A line of cumulus or cumulus congestus clouds that (in the northern hemisphere) lies to the south or south-west of a supercell thunderstorm. The clouds increase in height towards the main storm, with which they progressively merge. They indicate the position of the gust front or pseudo cold front: the boundary between the rear-flank downdraught and the inflow region. The term is often used for the similar line of clouds found with some multicell storms.
Subjects: Meteorology and Climatology.