popcorn convection
n.— «Popcorn Convection. Slang for showers and thunderstorms that form on a scattered basis with little or no apparent organization, usually during the afternoon in response to diurnal heating. Individual thunderstorms typically are of the type sometimes referred to as air-mass thunderstorms: they are small, short-lived, very rarely severe, and they almost always dissipate near or just after sunset.» —“National Weather Service Glossary” National Oceanic and Atmostpheric Administration Apr. 21, 2005. (source: Double-Tongued Dictionary)