HAMILTON, July 14 (Reuters) - Tropical Storm Bertha buffeted the eastern shores of Bermuda with high winds and heavy rains on Monday, and forecasters said it was expected to become a hurricane again as it strengthened slowly off the British colony.
The U.S. National Hurricane Center in Miami said Bermudian authorities issued a hurricane watch, which means hurricane conditions are possible, as Bertha's maximum sustained winds rose to near 70 miles per hour (110 km per hour), just below hurricane strength.
However, in a 11 p.m. EDT (0300 GMT) report, the center said the storm was moving steadily away from Bermuda, to the east into the open sea. The report said Bertha was making a "gradual right turn" away from the island and into colder water.
The intensity forecast and organization of the storm remained essentially unchanged, it said.
"Bertha is expected to become a hurricane during the next 24 hours," the hurricane center said. "There is some chance that this could occur before Bertha's strongest winds move past Bermuda during the next several hours."
Bertha, which has weakened since making its mark last week as the 2008 Atlantic storm season's first hurricane, knocked out power to 7,000 homes in Bermuda and was expected to dump up to 5 inches (12.7 cm) of rain on the mid-Atlantic territory.
Flights from the international airport in Bermuda were canceled, public beaches placed off limits as thunderous surf broke on the shoreline and many schools closed at midday.
By 11 p.m. EDT (0300 GMT), Bertha was located about 80 miles (100 km) northeast of Bermuda and was moving toward the north at 9 miles per hour (15 km per hour), the hurricane center said. It said the storm's strongest winds were expected to move past the island within the next several hours.
After its brush with Bermuda, Bertha was expected to eventually fade away in the hurricane graveyard of the north Atlantic.
At one point a "major" Category 3 hurricane on the five-step Saffir-Simpson scale of hurricane intensity, Bertha had weakened over the weekend as it churned up colder waters from beneath the sea surface, depriving it of the warm water that fuels tropical storms.
Wealthy Bermuda, home to much of the world's reinsurance industry, has some of the region's toughest building standards and a tropical storm -- or even a minimal Category 1 hurricane -- is unlikely to pose a serious threat to its 66,000 people.
Oil markets have paid close attention to Atlantic storms since a series of powerful hurricanes in 2004 and 2005 toppled oil rigs and severed gas pipelines in the Gulf of Mexico, where the United States gets a third of its domestic crude supply.
An area of disturbed weather midway between the Caribbean islands and Africa was of more interest to oil traders on Monday than Bertha.
That area of low pressure located around 1,200 miles (1,945 km) east of the Lesser Antilles was getting better organized and could become a tropical depression, the precursor to a tropical storm, later on Monday, the hurricane center said.
It was moving westward at 10 to 15 mph (16 to 24 kph), the center said.
Bertha formed near the Cape Verde Islands off Africa.
Its development that far east so early in the hurricane season is viewed by some experts as ominous. The six-month-long Atlantic storm season, which begins on June 1, rarely gets into high gear before August.
(Reporting by Matthew Taylor in Hamilton and Tom Brown in Miami; Editing by Michael Christie and Cynthia Osterman)