Latest snow storm forecast maps show fresh predictions for where winter weather will hit hardest

As millions of Americans hunker down for a massive winter storm sweeping the country, new maps are offering updated forecasts of snow and ice accumulations. 

More than 230 million people are under winter storm threats as snow, sleet, and freezing rain began to move across impacted areas — with possible dangerous conditions forecast across 35 states. Nineteen states and Washington, D.C., declared states of emergency, and at least 10 states have activated their National Guards as the sprawling weather system began to move across land. 

States under states of emergency include South Carolina, Virginia, Tennessee, Georgia, North Carolina, Maryland, Arkansas, Alabama, Delaware, Georgia, Kansas, Kentucky, Louisiana, Mississippi, New Jersey, New York, Indiana, Texas and West Virginia.

"It's the largest storm that we've seen impact the most states in this big of a population in possibly decades," Department of Homeland Security Secretary Kristi Noem said at a news conference.

FEMA officials said they have several distribution centers across the south and east stocked with over 7 million meals, more than 3 million liters of water, over 650,000 blankets and more than 180 generators.  

Forecasters also warned of frigid temperatures, gusty winds and dangerous wind chills. Areas at the center of the storm, including parts of Kentucky and Virginia, could see as much as two feet of snow between Saturday and Monday. 

Major cities, including New York City, Boston and Oklahoma City, could see between 12 and 18 inches of snow. The outer bands of the storm could bring between 1 and 6 inches to large swaths of the country.

New York City Mayor Zohran Mamdani said the city was forecast to face the coldest sustained temperatures it had seen in eight years.  

Maps show winter storm forecast

This map shows the storm system spanning from New Mexico and Texas to the Northeast, with parts of many states forecast to see 12 inches of snow or more.

The southern part of the country will see accumulations of both ice and snow. Ice accumulations can be more dangerous than snow, officials warned. The weight of ice on power lines is more likely to cause outages. It is also harder to clear than snow and can make for dangerous driving conditions. 

"Once we get more than about a quarter inch of ice on those lines, the lines either start sagging and failing, or more likely, you actually get the vegetation above it, the trees, to fall on the lines, and that causes potentially a larger number of outages," said Thomas Overbye, a professor of electrical and computer engineering at Texas A&M University.

Ice accumulations of up to 1 inch are forecast for spots of the South. Parts of Texas, Georgia, Arkansas, Mississippi, Alabama and Tennessee might see up to .75 of an inch of ice. Areas along the outer bands of the storm are expected to see up to a half inch.

Freezing rain was already coating roads Saturday in Texas and Alabama, and cars in Mississippi. Nearly 200 Florida utilities workers were in Georgia and South Carolina, in position for what is to come.

Tennessee has also started being walloped by snow and ice, with forecasters predicting up to six inches of snow expected from the storm, more than a season's worth in about one day.

The clear message from state leaders to residents was stay home and don't drive, but already dozens of drivers have slid off the roads.

Nashville city transportation officials only have 45 snow plows to clear hundreds of miles of roads. But once the storm shifts from snow to sleet, the plows may not help. 

On Saturday evening, icy conditions began accumulating in Tupelo, Mississippi, with a layer of ice blanketing the city. 

"Catastrophic impacts are expected where freezing rain amounts exceed a half inch, with over one inch totals possible in parts of northern Louisiana, central and northern Mississippi, southern Tennessee, and the southern Appalachians," the National Weather Service says.

Freezing temperatures are compounding the storm's effects. Snow that melts can quickly turn to ice. Wind chills are quickly bringing the mercury into the negatives. 

"If it gets out ahead of us and it becomes snow packed, solid sheets of ice, we get down into single digits — not a lot you can do," Justin Pierce, a plow driver with the Nashville Department of Transportation, told "CBS Saturday Morning." 

Over 47 million people are under an extreme cold warning, which means temperatures or wind chills are forecast to fall below 5 degrees Fahrenheit over the next 12 to 24 hours, according to the National Weather Service. Over 8 million people are under an extreme cold watch, which means those conditions are expected in the next 24 to 48 hours. 

More than 51 million people are under a cold weather advisory, which the weather service said is issued when either temperatures or wind chills are expected to fall to or below 15 degrees but remain about 5 degrees Fahrenheit. 

"In the wake of the storm, communities from the Southern Plains to the Northeast will contend with bitterly cold temperatures and dangerously cold wind chills," the weather service says. "This will cause prolonged hazardous travel and infrastructure impacts."