7. The Rapid Cloud Movement
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.
8. The “Freight Train” Sound
Perhaps one of the most important and maybe life-saving warning signals of an impending tornado is the unique sound sometimes described as like a goods train. This auditory information is so crucial that in a tornado scenario it might really make all the difference between life and death. Usually just moments before it strikes, a tornado is very near and the “freight train” sound is heard. The very high winds inside the tornado—which, in the most extreme forms might reach 200 miles per hour—cause it. Many survivors compare the loud, constant roaring noise produced by these winds, together with the trash they are carrying and the pressure variations they create, to the sound of a train passing rather near by. This indicator is very important since it can often be heard even in cases when a tornado is not clearly seen, like at night or when rain or buildings blocks the funnel. Many times, people have recounted hearing this sound and seeking cover right away only to find later that their prompt response saved their life. You have few seconds to act; the tornado is probably quite near by the time you hear this sound. Especially in severe weather, if you hear a roar or rumbling that sounds like a goods train, do not hesitate or try to visually confirm the presence of the tornado. Look for the strongest cover right away; preferably, an inside room on the lowest floor of a solid building or a basement. If you are in a car or mobile home, either lie flat in a nearby low-lying area or ditch as a last option or abandon it for sturdier cover if at all possible. Recall, this sound is the last, dire warning from nature. The choice to save your life could be to start heeding it right away.