(Reuters) - Hurricane Oscar is expected to weaken into a powerful extratropical - or mid-latitude - cyclone by Wednesday night, the U.S. National Hurricane Center (NHC) said in an advisory.

The system is located about 660 miles (1,060 kilometers) east-northeast of Bermuda with maximum sustained winds of 75 miles per hour, the NHC said.

“Although gradual weakening is expected during the next several days, Oscar is expected to remain a powerful post-tropical cyclone... into the weekend,” the Miami-based weather forecaster said.