Puerto Rico@ (Recasting with information from latest Hurricane Center advisory; storm preparations in Puerto Rico)
SAN JUAN, Puerto Rico, Sept 5 (Reuters) - Hurricane Irma, a record Category 5 storm, churned across the Atlantic on Tuesday on a collision course with Puerto Rico and the Virgin Islands, threatening to lash the northern Caribbean with a potentially devastating mix of fierce winds, surf and rain.
The eye of Irma, a monster storm packing winds of 185 miles (295 km) per hour, is expected to cross the northern Leeward Islands, east of Puerto Rico, on Tuesday night or early Wednesday, and is on track to reach Florida by Saturday, the U.S. National Hurricane Center (NHC) in Miami reported.
The threat posed to the U.S. mainland by Irma, described by forecasters as a "potentially catastrophic" storm, loomed as Texas and Louisiana continued to reel from widespread destructive flooding from Hurricane Harvey.
Hurricane warnings, the highest level of NHC alerts, were posted for several of the Leeward Islands, including Antigua, Barbuda, Anguilla, Montserrat, St. Kitts and Nevis, as well as for the U.S. and British Virgin Islands, Puerto Rico and the Dominican Republic.
"Preparations to protect life and property should be rushed to completion," the Hurricane Center said, warning that Irma "will bring life-threatening wind, storm surge and rainfall hazards" to those islands.
Along the beachfront of Puerto Rico's capital, San Juan, work crews scrambled to cover windows with plywood and corrugated metal shutters along Avenida Ashford, a stretch of restaurants, hotels and six-story apartments.
"I am worried because this is the biggest storm we have seen here," said Jonathan Negron, 41, as he supervised workers boarding up his souvenir shop. "We're doing all we can. We have the shutters, and we are covering the electronics in plastic."
On a nearby beach, where calm surf on Tuesday belied the fury that Irma was forecast to bring, Denise Watkins, 52, of Midlothian, Texas, was reconsidering her vacation plans.
"I just got off the plane, and I already want to leave. I do not want to be here for this storm," Watkins said. Pointing to boarded-up windows on oceanfront buildings, she said, "I see everything covered up like that and it makes me nervous."
At 5 p.m. EDT (2100 GMT), Irma was about 130 miles (210 km) east of Antigua in the eastern Caribbean and moving west at 15 miles per hour (24 kmh), according to the NHC. Maximum sustained winds of 185 mph, with hurricane-force winds extending 60 miles (95 km) from the storm's center, forecasters said.
The NHC said Irma ranked as one of the five most powerful Atlantic hurricanes during the past 80 years and the strongest in the Atlantic storm outside the Caribbean Sea and Gulf of Mexico in NHC records.
The storm was upgraded to a Category 5, the highest NHC designation, earlier in the day. While some fluctuations in intensity are likely, Irma is expected to remain a Category 4 or 5 for the next couple of days, the Hurricane Center said.
Puerto Rico Governor Ricardo Rossello urged the 3.4 million residents of the U.S. territory to seek refuge in one of 460 hurricane shelters in advance of the storm.
"This is something without precedent," Rossello told a news conference. He said he would ask U.S. President Donald Trump to declare a federal state of emergency even before the storm passes to allow disbursement of U.S. emergency funds.
Florida Governor Rick Scott has declared a state of emergency, and said on Tuesday he had also asked Trump to make a "pre-landfall" emergency declaration.
Irma was expected to reach southern Florida on Saturday, and shares in insurance companies with exposure in the state tumbled in Tuesday trading.
Gary Randall, head of the Blue Waters Resort on Antigua's north coast, said the staff had boarded up windows, stripped trees of coconuts and fronds and secured anything that could become a hazard.
"I wasn't that nervous yesterday, but today I'm nervous," Randall said by telephone, adding that he expected the hotel's beach to be swept away and much of the 108-room property to be flooded.
Hurricane watches were in effect for Guadeloupe, Haiti, the Turks and Caicos Islands and the southeastern Bahamas.
Julia Nuñez Rodriguez, a single mother of three who lives north of Santo Domingo, the Dominican capital, was most worried about the potentially high death toll. "I'm hoping and praying for the best," she said.
Airlines canceled flights to the region, and American Airlines added three extra flights to Miami from San Juan, St. Kitts and St. Maarten.
Irma is expected to become the second powerful storm to thrash the U.S. mainland in as many weeks, but its precise trajectory remained uncertain on Tuesday. The Atlantic hurricane season ends on Nov. 30.
Residents of Texas and Louisiana were still recovering from Hurricane Harvey, which struck Texas as a Category 4 hurricane on Aug. 25. It dumped several feet of rain, destroying thousands of homes and businesses, killed an estimated 60 people and displaced more than 1 million others. (Additional reporting by Alana Wise in New York and Ian Simpson in Washington; Writing by Ian Simpson and Steve Gorman; Editing by Jeffrey Benkoe and James Dalgleish)