The cumulonimbus cloud is the king of all clouds and can form into a supercell similar to the recent storm cells that moved through our region. Its vertical extent is impressive as it towers through the troposphere (the layer of the atmosphere between the surface and tropopause where all of our weather occurs). Born from the increased instability of the atmosphere the cumulonimbus cloud increases in height from warm moist air rising into a cold upper atmosphere. The stronger the updrafts, the higher the cloud will build. Sometimes, the updrafts are so strong that they actually poke through the tropopause to form an overshooting top. In addition, as the updrafts continue to provide more and more moisture, the cumulonimbus cloud begins to pile up under the tropopause to create the anvil portion of the cloud. Due to the weak return of air under the extended anvil head, mammatus clouds can form.

As the updrafts feed the cumulonimbus cloud, water vapor condenses to form ice crystals that gain weight by attracting water vapor and supercooled moisture droplets, which eventually fall toward the surface as a heavy rain. As more droplets begin to fall, a downdraft is created that flows through the base of the cumulonimbus toward the surface and ahead of the cloud as a gust front.
The upward spiraling effect of the updrafts can also create significant rotation causing a wall cloud to descend from the base of the cumulonimbus. This formation can set the stage for tornado development. Behind the storm cell, a flanking line can develop providing further development of another storm cell.

Watch a time lapse video of a Supercell developing.

Thunderstorms can develop quickly. When severe weather is expected in your area, pay close attention to weather updates from National Weather Service and the media. Although these formations can be impressive, they can cause unnecessary injury or death.