(CNN) One weather-related death has been reported in North Carolina as a result of this weekend's snowstorm.

Police in Matthews, about 12 miles south of Charlotte, said a tree fell on a vehicle. This led the vehicle to drive through the front lawn of a church until it hit the front of the building. The driver died and the passenger was taken to a hospital with minor injuries, police said.

A nasty mix of snow and ice gripped the Southeast this weekend, leading to treacherous driving conditions, canceled flights and thousands of people stranded at home.

"Over 20 million people are under winter weather alerts, over 8 million people are under a flash flood threat, and over 9 million people are under wind advisories," CNN meteorologist Haley Brink said Sunday.

More than 12 inches of snow fell Sunday in the southern and central Appalachians, the National Weather Service said. The area with the highest snowfall total was Whitetop, Virginia, at the border of North Carolina, which had 2 feet of snow, according to CNN meteorologist Gene Norman.

Raleigh-Durham International Airport received about 7 inches of snow Sunday, according to CNN affiliate WTVD , which was the most snow at the airport since 2002.

Charlotte also saw record-setting snowfall totals. With 2.7 inches, the city had its snowiest December since 1997, according to CNN affiliate WSOC-TV

Snowfall could total 12 to 20 inches over the Appalachians and into the Carolinas by Monday, when the storm is expected to move off the coast, the NWS said.

"Snowfall amounts in some locations will likely exceed a foot and result in several days of difficult or impossible travel, extended power outages, and downed trees," the agency said.

The storm already has knocked out power for more than 546,000 customers in the Southeast.

The bulk of the outages are in North Carolina, where 244,807 customers are in the dark. In South Carolina, more than 225,600 customers have lost power. And Alabama, Tennessee and Georgia each had about 20,000 and 30,000 customers without electricity.

A snow-covered car sits outside a home Sunday in Greensboro, North Carolina.

Those hoping to escape the storm may be out of luck. More than 1,100 Sunday flights into and out of North Carolina's Charlotte Douglas International Airport were canceled, according to flight tracking website FlightAware

More than half the Sunday flights at Raleigh-Durham International Airport and Piedmont Triad International Airport were also called off.

Virginia extends winter storm warning

A winter storm warning is in effect for most of Virginia until to 2 p.m. Monday, Norman said.

Virginia's western and central areas were also hit with snow. The city of Richmond and surrounding areas received about 9 inches of snow, according to the National Weather Service in Wakefield, Virginia. Areas south of Richmond got 6 to 8 inches of snow, Norman said.

Like it's neighboring states to the south, Virginia also saw power outages for thousands, and dozens of vehicle crashes.

As of Sunday, there were more than 15,000 customers without power in the western part of the state, according to Appalachian Power. In the Richmond area, Dominion Energy said there were more than 13,000 without power.

A snowplow is followed closely by cars as it clears US 301 in Hanover County, Virginia, on Sunday.

Virginia State Police reported nearly 60 crashes in Virginia because of the snow, with most crashes in the agency's Richmond division.

"The majority of the crashes involve only damage to vehicles. No traffic fatalities have been reported at this time," Virginia State Police spokesperson Corinne Geller told CNN affiliate WTVR

Virginia Department of Transportation officials told WTVR Sunday that road crews were working 12-hour shifts until all roads were passable.

Richmond International Airport reported Sunday that nearly 100 flights had been canceled, WTVR reported . One of those flights, a United Airlines flight to Denver, had passengers on the runway for hours.

WTVR reported that the flight was supposed to leave at 8 a.m. Sunday, but passengers were stuck on the runway until 11 a.m. after officials said the weather worsened. After deboarding and reboarding the plane, passengers sat on the runway again for four more hours until they returned to the gate at 5 p.m. when the flight was officially canceled, WTVR reports. United officials apologized for the inconvenience.

North Carolina has 500 car wrecks in 11 hours

In Durham County, residents typically get about 6 inches of snow over an entire year . But on Sunday morning, they woke up to see 6 inches of snow on the ground.

"The roads in Durham are treacherous and not safe for driving," the Durham County Sheriff's Office tweeted.

All that heavy wet #snow is starting to weigh #powerlines and tree branches down. Here on the 2800 block of Beck Rd a power pole has broken. Remember when the power goes out to safely use alternative heating and lighting sources. #NCWx #DurhamWeather #WinterStorm #WinterSafety pic.twitter.com/aikCgH3htM — Durham Sheriff (@DurhamSheriff) December 9, 2018

Authorities responded to more than 500 car crashes between midnight and 11 a.m. Sunday, North Carolina Gov. Roy Cooper said. One tractor-trailer ran off the road and into a river.

"We've seen too many collisions," Cooper said. "From Charlotte across central North Carolina, the biggest concern now is ice making roads even more dangerous."

A man tries to walk through blowing snow Sunday in Wake Forest, North Carolina.

Even before the storm hit, Cooper declared a statewide emergency. Grocery store shelves were cleared of bread, milk and other staples.

Cooper asked residents to check on vulnerable loved ones and the elderly, if possible. He said 11 emergency shelters have opened across the state.

North Carolina Highway Patrol said anyone who must drive should leave twice as much following space as normal behind the next car, in case that vehicle loses control.

Driving conditions remain hazardous. If you do not have to leave your home, please do not. If you must leave, be sure to slow down, increase following distances, have emergency supplies on hand and expect delays. #wintersafety #winterstorm pic.twitter.com/QYKZbJQU46 — NC Highway Patrol (@NCSHP) December 9, 2018

'Ice is becoming a big problem' in South Carolina

In South Carolina, a state known for palmettos rather than freezing rain, ice-covered roads were making driving conditions perilous.

It's never a good idea to be out on the roadways in winter weather, but when snow switches to nothing but ice, even a 4x4 will struggle. pic.twitter.com/MDwCpEz3Z7 — Trooper Bill SCHP (@SCHP_Troop3) December 9, 2018

The Greenville-Spartanburg area received between 2 inches and more than a foot of snow, NWS reported Sunday.

"Ice is becoming a big problem. Please stay off the roads," Greenville County Emergency Management pleaded.

The local National Weather Service office had to adjust its forecast map Sunday after it became clear more ice was expected near Interstate 85.

"We have increased our ice (accumulation) forecast quite a bit along the I-85 corridor," the NWS Greenville-Spartanburg office said.

The storm left a trail of misery in Texas

Before striking the Southeast, the moisture-heavy storm walloped Texas, causing flash flooding along the southern edge of the state and snow and ice in the north.

As the moisture moved east, it collided with a high-pressure system over the Ohio Valley that was funneling cold air into the region.

snow making my univ even more beautiful pic.twitter.com/WOLJU5vSNC — Kinsey Priesmeyer (@kpriesmeyer_) December 8, 2018

Parts of Lubbock were buried under 10 inches of snow, 2 inches more than the city usually gets in a whole year.

"They crushed their yearly average in 24 hours," CNN meteorologist Ivan Cabrera said.

More flight cancellations to come

Grounded airline passengers might remain stuck Monday as more flights get canceled.

The Charlotte airport said it expects cancellations through Monday morning, mostly involving small, regional planes.

American Airlines, whose second-largest hub is in Charlotte, has canceled 1,100 flights for Sunday. It's not clear when those passengers will be able to get on board, since another 320 flights scheduled for Monday already have been nixed.