Shelf Cloud vs Wall Cloud

LAKE CHARLES, LA (KPLC) - We’ve received a lot of pictures from viewers today much like the one pictured above. Comments and subject lines have ranged from cool cloud to scary clouds and I wanted to clarify a couple of things.

These shelf clouds formed on the leading edge of the storm, which means they were likely produced because of an outflow boundary. The outflow from a thunderstorm is usually cooler air than the air around it causing it to sink. This sinking air often displaces warmer air upward faster than it was rising before.

Which eventually leads to a lowering of condensation levels causing clouds to start forming lower than the base of the main thunderstorm. They can look scary, but in all reality this just means that the thunderstorm is probably strong and is producing gusty winds and heavy downpours.

Shelf clouds are a lot different from wall clouds not in looks, but in how they operate. Wall clouds usually occur at the rear end of a thunderstorm and are associated with rotation in the thunderstorm. These wall clouds are usually a good way to determine if there is the possibility for tornadic activity.

Thankfully, today we saw a shelf cloud move across the Lake area producing heavy downpours and some scary looking clouds.