The threat of tornadoes is moving east into the Mississippi Valley and Deep South a day after a massive storm system moving across the country unleashed winds that damaged buildings, whipped up dust storms that caused deadly crashes and fanned more than 100 wildfires in several central states.

Severe thunderstorm outlooks issued by NOAA's Storm Prediction Center can show a threat level from 1 to 5. They are used to show how widespread and intense severe weather could be on a given day.