MONITORING THE DYNAMICS AND ENVIRONMENTAL EFFECTS OF WEST AFRICAN LINE SQUALL USING SATELLITE IMAGERIES

This study investigates the dynamics and environmental impacts of West African squall lines using geostationary satellite imagery. A case study of a mesoscale convective system (MCS) that propagated across the Gulf of Guinea–Sahel corridor from 5–7 May 2008 was analyzed using Meteosat Second Generation (MSG) RGB frames at six-hourly intervals (0000, 0600, 1200, 1800 UTC). Storm positions were tracked to estimate propagation speeds and assess lifecycle phases in relation to diurnal forcing and synoptic steering. Results show a characteristic diurnal cycle, with afternoon invigoration (15–18 UTC), nocturnal maintenance, and morning decay (09–12 UTC). Propagation speeds ranged from ~5 m s⁻¹ during organization and decay to ~21 m s⁻¹ during mature phases, consistent with movement near the African Easterly Jet (AEJ). As the system approached the Gulf of Guinea, coastal friction and marine boundary-layer interactions induced westward veering and slowing. Environmental effects included severe gusts (>15–20 m s⁻¹), dust squalls reducing visibility below 1 km, short-duration heavy rainfall (30–50 mm h⁻¹), flash flooding, and localized infrastructure damage. These findings reaffirm that although squall-line MCSs represent a minority of convective systems, they contribute a disproportionate share of Sahel rainfall (50–90% in some areas) and pose substantial short-lead hazards. The study further highlights the operational importance of the Meteosat Third Generation (MTG-I1), whose Flexible Combined Imager (FCI) and forthcoming Lightning Imager significantly enhance convective initiation detection, cold-cloud-top monitoring, and gust-front visualization. Integrating MTG products into forecasting workflows, supported by enhanced ground-based observations and hazard-based warning tools, is recommended to strengthen nowcasting capacity and reduce vulnerability to high-impact convective weather across West Africa