Updated 11:15 PM ET
ST. LOUIS Powdery snow bombarded much of the nation's midsection Thursday, leaving as much as 17 inches in some places, shutting down airports, schools and state legislatures.
The storm system swirled to the north and east Thursday night, its snow, sleet and freezing rain prompting winter storm warnings from Kansas to Illinois. Forecasters say the storm will continue its crawl overnight, hitting the upper Midwest by Friday morning.
The system has already left impressive snow accumulations, especially in Kansas, where a foot and half of snow fell in Hays. Farther east in Topeka, 3 inches of snow fell in only 30 minutes, leaving medical center worker Jennifer Carlock to dread the drive home.
"It came on fast," Carlock said as she shoveled around her car. "We're going to test out traction control on the way home."
Corey Mead, a meteorologist with the National Weather Service's Storm Prediction Center in Norman, Okla., said the winter storm would be centered in the upper Midwest by Friday morning.
"Even across Kansas, the snowfall rates should continue to taper off through the evening," Mead said.
Chris Suchan, chief meteorologist at CBS affiliate KCTV Kansas City, told "CBS Evening News" anchor Scott Pelley Thursday that the worst is over with. "This morning we had widespread thundersnow from Levenworth, Kansas [and] Overland Park to Warrensburg, Missouri," Suchan said. "Snowfall rates of 2 to 3 inches per hour brought this area to its knees with our motoristsbridges were closed for a while.
"Now what we're anticipating is another round for this evening, perhaps another 2 to 4 inches of snowfall, some freezing drizzle right now, and wind chills in the single digits. The storm total for us is about 8 to 12-14 inches of snowfall for Kansas City."
Numerous accidents and two deaths were being blamed on the icy, slushy roadways. Most schools in Kansas and Missouri, and many in neighboring states, were closed and legislatures shut down in Kansas, Missouri, Arkansas, Nebraska and Iowa.
National Weather Service meteorologist Scott Truett said the "thundersnow" that rumbled through Kansas and Missouri earlier Thursday was the result of an unstable air mass, much like a thunderstorm.
"Instead of pouring rain, it's pouring snow," Truett said. And pouring was a sound description, with snow falling at a rate of 2 inches per hour or more in some spots.
All flights at Kansas City International Airport were canceled for Thursday night, and officials said they'd prepare to reopen Friday morning. In St. Louis, more than 320 flights at Lambert Airport were canceled, and traffic throughout the state was snarled by hundreds of accidents.
Northern Oklahoma saw between 10 and 13-and-a-half inches of snow. Missouri's biggest snow total was 10 inches, shared by the Kansas City metropolitan area, Rockport in the northwest corner and Moberly in the central part of the state.
But the highest amounts were in Kansas, where snow totals hit 14 inches Hutchinson, Macksville and Hanston, and 13 inches in Wichita.