Assertion: cumulonimbus cloud's top | /r/HasSubevent | shower
Facets:
value: ahead of the main rainband
type: OTHER
value: sometimes
type: TEMPORAL
Source sentences:
text: Occasionally, however, particularly if the air below the mid level cloud is very warm or unstable, some of the cumuli may become congestus and the tops of them may rise above the mid level cloud layer, sometimes resulting in showers ahead of the main rainband.