Hurricane Omar is bearing down on the islands of the eastern Caribbean, including Puerto Rico and the U.S. Virgin Islands, home to one of the world's largest oil refineries.

The AccuWeather.com Hurricane Center reports that Omar has been gathering strength as it spins south-southwest of Puerto Rico today. Omar is a Category 1 hurricane with sustained 85-mph winds.

Hurricane warnings are in effect for the U. S. and British Virgin Islands, St. Maarten, Saba, St. Eustatius, St. Barthelemy, Anguilla, St. Kitts and Nevis, Vieques and Culebra. A tropical storm warning and hurricane watch are in effect for Puerto Rico, Antigua, Barbuda and Montserrat.

According to Expert Senior Meteorologist John Kocet, "Omar has nowhere to go but northeast." A storm over the western Atlantic is steering Omar on a northeasterly path to the Virgin Islands, while a storm system moving into the East over the next couple of days will direct Omar away from the United States as it moves offshore this weekend.

The storm could reach Category 2 strength by the time it moves over or near the U.S. Virgin Islands tonight. The 15th named storm of the 2008 Atlantic Basin hurricane season is expected to lash St. Thomas, St. John and St. Croix with wind gusts above 100 mph, dangerous surf and heavy rain, making it the worst hurricane in over a decade for the region.

Most of the islands will receive at least 6 inches of rain; however, some areas could receive close to 2 feet of heavy rain that could trigger mudslides and flash floods.

Schools are closed and ferry services have been canceled in Puerto Rico and the U.S. Virgin Islands, where Emergency Management Agency director Mark Walters urged islanders to take the warnings seriously.

According to Meteorologist Jesse Ferrell, Omar is taking a unique approach to the islands. Tropical Storm Klaus in 1984 was the only other storm that has approached the Virgin Islands from the southwest.

St. Croix has been targeted by a number of hurricanes over the years. In 1989, the island suffered major damage when Hurricane Hugo made a direct hit.

Reuters reports that on Tuesday Omar slammed the island of Curacao, knocking down trees and lamp posts and cutting power in some areas. Flooding was reported in the capital and there were reports of 16-foot waves.

The hurricane is impacting operations at one of the world's ten largest oil refineries. St. Croix is home to HOVENSA, a wholly owned Virgin Islands subsidiary of Hess Corporation and the largest private employer in the Virgin Islands. The facility can process 500,000 barrels of crude oil per day.

HOVENSA spokesman Alex Moorhead tells AccuWeather.com that "all processing and auxiliary equipment at the facility has been shut down, with the exception of equipment necessary to supply power to the facility."

The U.S. Coast Guard on Tuesday closed the port facilities in Limetree Bay until the storm has safely passed. Moorhead says that the refinery will remain closed until inspectors determine it is safe to resume operations.

According to Reuters, the storm stopped tankers from loading crude oil at the Puerto La Cruz refinery in Venezuela on Tuesday.

Tropical Depression 16 will continue to drench Central America Thursday. According to the AccuWeather.com Hurricane Center, TD 16, with winds near 30 mph, is expected to remain very close to shore of the northern coast of Honduras through Thursday.

The system is forecast to dump 4 to 8 inches of rain over northeastern Nicaragua and northern Honduras, with up to 15 inches possible in some areas. The heavy rain will spark widespread flooding and dangerous mudslides.

A large dome of high pressure over the Southeast will steer the depression to the west, keeping it away from the U.S.