Mammatocumulus clouds

Mammatocumulus clouds,occurred before the epic Hailstorm that passed through Norfolk Nebraska on April 14th, 2012.

True to their ominous appearance, mammatus clouds are often harbingers of a coming storm or other extreme weather system. Typically composed primarily of ice, they can extend for hundreds of miles in each direction and
individual formations can remain visibly static for ten to fifteen minutes at a time. While they may appear foreboding they are merely the messengers appearing around, before or even after severe weather.