ATLANTA (AP) — Across the South, winter-weary residents woke up Wednesday to a region encased in ice, snow and freezing rain, with forecasters warning that the worst of the potentially "catastrophic" storm is yet to come.

From Texas to the Carolinas and the South's business hub in Atlanta, roads were slick with ice, thousands were without power, and a wintry mix fell in many areas. The Mid-Atlantic region also was expected to be hit as the storm crawled east.

Officials and forecasters in several states used unusually dire language in warnings, and they agreed that the biggest concern is ice, which could knock out power for days in wide swaths

In Atlanta, where a storm took the metro region by surprise and stranded thousands in vehicles just two weeks ago, emergency workers stood at the ready. Out-of-state utility vehicles gathered in a parking lot near one of the grandstands at Atlanta Motor Speedway, Georgia National Guard troops were on standby in case evacuations were needed at hospitals or nursing homes, and more than 70 shelters were set to open. More than 20,000 customers were reported without power across the state.

City roads were largely desolate Wednesday morning, showing few vehicle tracks as most people heeded warnings to stay home. Stinging drops of rain fell, and a layer of ice crusted car windshields. One emergency crew had to pull over to wait out the falling snow before slowly making its way back to the Georgia Emergency Management Agency's special operations center.

Atlanta and the surrounding region dodged a first punch Tuesday, but forecasters warned that the stormy second punch would likely bring a thick layer of ice and heavy winds.

On Tuesday evening from, Georgia Gov. Nathan Deal and Atlanta Mayor Kasim Reed implored people to get somewhere safe and stay there.

"The message I really want to share is, as of midnight tonight, wherever you are, you need to plan on staying there for a while," Reed said. "The bottom line is that all of the information that we have right now suggests that we are facing an icing event that is very unusual for the metropolitan region and the state of Georgia."

In an early Wednesday memo, the National Weather Service called the storm "an event of historical proportions."

It continued: "Catastrophic ... crippling ... paralyzing ... choose your adjective."

The forecast drew comparisons to an ice storm in the Atlanta area in 2000 that left more than 500,000 homes and businesses without power and an epic storm in 1973 that caused an estimated 200,000 outages for several days. In 2000, damage estimates topped $35 million.