MIAMI (AP) — A tropical depression has formed south of Cuba amid forecasts the system would become a named tropical storm later this weekend and possibly a hurricane within days. The U.S. National Hurricane Center said Tropical Depression 28 emerged Saturday about 255 miles south-southeast of the western tip of Cuba. It has top sustained winds of 30 mph and is moving slowly toward the north-northwest. Forecasters said the depression is expected to gradually strengthen into a tropical storm sometime Sunday and could become a hurricane over the southern Gulf of Mexico by Tuesday. The government of Cuba has issued a tropical storm watch for one of its provinces.