Winter storm Petra
© NOAA
A satellite of the storm is seen over the Eastern US as of 6.36pm ET on Tuesday
A massive winter storm with more than 200 million people in its path is bearing down on the East Coast.

Heavy flooding rains falling on much of the Deep South on Tuesday night are expected to change over to ice and snow as the system hits the mid-Atlantic and Northeast on Wednesday.

The storm is expected to affect parts of 39 states, and roughly 60 percent of the country's population is in its path.

'Snow will move from southwest to northeast into Ohio and the Mid-Atlantic region late tonight, changing to a wintry mix of sleet and freezing rain and eventually all rain for many,' the National Weather Service said in a flash bulletin on Tuesday.

The agency said that the time of changeover from snow to ice would vary by location, but would be delayed in the Central Appalachians, where significant ice accumulation of a quarter inch along with four to eight inches of snow could be possible.

'Major cities along I-95 from Boston to Richmond will likely see some from of frozen precipitation at the onset before changing over to rain,' the agency said.

Winter weather alerts are in effect for parts of many states in the Midwest and Northeast
© weather.com
Winter weather alerts are in effect for parts of many states in the Midwest and Northeast
Farther south, heavy rain is expected to continue Lower Mississippi Valley into portions of the Ohio Valley, drenching already saturated ground and raising the risk of flooding.

'Flood and flash flood watches are already in effect for many of these locations. Additional heavy rain is expected to begin for some of these same locations impacted by flooding Thursday night,' said the NWS.

The storm is referred to as Winter Storm Petra by the Weather Channel, a designation not recognized by the government or other forecasters.

Parts of southern Pennsylvania, West Virginia and Maryland face the highest risk of heavy ice accumulation and subsequent downed power lines and power outages.

For much of the mid-Atlantic and Northeast, snow and ice conditions will make the roads hazardous for evening commutes on Wednesday.

Schools throughout much of the mid-Atlantic are expected to close on Wednesday.

On Tuesday, a Delta flight from Milwaukee to Atlanta was forced to make an emergency landing in Chattanooga, Tennessee after the pilot reported a possible lightning strike, according to the FAA.