The warnings couldn't have been more dire.
"DO NOT TRAVEL," the National Weather Service in Amarillo, Texas, posted on its website, telling residents not to venture out in what it was calling "a crippling, historic blizzard."
The storm was dumping snow over the Texas Panhandle at a rate of 2 to 3 inches an hour. Oklahoma also was being hit hard, and parts of Kansas and Missouri were under winter storm warnings.
Almost all roads in the Texas Panhandle were impassable, and whiteout conditions forced the state Department of Transportation to pull virtually all of its snowplows off roads, Texas DOT spokesman Paul Braun said Monday morning.
On its Facebook page, the weather service posted a video of the wind and snow whipping a U.S. flag outside its Amarillo office.
"If after watching the last video you thought you could still get out and travel, well you haven't seen anything yet!" the Facebook post said.
And later, it followed that up with another indication of how bad things were getting.
"Amarillo Airport just recorded a gust of 65knots/75mph! This is truly a historic blizzard!" the second Facebook post said. "Conditions have NOT improved. Please stay inside and do NOT venture out."
As of noon Central time, 17 inches of snow had fallen in Amarillo, the weather service said in a Twitter post.
For some, the service's warnings didn't come soon enough.
Emergency crews were having trouble reaching drivers who were caught on the roads, Texas Department of Public Safety Trooper Gabriel Medrano said. Cars were in ditches, he said, because drivers couldn't tell where road ended and ditch began.
National Guard units were being sent to help stranded motorists, the Texas DOT said.
CNN iReporter Jason Boyett in Amarillo posted a video showing near-whiteout conditions at 7:40 a.m., and followed that with another showing a drift nearly 3 feet high outside his front door.
"We get high winds and we get big snowstorms, but they're not often combined," Boyett said.
Elsewhere in Amarillo, iReporter Michael Jaison shot video of the windblown snow outside his house. Drifts up to 3 feet high were forming, he said.
"I feel that we will be homebound for several days. There's no signs of the storm slowing down," Jaison said.
Whiteouts were also reported in Oklahoma, where as of 10 a.m. Central time, the state had closed all highways in six counties -- Ellis, Harper, Woodward, Beaver, Texas and Cimarron -- until further notice.
"Roadways and ditches are snow packed with no visibility, and are very slick and hazardous. All travel is discouraged," the Oklahoma Department of Transportation said. As much as 16 inches of snow could fall in western areas of the state, the weather service said.
Visibility was low in Fairview, Oklahoma, midway between the Panhandle and Oklahoma City, said CNN iReporter Brandi Whitacre.
"Right now it is snowing so heavily I can barely see down our driveway, which is 100 yards or so. It is coming down," said Whitacre, who added that'd she'd lost satellite TV service and was experiencing intermittent power outages.
The blizzard is the second major winter storm to hammer the region in a week.
The number of people under blizzard and winter storm warnings, watches and advisories totaled 35 million, according to CNN's weather unit.
"The unprecedented nature of this much snow in this short a period of time will create conditions ... across the entire city that are basically unprecedented for the traveling public," Joe Pajor of the Wichita, Kansas, Public Works and Utilities department, told CNN affiliate KSN. Parts of the area could see up to 26 inches of snow from the storm, the station reported, and the weather service said Wichita would be under a blizzard warning until 6 a.m. Tuesday.
Wichita schools were closed for the third straight school day as the new storm roared in on the heels of one that dumped up to 22 inches of snow on some areas late last week.