Sept. 29 (UPI) -- Humberto weakened slightly overnight, but remains a powerful Category 4 storm early Monday and a threat to the East Coast and Bermuda, the National Hurricane Center said. Humberto had maximum sustained winds of 140 mph, the National Hurricane Center said in its 2 a.m. AST update . It was located about 400 miles south-southwest of Bermuda and was moving northwest at 14 mph, according to the forecasters. Hurricane-force winds extend outward up to 60 miles from the center of the