Simplify the following text for a Grade 13 native English-speaking person.
Original: Cumulonimbus clouds form from cumulus clouds ( namely from cumulus congestus ) and can further develop into a supercell , a severe thunderstorm with special features .
Simplified: Cumulonimbus clouds form from cumulus clouds ( namely from cumulus congestus cloud ) and can further develop to a supercell , a severe thunderstorm with special features .