Jefferson County road crews clear Tyler Loop Road in the Paradise Valley area of Clay Chalkville, Alabama, after the area was hit by tornadoes early Monday. The severe weather cut power to tens of thousands of residents and downed trees and damaged homes in communities in central Arkansas, as well as in communities around Tuscaloosa and Birmingham.

At least 10 tornadoes struck the South overnight Sunday as a powerful storm system moved across the Great Lakes and into southern Canada.

The tornadoes were spawned along the southern end of a front that arced through the eastern US like a comma's tail, bringing severe thunderstorms, hail, and twisters to Arkansas, Mississippi, Alabama, and Tennessee before moving into Georgia later Monday morning.

The severe weather cut power to tens of thousands of residentswith moisture, we're going to have some problems," he says, referring to warm, moist air that typically hovers over the Gulf states. "That's what we saw last night beginning over Arkansas."

As the storm center pirouetted northeastward and intensified, its counterclockwise rotation swept relatively colder air to the storm's north around and down toward toward the warmer moist Gulf air. The clash between the two set up the conditions for the outbreak of severe thunderstorms.

So far this month, at least 21 tornadoes have touched down across the South, from Texas to North Carolina, as well as northward into southern Indiana, according to preliminary estimates from the NOAA's Storm Prediction Center.

The United States typically sees its first tornado of the year somewhere in the country about the second week of