Tornadoes are a dangerous weather event that can come up quick, take you by surprise, and cause devastating property damage and loss of life. Tornadoes can happen anywhere and anytime that the atmosphere has the right conditions. While they can occur worldwide, more tornadoes tear across the United States than anywhere else.
So what is a tornado? A tornado is a violently rotating column of air extending from a cumuliform cloud, such as a thunderstorm, to the ground.1
Each year, an average of 60-65 fatalities occur due to tornadoes, and about 1,500 injuries. So what makes a tornado so dangerous?
- Winds in excess of 200mph are possible
- A tornado can be 1 mile wide
- It can stay on the ground for about 50 miles
- Tornadoes can move in any direction, and can suddenly shift direction
- The average forward speed is 30mph, but can range from stationary to 70mph
- The United States averages 1,200 tornadoes per year2
A tornado can strike anywhere, but they are most common in the portion of the US referred to as “tornado alley” which centers on Texas, Oklahoma, Kansas, and Nebraska, but often includes South Dakota, Iowa, Illinois, Missouri, New Mexico, Colorado, North Dakota, and Minnesota.
A tornado is formed from a supercell thunderstorm. Fast moving winds create horizontal wind columns as a thunderstorm starts to build. During the formation of the thunderstorm, the air rises, which also makes these horizontal winds start to form an arch as they are pulled upwards. The storm begins to rotate on the updraft, and this can spawn a tornado. There is still a lot of unknowns about how a tornado fully forms, why some supercells spawn tornadoes while others don’t, and how a tornado eventually dies.3
Be Weather Alert
If you know there is a thunderstorm starting to build in your area, stay weather alert. Make sure you get severe weather updates on your phone or computer so you can stay aware of what is going on in your area. Tornadoes are more likely to occur in late spring and summer, but they can happen at any time, so be ready year-round.
Tornado Watch: Be prepared. Conditions are favorable for development of a tornado.
Tornado Warning: Take shelter. A tornado has either been spotted or is radar-indicated.
The advances in doppler-radar technology over the last few years has allowed meteorologists to spot potential tornadic activity much earlier, thus saving countless lives.
Figure 1 shows the winds on the Weather Service Doppler radar. The red indicates winds moving away from the radar system, and the green represents winds moving towards the radar. When those two colors start to get close together, and even create a small hook, that is indicative of rotation in the storm. It doesn’t necessarily mean that a tornado is on the ground, but it does mean there is a good chance and anyone in the vicinity should take shelter immediately.
Figure 2 shows a “hook echo” on the radar map. This is another way meteorologists determine if there is potential rotation in an area. The hook shows the rains and water vapor wrapping around each other. Again, this shows rotation, but does not mean that there is a tornado on the ground. It means that this area has a high chance for a tornado based on what the storm is doing at that moment.
Figure 3 shows the violent tornado that was on the ground at the time those two radar images were taken. In this case, they did show an actual tornado that had touched down in Northern Oklahoma.
A tornado is assigned a “rating” from the National Weather Service based on the estimated wind speeds and damage caused by the tornado. The scale is called the Enhanced Fujita Scale, and is shorted to the EF rating. (Before 2007 it was just the Fujita scale, and a tornado would be called an F1, F2, etc.) The wind speed is estimated from a 3 second wind gust measurement.
|EF0||65-85 mph||“Weak” tornado|
88% of tornadoes
|EF2||111-135 mph||“Strong” tornado|
11% of tornadoes
|EF4||166-200 mph||“Violent” tornado|
Less than 1% of tornadoes
|EF5||over 200 mph|
During a Tornado and After
If you are under a tornado warning, you need to seek shelter and stay alert. When you see or hear a tornado approaching, immediately seek shelter. Get yourself and your family into the safest room possible in your home, grabbing pets if there is time. The safest place to be during a tornado is underground, such as in a tornado shelter or a basement. When those aren’t available, make sure you are in a relatively small interior room on the lowest floor of a sturdy building with no windows.
For example, in our home, since we don’t have basements in Houston, when we’ve had tornado warnings we get the boys and cat and go hang out in the hall bathroom. It is surrounded on all sides by another room, and has no windows. This is also where I keep our In-Home Emergency Kit so we are as ready as we can be.
Do not stay in any kind of manufactured or mobile home, these are not safe in severe weather. Your vehicle is also not a safe place to be, but it’s still better than being outside without any protection.
Until you know the weather is clear, stay in the safe room. Keep your head covered with your hands or a blanket, and keep your children protected. They will be scared, so do whatever you can to keep them calm.
Once the storm has passed, still keep your radio or tv tuned to the weather to be aware of any changes and/or emergency information. Contact your family to let them know you are safe. Remember, a text is more likely to go through than a call when the lines are busy. Carefully assess the damage to your home and property and determine if it’s safe to stay there, or if it would be better to leave. Take any photos you can of the damage for insurance purposes.
Thankfully, I have never been in a tornado. I have been in many tornado warnings, and just a year ago we were pretty sure one was about to hit here, but it never did. We were woken up from the alert on our phones, turned on the news, and there was rotation in the area. Tyler woke up scared, so he and I went in the bathroom, and Justin watched the direction the storm was coming from while we opened Ryan’s door to grab him quick if needed. Suddenly he goes running past the bathroom, snatches Ryan from his crib, and comes in the bathroom with us. He watched the hanging plant outside get pulled upwards and that was enough. We stayed in there for about 30 minutes until the storm passed. Luckily, there was never a tornado that went through.
I was also at a friend’s house in middle school when a storm came up, so her mom made us get out of the pool. We were playing on the porch until we all watched a beach ball get sucked into the corner of the screen enclosure. We all ran inside and went straight to the closet. We found out later that a waterspout (tornado over the water) had come up the canal next to theirs.