Some 46 million people from the northern Rockies to the Northeast remain under winter weather alerts into the weekend, as two weather systems threaten to disrupt post-Thanksgiving travel with chilly temperatures, heavy snow and dangerous driving conditions.

Heavy lake-effect snow will continue across the Great Lakes region from Friday through early Saturday morning, with snow squalls bringing quick bursts of heavy snow and potential whiteout conditions for the interior Northeast on Friday, according to the National Weather Service .

More than 1,400 flights traveling to, from or within the U.S. were delayed as of midday Friday, according to flight tracking website FlightAware , with 24 flights canceled.

That storm already fueled rounds of heavy lake-effect snow across portions of t

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