Cumulonimbus flammagenitus (cloud) column of a volcano. In 2002, various sensing instruments detected 17 distinct cumulonimbus flammageniti in North America alone. Alternate spellings and abbreviations for cumulonimbus flammagenitus that may be found in the literature include Cb-Fg, pyrocumulonimbus, pyro-cumulonimbus, pyroCb, pyro-Cb, pyrocb, and pyro-cb. The World Meteorological Organization does not recognize the cumulonimbus flammagenitus as a distinct cloud type, but instead classifies it simply as cumulonimbus. On 18 January 2003, a supercell thunderstorm formed from a cumulonimbus flammagenitus cloud associated with a severe wildfire, during the 2003 Canberra bushfires in Canberra, Australia. The supercell resulted in a large fire tornado, rated at EF3
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