Hurricane and storm surge warnings were issued late Thursday for South Florida as Hurricane Irma advanced westward in the Caribbean, with a northward turn toward Florida expected over the weekend.

Irma battered Turks and Caicos early Friday, with waves as high as 20 feet expected to hit those islands. Communications went down as the storm struck, and the extent of the devastation was unclear.

An update at 2 a.m. EDT Friday from the National Hurricane Center showed Irma to be located 20 miles north of Great Inagua Island and about 535 miles east-southeast of Miami -- with wind gusts of 160 mph. The storm was moving at about 16 mph, the hurricane center said.

The hurricane center said its storm surge warning covers Jupiter Inlet southward around the Florida peninsula to Bonita Beach, as well as the Florida Keys.



Its hurricane warning covers Jupiter Inlet southward around the Florida peninsula to Bonita Beach, as well as the Florida Keys, Lake Okeechobee, and Florida Bay.

In addition, a storm surge watch has been issued for the east coast of Florida, north of Jupiter Inlet to Sebastian Inlet and for the west coast of Florida north of Bonita Beach to Venice.

A hurricane watch has been issued for the east coast of Florida

north of Jupiter Inlet to Sebastian Inlet and for the west coast of

Florida north of Bonita Beach to Anna Maria Island.

Meanwhile, the government of the Dominican Republic has discontinued the hurricane warning for the country's northern coast, the hurricane center said.

Earlier Thursday, Florida Gov. Rick Scott urged hundreds of thousands of people to evacuate before Hurricane Irma makes potential landfall — as forecast models on Thursday predicted the storm moving further west, more directly in the state's path.

"If you live in any evacuation zones and you're still at home, leave!" Scott warned Floridians at a news conference Thursday. "Do not try to ride out this storm ... we can't save you once the storm hits."

At least 500,000 people in South Florida now face evacuation orders.

Scott said that regardless of their location, people should be ready to get out. The governor noted that Florida's western coast "will still have hurricane conditions."

The storm is expected to travel west in the coming days, and will remain a Category 5, or possibly drop to a 4, according to the NHC.

With winds that peaked earlier at 185 mph, Hurricane Irma was the most powerful hurricane ever recorded in the Atlantic, and has killed at least 13 people, including four deaths in the U.S. Virgin Islands, according to the Associated Press.

HURRICANE IRMA'S STORM PATH: WHAT YOU SHOULD KNOW

“Irma will have major hurricane impacts,” Scott said, adding they should be expected along Florida’s east coast. The Florida Keys should expect effects from the storm Friday night, he said.

"Look at the size of this storm. It is wider than our entire state," Scott said. "Every Floridian should take this serious and protect your family."

Ahead of the storm's arrival, Scott ordered all public schools in the state closed, from Friday until Monday. That includes K-12 schools, state colleges and universities, as well as state offices.

Fox News Senior Meterologist Janice Dean said earlier Thursday the forecast still brings the eye of Irma close to South Florida Saturday night into Sunday, but timing of Irma's northward turn on Saturday will determine whether the storm moves east of, west of, or straight into South Florida.

"A track just east of South Florida and Miami would spare Miami-Dade from the worst winds and surge, but this track offshore and parallel to Florida's east coast would then bring Irma northward toward Georgia and South Carolina on Monday-Monday night as a hurricane," Dean said.

Hurricane conditions are possible in 48 hours in South Florida, according to Dean, but residents further up the coast should pay close attention.

"South Florida remains in the crosshairs for Irma, while coastal Georgia and South Carolina should closely monitor Irma's forecast for potential impacts from a hurricane Monday-Monday night," she said.

TRACK HURRICANE IRMA'S PATH

As Irma continues to barrel toward South Florida, residents in parts of the Miami metro area are under mandatory orders to leave their homes.

Mayors in Miami-Dade and Broward counties issued mandatory evacuation orders for barrier islands and low-lying mainland areas in the metro area of 6 million.

Officials in Miami-Dade County opened four additional shelters, including pet-friendly ones, for residents seeking safety from Irma.

Miami-Dade Mayor Carlos Gimenez expanded evacuation orders Thursday to cover Miami's downtown, as well as portions of the southern part of the county threatened by Irma's potential storm surge.

"This storm doesn't appear to be going anywhere," he said Thursday.

Miami Beach Mayor Philip Levine encouraged his city residents to evacuate, and referred to Irma on Fox News as a "nuclear hurricane."

An estimated 31,000 people left the Florida Keys as of 6 p.m. Wednesday, according to Scott, after all visitors were ordered to clear out, causing bumper-to-bumper traffic on the single highway that links the chain of low-lying islands to the mainland.

"It's just scary, you know? We want to get to higher ground. Never had a Cat 5, never experienced it," Michelle Reynolds told the Associated Press as she was leaving the Keys, where people filled gas cans and workers covered fuel pumps with "out of service" sleeves.

"You do not need to evacuate out of the state or hundreds of miles away" to be safe from Irma, Scott said, adding there are nearby shelters you can go to.

At an earlier news conference, Scott said the state's gas situation is a "top priority."

"I have been very clear to the retailers," Scott said. "We have to get the fuel as fast as we can out so people can evacuate."

The Florida Highway Patrol said in a news release troopers are monitoring the high volume of traffic heading north on Florida's Turnpike as people evacuate South Florida.

Extra troopers, road rangers and wreckers will be on the roadways to help drivers whose vehicles have become disabled, according to the FHP.

The agency said disabled vehicles left on the shoulders of the highways would be towed starting Thursday morning to make it easier for emergency workers who are trying to reach crash victims.

Turnpike officials are also using cameras along the road to monitor conditions.

Gov. Scott said he's activated 4,000 members of the National Guard in Florida, and all 7,000 will be deployed on Friday.

Further up Florida's coast, officials in Flagler County issued voluntary evacuations for coastal areas, while Brevard County in the Space Coast area issued a mandatory evacuation order for the barrier islands, Merritt Island and some mainland low-lying areas along the Indian River Lagoon.

"Those who live in mobile or manufactured homes or in other flood-prone areas are also vulnerable and should evacuate whether on the mainland or the barrier islands," county spokesman Don Walker said.

In Jacksonville, the city's mayor also issued a voluntary evacuation order issued for zones A & B, and urged those who can to leave early to avoid potential traffic issues.

MANDATORY EVACUATIONS IN GEORGIA, SOUTH CAROLINA

Shifting forecasts have also raised the threat to the Southeast from Irma, prompting emergency declarations in the Carolinas and coastal Georgia, including areas that haven't suffered a direct hit from a major hurricane in more than a century.

Georgia Gov. Nathan Deal ordered a mandatory evacuation starting on Saturday from the state's Atlantic coast ahead of Hurricane Irma, including the city of Savannah. Nearly 540,000 residents on the coast were ordered to evacuate inland.

South Carolina Gov. Henry McMaster also declared a state of emergency. A major strike there would be the first in nearly 28 years.

Fox News' Zoe Szathmary and The Associated Press contributed to this report.