Hurricane Irma's track has shifted slightly west, leading to new watches and warnings, according to the National Hurricane Center.
Irma, downgraded to Category 4 storm with sustained winds of 150 mph, slammed the Turks and Caicos archipelago early Friday before its powerful core headed between northern Cuba and the central Bahamas.
At least 18 people were killed this week as Irma pummeled northern Caribbean islands such as Barbuda and the US Virgin Islands. In Puerto Rico, hundreds of thousands of people -- nearly 70% of the US territory's utility customers -- were left without power, the governor's office said.
"A turn toward the northwest is expected by late Saturday," the advisory said. "On the forecast track, the eye of Irma should move near the north coast of Cuba and the central Bahamas today and Saturday, and be near the Florida Keys and the southern Florida Peninsula Sunday morning."
A Hurricane Watch has been extended northward along the east coast of Florida to the Flagler/Volusia County Line, and along the
west coast of Florida to Anclote River.
A Storm Surge Warning has been extended from Jupiter Inlet northward to Sebastian Inlet and from Bonita Beach northward to
Venice, according to the advisory. A Storm Surge Watch has been issued from north of Sebastian Inlet to Ponce Inlet.
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Here are the latest developments
-- Irma's bands whipped the Turks and Caicos and the southeastern Bahamas overnight, and is forecast to move between the north coast of Cuba and the central Bahamas through Saturday.
-- Irma led to at least 18 deaths in the Caribbean, including nine in French territories, one at the British overseas territory of Anguilla, one on Barbuda, four on the US Virgin Islands, and three in Puerto Rico. Officials didn't specify which French Caribbean territories had nine deaths but earlier indicated some had been on the island of St. Martin.
-- The three deaths in Puerto Rico were at least loosely linked to Irma. One person died from a fall while being taken to a shelter; another was killed in a car crash; a third died of electrocution, the governor said.
-- Hurricane warnings are in effect for parts of central Cuba, the Turks and Caicos Islands, and the southeastern, central and northwestern Bahamas. Hurricane warnings also are in effect for South Florida, from Jupiter Inlet on the east coast, southward around the Florida Peninsula to Bonita Beach on the west. The warning includes the Florida Keys, Lake Okeechobee and Florida Bay.
-- The Red Cross said as many as 26 million people could be exposed to destructive winds and torrential rain just in the Dominican Republic, Haiti and Cuba.
-- Both the French and Dutch portions of the island of St. Martin are suffering looting in the wake of Irma, authorities said.
The Bahamas, a nation of about 390,000, ordered evacuations ahead of Irma's arrival for six southern islands -- Mayaguana, Inagua, Crooked Island, Acklins, Long Cay and Ragged Island.
Irma could overwhelm parts of the Bahamas with storm surges of up to 20 feet -- well above the islands' elevation, CNN meteorologist Chad Myers said.
Tourists and hundreds of thousands of residents have also been evacuated from parts of Cuba. Usually busy hotels on the northern coast were empty Friday, CNN's Patrick Oppmann reported from Caibarien.
Some have been evacuated to bomb shelters built during the Cuban missile crisis of the 1960s.
Florida and the Southeast prepare for Irma
The National Hurricane Center warned Thursday it had become more likely that Irma would "make landfall in southern Florida as a dangerous major hurricane, and bring life-threatening storm surge and wind impacts to much of the state."
The center said possible storm surges could bring 5 to 10 feet of water above ground in coastal areas.
Its forecast moved the eye of the storm's most likely path to the west, with Miami possibly taking a devastating hit.
"It's not a question of whether Florida is going to be impacted -- it's a question of how bad Florida is going to be impacted," Federal Emergency Management Agency Administrator Brock Long said Friday, urging people to heed evacuation orders.
Though the core has the most power, Irma is huge, with winds of tropical-storm force extending up to 185 miles from the center. At some point late Saturday into Tuesday, the entire state could see at least hurricane-force gusts of 74 mph and above, CNN's Myers said.
The governor urged Floridians to be prepared regardless of which coast they live on. "This is not a storm you can sit and wait through," Scott said.
Scott said others in Florida need to watch Irma's path and be ready to move to shelters for safety if necessary. Schools will be closed Friday.
Evacuees stocked up on supplies, waited for hours at gas stations and sat through massive traffic jams.
Florida is not the only state preparing for possible impact. Some computer models show Irma potentially threatening Georgia and South Carolina.
Georgia's Gov. Nathan Deal declared a state of emergency for 30 counties and has ordered evacuations for coastal areas east of Interstate 95, including Savannah, starting Saturday.
The governors of North and South Carolina also declared states of emergency.
Devastation to islands
Irma brought heavy rain and powerful winds overnight to the low-lying Turks and Caicos Islands.
Residents of the islands, a British overseas territory with a population of about 35,000, were told to stay put.
Desmond Piccolo Henry took shelter in his concrete home with his wife and a friend on one of the islands, Providenciales, as the storm rocked the area early Friday.
"It's a concrete house, but trust me, it was shaking. My friend was saying, 'Oh my God, I think God is coming, why are we going through this?' "
Henry's home survived with just a few shingles lost, but people have told him that roofs were torn off nearby and debris crushed some cars. Video that he posted to Facebook showed downed tree limbs and other destruction.
The capital island of Grand Turk suffered "quite a bit of damage" Thursday night, including to part of a hospital's roof, Gov. John Freeman told CNN.
The UK Foreign Office said officials on the islands were working intensively on disaster preparedness and response.
In Puerto Rico, about 56,680 customers were without water, with the island's northeast hit the hardest, according to Jesus Poupart of the emergency operations center.
In the beachside area of Piñones near San Juan, Irma tore the roof off Cristian López's fried-food restaurant. He said he wouldn't be able to reopen the place for about five days.
"At least we are all alive," he said.
After Irma, Hurricane Jose looms
The Caribbean islands already pummeled by Irma have begun assessing the damage, finding shredded buildings, battered cars and streets submerged in water.
Barbuda is barely habitable, with about 95% of its buildings damaged, said Gaston Browne, the Prime Minister of Antigua and Barbuda.
Barbuda, which has 1,800 residents, is one of two major islands in the nation of Antigua and Barbuda. Browne estimated the damage will cost $100 million to fix.
"It looks like (a) garbage disposal," Marlon Carr, a photographer who toured the island with Browne, told CNN on Thursday. "There was rubble and roof galvanized all over the island. It looked like some of the houses ... were imploded on."
Witnesses told him of "40-foot containers flying, animals flying" during the storm, he said.
Irma's eye passed directly over Barbuda on Wednesday, and now the northeastern Caribbean nation is anxiously watching Hurricane Jose to the east, which has strengthened to a Category 3 storm.
Antigua and Barbuda are under a hurricane watch for Jose, which could pass close to those islands Saturday. The government has called for voluntary evacuations from Barbuda, Browne said.
The island of St. Martin was also badly hit, with about 50 people reported injured.
Dutch Prime Minister Mark Rutte described the looting situation in St. Maarten, the Dutch portion of the island, as serious, a spokesman for his office said Friday.
Local authorities, in collaboration with the Dutch military, are restoring order on the island, the spokesman said.
"Our worst fears have played out in Barbuda and elsewhere," said Walter Cotte, regional director for the Americas for the Red Cross. "We can't yet assess the full extent of damage, but we expect that the Red Cross will be delivering extensive support to many thousands over the coming weeks and months."