Severe storms and tornadoes threaten 20 states in Midwest and South.

The National Weather Service has warned that severe storms, including deadly tornadoes, are expected to hit parts of the Midwest and South of the US over the next few weeks, with Friday being one of the worst days. The highest risk zone includes 16.8 million people, and more than 66 million people overall should be on alert. The storms are expected to start Friday afternoon and go overnight, which is particularly dangerous because people can’t see them coming and often won’t seek shelter.