Why do scientists believe 'tornado alley' is shifting?

CENTRAL TEXAS, Texas (KXAN) — Scientists at the National Weather Service are looking through the damage to figure out the scope of Monday's tornadoes that ripped through Central Texas.
Since Central Texas saw multiple tornadoes along a complicated and long trek of populated areas, scientists say it may take a couple of days to come up with a scale for these storms.
Tornadoes are deciphered using an Enhanced Fujita scale (EF Scale). The EF Scale was developed based on damage intensity which