MIAMI (AP) — Hurricane Humberto is expected to produce dangerous surf for Bermuda and the U.S. East Coast this week while Tropical Storm Imelda is strengthening near the Bahamas, forecasters said. Humberto remained a powerful Category 4 storm in the Atlantic early on Monday and a Tropical Storm Watch was in effect for Bermuda, the National Hurricane Center in Miami said. Imelda formed Sunday and the hurricane center said it is gradually strengthening. Imelda was moving north at 8 mph (13 kph) with maximum sustained winds of 45 mph (75 kph), the center said. Portions of the Bahamas were under a tropical storm warning.