Heavy snow trapped dozens of travelers on at least two Indiana highways on Monday, while Chicago and other parts of the Midwest saw subzero wind chills, school closures and massive cleanup following a weekend storm.
The heavy lake effect snow in northern Indiana was part of a slow-moving storm that has been crawling across the Midwest since Friday night.
At least 15 deaths have been attributed to the storm, which dumped nearly two feet of snow in parts of Minnesota and Wisconsin before moving into Michigan and Indiana. On Monday, it stretched farther east, with snow in parts of Ohio, Pennsylvania and New York.
In northwest Indiana, up to 16 inches of lake effect snow fell in some areas around LaPorte. Lake effect snow develops when cold air rushes over the warmer water in Lake Michigan.

Kate Ergang wasn't worried when two jackknifed semi-tractors trapped her and a friend on an Indiana highway in a blizzard. They had eaten dinner already and had blankets and pillows in the car. They talked, listened to their iPods and dozed off.
But the May college graduate had a few minutes of panic Monday morning when she woke and realized that nearly 12 hours later, they were still in the same spot.
More than 100 vehicles were stuck Monday on Indiana's snow-covered highways. Strong winds and blowing snow hampered snow plow drivers' efforts to free them, but all motorists had been safely rescued by Monday evening, said Amy Bluhm, a dispatcher with LaPorte County 911.
Up to 16 inches of snow fell in northwest Indiana, where 70 drivers got stuck in drifts on a section of Indiana 2 in the Valparaiso area.
Ergang and her friend, Allison Frank, were among an unknown number trapped on U.S. 30.
They were driving home to Crown Point on Sunday after visiting friends in central Indiana. All was fine until they reached Wanatah, about 35 miles southwest of South Bend.
"It was a whiteout. It was like a tornado of snow," Ergang said.
Unable to see if a car was in front of her, Frank would nudge her 2000 Ford Focus slowly forward, stopping periodically, before all traffic came to a standstill about 7 p.m. because the semi-tractors had jackknifed at an interchange east of Valparaiso. Frank turned the car off, and the two made beds in their seats with the blankets and pillows.
In the morning, they flagged down a police officer headed the opposite way who told them a 7-mile stretch of the highway had been closed. The road to Wanatah opened a little later, about 6:30 a.m., and they headed back there. They and dozens of other motorists spent the next three hours in a service station convenience store, where they could use the bathroom and buy some food.
"It was definitely a relief to get out of the car and get in the warmth and talk with somebody else about what was going on," Ergang said when reached by phone later at home.
Indiana state police Lt. Lou Brown said some people made the situation worse by driving on roads that were closed or abandoning vehicles that got stuck.
"People would get into a snowdrift and couldn't go anywhere so they'd just leave the vehicle to get out of the weather," he said. "It just plugs things up and then snow plows can't get around them."
Truck drivers stopped at the Junction City Restaurant in Rolling Prairie near the intersection of U.S. 20 and Indiana 2 for lunch, hoping the conditions would improve. They said driving was particularly difficult in areas where wind was blowing across open farmland, sweeping the snow onto highways and making it hard to see.
Three retirees who drove 2 miles to meet at the diner for lunch said even their trip was difficult.
"We couldn't even see on the way over," said Bill Sullivan, 73, of Rolling Prairie. "It was blinding. You can't see nothing. We're going home and getting out of this crap."
In Chicago, thousands of travelers returned to O'Hare and Midway airports Monday after some 1,600 cancellations on Sunday', but getting out was still a problem.
Airlines cancelled 75 flights at O'Hare before 9 a.m. (CST), Karen Pride, Director of Media Relations of the Chicago Department of Aviation, told msnbc.com. More than 1,370 flights there were cancelled on Sunday.
Chicago's Midway Airport, which saw 300 cancellations on Sunday, had seen no delays before 9 a.m. Monday, she said.
The winter weather, "with dangerously cold wind chills in some areas," was expected to continue throughout the Midwest on Monday, . While the high winds were expected to die down during the week, the intense cold was set to linger in much of the Missouri and Mississippi Valleys, it reported.
"With the snow, pretty much the worst of it is over, but we're going to get cold temperatures through Tuesday," said Jim Taggart, National Weather Service meteorologist in Chanhassen, Minn.
The weather the region is experiencing is what it "normally would get in January," Taggart said.
The Western Plains, in contrast, would see warmer weather in the coming days, The Weather Channel reported.
Metrodome collapse
In Minneapolis, heavy snow caused the inflatable roof of the Metrodome to collapse Sunday. Video inside the stadium aired by Fox Sports showed the inflatable Teflon roof sagging before it tore open, dumping massive amounts of snow across one end of the playing field.
No one was hurt, but the Vikings' game against the New York Giants had to be moved to Detroit's Ford Field. The day of the game had already been pushed back from Sunday to Monday because the storm kept the Giants from reaching Minneapolis on time. Stadium officials were trying to repair the roof in time for the Vikings' next home game, Dec. 20 against Chicago.
In the Chicago area, only a few inches of snow fell, but wind gusts of up to nearly 50 mph blew the roof off a building at Navy Pier and sent waves from Lake Michigan crashing onto Lake Shore Drive.
'The worst flying experience'
Officials at O'Hare set up about 200 cots and provided amenity kits containing toothpaste and toothbrushes for stranded travelers, Pride said.
Jordan Ledoux was traveling back to Portland after a visit to Houston when he ended up stuck at O'Hare. He said it was possible he might not get home until Tuesday.
"This is the worst flying experience I've ever had," he told WBBM-TV.
Major highways in several states were closed due to poor driving conditions and accidents.
Seven vehicles crashed on Interstate 94 about 50 miles west of Milwaukee, prompting authorities to close the westbound lanes. A vehicle lost control on an ice-covered road and slammed into a tree in southeastern Wisconsin, killing 21-year-old Alejandria Abaunza of Chicago and injuring two other people inside.
Eight people in four states, including Indiana, have died in traffic accidents related to the storm, and a 79-year-old man snow-blowing the end of his driveway in western Wisconsin was killed when a plow backed into him.
Five more died after shoveling or blowing snow, and Kennenth Swanson, 58, of rural River Falls, Wis., died when a metal shed collapsed from the heavy snow, pinning him under debris and about 3 feet of snow.
Snow also blanketed Tennessee, where up to 4 inches was reported. WSMV-TV in Nashville said the weather forced several communities to cancel Christmas parades planned for Sunday.