What do cumulonimbus clouds often indicate?
Cold front, warm front, mixing of a cold and warm front, out none of the above.

Answer

Non of the above

Explanation:

Cumulonimbus clouds are associated with extreme weather such as heavy torrential downpours, hail storms, lightning and even tornadoes. Individual cumulonimbus cells will usually dissipate within an hour once showers start falling, making for short-lived, heavy rain.