 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 230 mi ( 370 km ) 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 . <unk> analysis indicated that the depression had reached tropical storm force strength , and it was upgraded to Tropical Storm Douglas on June 19 , while 230 mi ( 370 km ) southwest of Acapulco . Douglas reached peak strength of 65 mph ( 105 km / h ) on June 21 
