Wind gusts were forecast to top 50 mph in some areas. In Pico Rivera, a tornado with wind speeds reaching 85 mph traveled about a mile through a residential area of the city.

The storm, which forecasters said could produce tornadoes, is expected to strengthen Friday and move towards the central US.

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.