At the end of September 1979, three circulations developed within the monsoon trough that extended from the Philippines to the Marshall Islands. The westernmost disturbance developed into a tropical depression on October 1, to the west of Luzon, which would later become Typhoon Sarah on October 7. On October 3, the disturbance southwest of Guam developed into Tropical Storm Roger, and later on the same day, a third tropical disturbance that would later become Typhoon Tip formed south of Pohnpei. Strong flow from across the equator was drawn into Roger's wind circulation, initially preventing significant development of the precursor disturbance to Tip. Despite the unfavorable air pattern, the tropical disturbance gradually organized as it moved westward. Due to the large-scale circulation pattern of Tropical Storm Roger, Tip's precursor moved erratically and slowly executed a cyclonic loop to the southeast of Chuuk. A reconnaissance aircraft flight into the system late on October 4 confirmed the existence of a closed low-level circulation, and early on October 5, the Joint Typhoon Warning Center (JTWC) issued its first warning on Tropical Depression Twenty-Three-W.