Cities across the Midwest declared snow emergencies as the third heavy snowfall in less than two weeks was expected to blanket parts of Minnesota, Nebraska and South Dakota in white stuff Tuesday. Winter Storm Delphi was expected to bring as much as a foot of snow overnight.

In Iowa, eight inches of snow had accumulated in Sioux City by Monday afternoon, while 6.1 inches of snow was recorded in Sioux Falls, South Dakota, which was still recovering from a Nov. 20 storm that dumped 18 inches on the city. The cold weather brought 9 inches of snow in parts of Minnesota and Iowa Monday.

The snow storm came after the harsh weather system unofficially known as Delphi pounded the middle of the country over the Thanksgiving holiday weekend. This week, the Midwest was bracing for more cold weather, officials said. "We've still got plenty of moisture to work with and certainly a lot of cold air," Danielle Banks, a meteorologist for The Weather Channel, told NBC.

The winter-like climate made for poor road conditions. The Minnesota State Patrol responded to 145 crashes in metro Minneapolis-St. Paul area Monday as visibility was reduced to lass than a half-mile in some areas. More road problems were expected Tuesday.

“Pay close attention to the forecast as this storm unfolds,” Greg Gust, warning coordination meteorologist with the National Weather Service in Grand Forks, North Dakota, told local media.

Other offiicals were keeping a close watch on the storm. Winter weather advisories were in place from central Nebraska to northwest Wisconsin and northeast Minnesota. Chicago, Milwaukee, northern Indiana and northwest Ohio could be hit by Wednesday afternoon, according to forecasts.

Oklahoma Gov. Mary Fallin declared a state of emergency Sunday night for the state and more than 52,400 homes were without power, the state's two main power utilities reported Monday.