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Tornadoes come in all shapes and sizes, and are regarded as one of the most frightening weather phenomena in the world. They are rotating columns of air found within thunderstorms, usually on the back right flank of a storm, relative to is motion.
Tornado intensity is measured on the “Enhanced Fujita Scale” based on wind speeds, which are often estimated by damage caused by the storm. The strongest tornadoes in the world occur most frequently in the central United States in a region dubbed “Tornado Alley” and come most frequently during the Spring and early summer, from the Lower Mississippi Valley to Texas, north to Nebraska and Iowa. Along the East Coast and through the Upper Midwest, tornadic storms are most common in the summer months.
Tornadoes form within thunderstorms that are rotating, called super cells, or in rotating updrafts within larger thunderstorm complexes. Rotation starts sinking lower to the surface, drawing in colder air of the downdraft with warm air from the updraft, and when this rotation becomes more concise, it forms a funnel. When the funnel touches the ground, it is a tornado.
As with the size and shape of a tornado, their duration can be very different from storm to storm. Larger and longer lived tornadoes most frequently arise from supercells with strong updrafts that are uninfluenced by other nearby storms that could rob the tornadic cell of energy or introduce shear that could upset the updraft-downdraft balance of the supercell.
It is important to heed watches and warnings for tornadoes, and to understand what they mean. A watch simply means that conditions are favorable for tornado development. This means that there is a steep lapse rate, meaning temperatures are very warm at the surface in relation to their expected temperatures aloft, which would lead to very strong storms, and then there also needs to be a shear element to get the whole thing spinning, like a cold front or area of low pressure. A tornado warning means that there is either a confirmed, observed funnel cloud or tornado by trained spotters or law enforcement, or radar evidence strongly supports the existence of one. Watches cover a broad area, and residents in the area are encouraged to monitor the situation, while a warning is issued for a targeted location, which may be immediately impacted by the existing tornado. Residents within the warning area should seek shelter until an all clear is given.
The best place to seek shelter is in the lowest floor of the house, away from exterior walls or windows. If caught outdoors, a similar principle exists. Find the lowest ground you can, as winds and debris are more likely at higher elevations.

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