More than 90 million are under winter weather alerts as states from Texas to Maine brace for a treacherous mix of ice and snow

Still, the governor warned that power outages may occur due to circumstances unrelated to the grid’s capability, including falling trees or icy powerlines.

In the Midwest, the governors of Missouri and Oklahoma declared states of emergency until Thursday due to the impending storm.

Oklahoma City may see up to 8 inches of snow as well as ice accumulations in the quarter-of-an-inch range, with some areas seeing up to half an inch of ice, the National Weather Service said. In St. Louis, Missouri, heavy mixed precipitation is possible, with ice accumulations up to two tenths of an inch.

“The winter storm is expected to include a mix of freezing rain, sleet, snow, strong wind gusts, and low temperatures across the state beginning Wednesday, which may result in power outages,” Oklahoma Gov. Kevin Stitt said in a news release.

In addition to declaring the emergency, Missouri Gov. Mike Parson activated the National Guard, saying it will be ready to help the state’s highway patrol with stranded drivers if necessary.

Ice is this storm’s biggest threat

Forecasters are predicting the storm will bring heavy snow. Across the Midwest, some areas stand to see 15 to 20 inches of snow, according to CNN meteorologist Dave Hennen.

But the bigger threat will be the ice accumulation.

“I do think that ice usually ends up being a bigger threat due to the greater risk for power outages caused by downed tree limbs and power lines,” CNN meteorologist Robert Shackelford said. “Ice accumulations are usually very small — we are talking about fractions of inches.

“So ice usually is more efficient in causing disruptions. But some of these snowfall totals are going to be very impressive, and that also causes the same results,” he said.

After the storm pushes south and east from its origin in the Rockies region, conditions are expected turn more icy than snowy with the threat of significant ice accumulation for millions. The impacts could linger, especially in the South and mid-South, until Saturday or Sunday, according to forecasts.

In Arkansas, Gov. Asa Hutchinson has deployed about 88 members of his state’s National Guard. He also signed an executive order that will allocate $250,000 for recovery efforts.

And in Illinois, Gov. JB Pritzker also activated his National Guard and issued a disaster declaration. The state Department of Transportation said it will also deploy more than 1,800 trucks and equipment to plow, treat roads and respond to weather emergencies.

Meanwhile, areas north and east of the Dallas-Fort Worth metropolitan region are expected to bear the brunt of this storm.

Thousands of canceled flights and school closures

And those potentially dangerous conditions have led the Dallas Independent School District to close Thursday and Friday, and schools are not expected to make up those days, officials said Tuesday.

In Kansas City, Missouri, the school district also moved to shutter its doors Wednesday due to the storm’s potential impact.

Airlines including Southwest, American, United and Delta Air have issued travel waivers for those traveling in the plains and Midwest on Wednesday and Thursday, allowing travelers impacted by bad weather can rebook their trips free of charge.