A storm system that unleashed violent tornadoes in Texas has moved into the western Plains and Rocky Mountain states, bringing the threat of feet of snow and blizzard conditions. More than seven million Americans are under winter weather alerts and about 300,000 are under blizzard warnings on Sunday morning. Parts of the western Plains and Rocky Mountain states reported several inches of snow Saturday, and much more could be on its way on Sunday. Up to 18 inches of snow is possible in Denver, while areas north of Boulder could see more than two feet of snow, CNN meteorologist Tyler Mauldin said. The National Weather Service in Boulder reported moderate to heavy snow and poor travel conditions early Sunday from north of Denver to the Wyoming border. The Denver International Airport reported seven inches of snow late Saturday, according to the weather service. More than 2,000 flights into and out of Denver this weekend have been canceled. Across Colorado, several major roads are closed, including two stretches of interstates. Leadville, Colorado reported more than 10 inches of snow early Sunday morning while the town of Sawpit also saw nearly 10 inches of snow, according to snowfall totals posted by the National Weather Service. The snow coupled with high winds could mean that parts of Wyoming, Nebraska and South Dakota will see blizzard conditions, making travel in those areas next to impossible, according to Mauldin. Uinta County, Wyoming, could see snowfall totals of one to two feet, the weather service from Salt Lake City, Utah, projected. The weather service in Cheyenne, Wyoming, reported their office received more than eight inches of snow Saturday. A winter weather advisory remains in effect through 6 a.m. Sunday for the central Utah mountains, Wasatch Plateau and Book Cliffs while a winter storm warning is in effect through 6 p.m. Sunday for the western Uinta Mountains and Uinta County, Wyoming, the weather service said. Southeast could see flood concerns Meanwhile, flood watches and warnings are in effect for areas of Kansas and Missouri, while heavy rain is impacting parts of Nebraska and Iowa. "Be on lookout for localized flooding of typical flood-prone areas," the weather service in Wichita, Kansas, wrote on Twitter. As the storm system moves east over the next day or two, the Southeast could also face flood concerns. Parts of Alabama and Georgia could see between two to four inches of rain Monday and Tuesday. The weather service in Atlanta warned "multiple rounds" of rain and storms were expected Monday through Thursday with rainfall totals hitting two and three inches. In Texas, Randall County Sheriff Christopher Forbis warned on Saturday evening of multiple downed power lines and baseball-sized hail soon after the National Weather Service in Amarillo reported two simultaneous tornadoes in the area. On Saturday night, the sheriff said parts of the county had seen "extensive tornado damage" but no injuries had been reported. There were 40 preliminary severe storm reports on Saturday, 11 of which were tornadoes, according to Mauldin. Severe weather threats shift to Arkansas Sunday, where showers and strong thunderstorms are forecast throughout the afternoon and evening, according to the National Weather Service in Little Rock. "Damaging winds will remain the primary threat, but an isolated tornado cannot be completely ruled out," the service said early Sunday morning. Tornado potential was very low, officials said. Wind speeds could reach up to 60 mph, according to the service, while parts of the state may see up to quarter-sized hail. — Courtesy CNN