The fifth tropical storm of this year’s Atlantic hurricane season formed on Monday and was forecast to hit Puerto Rico as early as Tuesday night. Officials in the U.S. territory prepared for the arrival of Tropical Storm Ernesto by activating the National Guard and canceling the start of classes in public schools, the Associated Press reported. Ernesto was located about 295 miles east-southeast of Antigua around 5 p.m. Atlantic Standard Time, with maximum sustained winds of 40 mph and was moving west-northwest at 28 mph. In addition to Puerto Rico, the National Hurricane Center issued tropical…