark of the Great Plains states but scientists have noted the destructive storms appear to be moving east.
“What we've noticed over time is the precipitation line in the Great Plains shifting east a little bit,” Joe Strus, National Weather Service meteorologist said. “So the western Great Plains, western Kansas, western Nebraska, western Oklahoma, they're just running a little bit drier in those spots than maybe previous period of time. And so your precipitation has shifted east a little bit. Well, we've also seen a higher frequency of tornadoes.”
A changing climate is also leading to warmer and wetter nights, which raise the odds for nocturnal tornadoes.
Though tornadoes can and do occur year-round, late April to the middle of May is when the strongest tornadoes that cause fatalities usually appear.
“If you're in an area where severe weather is something you've experienced before, it can and it will happen again. And so we want you to this time of the year, start thinking about what do I need to be doing to make sure myself my family is protected ahead of severe weather,” Strus said.