A downburst is caused by sinking air from a thunderstorm hitting the ground and spreading out in all directions, creating powerful winds over 150 mph. Microbursts are downbursts less than 2.5 miles wide, while macrobursts are larger. One notable downburst occurred in North Carolina in 2004, causing over 200,000 power outages with winds from 50-65 mph that toppled trees and damaged property from 6pm to midnight without an accompanying thunderstorm. Safety precautions include having a weather radio, finding shelter away from windows or outside walls, and if outside, lying in a ditch covering your head.