MILWAUKEE • Heavy snow and powerful wind created blizzard-like conditions Monday across parts of the Midwest, prompting officials to cancel about 1,000 flights at Chicago’s airports and close hundreds of schools. But forecasters warned the most dangerous weather is yet to come: frigidly low temperatures that the region hasn’t seen in a quarter century.

Snowplow drivers had trouble keeping up with the snow in Minnesota and Wisconsin, where some areas got as much as 15 inches.

Chicago-area commuters woke up to heavy snowfall, with more than 5 inches already on the ground. In Michigan, nonessential government offices were closed, including the Capitol.

But the snow is only “part one, and maybe even the easier part” because temperatures will plummet over the next three days, said Brian Hurley, a meteorologist with the Weather Prediction Center.

Wednesday is expected to be the worst. Wind chills in northern Illinois could fall to negative 55 degrees, which the National Weather Service called “possibly life threatening.” Minnesota temperatures could hit minus 30 degrees with a wind chill of negative 60.

“You’re talking about frostbite and hypothermia issues very quickly, like in a matter of minutes, maybe seconds,” Hurley said.

The potentially record-breaking low temperature forecast in Milwaukee is negative 28 degrees, with a wind chill as low as negative 50.

The current record of minus 26 degrees was set in 1996.

“That’s 40 degrees below normal,” Hurley said. “When you think about it in that sense, that’s a big ‘whoa.’”

Cold weather advisories are in effect across a broad swath of the central U.S., from North Dakota to Missouri and spanning into Ohio. Temperatures will be as many as 20 degrees below average in parts of the Upper Great Lakes region and Upper Mississippi Valley, according to the National Weather Service.

The unusually frigid weather is attributed to a sudden warming way above the North Pole.

A sudden blast of warm air from misplaced Moroccan heat last month made the normally super chilly air temperatures 20 miles above the North Pole rapidly rise about 125 degrees.

That split the polar vortex into pieces, which then started to wander, according to Judah Cohen, a winter storm expert for Atmospheric Environmental Research, a commercial firm outside Boston. One of those polar vortex pieces is responsible for the sub-zero temperatures across the Midwest this week.

Homeless shelters were preparing for the onslaught of cold.

Pedestrians cross an icy Chicago River near the Civic Opera House in Chicago on Monday. Wednesday’s wind chill is expected to be negative 55 degrees.

the associated press