Predictability of Summer (July-September) Extreme Precipitation Days over West Africa during 1982-2022

Extreme precipitation events have substantial socioeconomic effects due to their frequency and intensity. However, predicting and mitigating its effects is difficult due to their influence on society. The present study aims to investigate the predictability of extreme summer precipitation days (EPDs) over West Africa (WA) from 1982 to 2022. Based on daily CHIRPS data spanning 41 years over WA, EPDs were defined using a 90th-percentile threshold at each grid point. A set of Physics-based Empirical (P-E) models is established using the selected predictors. The simultaneous lower boundary anomalies linked to each EPDs index were also analyzed and found that the increased EPDs over WA are accompanied by a Pacific Sea Surface Temperature (SST) impact on monsoon flow and the warming of the SST in the Tropical Atlantic Ocean and western tropical Pacific Ocean. The temporal correlation coefficient (TCC) skill of the cross-validated forecast is 0.80 when the P-E model is constructed using data from 1982 to 2011. The independent forecast determines a significant TCC skill with a 95% level of 0.50 for the remaining period.