US braces for 'catastrophic' flooding as Storm Debby drenches Florida

At least one person was killed as Tropical Storm Debby began dumping what could become historic levels of rain over Florida Monday, with the southeastern United States braced for potentially "catastrophic" flooding.

A 13-year-old boy died when a tree was blown onto a mobile home in Levy County, the sheriff's office there said, after Debby made landfall on Florida's Gulf Coast earlier in the day as a Category One hurricane.

Authorities say the danger remains high as the storm moves over the state and into Georgia and South Carolina, despite the downgrade by the National Hurricane Center.

"This is a level four out of four risk for excessive rainfall," Michael Brennan, director of the NHC, told reporters.

"We're going to see the center of the system just crawl along the southeast coast of the United States for two to three days.

"This is going to result in a prolonged extreme rainfall event with potential for catastrophic flooding across coastal portions of Georgia, South Carolina, even extending up into North Carolina," he said.

Florida governor Ron DeSantis also warned of "significant" flooding over the coming days, and said the state had already seen storm surge and some water rising.

More than 300,000 customers have lost electricity so far, according to tracker poweroutage.us.

"We have a lot of restoration personnel ready to go to get it back on," DeSantis said.

- Storm surge and flooding -

The National Hurricane Center warned of life-threatening storm surges along the Gulf coast, with up to six feed (1.8 meters) of inundation above ground level in some areas.

The storm will probably cause catastrophic flooding with "potentially historic heavy rainfall" when Debby moves northeast across Georgia and South Carolina over the next few days, the NHC said.

But it said Debby was weakening. The storm's maximum sustained winds were 80 miles (130 kilometers) per hour at landfall but dropped to 70 mph shortly after, resulting in its downgrade to Tropical Storm status.

Debby is expected to dump six to 12 inches of rain in parts of Florida, and as much as 20 to 30 inches in coastal Georgia, South Carolina, and parts of North Carolina before the week is over, the NHC said.

Mandatory evacuations were ordered for part of Citrus County, Florida, with eight other counties under voluntary evacuation orders, local media reported.

The governors of Georgia and South Carolina declared a state of emergency ahead of the storm's arrival.

President Joe Biden on Sunday approved an emergency declaration for Florida, allowing federal aid to be expedited.

DeSantis has activated the state's National Guard, with 3,000 service members on standby to help with storm response.

Meanwhile in the Florida Keys, Debby washed ashore 25 tightly wrapped packages of cocaine worth more than $1 million, according to a post on X by US Border Patrol acting chief patrol Agent Samuel Briggs II.