(CNN) -- Does the end of the world start with a snowstorm?
Probably not, but a blizzard in the upper Midwest is proving potent enough to cut power to tens of thousands of homes and force schools to call it quits from Nebraska to southern Wisconsin Thursday -- one day ahead of the official arrival of winter and, as it happens, the predicted Mayan apocalypse.
As much as another foot of wet, heavy snow is expected in places, accompanied by winds gusting to 50 mph and blowing snow that could reduce visibility to just about zero, forecasters warn.
In Omaha, Nebraska, utility crews struggled overnight -- sometimes in near whiteout conditions -- to restore power to 38,000 customers left in the dark by the storm, according to the Omaha Public Power District. The utility urged customers to brace for slow going.
In neighboring Iowa, more than 30,000 customers were without power, most of them in the Des Moines area, according to MidAmerican Energy.
The storm -- the first blizzard of the season -- made travel treacherous throughout the region. Nebraska authorities closed much of snow-packed I-80 through the state Thursday morning as blowing snow dangerously reduced visibility.
In Wisconsin, Gov. Scott Walker declared a state of emergency, put the National Guard and state patrol on standby and closed state offices to the public in 20 counties most likely to be affected by the storm. Employees were still expected to report for work.
As much as 7 inches was already on the ground Thursday morning in parts of southern Wisconsin, with as much as another foot on the way during the storm's predicted Thursday afternoon peak.
The Wisconsin State Patrol and National Weather Service urged people to avoid traveling.
Blizzard warnings were up Thursday for portions of Nebraska, Missouri, Minnesota, Illinois and Wisconsin and virtually all of Iowa. Winter storm warnings extended further into Missouri, Illinois and Wisconsin, as well as into Michigan and Indiana.
Most airports were operating normally, the FAA reported. One major exception was O'Hare Internatonal Airport in Chicago, where incoming flights were running nearly two hours behind because of high winds, the FAA said.
The storm is expected to slide over New England by Friday.
-- CNN's Jim Kavanagh, Laura Smith-Spark, Carma Hassan and Joe Sutton contributed to this report.
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