UC Berkeley

Abstract Mesoscale convective systems (MCS) and low‐pressure systems (LPS) are both strongly associated with precipitation across the regions where they occur, particularly within global monsoon systems; however, their co‐occurrence and its relationship to precipitation have not been systematically examined. Here, we use LPS and MCS trackers to detect compound MCS and LPS events in five monsoon regions and assess the association of this co‐occurrence with anomalies of winds, precipitation, and other atmospheric variables. Additionally, we investigate the spatial distribution of precipitating MCS and LPS events. Our results show that most (∼60%) MCS and LPS co‐occurrences are located in the lower latitudes, where they contribute up to 40% of annual precipitation. We find that compound events generally produce more extreme precipitation than MCS‐only or LPS‐only events. Furthermore, our assessment of the synoptic and mesoscale composites reveals that the underlying dynamics of compound events exhibit anomalously positive convective available potential energy and an anomalously low‐pressure within the location of the event. In terms of the synoptic environment of the features, the compound MCS and LPS events are associated with inverted troughs in three out of five monsoon locations assessed. Plain Language Summary This study aims to examine the relationship between low‐pressure systems and mesoscale convective systems and their combined influence on precipitation in near‐equatorial regions. Our results show that these systems could lead to ∼40% of the precipitation in the regions where they occur and further lead to extreme precipitation during their co‐occurrence. Our results provide a systematic approach to assessing the weather during single events and co‐occurrence. Key Points 60% Mesoscale convective systems (MCS) and low‐pressure systems (LPS) co‐occurrences are located in the lower latitudes, and contribute up to 40% of annual precipitation Compound events generally produce more extreme precipitation than MCS‐only or LPS‐only events Compound MCS and LPS events could be associated with inverted troughs