The main updraft of warm, moist air is entering the storm at the cloud base below the main storm tower. Strong winds aloft are blowing from the southwest to northeast. Air in the upper portion of the updraft eventually becomes colder than the surrounding air and upward motion decelerates. As precipitation begins to occur, downdrafts are created. A second downdraft forms just southwest of the updraft.
Large hail is likely to fall just outside the updraft core, mainly northeast of the updraft.
As described earlier, some of the more important features associated with supercells include the rain-free base and the wall cloud. The rain-free base is an area of smooth, flat cloud base beneath the main storm tower from which little or no precipitation is falling. The rain-free base is an area of smooth, flat cloud base beneath the main storm tower from which little or no precipitation is falling. The wall cloud is an isolated cloud lowering attached to the rain-free base. It is usually about 2 miles in diameter and marks the area of strongest updraft in the storm.