Contributions of Anomalous Large‐Scale Circulations to the Absence of Tropical Cyclones Over the Western North Pacific in July 2020

No tropical cyclone (TC) formed over the western North Pacific (WNP) in July 2020, which is record-breaking. Some recent studies suggested that this extreme event was mainly caused by strong WNP subtropical high (WNPSH) might not be only reason. In study, results from statistical and composite analyses indicate WNPSH, South Asian high, westward extended upper-tropospheric trough, weak summer monsoon are all detrimental to TC genesis contribute absence of TCs 2020. Results sensitivity experiments using a regional atmospheric model can resolve further demonstrate it collective effect, any individual large-scale circulation anomalies, induced extremely unfavorable conditions for thus led record-breaking inactive month.