Rare nor'easter to slam 13 states with hurricane-force winds and 12-foot waves starting TODAY: 'Very serious situation'

A massive nor'easter storm sweeping across the eastern US has set off flood warnings and dangerous wind alerts for millions across 13 states.

The National Weather Service (NWS) has issued coastal flood advisories in Delaware, Maryland, New Jersey and Virginia, with forecasters warning that areas along the Atlantic could see waves reach 12 feet in height.

Heavy downpours and wind gusts as powerful as a tropical storm are expected to make conditions potentially life-threatening from Michigan to Georgia, with the heaviest rain falling in parts of Pennsylvania, Maryland, Virginia, West Virginia and North Carolina.

Flood warnings have already been issued in Ohio and West Virginia which last into Tuesday night. However, meteorologists with AccuWeather have warned that flash floods could break out throughout the region well into Wednesday.

Nearly four inches of rain had fallen in West Virginia as of Tuesday morning, and forecasters warned that a high-pressure system near the Great Lakes was acting like a 'block' that caused the storm to stall over the Mid-Atlantic and Northeast.

At the same time, a new storm is forming along the East Coast, bringing winds over 60 mph and coastal flooding to cities in New York, New Jersey, Connecticut, Rhode Island, Massachusetts, New Hampshire and Maine this week.

Coastal flooding is only projected to get worse later in the week, with deadly rip currents and rough surf developing along shorelines for hundreds of miles throughout the first week of fall.

Meteorologist Joe Bastardi said on X: 'This could be a very serious situation. Three to four days of easterly fetch [winds] into the coast, with the storm coming from the southeast, is going to pile a heck of a lot of water piling up.'

Officials with NWS have warned drivers in areas with active flood watches or flash flood warnings to get off the road and avoid any areas where water in visible on the ground.

'Turn around, don`t drown when encountering flooded roads. Most flood deaths occur in vehicles. Be especially cautious at night when it is harder to recognize the dangers of flooding,' the agency wrote in a statement.

As for residents in coastal communities, officials warned that high surf, especially around high tide, would likely cause localized flooding while also making conditions dangerous for anyone swimming in the Atlantic this week. 

This includes cities such as Annapolis, North Beach, Solomons and Ocean City in Maryland; Alexandria, Arlington, Virginia Beach, Norfolk, Hampton, Newport News, Portsmouth, Chesapeake and Suffolk in Virginia; and Atlantic City and Cape May in New Jersey.

AccuWeather added in a statement: 'Coastal flooding, especially around high tide, is likely from North Carolina to Massachusetts from Tuesday through Friday.'

'The threat may persist along the northern mid-Atlantic coast and expand into southeastern New England this weekend.'

A nor'easter is a strong storm that forms along the US East Coast, named for the northeast winds that blow over the Mid-Atlantic and New England when a low-pressure system sits over the ocean.

While they are usually thought of as giant snowstorms, nor'easters can happen at any time of the year, with the strongest ones hitting in late fall through winter. However, a storm hitting at the beginning of autumn is considered very rare.

While snow is not in the forecast for this week's nor'easter, AccuWeather noted that temperatures throughout the Northeast and Mid-Atlantic would still plunge as the storm moves in.

Temperatures from Main to Virginia along the East Coast are expected to fall five to 15 degrees Fahrenheit below their normal averages for the beginning of autumn, which usually sit in the 60s and 70s.

AccuWeather Senior Meteorologist Chad Merrill added: 'Regardless of the severity of the nor'easter, there will be no shortage of cool autumn air in the Northeast, especially over the Appalachians this week.'

However, the greatest danger along the East Coast later this week and into the weekend will be from increasingly dangerous wind gusts and more flooding from the Atlantic.

Wind gusts of up to 60 mph, severe beach erosion and coastal floods are expected to impact parts of New Jersey, New York, Connecticut, Rhode Island, Massachusetts, New Hampshire and Maine starting Friday.

AccuWeather has warned that coastal areas in Massachusetts, Rhode Island, eastern Connecticut and southern Maine will see the heaviest downpours and possible power outages due to the nor'easter.

Major travel disruptions are expected to continue throughout the week along the East Coast as the storm affects at least 50 million Americans living along the Atlantic.