Florida almost certain to feel Irma’s fury, but where remains uncertain

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 will begin turning to the northwest tonight 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. adivisory 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. Due to track errors ranging from 175 to 225 miles, they warned that more attention should be paid to the forecast cone.

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National Hurricane Center

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 will likely get hurricane force winds tonight, 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, 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.”

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Because Irma is so large, stretching some 120 miles across, forecasters urged caution in paying too much attention to its exact track.

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 Islaneds 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 Cat 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 President Donald 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 helicopts 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.

Utilities have been asked to begin posting outage and restoration information as the storm hits and are contacting other utilities to help out with repairs, Scott said in a statement. NO fuel shortages have been reported, the statement said, but the state has contacted fuel suppliers in case emergency supplies are needed. The state insurance agency has also authorized early prescription refills.

Across the mainland, the South Florida Water Management District has already 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 press 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.

Timing is another issue.

“If you take eight to 10 inches over several days, or compact it in 30 minutes, those are two different things,” he said.

The U.S. Army Corps of Engineers is also keeping a close eye on the aging dike around Lake Okeechobee, where water levels Tuesday were at 13.65 feet, still well below the 15.5 feet level where discharges begin and the more than 18 feet limit set to protect the dike.

While models have shifted Irma’s path up and down over the weekend, Tuesday morning’s runs largely agree on the storm’s path over the next three days, with less certainty after that.

Over the last week, Irma has also undergone repeated eyewall replacements, a common structural change for such massive storms. While the replacement may initially weaken the storm, it allows it to spread and grow in size. With each replacement, Irma has also been able to regain steam.

Meanwhile, Tropical Storm Jose formed in the fast east Atlantic Tuesday morning. At 11 a.m., the storm was located more than 1,500 miles east of the Lesser Antilles, moving west, northwest at 13 mph. Sustained winds reached 40 mph, with Jose reaching hurricane strength by Friday, forecasters said.