Which cloud type is most associated with severe thunderstorms and tornadoes?

The cloud type most associated with severe thunderstorms and tornadoes is the cumulonimbus cloud. These clouds are large, towering formations that reach high into the atmosphere and are characterized by their anvil-shaped tops. They develop in unstable air conditions where warm, moist air rises rapidly, leading to significant vertical development.

Cumulonimbus clouds are essential for severe weather because they are capable of producing intense thunderstorms, heavy rainfall, hail, lightning, and tornadoes. The updrafts and downdrafts within these clouds create turbulent conditions that can lead to the formation of supercell thunderstorms, which are particularly associated with severe weather phenomena.

In contrast, cumulus clouds are typically fair weather clouds and do not have the vertical development necessary for severe storms. Stratus clouds are low, gray clouds that often bring light rain or drizzle and lack the characteristics necessary for severe weather. Altostratus clouds are mid-level clouds that can indicate moisture and possibly precipitation, but they do not have the capability to produce the severe weather patterns typically linked to cumulonimbus clouds.