Russell said they are finished with the primary assessment of the damage and are moving into the secondary assessments, checking more methodically in the morning.
Tornadoes are also not the only source of such sounds in severe thunderstorms; any strong, damaging wind, a severe hail volley, or continuous thunder in a thunderstorm may produce a roaring sound.
By comparison, during the same tornado outbreak, more than 2,000 homes were completely destroyed and another 7,000 damaged, and yet only a few dozen people died in their homes.
There are more than 230,000 trained Skywarn weather spotters across the United States.