CNN  — 

A strengthening storm that hit Florida with heavy rains and powerful winds this weekend is roaring its way up the East Coast, threatening floods, dangerous surf, power outages and travel disruptions.

More than 12 inches of rain fell near Georgetown, South Carolina on Sunday, according to the National Weather Service office in Wilmington, North Carolina. Other cities in the Southeast that saw substantial rain include Gainesville, Florida, with 7.3 inches; Jacksonville, Florida, with 5.70 inches and Clemson, South Carolina, with 3.94.

There was one unconfirmed tornado reported by spotters just west of Myrtle Beach, South Carolina, but there were no immediate reports of injuries.

A tornado watch was in effect for almost 100,000 people in coastal parts of North Carolina until 2 a.m. ET, the weather service posted on X, formerly known as Twitter.

Intense winds created tides as high as 9.86 feet in Charleston Harbor, South Carolina, on Sunday. It was the fourth-highest tide on record for the region and well above the highest tide for a non-tropical system, the weather service said.

“Widespread dangerous flooding continues,” the agency warned.

More than 25,000 customers total were without power across North Carolina and Virginia as of 10:45 p.m. ET as the storm moved up the coast, according to PowerOutage.us.

Flooding after a storm in Myrtle Beach, South Carolina, on Sunday, December 17.

After moving through Florida Saturday, the storm hugged the East Coast Sunday and expanded its impacts from Georgia to parts of the Northeast.

The National Weather Service issued high wind warnings on Sunday for portions of southern Connecticut, southeastern New York and Boston, warning of the potential for downed trees and power lines.

Travel in those areas will be difficult, the weather service said, “If possible, remain in the lower levels of your home during the windstorm, and avoid windows. Use caution if you must drive.”

Gusty winds and reduced visibilities also delayed some air travel. More than 5,200 flights into or out of US airports were delayed Sunday and at least 115 were canceled, according to the tracking website FlightAware.com. John F. Kennedy International Airport in New York was experiencing wind-related ground delays, according to the Federal Aviation Administration website.

The storm swept through much of Florida as it impacted the region.

December 17, 2023, St. Petersburg, Florida, USA: Local resident VALERIE CHILDRESS walks through flooding near the intersection of 62nd Avenue NE and Bayou Grande Boulevard NE. (Credit Image: © Jefferee Woo/Tampa Bay Times via ZUMA Press Wire)

The storm’s future

The storm will reach its peak strength on Monday, just in time to deliver disruption to a large portion of the Northeast. It is forecast to track close to the Northeast coast during this time – but could also move farther away from the coast.

Regardless of its exact track, the storm will bring nor’easter-like impacts to the coastal Northeast on Monday — minus the snow.

“Strong winds could bring down some tree limbs, resulting in localized power outages. Outdoor holiday decorations may become damaged or get blown away,” the National Weather Service office for the Philadelphia area posted on X.

The storm also threatened to bring river flooding to more than 60 million people, according to the weather service.

 CNN’s Robert Shackelford, Mary Gilbert, Taylor Ward and Steve Almasy contributed to this report.