7. The Rapid Cloud Movement
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Seeing clouds move can provide one important new perspective on the possibility for tornado development. Particularly fast moving clouds—especially those moving in various directions at different altitudes—can indicate the great atmospheric instability and wind shear linked with tornadic storms. Low-level clouds may be seen rapidly, usually in a different direction from higher-level clouds, as a tornado-producing storm gets close. One important clue that the storm can generate a tornado is this phenomena called cloud base rotation. Though it starts slowly, as the storm gets stronger the rotation picks up speed. Apart from directional changes, notice any declining sections of the clouds, especially if they seem to be pointing towards the ground. A funnel cloud, which can grow into a tornado, could start here. Furthermore important is vertical cloud movement. Visible as fast rising clouds, strong updrafts point to strong convection inside the storm. Since they enable the stretching and tightening of the rotation capable of producing a tornado, these updrafts are absolutely vital for the development of tornadoes. Accurate interpretation of cloud motions calls for some knowledge and expertise, therefore. Nevertheless, especially when combined with other warning indicators, very quick or chaotic cloud motions should raise questions even for the uneducated eye. If you detect fast or unexpected cloud movements during a storm, you should be alert, keep an eye on official weather forecasts, and be ready to rapidly find cover when needed. Remember, amid severe storms your first concern should always be your safety.
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