An area of tropical disturbance centered about 90 miles (150 km) south-southwest of Puerto Angel, Mexico, developed into Tropical Depression Fifteen-E on the afternoon of October 11. Due to its proximity, attention was immediately paid to it, and Mexico began issuing watches early the next day. With the 2 pm PDT (2100 UTC) update on October 12, it was upgraded to a tropical storm and named Lester.