Tornadoes in the winter and early spring are often associated with strong, frontal systems that form in the Central States and move east. Occasionally, large outbreaks of tornadoes occur with this type of weather pattern. Several states may be affected by numerous severe thunderstorms and tornadoes. Tornado-producing thunderstorms may form as the dryline moves east during the aftemoon hours. If other favorable conditions exist, these thunderstorms can produce tornadoes.
Tornadoes occasionally accompany tropical storms and hurricanes that move over land.
Tornadoes are most common to the right and ahead of the path of the storm center as it comes onshore. This type of 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.