Miami (CNN) -- A slightly-strengthened Tropical Storm Sean was meandering southwest of Bermuda on Wednesday, but a tropical storm warning was issued ahead of its approach.
As of Wednesday morning, the center of Sean was about 470 miles southwest of the Atlantic island. The storm's maximum sustained winds were at about 50 mph, and Sean was moving westward at about 3 mph, the Miami-based National Hurricane Center said.
A tropical storm warning means tropical storm conditions, including sustained winds of at least 39 mph, are possible within 36 hours. Bermuda should begin experiencing tropical storm conditions Thursday afternoon or evening, forecasters said.
A National Oceanic and Atmospheric Administration buoy recently reported a sustained 40-mph wind and a wind gust of 45 mph from Sean, forecasters said Wednesday.
Sean is expected to begin turning north and then northeast, the Hurricane Center said. Computer models show the storm remaining below hurricane strength as it passes northwest of Bermuda and heads out into the open Atlantic.
Tropical storm-force winds extend outward up to 290 miles from Sean's center, forecasters said. Some strengthening is possible Wednesday.
Swells generated by Sean are expected to affect portions of the southeastern United States over the next two days, forecasters said, and can spawn potentially life-threatening surf and rip currents.