Ice storms, heavy snowfall, possible tornadoes and the threat of flash floods are expected to create travel nightmares this weekend in many parts of the US, causing flight delays and unsafe road conditions for some of the millions of people traveling ahead of Christmas.

The National Weather Service on Saturday issued tornado watches for Tennessee, Arkansas and Louisiana, and warned of ice and sleet in upstate New York as well as snowfall for areas from Kansas to the Milwaukee region in southeast Wisconsin.

Some 85.8 million people will be on the roads between Dec. 21 and New Year's Day, and 5.5 million will fly, according to the automotive group AAA.

A massive storm system closed roads and hampered travel in southeast Missouri on Saturday with heavy rain totaling 3 to 6 inches (7 to 15 cm), said Jim Sieveking, meteorologist for the National Weather Service in St. Louis.

About 150 sections of various highways were closed due to flooding, according to the Missouri Department of Transportation website.

Meanwhile, ice was coating some roads to the north, Sieveking said, and the Department of Transportation advised drivers not to travel in central and northern Missouri late on Saturday.

Freezing rain combined with snow that melted during recent unseasonably warm temperatures also made roads icy in upstate New York near the Canadian border on Saturday, according to the New York State Department of Transportation website.

The National Weather Service forecast an inch (2.5 cm) of ice could accumulate overnight, prompting New York Governor Andrew Cuomo to declare a winter ice storm emergency.

The ice storm that struck the state of Kansas and Oklahoma City in recent days turned to snow on Saturday. A total of 4 to 8 inches (10 cm to 20 cm) was expected to fall from Kansas to Wisconsin, according to the weather service.

"It pretty much stretches the entire center of the country and is impacting travel for sure," Sieveking said

Most Midwest airports had only modest delays of 15 to 30 minutes on Saturday, according to the Federal Aviation Administration website. Airport representatives in Detroit, Indianapolis and Chicago said it was too early to predict scheduling changes.

Forecasters predicted that Chicago, where O'Hare International Airport is expecting some 200,000 passengers on Sunday, would experience freezing rain overnight.

While the Midwest was seized by cold temperatures, a weather problem of a different nature took shape in Arkansas as suspected tornadoes wreaked havoc, injuring several people, damaging homes and in one case sweeping trucks off a highway, officials said.

The most widespread damage was near Dermott, Arkansas, in the southeast corner of the state, where five homes were seriously damaged, said National Weather Service meteorologist David Cox in Jackson, Mississippi.

The bad weather is expected to subside by the end of the day on Sunday, but only slightly, said Rich Thompson, lead forecaster at the Storm Prediction Center in Norman, Oklahoma.

"The central states will get better and the south will get better Sunday, but it will still be dicey along the Great Lakes states, the Northeast and the East Coast," he said. – Reuters