The 5 p.m. update from the National Hurricane Center has shifted the track of Hurricane Irma significantly west, which could be bad news for Florida.
"This is the worst-case scenario for Florida," FOX8 Chief Meteorologist Van Denton said, adding that the path of the storm is still not a certainty.
Denton also said that, while the shift in the track is bad news for Florida, it is better news for the Carolinas.
The newest data from the National Hurricane Center has Irma hitting Florida as a Category 4 storm but weakening to a Category 1 by the time it gets into Georgia.
South Florida under hurricane watch as deadly Irma nears
The Turks and Caicos Islands and the Bahamas braced Thursday for deadly and massive Hurricane Irma as Florida's governor warned everyone in his state to be ready to take shelter.
Irma -- a Category 5 storm churning in the Atlantic with 175 mph sustained winds -- killed at least six people a day earlier as it devastated small northeastern Caribbean islands such as Barbuda and left hundreds of thousands of customers in Puerto Rico without power.
"Regardless of which (Florida) coast you live on, be prepared to evacuate," Florida Gov. Rick Scott said Thursday at a news conference, with forecasters warning the storm could reach South Florida by Sunday.
Mandatory evacuations have been issued for the Keys and parts of Miami-Dade and Broward counties near the ocean, but Scott said others in Florida need to watch Irma's path and be ready to move.
"This is not a storm you can sit and wait through," he said. He added later: "You don't have to drive hundreds of miles or leave the state to be safe. Go to shelters."
Georgia, too, is ordering coastal evacuations. People in the Savannah area and everywhere along the coast east of Interstate 95 -- including Brunswick and St. Simons Island -- are ordered to leave, starting Saturday, Gov. Nathan Deal said.
Irma still was battering the mountainous, northern parts of Haiti and the Dominican Republic on Thursday afternoon. It could leave up to 15 inches of rain there -- amounts that could trigger dangerous flooding and mudslides, the US National Hurricane Center said.
Meanwhile, the northeastern Caribbean islands just hit by Irma are anxiously watching Hurricane Jose to the east. On Thursday, Antigua and Barbuda issued a hurricane watch for Jose, which could pass close to those islands Saturday.
Irma left at least six people dead Wednesday, including four on St. Martin, one on Anguilla, and one on Barbuda, officials said. The latter is barely habitable, with nearly all its buildings damaged, the Prime Minister of Antigua and Barbuda said.
Here are the latest developments
-- Around 2 p.m. ET, Irma's center was about 70 miles southeast of Grand Turk Island, moving west-northwest with maximum sustained winds of 175 mph. Irma previously had winds over 180 mph, keeping those speeds longer than any storm ever recorded in the Atlantic basin.
-- Irma could be near the Turks and Caicos, a British overseas territory north of Haiti and home to about 52,000 people, by Thursday afternoon. It could cross the southeastern Bahamas on Thursday evening and be near the central Bahamas on Friday.
-- Hurricane warnings are in effect for parts of the Dominican Republic, Haiti, the Turks and Caicos Islands, and the southeastern, central and northwestern Bahamas.
-- A hurricane watch has been issued for parts of the Florida Keys and South Florida, including the Naples, Miami, Fort Lauderdale and West Palm Beach areas. A watch also is in effect in Cuba from Matanzas province to Guantanamo province.
-- Scott, Florida's governor, said Thursday he has directed state law enforcement to escort gas trucks to gas stations in an attempt to address reported fuel shortages. "We know fuel is very important" as people prepare to evacuate inland, he said. "While we're making progress, you will see lines and outages, unfortunately."
-- Irma is one of three active hurricanes in the Atlantic basin -- the last time this happened was in 2010. The others are Jose, in the open Atlantic far to the southeast of Irma, and Katia in the Gulf of Mexico.
Will it hit Florida, Southeastern US?
Some computer models show Irma could churn near Florida's southern and east coasts by Sunday, and potentially threaten the coasts of Georgia and South Carolina later. Florida officials are ordering some evacuations and shutting down schools.
Winds of at least tropical storm strength (39 mph and greater) extend up to 185 miles from Irma's center.
Many spent Thursday stocking up on food or making plans to head inland. Video from WSVN showed Miami International Airport crowded with people looking to leave the area.
Miami resident Ashley Hahn was at a beach Thursday with her 4-year-old daughter, saying they were taking a final few dips before fleeing the storm.
"It is chaotic with the lines and gasoline and waiting for water -- you kind of need a break," she said.
"We are probably going to head north, just to be safe. I went through (1992's Hurricane) Andrew as a child, and ... I have seen videos of destruction and everything that it entails. I don't want (my daughter) to be around for that."
In Broward County, which includes Fort Lauderdale and other cities north of Miami, a mandatory evacuation will go into effect at noon Thursday for some areas, Mayor Barbara Sharief said.
Miami-Dade County ordered people out in some areas, including mobile homes and barrier islands.
Florida is not the only state preparing for possible impact.
Georgia's governor, besides ordering coastal evacuations from Saturday, declared a state of emergency for 30 counties. North Carolina Gov. Roy Cooper and South Carolina Gov. Henry McMaster also declared states of emergency.
Schools in some districts in and around Charleston, South Carolina, said they will be closed from Friday through Tuesday.
Turks and Caicos, Bahamas in Irma's path
Irma could be near the low-lying Turks and Caicos Islands on Thursday night and parts of the Bahamas on Friday.
Storm surges could reach up to 20 feet, the National Hurricane Center says -- twice as high as some of the islands' elevations.
"Some of these Turks and Caicos (Islands) will be completely overwashed," CNN meteorologist Chad Myers said.
The Turks and Caicos are a British overseas territory with about 35,000 people. Officials there are "working intensively on disaster preparedness and response ... (and) liaising with their counterparts in the Cayman Islands for assistance," UK Foreign and Commonwealth Office Minister Alan Duncan said Thursday.
The Bahamas, a nation of about 390,000, ordered evacuations for six southern islands -- Mayaguana, Inagua, Crooked Island, Acklins, Long Cay and Ragged Island.
"This is the largest such evacuation in the history of the country," Prime Minister Hubert Minnis said.
Trail of destruction
Irma's eye passed directly over Barbuda on Wednesday, leaving the small island's 1,800 residents largely incommunicado for hours because it knocked over the telecommunications system and cell towers.
About 95% of the buildings in Barbuda, one of two major islands in the nation of Antigua and Barbuda, are damaged, Prime Minister Gaston Browne said.
"It looks like (a) garbage disposal," Marlon Carr, a photographer who toured the island with the Prime Minister of Antigua and Barbuda, told CNN on Thursday. "There was rubble and roof galvanized all over the island. It looked like some of the houses ... were imploded on.
"The rubble stayed in the same position the house was, but it was flat -- completely flat."
Witnesses told him of "40-foot containers flying, animals flying" during the storm. Some spoke of taking shelter in bathrooms as their homes were torn apart.
Browne described the damage as "unprecedented" and "absolutely devastating," estimating it will cost $100 million to rebuild.
Browne said that Jose, approaching so soon after Irma, is a serious concern. Officials are transporting people from Barbuda to the nation's more populous Antigua island, he said.
In St. Thomas in the US Virgin Islands, Kelsey Nowakowski posted images to Instagram of the aftermath there.
"This doesn't look like it was ever a tropical paradise. It looks like an eerie fairytale forest," she said in her post. "During the storm there were a handful of times when we thought we were losing the house's roof on the floor above, but when we emerged we found our roof intact."
Michael Coleman took shelter in a cement bunker in St. Thomas.
"The wind was so intense. Trees and roofs flying," he said.
He posted a video on Twitter showing mangled patio and roofing scattered all around.
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. Emergency officials are still taking in reports to determine the extent of the damage.
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.
In the northeast city of Fajardo, authorities conducted at least 10 rescues, an emergency dispatcher there told CNN. Of those, five were from flooded homes, two of people trapped in vehicles, and three who were trapped in an elevator, the dispatcher said.
There were no immediate reports of injuries in the US territory of about 3.4 million people.