Assertion: cumulonimbus cloud | /r/RelatedTo | tornado
Facets:
value: on rare occasions
type: TEMPORAL
Source sentences:
text: A cumulonimbus is a common sign of a thunderstorm and on rare occasions is associated with tornadoes.
text: Cumulonimbus clouds are associated with extreme weather such as heavy torrential downpours, hail storms, lightning and even tornadoes.