A tropical storm churning toward the Caribbean was expected to strengthen into the first Atlantic hurricane of what promises to be a busy season, US forecasters warned on Wednesday. The system, named Gonzalo, was bearing west and picking up speed but remained some 1,200 miles (1,900 kilometers) out in the Atlantic from the southern Windward Islands. It was packing sustained winds of 50 miles (80 kilometers) per hour and was expected to build up to hurricane strength by Thursday, according to a National Hurricane Center bulletin. The system could reach the Venezuelan coast and the Windward Islands by Saturday, forecasts show. However, no storm warnings have yet been issued. Forecasters predicted this year's Atlantic storm season will be particularly busy, with up to 10 hurricanes expected. An average season produces six hurricanes. A jump in activity was already apparent with Gonzalo, which is seventh tropical cyclone so far this year. Philip Klotzbach, a meteorologist at the University of Colorado, wrote on Twitter that Gonzalo marks the first time since 2005 that seven tropical cyclones have formed in such a short period. lm/jme/jm