Hurricane Florence, meanwhile, brought high winds and heavy rain to Newfoundland in Canada.
Helene had top sustained winds near 40 mph, just above the 39-mph threshold for a tropical storm. The eighth-named storm of the Atlantic hurricane season formed late Wednesday night.
At 5 a.m. EDT, it was located 695 miles west of the southernmost Cape Verde Islands and moving west over warm Atlantic waters at 22 mph, forecasters said. A gradual turn toward the west-northwest was expected over the next 24 hours.
Gordon was upgraded to a Category 3 hurricane late Wednesday when its top sustained winds jumped to 120 mph, up from 110 mph earlier in the day, forecasters said.
The hurricane was moving out to sea and was no threat to land, according to the hurricane center. Gordon's clearly defined eye was centered about 550 miles east-southeast of Bermuda and moving north-northeast near 13 mph. Some gradual weakening was expected over the next 24 hours, forecasters said.
"Although Gordon's eye remains distinct, it has become smaller and a little less well-defined," said Richard Knabb, a senior hurricane specialist.
Some waves could reach Bermuda, but the British territory should not feel tropical storm force winds, forecaster said.
In the Pacific, Tropical Storm Lane strengthened Thursday as its outer rainbands affected the Pacific coast of Mexico, forecasters said.
A tropical storm warning remained in effect for the coast of Mexico from Tecpan De Galeana to Manzanillo. That means tropical storm conditions are expected within the next 24 hours. A tropical watch remains in effect for the coast of Mexico from west of Manzanillo to Cabo Corrientes. That means tropical storm conditions are possible within the next 36 hours.
At 2 a.m. PDT, Lane was about 90 miles south-southwest of Lazaro Cardenas, Mexico and about 170 miles south-southeast of Manzanillo, Mexico. It's moving toward the west-northwest near 10 mph. Maximum sustained winds were near 40 mph.
Florence's remains brought wind gusts of more than 100 mph and bands of rain to southern and southeastern Newfoundland, and dangerous surf was expected, according to the Canadian Hurricane Center.
Tropical storm warnings were discontinued late Wednesday as the extratropical storm pulled away from Newfoundland.
Extratropical storms get their energy from the collision of warm and cold fronts, not the steamy ocean waters that tropical systems feed on.
The Atlantic hurricane season began June 1 and ends Nov. 30. The National Hurricane Center's latest forecast for the season expects between seven and nine hurricanes.