MIAMI — The most powerful hurricane ever recorded in the Atlantic, outside the Gulf of Mexico and the Caribbean, is expected to pound Florida with damaging winds, but where, and just how bad the state gets hit, hinges on two competing weather systems.
On its forecast track, Hurricane Irma was expected to begin turning to the northwest Tuesday night across the Leeward Islands toward Puerto Rico, steered by a strong high pressure ridge. After that, the ridge is expected to collide with a low pressure trough now moving across the United States, allowing Irma to slide north as the ridge weakens. Where that collision occurs, and Irma makes the turn, will likely determine which way Irma heads, and how Florida gets hammered.
Forecasters said in their 5 p.m. advisory that forecast models generally agree over the next 72 hours, but after that they begin to spread, raising uncertainty. In their track, they point the storm toward the middle, threading the needle between the Bahamas and Cuba. Because of track errors ranging from 175 to 225 miles, they warned that more attention should be paid to the forecast cone.
Across the Caribbean, islands are likely to take a beating. Storm surge in the Turks and Caicos and southeastern Bahamas could reach 15 to 20 feet, with other islands in Irma’s path expected to get anywhere from a foot to 11 feet.
The Leeward Islands were set to get hurricane force winds Tuesday night, with Puerto Rico and the Virgin Islands slammed Wednesday. Next in line: the Dominican Republic on Thursday.
At 5 p.m., Irma was located 130 miles east of Antigua, moving west at 15 mph. Maximum winds remained at an astonishing 185 mph, with higher gusts.
As the storm closed in, the islands raced to prepare. In Puerto Rico, the governor asked President Donald Trump to declare a state of emergency, while the electric company warned Irma’s fierce winds could leave the island without power for four to six months.
While it’s still not known what part of Florida will take the brunt, officials across the state made clear that Irma is a serious threat. With tropical storm force winds expected to arrive as early as Friday, Florida Gov. Rick Scott has declared a state of emergency for all 67 counties and ordered all 7,000 members of the state’s National Guard to report to duty on Friday. Highway tolls across the state were lifted at 5 p.m. Tuesday.
Mayor Carlos Gimenez also declared a state of emergency for Miami-Dade County Tuesday afternoon and said evacuations could begin as early as Wednesday on barrier islands and along the coast. Monroe County issued a mandatory evacuation of all residents beginning at 7 p.m. Wednesday.
“This is a powerful storm which poses a serious threat to our area,” Gimenez said. “I would rather inconvenience residents on this occasion than suffer any loss of life.”
Monroe County said there will be no roadblocks into the Keys before the storm, to allow property owners and family members to help out with evacuations. However, plans should be completed quickly. Schools and county offices will also be closed beginning Wednesday.
“If ever there was a storm to take seriously in the Keys, this is it,” Monroe County Emergency Management Director Martin Senterfitt said. “The sooner people leave, the better.”
At 120 miles wide, Irma is nearly as wide as Florida. Tropical storm force winds reach another 160 miles.
In addition to the northern islands in the Antilles, hurricane warnings have been issued for Puerto Rico, the Virgin Islands and parts of the Dominican Republic. Watches are in effect for Haiti, the southeastern Bahamas and Turks and Caicos, with dangerous winds, storm surge and heavy rain expected Thursday and Friday. Puerto Rico’s government is preparing to open 456 shelters that can house more than 62,000. The Turks and Caicos has ordered Salt Cay, its southernmost inhabited island, evacuated beginning Wednesday.
Irma could strike a direct blow on the remainder of the Bahamas and Cuba later in the week, forecasters said.
While wind speeds could fluctuate over the next day or two, forecasters say Irma will likely remain a very dangerous Category 4 or 5 storm as it heads westward. At 185 mph, forecasters said the storm is the most intense storm ever recorded in the Atlantic outside the Gulf of Mexico or Caribbean.
In addition to a state emergency, Scott said he asked Trump to request a federal emergency in advance of Irma’s arrival and began coordinating rescue efforts that include 13 helicopters and 1,000 high-wheeled truck capable of driving through high water. North Carolina’s National Guard is also on standby to help with evacuations from the Keys, if needed, and the National Guard is lining up an additional 30,000 troops, 4,000 trucks and 100 helicopters to be on standby, the governor’s office said in a statement.
The Florida Highway Patrol and Department of Transportation are also on standby to help with evacuation efforts, the statement said.
The South Florida Water Management District already has begun inspecting pumps and gates and lowering canals to make room for heavy rain, flushing as much water as possible starting in South Dade. In a morning news conference, Chief Engineer John Mitnik said he expects the storm to dump between eight and 10 inches of rain, but where it falls depends on Irma’s track. Unlike Harvey, Irma is not forecast to linger and deliver the kind of punishing rain that triggered widespread flooding and likely billions of dollars in damage. Mitnik said South Florida’s extensive system of canals are also capable of moving water quickly, however local drainage depends on flood controls set up in neighborhoods and subdivisions.
“If your particular subdivision was designed to have street flooding, then that’s what you’ll expect to see,” he said.