Humberto turns back into tropical storm: NHC Mon Sep 16, 2013 11:05am EDT (Reuters) - Humberto, the first hurricane of the 2013 Atlantic hurricane season, has become a tropical storm again, the U.S. National Hurricane Center said in its latest advisory. The storm was expected to slowly strengthen during next 48 hours while turning north-northwest, NHC added. Humberto was located about 1,200 miles southwest of the Azores with maximum sustained winds of 40 mph (65 km/h), the Miami-based weather forecasters said. Reporting by Shrutee Sarkar and Ratul Ray Chaudhuri, in Bangalore; Editing by Gerald E. McCormick