Tropical Storm Chris further weakened Thursday morning as it swept through the eastern Caribbean, prompting hurricane warnings to be downgraded and one forecaster to predict the storm would not grow stronger.

At 5 a.m, Chris had top maximum sustained winds of 45 mph, down 15 mph from Wednesday night, according to the National Hurricane Center in Miami. The center of the storm was about 315 miles east-southeast of Grand Turk Island and about 135 miles north of San Juan, Puerto Rico.

The third named storm of the Atlantic hurricane season was moving west at 13 mph and was expected to move away from Puerto Rico and the Virgin Islands sometime Thursday, forecasters said.

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Tropical storm warnings for Puerto Rico and the U.S. and British Virgin Islands were discontinued. The Bahamas downgraded a hurricane watch to a tropical storm watch for the Turks and Caicos Islands and for the southeastern Bahamas, including the Acklins, Crooked Island, the Inaguas, Mayaguana and the Ragged Islands.

"We sent a plane in and found that the storm encountered upper level winds that are not favorable for development," said Lixion Avila, hurricane specialist. "It's very likely that it will not intensify anymore."

A tropical storm watch remains in effect for the coast of the Dominican Republic from the northern border of Haiti to Cabo Engano. A tropical storm watch means tropical storm conditions are possible within the next 36 hours.

Authorities in the Bahamas, an archipelago of 700 islands accustomed to stormy weather, had earlier urged people to stock up on water and canned food and to board up their windows as the storm approached.

In Staniel Cay, about 75 miles south of Nassau, the Bahamas' capital city, boat owners secured their vessels and tracked the storm's progress through the eastern Caribbean.

"We're just battening down the hatches and tying everything down," said Ernie Sullivan, a boat owner at the Staniel Cay Yacht Club. "You just can't say if this thing will pick up steam."

Some 600 tourists evacuated Culebra and Vieques, small islands off Puerto Rico's east coast, as the storm approached. The storm was projected to pass at least 100 miles north of Puerto Rico.

People in the islands of Antigua and St. Maarten awoke to a light rain. There were no reports of major flooding or other damage from the storm.

Royal Caribbean, the cruise line operator, said it was altering the itineraries of three ships — the Navigator of the Seas, the Explorer of the Seas and the Freedom of the Seas — to avoid the storm.

In Anguilla, Chris brought heavy rain and strong winds overnight but the storm was much less severe than expected because it shifted to the north at the last minute, said Elizabeth Klute, director of the disaster management agency for the British Caribbean territory.

"It just kind of skirted us," Klute said. "It's moving on."

Richard Pasch, a hurricane specialist at the U.S. National Hurricane Center in Miami, said the storm was likely to churn past the island of Hispaniola, which is shared by the Dominican Republic and Haiti, where even minor storms can send water gushing down denuded hills.

"It would seem that it would stay on the fringes of the island as we're seeing this storm on a more westward track," Pasch said. "But it's a little uncertain at this stage."

The first named storm of the 2006 season, Tropical Storm Alberto, swept over Florida in mid-June, then plowed northward along the U.S. coast past the Outer Banks. It was blamed for one death.

Last season was the worst in more than 150 years of records. A record number of tropical storms and hurricanes formed, including the devastating Hurricane Katrina.

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