This image obtained from NASA's GOES Project shows Hurricane Irma on September 4, 2017. Image Credit: AFP

Miami: Hurricane Irma surged to a dangerous Category Four storm Monday as it churned toward the Leeward islands, sparking alarm and alerts from the Caribbean to Florida, which declared an emergency.

The National Hurricane Centre said at 9pm GMT (1am Tuesday UAE) that the storm was packing top sustained winds of 215 km/h. “Additional strengthening is forecast during the next 48 hours,” the NHC warned.

“On the forecast track, the center of Irma will move near or over portions of the northern Leeward Islands Tuesday night and early Wednesday.”

A Category Four storm on the Saffir Simpson scale is capable of doing widespread major structural and infrastructure damage; it can easily tear off roofing, shatter windows, uproot palm trees and turn them into projectiles that can kill people.

Category four strength was the maximum attained by Hurricane Harvey, which recently devastated parts of Texas and Louisiana.

Irma is projected to reach the Leeward Islands, east of Puerto Rico, by late Tuesday or early Wednesday, bringing water levels up to 9 feet (3 meters) above normal levels, rainfall of up to 10 inches (25 centimeters) in areas, and “large and destructive waves.”

In Puerto Rico, a US territory of 3.5 million, Governor Ricardo Rossello activated the National Guard and announced the opening of storm shelters able to house up to 62,000 people. Schools will be closed Tuesday.

US carrier in position

A US aircraft carrier carrying 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. A warning means hurricane conditions are expected in the next 36 hours.

Hurricane watches — meaning hurricane conditions are possible within 48 hours — have been issued for some of the more populous parts of the Caribbean, including Puerto Rico; as well as Guadeloupe and the US and British Virgin Islands.

Irma is expected to produce total rainfall accumulations of 3 to 6 inches across the Leeward Islands, with isolated maximum amounts of 10 inches across the northern Leeward Islands. These rainfall amounts may cause life-threatening flash floods and mudslides,” the NHC said.

The Haitian authorities issued an early alert for a storm that said could hit them for three days, with potential for landslides and flooding.

On the French island of Guadeloupe, people have been stocking up on provisions, leaving some store shelves empty.

Schools on Saint Barthelemy and Saint Martin have delayed their reopening after summer vacation.

Authorities elsewhere in the region were alerting residents to the location of storm shelters, and urging them to closely monitor the developing storm.