More than 75 million are under winter weather alerts from the central Plains to the Northeast as a potent wintry mix is expected this weekend.
A winter storm will develop in the central Plains on Saturday evening and expand overnight into the Mississippi River Valley. It will push into the Ohio River Valley and the Northeast by Sunday.
The system will be fast but fierce before moving out by Monday afternoon.
The heaviest snow is forecast across eastern Colorado and Kansas, where 4 to 6 inches of snow is likely. The Kansas City area and St. Louis are calling for 2 to 4 inches of snow through Sunday, CNN meteorologist Haley Brink said.
Temperatures Sunday in the central United States will be 30 to 50 degrees F below normal for this time of year, Brink said. By midweek, they will be 15 to 20 degrees below normal in the East.
In the Southeast, more heavy rain and severe storms are expected as areas continue to cope with extreme flooding, especially along the Mississippi River.
The timing of the storm
Snow is expected to begin falling midday Sunday across the Ohio River Valley, but it will likely get less than an inch. The system will then quickly track toward the Northeast, with winter weather falling across New York, Connecticut and Massachusetts by early Sunday evening.
The snow will persist overnight, with a few showers expected to linger through Monday morning. The skies should start to clear by Monday evening.
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Much of the Northeast could see 2 to 4 inches of snow, with higher localized totals possible.
One to 2 inches of snow is expected in Washington, with 2 to 4 inches forecast for Philadelphia, 3 to 5 for New York City and 4 to 6 for Boston.
Temperatures across the region will hover close to the freezing mark so that the snow will be more of the heavy, wet type.
This snow will be much harder to shovel than the powdery stuff, CNN meteorologist Chad Myers says, adding that this particular system has the potential to produce thundersnow.
Severe weather possible in the Southeast
The Storm Prediction Center issued a slight risk for severe weather Sunday stretching from eastern Louisiana to southwest Georgia. Wind is expected to be the greatest threat, but there is also the potential for a few tornadoes.
Meanwhile, more heavy rain is expected to fall across already saturated regions of Mississippi, Alabama, Georgia, Tennessee, and the Carolinas. Two to 4 inches of rain are likely, with many areas remaining under river flood warnings.