A tropical wave moved off the northwest coast of Africa on June 5. It continued westward across the tropical North Atlantic and Caribbean Sea without significant development. The wave entered the northeastern Pacific Ocean on June 16, where it generated an area of increased cloudiness. Organization of thunderstorm activity increased late on June 18 and early on June 19. Tropical Depression Four-E formed on June 19, when it was south of Acapulco, Mexico after evidence of low-level circulation for the past 24 hours. The depression moved in a west-northwest direction, due to a subtropical ridge north of the depression. Satellite analysis indicated that the depression had reached tropical storm force strength, and it was upgraded to Tropical Storm Douglas on June 19, while southwest of Acapulco. Douglas reached peak strength of on June 21