Arctic chill spreads across Upper Midwest, Rockies November 11, 2014: A cyclist braving the cold temperatures cruises down a snow-covered path in Bozeman, Mont. AP Photo/Bozeman Daily Chronicle, Adrian Sanchez-Gonzalez DETROIT - The Arctic chill that has gripped the Upper Midwest and Rockies is spreading. Other parts of the U.S. are expecting sharp drops in temperature in the coming days from a powerful weather system that hit Alaska with hurricane-force winds over the weekend. The system has dumped 3 feet of snow in some places. A look at the system and its effects: As much as 3 feet of snow blanketed parts of Michigan's Upper Peninsula, with temperatures in the 20s and 30s early Wednesday. Up to 18 inches fell in northern Wisconsin and parts of central Minnesota saw more than 16. Many roads were snow-covered and slippery Wednesday morning in the Upper Peninsula, where residents are accustomed to snowy conditions. Of his drive into work, meteorologist Justin Titus said that roads were "just rutted out and kind of felt like you were driving over a washboard." The National Weather Service said some lake-effect snow, mainly in Michigan, is forecast through the weekend. The unseasonably low temperatures are spreading. In northern Illinois, temperatures fell more than 30 degrees in less than a day, from a high of 58 on Tuesday to 26 degrees on Wednesday morning. The chill was expected to hit the Appalachians and mid-South by Wednesday morning, and the East Coast by Thursday. In Billings, Montana, where temperatures fell from the high 60s into the single digits on Tuesday, Patsy Kimmel said she was warned about the weather before arriving from Oklahoma to celebrate her 70th birthday with family. "Yesterday I was wearing sandals and a short-sleeve shirt, and today I'm wearing a coat and scarf and turtleneck and sweatshirt and gloves," she said. In the Texas Panhandle, temperatures plunged from 70 degrees into the teens overnight. Oklahoma City went from a high of 80 degrees Monday to a low of 30 Tuesday morning. In the Dakotas, wind chills made it feel like 20 below in some places. That was good news for Action Mechanical Inc. of Rapid City, South Dakota, a heating and ventilation business that was doing booming trade. Bang! We get this arctic blast, and it just opens the floodgates," said John Hammond Jr., a department head. We're behind right now as we're sitting here talking. Meteorologists are adamant the weather isn't because of the polar vortex, a giant upper air pattern that normally pens in cold air in the Arctic in the winter. Instead, they say it's being pushed in by a different weather phenomenon more related to the remnants of a powerful typhoon. The polar vortex itself has not moved south. It's still in the Arctic where it always is," said National Weather Service spokeswoman Susan Buchanan. Whatever the case, the cold is expected to linger. Some regions will go from record warm to record cold in just two days, with temperatures dropping 15 to 20 degrees below normal on the East Coast Friday and Saturday. Freezing temperatures will likely dip as far south as Atlanta on Friday, said Jeff Masters, meteorology director of the Weather Underground. The early wintry weather in the Midwest gave Principal Lynn Grewing an opportunity to test a virtual classroom: She asked students of St. Cloud Cathedral high school in central Minnesota to work from home using laptops or iPads. Grewing said her students' cherished snow days are now a thing of the past. "This is what we will be doing every single snow day going forward," she said. I'll be honest. There has been some grumbling. Private schools such as Cathedral, as well as some public school districts nationwide, are starting to use the flexibility that technology provides to meet school mandates without needing makeup days when bad weather keeps students at home. Cathedral senior Tommy Auger said doing classwork at home using his school-provided MacBook Air didn't feel very different to a day in class. Once they got over the initial disappointment of missing a snow day off, Auger said he and his classmates agreed they would rather skip a day of sledding than make up the missed school days in the summer. "It's hard to think ahead, but it's definitely better," he said.