Irma picked up strength and has become an "extremely dangerous" Category Five hurricane as it approached the Caribbean on Tuesday, the Miami-based National Hurricane Centre reported.
"Preparations should be rushed to completion in the hurricane warning area," the NHC said in its bulletin.
The monster hurricane, the most powerful of the five-level Saffir-Simpson scale, is about 270 miles east of the island of Antigua packing maximum sustained winds of 175 miles per hour.
Hurricane advisories were issued for territories that dot the West Indies, including parts of the Leeward Islands, the British and US Virgin Islands and Puerto Rico in preparation for the intensifying storm that could pummel the area with life-threatening wind, storm surges and torrential rain by Tuesday evening, according to the US National Hurricane Center (NHC).
Irma's centre was about 410 miles (660 kilometers) east of the Leeward Islands, grinding westward at 13 miles per hour (20 kilometers per hour), the NHC said.
“On the forecast track, the centre of Irma will move near or over portions of the northern Leeward Islands Tuesday night and early Wednesday.”
“Preparations to protect life and property should be rushed to completion,” it stressed.
Irma is expected to make landfall along the string of French islands that includes Guadeloupe late Tuesday before heading to Haiti and Florida.
The storm was moving towards the west at 14 miles per hour, and is expected to drop between four and eight inches of rain when it hits land.
"These rainfall amounts may cause life-threatening flash floods and mudslides," the NHC warned.
The storm is also is expected to "cause life-threatening surf and rip current conditions."
Hurricane Irma – which has triggered alarm and alerts from the French West Indies to Florida – comes after of Hurricane Harvey devastated parts of Texas and Louisiana late last month.
A Category Four strength was the maximum attained by Harvey, which dumped as many as 50 inches of rain in some parts of Houston, turning neighbourhoods into lakes.
The NHC cautioned that it was still too early to forecast Hurricane Irma's exact path or what effects it might have on the continental United States, but warned of likely effects to hit some areas by later this week.
This enhanced satellite image made available by the NOAA GOES Project shows Irma, in the middle of the Atlantic Ocean on Saturday, Sept. 2, 2017 (AAP) Source: AAP
“There is an increasing chance of seeing some impacts from Irma in the Florida Peninsula and the Florida Keys later this week and this weekend. In addition, rough surf and dangerous marine conditions will begin to affect the southeastern US coast by later this week,” the centre said.
Irma will be the second powerful hurricane to thrash the United States and its territories in as many weeks.
Residents in Texas and Louisiana are still reeling from the catastrophic effects of the deadly Hurricane Harvey, which struck Texas on Aug. 25 and dumped several feet of rain, destroying thousands of homes and businesses.
Irma is forecast to strengthen over the next 48 hours and could “directly affect Hispaniola, the Turks and Caicos, the Bahamas, and Cuba as a dangerous major hurricane later this week,” the NHC said.
In preparation for the storm, the economically struggling Puerto Rico government on Monday declared a state of emergency and activated the National Guard. Governor Ricardo Rossello announced the opening of storm shelters able to house up to 62,000 people. Schools will be closed on Tuesday.
“Despite the economic challenges Puerto Rico is facing, the approved budget has $15 million for the emergency fund,” Governor Ricardo Rosselló said in a statement.
Emergency shelters
The island of about 3.4 million people has 456 emergency shelters prepared to house up to 62,100 people.
To help residents prepare for the storm, the Puerto Rican government activated a price freeze on basic necessities, including food and water, medicines, power generators and batteries.
Telemundo TV station WIPR in Puerto Rico showed long lines of shoppers stocking up on bottled water, flashlights, batteries, generators, food and other items.
The executive director of the state power authority, Ricardo Ramos, told the station that the power grid was so vulnerable from lack of investment that parts of the US territory could be without power for three to four months.
“We’re preparing for the worst-case scenario,” he said.
US carrier in position
A US aircraft carrier with a field hospital and dozens of aircraft able to conduct rescue or supply missions has been positioned protectively in the area, according to Alejandro de la Campa of the Caribbean division of the US Federal Emergency Management Agency (FEMA). Local press identified the carrier as the USS Kearsarge.
San Juan Mayor Carmen Yulin Cruz Soto ordered 900 municipal employees – police, emergency personnel, and aid and social workers – to report for rotating 12-hour shifts.
Even if that island is spared a direct hit, the mayor said, three days of pounding rain will do heavy damage.
Irma's precise path remains unclear. But several projections have it passing over the Dominican Republic, Haiti and Cuba before turning north toward Florida and then possibly swinging up the US East Coast.
Scrambling amid the uncertainty, Florida declared a state of emergency to facilitate preparations.
For now, hurricane warnings have been issued for the islands of Antigua, Barbuda, Anguilla, Montserrat, St. Kitts and Nevis, St. Martin, Sint Maarten, St. Barthelemy, Saba and St. Eustatius; the British Virgin Islands; US Virgin Islands; Puerto Rico, Vieques and Culebra. A warning means hurricane conditions are expected in the next 36 hours.
Anne Laubies, prefect of Saint Barthelemy, warned the hurricane posed the greatest danger the island had faced in 20 years, with more people endangered in flood-prone areas because of a rise in population.
Long queues of people rushed to get batteries and bottled water, while many cut trees around their dwellings and sought to tie down objects and seal their windows.
A hurricane watch – meaning hurricane conditions are possible within 48 hours – has been issued for Guadeloupe.
Irma is expected to produce total rainfall accumulations of 3 to 6 inches (7.6-15 cm) across the Leeward Islands, with isolated maximum amounts of 10 inches (25 cm) across the northern Leeward Islands.
