About 42 million people are under winter alerts from California to Maine, with Minneapolis bracing for its biggest snowstorm in more than a decade and potentially life-threatening travel conditions.
Blizzard warnings have been issued for parts of the Rockies, the northern Plains and the Upper Midwest. St. Cloud, Minnesota, was already under one.
The extreme weather was the result of multiple winter fronts moving west to east and pulling cold air from the north, federal forecasters said.
Forecasters cautioned that Minneapolis could be added to the cities under blizzard warnings later Tuesday, which would be rare for the historically snowy city.
Up to 1 foot of snow has already fallen in northern Minnesota, according to the National Weather Service.
"Due to obstructions, it is hard to get blizzard conditions in major metropolitan areas such as the Twin Cities, but with the actively falling snow and strong winds, this would be an event that could do so," the National Weather Service in the Twin Cities said in its Tuesday morning forecast.
The storm will feature two rounds of snow totaling 1 to 2 feet by the time the system wraps up Thursday.
Timeline of snow
The first round of snow started around lunchtime Tuesday across the region, with 5 to 7 inches (locally higher of 8 to 9 inches) possible through the night. Winds are expected to be 10 to 15 mph.
A lull is expected Wednesday from 6 a.m. to noon local time. Light snow could fall, but some locations along Interstate 90 could get a complete break.
The second round is expected to begin around noon Thursday, adding 10 to 15 inches to snowfall totals and producing 45-50 mph wind gusts at times.
By the time that round ends, a large area of southern Minnesota will have over a foot of snow, with some areas having picked up nearly 2 feet.
Rapid City, South Dakota, is forecast to get 8 to 14 inches and Marquette, Michigan, could get 12 to 18 inches.
Differentiating winter storm watches, warnings and advisoriesJan. 26, 202301:46
Should the current forecast of 18 to 25 inches of snow come to fruition for Minneapolis, it will be the city’s biggest snowstorm in 12 years, according to the Minnesota Department of Natural Resources, and it has the potential to be one of the city's five biggest snow days.
Travel will be affected
Heavy snow falling at 1 to 2 inches per hour combined with strong wind gusts will make travel impossible and life-threatening for 12 or more hours Wednesday night into Thursday in and around the Twin Cities.
Cities most likely to experience treacherous travel conditions, power outages, downed trees and whiteout conditions due to a glaze of ice include Chicago; Detroit; Hartford, Connecticut; Des Moines, Iowa; Madison, Wisconsin; Grand Rapids, Michigan; and Buffalo and Albany in New York.
As many as 8 million people are at risk for severe storms Wednesday from northern Missouri to the Oklahoma-Texas border. All hazards will be possible, including hail, high winds and a tornado or two. Oklahoma City and Tulsa will be the cities most at risk for damaging winds due to very fast-moving storms.
Some precipitation was already moving through parts of the South into Ohio and Pennsylvania on Tuesday, with up to a half-inch of rain and snow reported, according to weather service data.
Snow in California
The first of three additional fronts was moving into California with the promise of snow in the southern part of the state, including high desert communities and some valleys, reaching elevations as low as 1,500 feet, forecasters said.
National Weather Service senior meteorologist Alex Tardy said in a video presentation that Southern California snowfall could be historic.
Thursday's front is expected to produce an “atmospheric river” of precipitation from the tropical Pacific. Atmospheric rivers are known for their relatively moderate temperatures, but the front will bring both heavy precipitation and cold temperatures, forecasters said.
Sustained winds along the coast of up to 50 mph were forecast for later in the week. Tardy said it was a 10-year event.
“It’s quite remarkable to see something like this in Southern California,” Tardy said.
A winter storm watch was issued Tuesday for parts of the San Francisco Bay Area. The last time that happened was in 2011.
Up to 3 inches of snow is likely in the Santa Cruz Mountains and the eastern hills of Santa Clara County on Wednesday night. The area is likely to get another watch Thursday as an even colder storm arrives.
Any snow accumulation will be very unlikely in major cities such as San Francisco and Los Angeles, but snow is likely to fall nearby in lower-elevation mountains.
The first storm for the West Coast this week was making its mark Tuesday.
More than 185,000 utility customers were without electricity in California as of around 10 p.m., according to grid tracker PowerOutage.us, many of them in the San Francisco Bay Area counties of San Mateo and Santa Clara.
A downed tree blocked three lanes of westbound traffic on the Bay Bridge, NBC Bay Area reported, citing the California Highway Patrol, and the San Francisco Fire Department reported trees and wires down.
Meanwhile, temperatures could soar 20 to 30 degrees above average in other parts of the country, leading to close to 100 daily records.
If Washington, D.C., hits 80 degrees Thursday, it will be just the fourth time it has done so during a winter month. Orlando, Florida, could hit the 90s.