After parts of 41 states were under weather alerts Tuesday, places like Dallas, Chicago and Boston were feeling the nighttime impacts of multiple winter storms and cold fronts.
Temperatures plunged into the 30s in Dallas, "fluffy flakes" of snow were falling in Chicago, and "a nasty evening" of rain had begun in Boston, according to National Weather Service offices.
A blast of arctic cold in the West and into the Northern Plains was also expected to be the longest-duration cold outbreak of the winter season so far.
The first storm was impacting the Midwest and Mississippi Valley to New England through Wednesday.
On Tuesday, this storm system was producing snow and wind on the northern side across the Upper Midwest and Great Lakes, and severe thunderstorms and flooding rainfall on the southern side across the Mississippi, Ohio and Tennessee Valleys to the Southeast.
A wintry mix of snow, sleet and freezing rain was expected to move into parts of New England overnight. Rain was in the forecast for the Interstate 95 corridor, including for New York City.
Snow on Tuesday will be heaviest across parts of Minnesota as well northern Wisconsin and northern Michigan. Additional snowfall of up to 6 inches will be possible, bringing storm totals of 1 to 2 feet in some areas. The snow, combined with wind gusts up to 30 mph, will lead to dangerous travel conditions.
An ice storm warning was also in effect for parts of Central Michigan, where up to 0.4 inches of ice was possible.
One to 3 inches of rain was forecast to fall across the Ohio, Tennessee and Mississippi Valleys through Wednesday. Some areas could see up to 4 inches or more.
The greatest risks for flooding will be across western Kentucky and northern Alabama. Nearly 100 river gauges were also expected to rise into minor to major flood stage, with the highest concentration along the Ohio River.
In the southeastern U.S., 11 million people were under the threat for severe thunderstorms. The greatest risk overnight will be damaging winds up to 75 mph followed by isolated tornadoes. Cities to watch include Memphis and Nashville in Tennessee and Louisville, Kentucky.
The second storm system will affect the West Coast to the Northeast, starting Tuesday and lasting through Friday, forecasters said. Rain was already falling in Southern California Tuesday night.
Rain and snow accumulations on the West Coast were expected to be minimal but still welcome after an exceptionally dry period the last several weeks.
On Wednesday, snow will fall over the Central Rockies as an icy mix breaks out across parts of the Southern Plains.
On Thursday, more heavy rain and strong thunderstorms will be possible across the South while snow and an icy mix spread across the Midwest and into the southern Great Lakes.
By Friday, the newest system reaches the East Coast bringing mostly snow to New England, from Boston and northward, and an icy mix and cold rain to the Northeast and Mid-Atlantic. New York City could experience all types of precipitation, including rain, sleet, freezing rain and some snow.