WASHINGTON — A blizzard menacing the Eastern United States started dumping snow in Virginia, Tennessee and other parts of the South on Friday as millions of people in the storm’s path prepared for icy roads, possible power outages and other treacherous conditions.

Snowfall as heavy as 1 to 3 inches an hour could last for 24 hours or more in some areas, said meteorologist Paul Kocin with the National Weather Service. That puts estimates at more than 2 feet for Washington, a foot to 18 inches for Philadelphia and 8 inches to a foot in New York.

Kocin compared the storm to “Snowmageddon,” the first of two storms that “wiped out” Washington in 2010 and dumped up to 30 inches of snow in places, but he said the weekend timing and days of warning could help limit deaths and damage.

Washington Mayor Muriel Bowser asked residents to “hunker down” and “shelter in place” Friday morning. She said snow is expected to start arriving between 1 p.m. and 3 p.m., a little earlier than previously forecast.

“The forecast does not show any evidence of lightening up,” she said, calling it a “major storm” with “life and death implications.”

At sunrise in Memphis, Tennessee, ice covered parked cars after an overnight dusting of snow. Roads were manageable, but downtown was quieter than usual. Danielle Aldridge couldn’t find her ice scraper, so she used a plastic kitchen cutting board on her windshield. She had to get to work as a nurse at a family practice clinic. Unlike government offices and many private businesses in the city, the clinic is open Friday.

“Sick people will come in today,” she said. “That’s part of the deal. Like the post office — rain or shine or sleet or snow, I will take care of my patients.”

In the mountains of Craigsville, West Virginia, people bought the usual kerosene heaters, propane tanks and gas cans, but also a special item: a rake that helps homeowners get snow off their roofs.