A rash of tornadoes has torn through the southern US.
Since Sunday, tornadoes have touched down in 13 states. The most were reported in Mississippi but they've been as close as central Nebraska and south central Iowa. It's a sign that spring weather is in full swing.
As warm, moist air travels north from the Gulf Of Mexico into the plains, it meets up with with cool dry air masses from the north leading to storm development. The Rocky Mountains help trap the warm moist air in place by keeping it in the plains.
This graphic shows areas most prone to tornadoes, east of the Rockies and into the plains. The areas most likely to get hit are northern Texas, through Oklahoma, Kansas, Nebraska, to the southeastern tip of South Dakota.
While low pressure has been slow to leave us, it's also been feeding the colder air to our south into the warm moist air. The combination of that, and other upper level features has allowed for the slow progression of the severe storms in the southern states this week.