Both services have always contributed roughly equal amounts of manpower. In 1959 two Air Force and two Navy weather officers, as well as six enlisted personnel, three from each service manned JTWC. The senior of the two Air Force meteorologists was the Director of JTWC. The warnings were issued four times daily for each tropical cyclone in the northwest Pacific. The warnings contained initial position, plus 12-, 24-, and 48-hour forecast positions. In 1961 the manning was increased to three weather officers from both the Air Force and the Navy. In 1962 the forecasts were extended to 72 hours, but not on a routine basis.
In 1967, JTWC began issuing Prognostic Reasoning messages for tropical cyclones of tropical storm strength or greater in the northwest Pacific, and also began issuing Significant Weather Advisory for the northwest Pacific from May through December. By 1968 the warnings were issued with alternating 48 hour and 72 hour forecasts, and tropical depression warning forecasts went out to 24 hours.
Tropical Cyclone Formation Alerts were established in 1970. In 1972 the manning was increased to four weather officers from each service and all warnings were extended to 72 hours. In 1975, The Significant Tropical Weather Advisory (ABEH) was issued daily throughout the entire year , and was split in August 1985 into the ABPW for the Western Pacific Ocean northern and southern hemispheres, and the ABIO for the Indian. This was in recognition to the differing times during which daytime visible metsat imagery was available over the JTWC AOR.
By December 1985, a newly established position of JTWC Technical Advisor was filled by Mr Frank Wells, a former METSAT Coordinator. June 1987 the Air Force added a Data Development Officer and three NCOs; a satellite analyst, a satellite techniques development NCO and another TDA to offset the discontinuation of aerial reconnaissance. By 1995, typhoon duty officers began forecasting out to 120 hours in-house, and advising the synoptic weather forecasters on tropical cyclone placement on the 96- and 120- hour weather charts.