This information is thanks partly to hard-working satellites that keep a constant eye on the weather. However, predicting tornadoes precisely is a different story. One minute it's just raining or hailing, and the next minute the roof or even the whole house is gone.
If you were lucky, you and your family had a few seconds to find some shelter where you would not be picked up by the violent winds or seriously injured by large chunks of flying debris. Where do these violent and unpredictable storms come from? Why do they destroy some buildings, but leave others nearby untouched? And is there any way weather forecasters could give people right in their path a little more warning?
Certain conditions make tornadoes more likely. So, in that way, they are somewhat predictable. But no one ever knows when, where, how intense, and how many tornadoes a thunderstorm will create. Conditions are ripe for tornadoes when the air becomes very unstable, with winds at different altitudes blowing in different directions or at different speeds—a condition called wind shear.
The first result is a large thunderstorm. Inside the huge thundercloud, warm and humid air is rising, while cool air is falling, along with rain or hail.
All these conditions can result in rolling, spinning air currents inside the cloud. Although this spinning column of air starts out horizontal, it can easily go vertical and drop down out of the cloud. Tornadoes can produce winds in excess of miles an hour , but even much weaker tornadoes can devastate an area. Tornadoes are typically to yards wide, though some of the largest ones have spanned a width of more than two miles. Tornadoes typically last no more than a few minutes and travel less than a mile along the ground before a shift in the forces that sustain them causes them to dissipate.
But some especially powerful tornadoes travel for dozens of miles, destroying entire communities along the way. Because tornadoes are so brief and violent, their intensity is hard to measure. The scale runs from EF-0 for the weakest twisters to EF-5 for the most destructive.
EF-0 and EF-1 tornadoes have winds of up to miles an hour. These twisters cause relatively light damage, such as broken tree branches and exterior damage to houses. EF-2 and EF-3 tornadoes, with winds of to miles an hour, can cause severe damage — uprooting trees, tearing off roofs and lifting cars, trucks and even trains off the ground.
The most powerful tornado that hit Alabama was rated EF-4, meaning it had winds of to miles an hour. EF-4 twisters can level homes and other structures. A supercell is a rotating thunderstorm. Cold air rushing out of the storm cloud, producing a gust front. During this mature phase of the thunderstorm or supercell; heavy rain, lightning, hail and very strong winds are expected. Sometimes, you will feel a strong gust of wind a few moments before the rain arrives.
This is called a gust front. This is caused by cool air being forced down from the storm cloud. When the cold air hits the ground, it spreads out quickly, ahead of the storm. This is a sure sign that a storm is near. The formation of a tornado. Tornadoes are usually formed from supercells. These supercells develop when there are several ingredients in place to help them thrive: instability, lift and wind shear. Within the supercell, wind shear becomes a crucial component to the storms development.
Shear is when winds change directions with height. This creates spin within the thunderstorm cloud. Another force that's acting inside the supercel l is a downdraft.
This is an area of drier air that is pushed down from the storm. As it's forced down, it wraps around the backside of the storm. The updrafts and downdrafts work in tandem to pull the horizontal column of air down to form the tornado. This vertical column of air is called a funnel cloud until it touches the ground -- at that point it becomes a tornado.
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