A cross-country winter storm system is expected to bring severe weather to the South and Northeast.
About 16 million people are at risk of an outbreak of severe weather Tuesday in the Mississippi and Tennessee river valleys, which will include parts of Alabama, Arkansas, Louisiana, Mississippi and Tennessee.
Strong, long tornadoes will be possible along with baseball-sized or larger hail and potentially damaging winds of 75 mph.
The National Weather Service issued a tornado watch as of Tuesday afternoon for an area that includes northeast Louisiana, southern Arkansas and central Mississippi.
The agency called the threat of tornadoes “a particularly dangerous situation” and warned those in the area to be prepared.
Jackson, Mississippi is in the center of the severe weather risk area, with other cities to watch including Memphis, Tennessee; New Orleans; Birmingham, Alabama; and Shreveport, Louisiana.
Since sunsets are before 5pm in most of the risk area, most dangerous storms will occur after dark. This will increase the danger, as nighttime tornadoes are 2.5 times more likely to be deadly than daytime ones.
Flood watches are also in effect along parts of the east-central Gulf Coast, where storms could cause flash flooding through Wednesday morning.
The storm system will move east on Wednesday, bringing strong storms, heavy rain and wind to the East Coast. Rain and wind will be the main weather factors for the Mid-Atlantic area in New England, with strong storms possible from Georgia to northern Florida.
Atlanta; Mobile, Alabama; New Orleans; and Tallahassee, Florida could see severe thunderstorms, especially in the first half of the day.
Rain is likely in New York City for the tree lighting at Rockefeller Center on Wednesday. There will also be wind gusts near 40 mph in the city, with temperatures expected to be in the 50s.
According to FlightAware.com, more than 1,990 flights traveling to or from U.S. airports were delayed and 233 flights were canceled as of 1:45 p.m. ET Tuesday. Most of those cancellations, 150, were at Seattle-Tacoma International Airport, where Alaska Airlines canceled 90 flights due to winter weather expected in the area.
“Our flight operations will be affected on Tuesday and throughout the week,” the airline said in a statement. “Additional cancellations are possible as we assess the impact of the weather on our operation.”
The northern side of this cross-country storm system will bring snow, affecting the Upper Midwest.
As of Tuesday morning, snow was moving across parts of the central Rockies and northern Great Plains into the Upper Midwest, including parts of Iowa and Minnesota.
This area of snow is expected to continue eastward and move into places like Minneapolis-St. Paul metropolitan area Tuesday afternoon and early evening. Snowfall rates of 1 to 2 inches per hour could occur at times during the evening rush hour.
Snow totals of 3 to 6 inches are likely from southern Minnesota to western Michigan’s Upper Peninsula through Wednesday.
Mirna Alsharif is a breaking news reporter for NBC News.
Kathryn Prociv
Kathryn Prociv is a senior meteorologist and producer for NBC News.