Nearly 10 million people living in communities across North and South Carolina are bracing for tornadoes, as a series of deadly storms that already wreaked havoc in the South the day before is barreling toward the Eastern Seaboard.

Oklahoma is in the heart of the states traditionally labeled "Tornado Alley." But over five decades, tornado frequency has increased in other areas.

Researches found little evidence that tornadoes were getting weaker. Instead, it appears that a subjective tornado grading system is to blame.

A mammoth and multifaceted storm – which was dealing wind, fire, choking dust and the threat of a blizzard – pummeled much of the country as it marched east.

The official forecast on March 18, 1925, for parts of Missouri, Illinois and Indiana called for “rains and strong shifting winds.” There were no tornado warnings or watches, not even severe storm warnings or watches that day.

A powerful and damaging spring storm system that wreaked havoc on the South earlier this week is continuing to barrel toward the East Coast, where more than 64 million people from Florida to New

In the aftermath of Tuesday's devastating storms, a second EF-1 tornado is believed to have occurred in North Texas, according to the National Weather Service.

Severe thunderstorms may cause power lines and trees to be blown down, and mobile homes and other buildings to be damaged, the NWS said. The agency added that flying debris from deadly winds can be deadly, and urged people to stay away from windows. "Seek shelter in a sturdy structure until the storm has passed," the NWS said.

Tornadoes can form in minutes, leaving little time to prepare. Knowing the difference between alerts and having a safety plan in place is critical.