Tropical Storm Debby moved menacingly into some of America's most historic Southern cities and was expected to bring prolonged downpours and flooding throughout the day Tuesday after slamming into Florida and prompting the rescue of hundreds from flooded homes.

Record-setting rain from the storm killed at least five people Monday, four in Florida — including two children — and one in Georgia. President Biden authorized emergency declarations from governors in both states as well as South Carolina.

Debby was expected to move offshore of the Georgia coast later on Tuesday, the National Hurricane Center said. As of 2 p.m. EDT Tuesday, Debby's center was some 10 miles southeast of Savannah, Georgia, and 80 miles southwest of Charleston, South Carolina, and was moving east-northeast at 5 mph with maximum sustained winds of 40 mph, the hurricane center said. 

Forecasters warned of serious flood threats to various parts of the southeastern United States this week, with potentially major impacts to Georgia, South Carolina and North Carolina over the next few days as Debby lingers near the South Carolina coast. Although the storm is weakening, forecasters said they expect Debby to strengthen again somewhat on Wednesday and Thursday as it moves offshore.

"Debby is expected to produce potentially historic rainfall totals of 10 to 20 inches, with maximum amounts of 25 inches, bringing areas of catastrophic flooding across portions of southeast Georgia, the eastern half of South Carolina, and southeast North Carolina through Friday," the Miami-based hurricane center said. "From northern North Carolina through portions of the Mid-Atlantic States, 4 to 8 inches of rainfall, with local amounts to 12 inches, are expected through Sunday morning. This rainfall will likely result in areas of considerable flash and urban flooding, with river flooding possible." 

"On the forecast track," the hurricane center said, "the center of Debby is expected to move offshore the coast of Georgia later today and tonight, continue to drift offshore through early Thursday, and then move inland over South Carolina on Thursday."

Tropical storm-force winds extended outward up to 205 miles east of the center, the center added.

CBS News senior weather and climate producer David Parkinson said at 6 a.m. EDT that, "Much of the low country of South Carolina has already received around a foot of rain. Some bands over the state now are bringing rain at a rate of 2-3 inches per hour. In Savannah, they're beginning to get on the back side of the storm, so the worst rain is over, but another 3 inches or so is possible."

"In Charleston, however, they're in the thick of it right now, and will see torrential rain off and on for at least the next 36 hours," he said. "That area is the best candidate for a total above 2 feet by the conclusion of the storm. There is still another 12-16 inches coming to many areas from Debby."

Debby made landfall along the Gulf Coast of Florida early Monday as a Category 1 hurricane. It weakened to a tropical storm and was moving slowly, bringing drenching rain and severe flooding to many areas.

Racing to cope

Flash flood warnings were issued in Savannah, Georgia, and Charleston, South Carolina, among other areas of coastal Georgia and South Carolina. Both Savannah and Charleston announced curfews Monday night into Tuesday.

In South Carolina, Charleston County Interim Emergency Director Ben Webster called Debby a "historic and potentially unprecedented event" three times in a 90-second briefing Monday.

Over 100,000 customers had no power Tuesday afternoon in Florida, Georgia and South Carolina, according to PowerOutage.us. Most of the outages were reported in Florida, with a few thousand additional outage reports cropping up in North Carolina as the day progressed.

Hundreds of flights meant to depart or arrive in the U.S. were canceled on Tuesday, and another 1,400 or so were delayed, according to FlightAware.com. Those numbers were down from upwards of 1,600 flight cancellations nationwide on Monday, many of which were either routing into or from Florida airports. 

In addition to its curfew, the city of Charleston's emergency plan includes sandbags for residents, opening parking garages so residents can park their cars above floodwaters and an online mapping system that shows which roads are closed due to flooding.

South Carolina Emergency Management Division Director Kim Stenson warned that, "The heavy rains and flooding currently predicted this week are historic in scope and scale. Our experts with the National Hurricane Center believe flooding to be catastrophic for many parts of South Carolina. Take no chances with this storm."

Debby a menace

A tornado hit Monck's Corner, a town in South Carolina, overnight, causing minor damage to a dialysis center and major damage to several businesses including an Arby's and a Walmart, the town's fire chief, Robert Gass, told CBS News on Tuesday morning. One person sustained minor injuries tied to the twister, which also overturned cars in the area, Gass said. 

Monck's Corner Mayor Thomas Hamilton said earlier that a suspected tornado had struck the town, adding that there were no major injuries reported but some buildings and vehicles were damaged.

Hamilton offered photos of some of the damage:

In Edisto Beach, South Carolina, a tornado touched down Monday night, damaging trees, homes and taking down power lines, the Colleton County Sheriff's Office said on social media. No injuries were immediately reported, officials said.

About 500 people were rescued Monday from flooded homes in Sarasota, Florida, a beach city popular with tourists, the Sarasota Police Department said in a social media post. Just north of Sarasota, officials in Manatee County said in a news release that 186 people were rescued from flood waters.

"Essentially we've had twice the amount of the rain that was predicted for us to have," Sarasota County Fire Chief David Rathbun said on social media.

Florida Gov. Ron DeSantis warned that the state could continue to see threats as waterways north of the border fill up and flow south.

"It is a very saturating, wet storm," he said. "When they crest and the water that's going to come down from Georgia, it's just something that we're going to be on alert for not just throughout today, but for the next week."

The Manatee County Emergency Operations Center in Bradenton, Florida, said Tuesday morning that the region was hit with record levels of rain — with 18 inches falling in some places. Officials said they had already carried out 55 water rescues since Debby struck, for 210 people and two horses, while fielding thousands of emergency calls. Local officials were in touch with the Federal Emergency Management Agency as they braced for another 4 or 5 inches of rain, at least. DeSantis said the area could see as much as 8 more inches of rainfall.

Debby already deadly 

Five people had died due to the storm as of Monday night, including a truck driver on Interstate 75 in the Tampa area after he lost control of his tractor trailer, which flipped over a concrete wall and dangled over the edge before the cab dropped into the water below. Sheriff's office divers located the driver, a 64-year-old man from Mississippi, in the cab 40 feet below the surface, according to the Florida Highway Patrol.

A 13-year-old boy died Monday morning after a tree fell on a mobile home southwest of Gainesville, Florida, according to the Levy County Sheriff's Office. In Dixie County, just east of where the storm made landfall, a 38-year-old woman and a 12-year-old boy died in a car crash on wet roads Sunday night.

In southern Georgia, a 19-year-old man died Monday afternoon when a large tree fell onto a porch at a home in Moultrie.

Disasters declared

Mr. Biden approved a request from South Carolina's governor for an emergency declaration, following his earlier approval of a similar request from Florida. Mr. Biden also approved a request from Georgia Gov. Brian Kemp to issue an emergency declaration to speed the flow of federal aid to his state.

Vice President Kamala Harris postponed a campaign stop scheduled for Thursday in Savannah.

North Carolina is also under a state of emergency after Gov. Roy Cooper declared it in an executive order he signed Monday. Several areas along the state's coastline are prone to flooding, such as Wilmington and the Outer Banks, according to the North Carolina Floodplain Mapping Program.

North Carolina and South Carolina have dealt with three catastrophic floods from tropical systems in the past nine years, all causing more than $1 billion in damage.

In 2015, rainfall fed by moisture as Hurricane Joaquin passed well offshore caused massive flooding. In 2016, flooding from Hurricane Matthew caused 24 deaths in the two states and rivers set record crests. Those records were broken in 2018 with Hurricane Florence, which set rainfall records in both Carolinas, flooded many of the same places and was responsible for 42 deaths in North Carolina and nine in South Carolina.