If you could only look at one storm feature to determine its severe potential,it would be the lowering . For one thing, every strong storm seems to have a unique one. More practically, it is the site of the main, focused updraft into the system.
Air enters the lowering from both the warm inflow and the cool outflow sides.
Moist air moving out of the rain area is drawn into the updraft and condenses at a lower level below the original storm base. When this mixing of two different air masses is irregular the lowering is also irregular. When the updraft is stronger, more focused, or structurally more compact, it shows as a tighter, more complete lowering. The range of shapes and sizes is endless, but there are definite differences as we compare weaker storms to severe ones. Lowerings which are incomplete, tilted, elongated, or ragged are weaker.