sentences:  Karen slowly strengthened over the warm waters of the Gulf Stream, and the storm intensified to a hurricane later on October 13.Convection continued to develop, and organized into a ring around the eye as Karen reached its peak intensity of 80 mph (130 km/h) on October 14 while located about 400 miles (640 km) south of Halifax, Nova Scotia.Karen quickly weakened as it moved over cooler waters, and late on October 14 it degenerated back into a tropical storm as it accelerated northward.