Squall lines (SLs) form an important component of the meteorology of northern Africa, and in particular, contribute substantially to rainfall totals. Their generation requires the existence of a potentially unstable low-level supply of moisture overlain by dry desert air and vertical wind shear beneath the midlevel African easterly jet. The instability may be released (and an SL initiated) by factors such as surface heating, topography, African waves, or surface evaporation. The relative importance of each of these factors and the means by which they impact on SL generation is reviewed. This is followed by a detailed analysis of one month of satellite imagery and surface data for August 1985 over a portion of central northern Africa. The novelty of our study lies in the temporal resolution of the satellite imagery, which with 21 images per day allows the identification of a large number of short-lived SLs (4-h duration or less). On the southern fringes of the Sahara these are likely to contribute... Abstract Squall lines (SLs) form an important component of the meteorology of northern Africa, and in particular, contribute substantially to rainfall totals. Their generation requires the existence of a potentially unstable low-level supply of moisture overlain by dry desert air and vertical wind shear beneath the midlevel African easterly jet. The instability may be released (and an SL initiated) by factors such as surface heating, topography, African waves, or surface evaporation. The relative importance of each of these factors and the means by which they impact on SL generation is reviewed. This is followed by a detailed analysis of one month of satellite imagery and surface data for August 1985 over a portion of central northern Africa. The novelty of our study lies in the temporal resolution of the satellite imagery, which with 21 images per day allows the identification of a large number of short-lived SLs (4-h duration or less). On the southern fringes of the Sahara these are likely to contribute...