McLEAN, Va. – More than 60 million Americans faced winter weather alerts Monday as snow, ice and a wintry mix from two closely aligned storms swept across much of the Midwest and East.

The National Weather Service posted winter weather advisories – possibly hazardous conditions expected – for more than 55 million people and winter storm warnings to 6 million more. A storm warning means, among other things, that at least 4 inches of snow or 1/4 inch of ice likely are on the way.

Missouri was a prime target for the misery: Snow Sunday from the first storm that force State Highway Patrol to handle more than 1,000 stranded motorist and vehicle crash calls. On Monday morning, commuters struggled through a wintry mix from the second storm. That forced St. Louis Public Schools to cancel classes for 30,000 students, and tens of thousands more kids around the state also gained an impromptu weather holiday.

“We’re expecting another round of heavy snow today across parts of east-central Missouri and southwest Illinois,” the National Weather Service in St. Louis warned. “This includes the St. Louis metro area from approximately 9am through 6pm.”

More than 200 flights were delayed or canceled Sunday at St. Louis Lambert International Airport, and dozens more already were affected early Monday.

In Indianapolis, mist and freezing drizzle greeted early risers. The local school district was more hopeful that St. Louis, ordering a two-hour delay for its 30,000 kids. But National Weather Service meteorologist Mike Ryan made it clear the storms were not over.

“By the time it ends late tonight we’re talking an additional 3 to 4 inches,” Ryan said. “That’s on top of the 3 to 4 we’ve already had. There may be spots that have 6 to 7 inches.”

Portions of the Northeast that missed out on any snow from the first storm could get blanketed with several inches of snow from the second, stronger storm, AccuWeather reported. Northern Pennsylvania and much of upstate New York into New England were viewed as primary targets.

“There is likely to be a narrow swath of 6- to 12-inch snowfall totals in the Northeast as well, but confidence remains low on exactly where that stripe will occur,” said AccuWeather Senior Meteorologist Rob Miller.

Downtown Washington, D.C., saw a mix of snow and sleet to start the morning before the precipitation turned to rain. But outlying areas were dealing with snow, sleet and snarled traffic conditions deeper into the morning. Manassas City Public Schools officials delayed their opening by two hours and promised to “monitor the conditions and make an additional announcement regarding the status of school if necessary.”

Farther south, heavy winds and rain were targeting western Tennessee, western Arkansas, Louisiana, Mississippi and Alabama and will threaten Nashville and Memphis, Tennessee, and Jackson, Mississippi, AccuWeather said.

“These storms will be capable of producing damaging wind gusts, torrential downpours, hail and even an isolated tornado or two,” said AccuWeather Meteorologist Brandon Buckingham. “These threats will continue for a time into the evening hours, becoming even more dangerous in the dark.”

Contributing: Crystal Hill, Indianapolis Star

USA Today