This horizontal rotation can be tilted vertically by violent updrafts, and the rotation radius can shrink, forming a vertical column of very quickly swirling air. This rotating air can eventually reach the ground forming a tornado. The wall cloud is most likely the size and location of the rotating updraft formed in supercell thunderstorms. Because this air is so moist due to it's rain saturated nature, it tends to reach it's dew point rather quickly when IT is pulled upward and results in a lower cloud base, called the wall cloud. Areas of the United States where warm tropical air masses and cold arctic air masses tend to collide frequently are much more likely to experience tornadoes.
Most tornadoes occur in the spring months.
These are months when the battle between warm and cold air is most active. Many times they move very quickly and turn and weave at very unpredictable times. This should serve as a warning to anyone who observes a tornado. Although it may look as if it is moving away or it is at a large distance away, it could turn at any moment and put YOU in harm's way. Tornadoes do not transport you to the mystical Land of Oz, they WILL kill you.