Most strong and violent tornadoes form within this area of strong rotation. Some tornadoes may form during the early stages of rapidly developing thunderstorms. This type or tornado is most common along the front range of the Rocky Mountains, the Plains and the western states. Tornadoes may appear nearly transparent until dust and debris are picked up. Occasionally, two or more tornadoes may occur at the same time.
Waterspouts are weak tornadoes that form over warm water.
Waterspouts are most common along the Gulf Coast and southeastern states. Waterspouts occasionally move inland, becoming tornadoes causing damage and injuries. Some tornadoes appear as a visible funnel extending only partially to the ground. Look for signs of debris below the visible funnel. Some tornadoes are clearly visible while others are obscured by rain or nearby low-hanging clouds.