The chance of formation into a tropical storm through 48 hours remains high - 90 percent - according to the NHC. Additional strengthening is possible as well due to the warm waters and low wind shear directly above the storm.
Oscar, the 15th named storm this season, was about 660 miles southeast of Bermuda and 645 miles northeast of the Northern Leeward Islands, the National Hurricane Center said in its 11 p.m. advisory.
The storm is expected to morph into a hurricane later on October 28, the National Hurricane Center said. There are no coastal watches or warnings in effect. The storm is continuing to transition from a hybrid storm to a full-fledged tropical system on Saturday night.
The storm does not pose threat to Florida, U.S. Oscar is forecast to begin moving toward the north and then the northeast by early next week.
Forecasters said Oscar is expected to become a hurricane Sunday as its track curves toward the North Atlantic.
Oscar has become the eighth hurricane of the 2018 Atlantic season, but the storm is far out in the Atlantic where it poses no threat to land.