ST. LOUIS – A complex of storms rolled out of northwest Missouri and across our viewing area Friday morning. An impressive shelf cloud was seen as these storms moved through.
A shelf cloud is a low-hanging, wedge-shaped cloud that forms along the outflow of a line of storms. These clouds are typically harmless. However, the storms they form along can sometimes cause strong to damaging wind gusts.
As rain-cooled air flows from the storm to the ground, often times it’ll start to move out ahead of the storm, forming an outflow boundary. The warm and unstable air out ahead of the storm that flows up into the storm, fueling it, is called the updraft.
As the warm, moist air in the updraft rides up along the cool outflow boundary, the warm air condenses and forms these wedge-shaped clouds.