Cumulus congestus cloud (No official abbreviation) is a free convective cloud associated with volcanic eruptions and large-scale fires. Pyrocumulus isn't recognized by the WMO as a distinct genus or species, but is, in essence, cumulus congestus formed under special circumstances that can also cause severe turbulence. Cumulus congestus will mature into cumulonimbus calvus under conditions of sufficient instability. This transformation can be seen by the presence of smooth, fibrous, or striated aspects assumed by the cloud's upper part. This cloud type produces precipitation, often in abundance. These clouds also produce fair weather waterspouts. An approaching weather front often brings mid level clouds such
Wall cloud within the leading edge (typically of a quasi-linear convective system (QLCS) or squall line) on rare occasion. The wall cloud feature was first identified by Ted Fujita and as associated with tornadoes in tornadic storms following a detailed site investigation of the 1957 Fargo tornado. In the special case of a supercell thunderstorm, but also occasionally with intense multicellular thunderstorms such as the aforementioned QLCS, the wall cloud will often be seen to be rotating. A rotating wall cloud is the area of the thunderstorm that is most likely to produce tornadoes, and the vast majority of intense tornadoes. Tornadogenesis