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The deadly rainstorm that sent rivers of mud crashing into dozens of Southern California homes is sweeping eastward — and threatening snow, flooding and flash freezing for 60 million Americans through the weekend.

Snow and a band of freezing rain and sleet were falling Thursday afternoon from parts of northeast Minnesota into Illinois and Wisconsin, forecasters said. Up to 9 inches of snowfall has been reported in parts of the Plains.

The system is expected to send strong winds and widespread snow across the upper Great Lakes and the Midwest through Friday morning — making the morning's commute potentially dangerous and slippery in cities such as Detroit, Indianapolis and Nashville and Memphis, Tennessee.

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Ice accumulations could reach a 10th of an inch to a quarter-inch east of St. Louis into parts of Illinois, Kentucky, Indiana and Tennessee, forecasters said.

Lieutenant Rust in Marion county providing this image.



K150 Milepost 11



The roads are deceiving.

They do not look slick but they are. #KSwx pic.twitter.com/p0UokhSnZy — Trooper Ben (@TrooperBenKHP) January 11, 2018

The storm will continue moving into the Ohio Valley and New England, where ice could thicken to a quarter of an inch to a half-inch, forecasters warned. Snow could also pile up from 6 to 12 inches.

In addition, a flood watch was in effect for 20 million people from Buffalo, New York, to Boston, as part of a different weather system that's bringing rain and unseasonably warmer temperatures to the Eastern Seaboard.

"We're real concerned about the potential flooding because already you got snow," Weather Channel meteorologist Heather Tesch said. "You're going to see the snow melting. You add rain on top of that — you're going to find, too, we could see some ice jams coming in."

Boston, which was already cleaning up from last week's winter storm, which brought record flooding, could see 2 to 3 inches or more of flooding from Friday morning to Saturday afternoon, forecasts said.

The mess of #ice and #snow from #Winter Storm #Hunter arrives in the Ohio Valley starting tonight, spreads into parts of the Northeast later Friday into Saturday. https://t.co/iCkBsWqZ8s pic.twitter.com/VZKK5kaVbF — The Weather Channel (@weatherchannel) January 11, 2018

In all, the snow in upstate New York could accumulate 8 to 12 inches in Syracuse and 5 to 8 inches in Buffalo, according to The Weather Channel. Cleveland could see 3 to 5 inches of snow, and Midwestern cities such as Chicago, Minneapolis and Kansas City, Missouri, could get up to 3 inches.

Meanwhile, another Arctic chill is set to make temperatures plunge 20 to 40 degrees from the central Plains to the Northeast once the storm rolls out. New York City, for instance, could go from a high of 60 degrees on Friday to 33 on Sunday.

"It's such cold air on the backside. ... You could see some flash freezing," Tesch said, "and that could mean some really icy travel conditions."