What is a Wall Cloud?

A wall cloud is a prominent, often ominous-looking, low-hanging cloud formation that develops beneath the base of a thunderstorm. It typically forms in the updraft region of a supercell and is a key indicator of potential tornado formation. Wall clouds can appear dark and may exhibit rapid rotation, which is a warning sign for severe weather.

Wall clouds form when warm, moist air is drawn upward into a storm’s updraft, cooling and condensing as it rises. This process creates a lowering effect beneath the thunderstorm’s base. Not all wall clouds produce tornadoes, but many tornadoes originate from rotating wall clouds, making them a crucial feature for storm spotters and meteorologists to monitor.

A distinguishing characteristic of a wall cloud is its rotation. While some wall clouds may be non-rotating and relatively harmless, those that spin vigorously indicate increasing storm intensity and a heightened tornado risk. If a wall cloud begins to develop a funnel extending downward, a tornado may be imminent.

Recognizing a wall cloud is essential for safety. Individuals in storm-prone areas should be aware of their presence and take immediate action if rotation is observed. Seeking shelter in a storm shelter or safe room can be a life-saving measure when a tornado warning is issued.