On late Tuesday in the Caribbean Sea, the 15^th named storm of the 2008 hurricane season, Omar achieved hurricane status, and turned from the eastern Caribbean to the western Caribbean Sea, threatening Puerto Rico and the Virgin Islands.

As of 11 p.m. EDT, Omar’s maximum sustained winds were up to 75 mph (120 kph), where they were only 40 mph at 11 a.m., according to the National Hurricane Center in Miami. The NHC expects Omar to further increase in strength come Wednesday.

The Center posted hurricane warnings for the U.S. Virgin Islands and for the British Virgins and St. Martin, Saba, St. Eustatius, St. Barthélemy, Anguilla, St. Kitts and Nevis, Antigua, Barbuda and Montserrat.

According to the center’s report, Omar was 315 miles (505 km) south-southwest of San Juan, Puerto Rico and was headed Northeast at 6 mph (9 kph). Hurricane winds extended 15 miles (30 km) from the eye of the storm, and tropical storm winds extended as far as 90 miles (145 km).

The storm is expected to hit the northern Leeward Islands late on Wednesday, and the hurricane is also likely to bring heavy rain – as much as 20 inches – to Puerto Rico and other, smaller islands in its path, as well as to the northern coast of Venezuela. The rains could, warns the NHC, trigger flash floods and mudslides, as well as heavy swells and battering surf. The swells could cause beach erosion and damage coastal structures.

This year’s Atlantic hurricane season began on June 1 and ends on Nov. 30