How Does Extreme Precipitation Occur in SudanDuring the summer of 2020?

In summer 2020, media and aid organizations reported on severe flash and riverine floods in many countries in the Greater Horn of Africa caused by a sequence of extreme precipitation events. However, this event was relatively controversial and much was speculated about how it occurs.  Here, the ECMWF-ERA5 dataset was used to investigate the atmospheric circulations that led to unusual extreme precipitation resulting in several loss of life and destructive socio-economic impacts over Sudan during summer 2020. Extreme rainfall over Sudan is concurrent with a well-developed La Nina pattern over the tropical Pacific Ocean and associated with basin-wide anomalous high sea surface temperature (SST) over the Indian Ocean, especially over the Gulf of Oman (GO), where +2 °C has been observed. The unusual warming over GO seems to have three main roles: 1) deepen the monsoon layer, trigger the water vapor transport, contribute excess moisture in the entire troposphere, reduce the convective inhibition and thus, increase the extreme precipitation in the study region. 2) Enhance activity of the African Easterly Jet Stream, where above 3 m/sec wind speed anomaly over 600 GPH has been observed over the GO area. Therefore, the aforementioned reasons may be responsible for the extreme precipitation over the study area.