Original: The Hurricane Katrina tornado outbreak was a tornado outbreak across the eastern United States from August 29 to August 31, 2005, spawned mostly by the outer bands of Hurricane Katrina (or the remnants thereof).
Simplified: The Hurricane Katrina tornado outbreak was a tornado outbreak across the eastern United States from August 29 to 31, 2005, spawned mostly by the outer bands of Hurricane Katrina (or the remnants thereof).