(CNN)As Floridians cleared supermarkets of bottled water and emptied gas pumps, people in the northeastern Caribbean were making last minute-preparations before powerful Hurricane Irma hit their islands. Late Tuesday, the massive Category 5 storm was almost upon islands like Antigua and Barbuda with near-record 185 mph sustained winds. In its 11 p.m. ET advisory, the US National Hurricane Center said the eye of the hurricane was 50 miles from the two islands. The center of the storm was moving to the west-northwest at 15 mph. The hurricane center said the extremely dangerous core of Irma would hit the northern Leeward Islands -- which include Antigua and Barbuda, St. Kitts and Nevis, and Anguilla -- Tuesday night or Wednesday morning. It's too early to tell whether the storm will make landfall on the US mainland, but forecasts show it could turn toward Florida over the weekend. Until the early 1950s, tropical storms and hurricanes were tracked by year and the order in which they occurred during that year. Over time, it was learned that the use of short, easily remembered names in written as well as spoken communications is quicker and reduces confusion when two or more tropical storms occur at the same time. In the past, confusion and false rumors resulted when storm advisories broadcast from radio stations were mistaken for warnings concerning an entirely different storm located hundreds of miles away. In 1953, the United States began using female names for storms and, by 1978, both male and female names were used to identify Northern Pacific storms. This was then adopted in 1979 for storms in the Atlantic basin. NOAA’s National Hurricane Center does not control the naming of tropical storms. Instead, there is a strict procedure established by the World Meteorological Organization. For Atlantic hurricanes, there is a list of male and female names which are used on a six-year rotation. The only time that there is a change is if a storm is so deadly or costly that the future use of its name on a different storm would be inappropriate. In the event that more than twenty-one named tropical cyclones occur in a season, any additional storms will take names from the Greek alphabet.