Tropical Storm Danny weakens off U.S. East Coast

MIAMI, Aug 28 (Reuters) - Tropical Storm Danny weakened in the Atlantic on Friday but could produce dangerous surf conditions and life-threatening rip currents along the U.S. East Coast in the next day or two, the U.S. National Hurricane Center said.

Now barely a tropical storm, Danny's maximum sustained winds fell to 40 miles per hour (64 kph), with the strongest winds confined to the northeast of the storm's eye, the Hurricane Center said in its 5 a.m. (0900 GMT) advisory.

"There is small opportunity for slight restrengthening today," it added. Danny is the fourth tropical storm of the 2009 Atlantic season. Tropical storms have maximum sustained winds ranging from 39 to 73 mph (63-118 kph).

Forecasters said most tracking models kept the heart of the storm away from the U.S. East Coast. But there were storm alerts for the North Carolina coast, and residents from the Carolinas to New England and the Canadian Maritimes were urged to monitor Danny.

The storm could bring blustery weather by the weekend to Martha's Vineyard, Massachusetts, where U.S. President Barack Obama is vacationing this week and to Boston, where Senator Edward Kennedy's funeral is scheduled on Saturday.

Danny was 400 miles (643 km) south of Cape Hatteras, North Carolina, and was moving north-northwest near 9 mph (14.5 kph). A turn to the north with increased forward speed was expected later on Friday, forecasters said.

Tropical storms and hurricanes are tracked closely by energy traders concerned about disruptions to oil and gas production in the Gulf of Mexico and Canada's Atlantic region, and by commodities traders for damage to citrus, cotton and other crops. (Writing by Peter Cooney; Editing by Robin Pomeroy)