Synoptic analyses were conducted of the major active-break cycle of the summer monsoon and its interaction with the circulation in Eurasia and the western Pacific (10-70°N, 20-180°E) in a MONEX year (1979) and are compared to the recent years (1964-1974). The series of 5-day mean 500mb height and sea level pressure data were used for above regions to monitor the change in the monsoon and adjacent circulations. The weekly rainfall data for the meteorological sub-divisions in India for 1964-1974, 1979 were used to monitor the major active-break cycle of the summer monsoon rainfall in Central India.
Evidence has been shown that development of the major break monsoon in Central India during the high summer period (50 days from 15 July to 2 September) are deeply associated with the circulation in the middle latitudes of Eurasia and western North Pacific near Kyushu Island. The major break monsoon during the high summer are preceded by the development of a 500mb ridge near the Caspian Sea (50°N, 50°E). If a sharp drop in the sea level pressure at Naze 28°23'N, 129°30'E) to a value below 5-day mean of 1004mb (often associated with the major typhoons moving north near 30°N, 120-130°E) are observed, the major break monsoon in Central India were shown to begin within one week of this event.