Mesoscale Convective Systems in Africa and the Atlantic Ocean under a Kilometer-Scale Future Climate Scenario

Abstract Mesoscale convective systems (MCSs) over North Africa provide critical rainfall while posing flood risks and, often when coupled to African easterly waves, serve as precursors to Atlantic tropical cyclones. This study investigates how MCSs in the Africa–Atlantic region respond to a future climate warming scenario using 3-km convection-permitting simulations with the Model for Prediction Across Scales–Atmosphere. We simulate September 2006 convective activity under both present and future climate conditions using a pseudo–global warming approach. Results from our objective MCS tracking algorithm show that despite increased convective available potential energy (CAPE), MCS numbers decrease in future climate scenarios due to substantial increases in convective inhibition (CIN). While changes in future MCS intensity measured by brightness temperature are not as evident, both future organized and disorganized MCSs show rainfall increases. The increase, especially in future organized MCS rainfall, is larger over water than over Africa due to relative humidity increasing over water and decreasing over land. Geographically, future MCSs shift southward, while they move eastward over Africa and westward over the Atlantic, becoming less overlapped with the location of the African easterly jet and more closely linked to the location of the West African monsoon and African easterly waves. The most extreme future MCSs of the Africa–Atlantic region have stronger updrafts and downdrafts and drier mid-to-lower troposphere helping explain enhanced rain evaporation. Significance Statement Large storms over North Africa bring needed rain but can also cause dangerous flooding. Some travel across the Atlantic and develop into hurricanes affecting the Caribbean and the United States. Our study used an advanced weather model to explore how convective storms might change in a warmer future climate. While overall storm numbers may drop, those that do form could produce more extreme rainfall. Storms are expected to shift southward, forming farther east over Africa and farther west over the Atlantic. Future intense storms will likely have more moisture, stronger vertical air movement, and drier mid-to-lower troposphere. These changes relate to shifting wind patterns and have major implications for flood risk, water supply, and agriculture in vulnerable regions.