A large mesoscale convective system (MCS) which is about the size of the state of Ohio or Iowa and lasts at least 6 hours. Forming during the afternoon and evening, this is the peak time for associated severe weather. The complex normally reaches its peak intensity at night when heavy rainfall and flooding become the primary threat.
A large organized convective weather system comprised of a number of individual thunderstorms. The size of an MCC can be 1000 times larger than an individual air-mass thunderstorm.
Organized, persistent areas of deep convection noted in METSAT imagery during the warm season, especially over the US