Clouds from which Cumulonimbus may form
Cumulonimbus most commonly evolves from:
Cumulonimbus also forms from:
- Altocumulus castellanus (Cb altocumulogenitus); the base of the Cumulonimbus is unusually high
- Stratocumulus castellanus (Cb stratocumulogenitus)
- Transformation and development of a portion of Altostratus or Nimbostratus (Cb altostratogenitus or Cb nimbostratogenitus)
In the majority of these cases, the transformation into Cumulonimbus passes through the Cumulus congestus stage.