Millions of Americans from Texas to Maine are under a winter storm watch as forecasters warn of flash flooding, severe thunderstorms and heavy snow in many areas.
The National Weather Service said Wednesday a tornado watch is also in effect for parts of Florida and Georgia.
It comes a day after a tornado ripped through Texas, causing severe destruction along its route.
There have been no reported deaths.
According to PowerOutage.us more than 160,000 homes and businesses in Arkansas, Missouri and Texas were without power Wednesday morning.
At least 250 flights have been delayed and more than 300 cancelled.
Chicago Midway International Airport and Chicago O'Hare International Airport account for most of the cancellations.