US prepares for potentially catastrophic ice storm

Millions of Americans from New Mexico to the Carolinas are bracing for a potentially catastrophic ice storm that could crush trees and power lines and knock out power for days.

Washington DC, Philadelphia, New York City and Boston could see enough snow to make travel very difficult or nearly impossible, forecasters say.

About 160 million people — nearly half the population of the United States — are under a variety of watches, warnings and other alerts associated with the winter storm, the National Weather Service announced on Thursday afternoon.

The alerts stretched from Arizona and Montana in the west to the Carolinas and Maine in the east.

The storm, expected to begin on Friday and continue through the weekend, is also projected to bring heavy snow and all types of wintry precipitation, including freezing rain and sleet.

An atmospheric river of moisture could be in place by the weekend, pulling precipitation across Texas and other states along the Gulf Coast and continuing across Georgia and the Carolinas before heading northeast, forecasters said.

"Snow amounts could reach a foot or more in the Interstate 95 major cities from DC to Boston," said weather service forecasters on the east coast, who are increasingly confident the storm will strike the big cities.

In Washington, DC, "the combination of heavy snow and ice alongside prolonged very cold temperatures presents a unique and significant risk to life and property across virtually the entire region," forecasters said in the weather service's Washington/Baltimore office.