More than 20 million people are under winter storm watches and warnings from New Mexico to North Carolina, where authorities have declared a statewide emergency as some areas could get over a foot of snow.
"Snow may be beautiful but it can also be treacherous and I urge North Carolinians to take this storm seriously and get ready for it now," Gov. Roy Cooper said in a statement.
Charlotte could see up to half a foot of snow.
"Six inches will shut that city down," CNN meteorologist Allison Chinchar said. "It's very much like any other Southern city ... where they don't have the resources that a lot of other cities have. They have few salt trucks, few snowplows. It takes them longer to clean something like that up."
As this multifaceted storm develops, here is what meteorologists are expecting, where and when:
Eastern Tennessee, Georgia and the Carolinas
Timing: Saturday morning through Monday morning
Precipitation creeps in early Saturday, with rain in Georgia and some light, wintry precipitation in the mountains. It picks up late Saturday when blizzard conditions are possible in the higher Appalachians, with larger accumulations Sunday into early Monday morning across the zone. The storm probably will move out to sea Monday, but it also could turn and climb up the East Coast, bringing heavy snow to major metro areas.
The culprit is a moisture-heavy storm that brought downpours and flash flooding along the southern edge of Texas and snow and ice in the north, including more than 9 inches of snow in Lubbock. As that moisture moves eastward, it is colliding with a high pressure system over the Ohio Valley that is funneling cold air into the region.
"It's kind of a big deal," Chinchar said. "It's December. This is not the time of year that they would typically get this stuff."
Impact: Record snow, blizzard conditions, wintry mix and heavy rain
Significant snow is expected -- but not certain -- across the mountains of northeast Georgia and the Carolinas.
Parts of North Carolina could see record snowfall, described by the National Weather Service as a "once-in-a-generation event." The mountains and foothills west of Interstate 85 could get up to a foot of snow.
Cities such as Asheville and Morganton in the mountains could get up to 16 inches of snow, increasing the threat of power outages as high accumulations could bring down trees on power lines, according to Chinchar.
"This storm comes at a time of year when North Carolinians are usually hearing carols about snow, not actually seeing it. But this time, the real thing is headed our way and North Carolina is getting prepared," Cooper said, according to CNN affiliate WSOC in Charlotte. "A winter storm's not a Christmas carol snow. It's serious, and you need to take steps now to get your family ready."
However, predictions sharply drop to 2 to 3 inches of snow in Raleigh and down to 1 inch in Greenville, South Carolina.
The flooding and winter precipitation may also affect Georgia. Heavy rain with 1 to 3 inches is projected Saturday, with "rates expected to be high at times, increasing the threat of flooding," the weather service said.
About 1 to 2 inches of snow could fall in the higher elevations of North Georgia, with up to 5 inches on the highest ridges Sunday night into Monday. Possible freezing rain and dusting snow could also reach the I-85 corridor.
Arkansas and western Tennessee
After seeing some precipitation Friday, Arkansans are expected to get some winter weather Saturday as the storm moves east toward Tennessee.
Impact: Flooding rains, wintry mix, mountain snow
North Arkansas will see up to 6 inches of snow and up to one-10th of an inch of ice.
"That may not sound like a lot," Chinchar said of the ice accumulation, "but it is enough to cause slick roadways and cause travel problems. ... Because they will get snow as well, the ice will likely be hidden underneath the snow, so it may be very difficult to know if roadways have ice on them."
The southern half of Arkansas faces up 4 to 5 inches of rain, with flash flooding possible. Central Arkansas looks to pick up, at most, 1 inch of snow. Meanwhile, the higher elevations of the Ozark Mountains will likely see 2 to 6 inches of snow on top of a glaze of ice up to a quarter of an inch.
Snow totals will be lower in northeastern Arkansas and northwestern Tennessee, where a trace to 1 inch of snow is possible.
Timing: Saturday morning through Saturday evening
Precipitation began Friday in central and northern Texas, moving east overnight where fears of flash flooding will increase through Saturday. Up to 2 inches are possible hourly in coastal towns.
San Antonio and Houston could see flash flooding as rainfall totals could reach 3 to 6 inches, with as much as 10 inches in isolated spots. As of Friday evening, Austin had 2.95 inches of rain, and an area of East Texas saw 3.4 inches.
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