Accessory cloud types can form at various altitude ranges depending on the main clouds with which they are associated. The World Meteorological Organization classifies most accessory clouds as "supplementary features". The height range classification of a supplementary feature is the same as the parent cloud. As an example, the anvil cloud (supplementary feature incus) forms at high altitude but is not classified by the WMO as a high cloud because of its association with the genus cumulonimbus. It is "very rare" for any accessory cloud to generate its own precipitation. However, the parent cloud may generate precipitation. Precipitation from the parent cloud
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