What visual indicators signify extreme turbulence in thunderstorms?

Frequent lightning and roll clouds are strong visual indicators of extreme turbulence associated with thunderstorms. Lightning is a key sign of intense convective activity within thunderstorms, suggesting that the storm is well-developed and likely producing turbulent air currents. Roll clouds, which are horizontal, tube-shaped clouds that form at the leading edge of a thunderstorm, signify the presence of severe wind shear and can be associated with powerful updrafts and downdrafts, both of which contribute to turbulence.

In contrast, heavy rainfall with low visibility can occur in various storm conditions and does not always indicate extreme turbulence, as it may simply reflect rain intensity rather than air movement. Cumulonimbus clouds and a clear sky would not make sense together because cumulonimbus is typically a towering cloud, indicating storm development, which precludes the presence of a clear sky. High cirrus clouds with scattered rain often suggest that a storm is far away or weakening, indicating less likelihood of extreme turbulence.