A "few" tornadoes are possible over parts of coastal east-central and northeastern Florida on Thursday morning, according to the National Weather Service.

The tornado threat will spread northward across parts of southeastern Georgia and the Carolinas later Thursday through Friday morning.

Meanwhile, "large" swell waves generated by Nicole will affect the northwestern Bahamas, the east coast of Florida and much of the southeastern U.S. coast during the next few days.

"These swells are likely to cause life-threatening surf and rip current conditions," the National Weather Service said in a public advisory on Thursday morning.

A "dangerous" storm surge from Tropical Storm Nicole combined with the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline, according to the National Weather Service.

If the peak occurs at the time of high tide, the National Weather Service said, the water could reach up to 5 feet above ground from Florida's Jupiter Inlet to Georgia's Altamaha Sound, from Florida's St. Johns River to the Fuller Warren Bridge, and from Anclote River to Ochlockonee River in Florida.

"The deepest water will occur along the immediate coast near and to the north of the landfall location, where the surge will be accompanied by large and destructive waves," the National Weather Service warned in a public advisory on Thursday morning.

Through Saturday, Nicole is expected to produce 3 to 5 inches of rainfall from the northwestern Bahamas into portions of the Florida Peninsula, with a maximum of 8 inches of localized rain. The southeastern United States into the central Appalachian Mountains and eastern portions of Tennessee, Kentucky and Ohio could see 2 to 4 inches of rainfall, with a maximum of 6 inches of localized rain along the Blue Ridge Mountains. The northern Mid-Atlantic region into New England could get 1 to 4 inches of rainfall.

"Flash and urban flooding will be possible, along with renewed river rises on the St. Johns River, across the Florida Peninsula today," the National Weather Service added. "Heavy rainfall from this system will spread northward across portions of the Southeast, upper Ohio Valley, Mid-Atlantic, and New England today through Saturday, where limited flooding impacts will be possible."

The center of Tropical Storm Nicole is expected to move across central Florida on Thursday morning, possibly emerging over the far northeastern Gulf of Mexico on Thursday afternoon, then move across the Florida Panhandle and Georgia on Thursday night and Friday, according to the latest forecast from the National Weather Service.

Although "additional weakening" is in the forecast, the National Weather Service warned on Thursday morning that "Nicole remains a large tropical storm" and "strong wind, dangerous storm surge and waves, and heavy rains continue over a large area." Tropical storm-force winds extend outward up to 450 miles from Nicole's center, especially to the north. Sustained winds of 49 mph with a gust of 70 mph were reported early Thursday in Daytona Beach, Florida.

According to the National Weather Service, tropical storm conditions will continue along portions of the eastern coastlines of Florida, Georgia and South Carolina in the warning areas on Thursday. Tropical storm conditions are expected to occur within the warning area along Florida's west coast through Thursday night.

More than 215,000 customers were without power across Florida on Thursday morning due to Tropical Storm Nicole, according to data collected by PowerOutage.us.

As of 7:04 a.m. ET, a total of 215,443 customers did not have power.

-ABC News' Robinson Perez

Tropical Storm Nicole barrelled toward the northwestern Bahamas and eastern Florida on Wednesday morning, with maximum sustained winds near 70 miles per hour -- almost as a strong as a hurricane, according to the latest forecast from the National Weather Service.

To be classified as a hurricane, a tropical cyclone must have maximum sustained winds of at least 74 mph.

The center of Nicole is forecast to approach the northwestern Bahamas on Wednesday morning, move near or over those islands by midday, then approach the east coast of Florida within the hurricane warning area on Wednesday night. The storm's center is expected to move across central and northern Florida into southern Georgia on Thursday, then across the Carolinas on Friday.

"Some strengthening is expected today, and Nicole is forecast to become a hurricane near the northwestern Bahamas and remain a hurricane when it reaches the east coast of Florida tonight," the National Weather Service said in a public advisory on Wednesday morning. "Nicole is expected to weaken while moving across Florida and the southeastern United States Thursday through Friday, and it is likely to become a post-tropical cyclone by Friday night over the Mid-Atlantic states."

As of early Wednesday, Nicole was already spreading gusty winds and rain showers into Florida, where it is later expected to make landfall between the southeastern cities of West Palm Beach and Melbourne as either a tropical storm or a Category 1 hurricane. Its tropical storm-force winds currently extend outward up to 460 miles, especially to the north of the center. In the early morning hours, a National Ocean Service station at the Lake Worth Pier, just south of West Palm Beach, reported sustained winds of 44 mph and a wind gust of 55 mph, according to the National Weather Service.

Because Nicole is so close to hurricane strength, the National Weather Service has issued hurricane and storm surge warnings along Florida's east coast from Daytona Beach to West Palm Beach. Meanwhile, Miami is under a tropical storm watch and tropical storm warnings have been issued for Florida's west coast as well as from Jacksonville up through Savannah, Georgia, to Charleston, South Carolina.

Storm surge will be the highest on the eastern coastlines of Florida and Georgia, from the border down to West Palm Beach, where water could rise as much as 5 feet above normal tide levels. Some storm surge is also possible on Florida's east coast from Sarasota to Tampa, where water could rise as much as 3 feet and up to 4 feet in the Big Bend area and Apalachicola. Storm surge will be felt all the way to Charleston, South Carolina, where water could rise up to 4 feet.

The areas that will see the heaviest rainfall will be right where the storm touches down on Florida's east coast, with the potential for up to 8 inches of localized rain. Heavy rain will track north and inland, into Georgia, the Appalachian Mountains from Tennessee and North Carolina to Pennsylvania and into western New York where more than 4 inches of rain is possible.

-ABC News' Max Golembo