On May 7, a tropical wave left the coast of Africa. The wave moved across the Atlantic Ocean showing little signs of development until May 18, when a low pressure center began organizing along the wave over Costa Rica and Panama. The low entered the Pacific Ocean on May 22, and Dvorak classifications—satellite-based intensity estimates—began two days later. At first the system was disorganized, but convection quickly concentrated near the center, and on May 25 the disturbance developed into Tropical Depression One-E while located about south-southwest of Acapulco, Mexico.