SAN JUAN, Puerto Rico — Armed with the most powerful winds ever recorded for a storm in the Atlantic Ocean, Hurricane Irma bore down Tuesday on the Leeward Islands of the northeast Caribbean on a forecast path that could take it toward Florida over the weekend. The storm, a dangerous Category 5, posed an immediate threat to the small islands of the northern Leewards, including Antigua and Barbuda, as well as the British and U.S. Virgin Islands and Puerto Rico. "The Leeward Islands are going to get destroyed," warned Colorado State University meteorology professor Phil Klotzbach, a noted hurricane expert. "I just pray that this thing wobbles and misses them. This is a serious storm." LIVE BLOG: Get the latest updates on Hurricane IrmaIrma had maximum sustained winds of 185 mph as it approached the Caribbean from the east, according to the U.S. National Hurricane Center in Miami. Four other storms have had winds that strong in the overall Atlantic region but they were in the Caribbean Sea or the Gulf of Mexico, which are usually home to warmer waters that fuel cyclones. Hurricane Allen hit 190 mph in 1980, while 2005's Wilma, 1988's Gilbert and a 1935 great Florida Key storm all had 185 mph winds. What makes Irma so strong is unusually warm waters for that part of the Atlantic. ARE YOU PREPARED?: Complete 2017 hurricane preparedness guideThe center of Irma was about 180 miles east of Antigua and about 185 miles east-southeast of Barbuda on Tuesday afternoon, prompting an ominous warning from officials as the airport closed. People in the two-island nation should seek protection from Irma's "onslaught," officials warned in a statement, closing with: "May God protect us all." The storm was moving west at 14 mph (22 kph), and the hurricane center said there was a growing possibility that its effects could be felt in Florida later this week and over the weekend. If it stays on the forecast track and reaches the Florida Straits, the water there is warm enough that the already "intense" storm could become much worse with wind speeds potentially reaching 225 mph, warned Kerry Emanuel, an MIT meteorology professor. "People who are living there (the Florida Keys) or have property there are very scared, and they should be," Emanuel said. The storm's eye was expected to pass about 50 miles from Puerto Rico late Wednesday. "Puerto Rico has not seen a hurricane of this magnitude in almost 100 years," Carlos Anselmi, a National Weather Service meteorologist in San Juan, told the Associated Press. Authorities warned that the storm could dump up to 12 inches of rain, cause landslides and flash floods and generate waves of up to 23 feet. Government officials began evacuations and urged people to finalize all preparations as store shelves emptied out on islands including Puerto Rico."The decisions that we make in the next couple of hours can make the difference between life and death," Puerto Rico Gov. Ricardo Rossello said. "This is an extremely dangerous storm." Antigua and Barbuda Prime Minister Gaston Browne said he was confident Barbuda would weather the storm. "I am satisfied that at a governmental level that we have done everything that is humanly possible to mitigate against the effects or the potential effects of this storm," he said. "What is really required now is for Antiguans and Barbudans ... to follow the warnings and to act appropriately so that we do not end up with any serious casualties." Puerto Ricans braced for blackouts after the director of the island's power company told reporters that storm damage could leave some areas without electricity for about a week and other, unspecified areas for four to six months. The utility's infrastructure has deteriorated greatly during a decade-long recession, and Puerto Ricans experienced an island-wide outage last year. Both Puerto Rico and the U.S. Virgin Islands expected 4 inches to 10 inches (of rain and winds of 40-50 mph with gusts up to 75 mph. "This is not an opportunity to go outside and try to have fun with a hurricane," U.S. Virgin Islands Gov. Kenneth Mapp warned. "It's not time to get on a surfboard." A new tropical storm also formed in the Atlantic on Tuesday, to the east of Irma. The hurricane center said Tropical Storm Jose was about 1,505 miles east of the Lesser Antilles with maximum sustained winds of 40 mph. It was moving west-northwest at 13 mph and was expected to become a hurricane by Thursday.