Large Summer Rainfall Events and Their Importance in Mitigating Droughts over the South Western Cape, South Africa

Abstract Although the south Western Cape receives most of its rainfall between May and September, there are substantial events in some summers. These interest themselves as well for their possible role mitigating frequent winter droughts that region suffers from. Most recently, greater Town suffered a devastating drought during 2015–18 known Day Zero due to high risk urban areas running out piped water supply. Estimated data from city show major dam levels increased more than 1% cases after large (LREs) summer 2018/19. This increase is significant often decrease by several percent per month hot summer. In this study, LREs over (October–March) investigated together with level data. result atmospheric rivers (ARs) or cutoff lows (COLs). ARs have not been previously studied South African except one study showed they responsible almost all heavy Cape. COLs common transition months, can also occur midwinter tend last longer cover larger ARs, which typically yield relatively short bursts intense mostly concentrated around Town. After each LRE, average up 5%, suggesting very important recovery. particular, following anomalously dry winters 1980, 1984, 2003, 2004, played an those droughts.