The storm was expected to strengthen to a hurricane by about 8 a.m. on Monday.
Tropical Storm Chris is expected to bring swell and showers to Bermuda towards the middle of this week.
Meanwhile, tropical storm Beryl was located about 240 miles east of Barbados, packing maximum sustained winds of 45 mph, the NHC said early Sunday.
Dominica and Guadeloupe remain on tropical storm warning while Martinique, St Martin, St Barthelemy, Saba, St Eustatius and St Maarten are on tropical storm watch.
As of Sunday evening, Chris was about 180 miles south-southeast of Cape Hatteras, North Carolina, with maximum sustained winds of about 50 mph.
"It is going to meander a bit for the next 24 hours off the Carolina coast, and then it's expected to start heading northeast", Kim Buttrick, a meteorologist for the National Weather Service said.
How rescuers plan to get trapped boys out of Thai cave
He said the rescue operation was pausing for about 10 to 20 hours to check the escape route again for safety before being resumed. The initial euphoria of finding the boys alive tuned into deep anxiety as rescuers raced to find a way to get them out.
"Based on the current track by the National Hurricane Center, it looks to be tracking well southeast of Nantucket", Buttrick said. It was centered 210 miles (335 kilometers) east of Martinique and was moving west-northwestward at 23 mph (37 kph).
Tropical Storm Chris continues to spin just off the North Carolina coast and is now centered roughly 150 miles to the south of Cape Hatteras, North Carolina.
High surf and risky rip currents are expected along parts of the Carolina and mid-Atlantic coasts through early week.
The storm was forecast to weaken into a low-pressure system Monday by the time it reaches seas just south of Puerto Rico, which was devastated by Hurricane Maria in September.
Forecasters expect gradual weakening during the next 48 hours and it will degenerate into a trough of low pressure as it moves across the Lesser Antilles and into the eastern Caribbean Sea by Monday.
About 7,000 houses and businesses in Puerto Rico still lack power after Hurricane Maria leveled an electricity grid that was ill-maintained before the storm.
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