Long-lived mesoscale convective systems over eastern South Africa

Abstract A climatology of large, long-lived mesoscale convective systems (MCSs) over eastern South Africa for the extended austral summer (September-April) from 1985-2008 is presented. On average, 63 MCSs occur here in summer, but with considerable interannual variability frequency. The mainly between November and March, a December peak. This seasonal cycle MCS activity shown to coincide favorable CAPE vertical shear profiles across domain. Most tend along escarpment adjacent warm waters northern Agulhas Current nocturnal life cycle. Typically, initiation begins early afternoon, status reached mid-afternoon, maximum extent night termination around midnight or shortly thereafter. It found that most initiate land, ocean last longer than those develop land. results also show there are differences continental oceanic MCSs, containing two intraseasonal peaks (December April). There relatively strong positive relationship Southern Annular Mode (SAM) For late frequency appears related strength Mascarene High Mozambique Channel Trough which modulate inflow moisture into stability lower atmosphere region.