- 1 What is a Tornado?
- 2 Tornado features:
- 3 How do Tornadoes form?
- 4 Here is how they form:
- 5 Profiles of Tornadoes
- 6 The impact of Tornados
- 7 Before, during and after a Tornado?
- 8 Before a tornado:
- 9 During a tornado:
- 10 After a tornado:
- 11 Tornado refuge area (shelter)
- 12 Iteresting tornado tips
- 13 Tornado watch, prediction and warning
- 14 Tornado vortex
- 15 Tornado chasers
- 16 Damages per year of tornado
- 17 Worst Tornado
- 18 Worst Tornado Season
What is a Tornado?
Tornadoes are violent storms that strike as a powerful rotating mixture of wind and thunderstorm clouds, extending from the clouds to the ground in a funnel shape. They are known to be the most powerful and destructive atmospheric generated phenomena (wind systems), and are very common in the USA, particularly from the middle belt extending to the east coast.
Every year, there is an average of 800 tornadoes that hit various parts of the USA. Even though many of them are very mild and could be seen as just strong winds, there has been a few tornadoes that have been very devastating and flattened many homes, schools and structures along its path.
Tornado incidents are distributed all year through, forming particularly in late spring (March), with the most incidents occurring in the summer (May and June), and reducing in numbers and strengths in the fall.
Tornadoes occur usually during the daytime, from mid-afternoon till about early evening. Their movement is usually from the southwest to the northeast. Sometimes they move in any direction, and in the general path of the thunderstorm. The spinning winds cover an area of about 300 — 400 yards, and can travel on a path for about 5 miles (some tornadoes travel for over 80 miles), at a speed of about 5 — 60mph.
Sometimes tornadoes develop in a very short time frame, leaving very little lead time for warning and preparation.
How do Tornadoes form?
This question is one that has not been a bit uncertain among people who study weather, but here is an explanation that many believe is the closest possible cause of tornadoes.
Tornadoes are simply borne out of supercell storms (Supercell tornadoes are more powerful than those that do not come from supercells). A supercell storm is a thunderstorm characterized by powerful updrafts. Example of non-supercell tornadoes are ‘gustnadoes’ and ‘landspouts’.
Here is how they form:
Step 1: Like all winds and storms, tornadoes begin when the sun heats up the surface of the land. As the warm, less heavy air begins to rise, it meets the colder, heavier air above it. Note that wind shears make it even easier to set them off. A wind shear is when two winds at different levels and speeds above the ground blow together in a location.
Step 2: The faster moving air begins to spin and roll over the slower wind. As it rolls on, it gathers pace and grow in size.
Step 3: At this stage, it is an invisible, horizontal wind spinning and rolling like a cylinder. As the winds continue to build up, stronger and more powerful warm air forces the spinning winds vertically upward, causing an updraft.
Step 4: With more warm air rising, the spinning air encounters more updraft. The winds spin faster, vertically upwards, and gains more momentum.
Step 5: At this stage, the spinning winds, creates a vortex and the wind has enough energy to fuel itself.
Step 6: The tornado is fully formed now and moving in the direction of the thunderstorm winds. When the pointed part of the tornado touched the ground from the cloud, it is often referred to as ‘touch down’ As it moves it rips off things along its patch.
Profiles of Tornadoes
In the first page, we mentioned an average of 800 tornadoes in the USA occurring every year. How come we do not hear of each of them? It is because they come differently in terms of their destructive power. There are 6 categories of tornadoes, scaled from F0 up to F5, and is measured with a scale called The Fujita Tornado Damage Scale. Here are the descriptions, in terms of the damage it does:
F0—LIGHT: These come as strong winds, with little damage to roofs that are poorly maintained. These winds can displace light-weight objects such as trash cans. They occur very often, making up about 60% of the total number of tornadoes in the year.
F1—MODERATE: These make up about 28% of the total number of tornadoes. They cause minor damage to landscape, young trees, building roofs and break windows. They can displace heavier objects.
F2—CONSIDERABLE: These make up about 9% of the total number. They break tree branches and bend trees. They cause considerable damage to property as a result of airborne debris. They can move and displace a garden shed with poor foundations.
F3— SEVERE: These can uproot trees and break walls of buildings. They can rip off roofs and cause severe damage. These make up about 3% of the total number of tornadoes, and their destruction usually make it to the news on TV.
F4—DEVASTATING: These are pretty destructive, as small cars are blown over and displaced. Well constructed homes are broken, trees are uprooted and blown away. They carry heavy debris and destroy anything in its path. They make up only about 1%.
F5 d—INCREDIBLE: These make up less than 1% in number. They are so powerful that they flatten pretty much any structure in its path. Mature trees are left with no branches, others are uprooted and blown away, and automobiles are significantly blown away and displaced.
After a while, the funnel shape of the tornado thins out as it reaches the end of its life, looking like a rope. This is called the rope stage.
The impact of Tornados
Like all natural disasters such as hurricanes, earthquakes, floods and others, they end up with massive destruction to homes, property, infrastructure and cause many deaths as well. Each year, about 60 people are killed by tornadoes, mostly from airborne debris. Source: noaa.gov. This means individuals, families, communities and the government are all affected in one way or the other.
Here are a few examples:
April 25-28, 2011, USA:
More than 200 tornadoes across Northern Mississippi, Central and Northern Alabama, Eastern Tennessee, Southwestern Virginia and Northern Georgia resulted in 316 deaths. 15 of the tornadoes measured 4-5 on the E-F Scale, with 8 of them traveling for more than 50 miles. In Alabama, there were more than 2000 more injuries, with property damage in excess of 4.2billion dollars.
Source: The Historic Tornadoes of April 2011., U.S. DEPARTMENT OF COMMERCE REPORT, National Oceanic and Atmospheric Administration
Tuesday, April 29, 2014, Mississippi, USA:
On this day, a massive Tornado ripped through Townships in Arkansas and Mississippi killing at least 34 people. It also caused various degrees of injuries to 200 more people. Homes were flattened and trees and cars were flying around. The tornado measured F3 on the Enhanced Fujita Scale. More than 2,000 homes and 100 commercial properties were reported to be damaged.
Monday, November 18, 2013, Illinois, Indiana and Kentucky, USA:
Powerful tornadoes, numbering about 30 swept through the US Midwest, killing about 8 and injuring many more. Many people were trapped in buildings. Winds up to about 68mph, carrying rain and hailstones as big as tennis balls caused massive damage to buildings and property. Entire communities were wiped away leaving nothing left.
It is known that tornadoes cause a yearly average of 400 million dollars in losses to the USA, putting tornadoes at par with hurricanes, according to a report by Lloyds in London. In 2011, about 1600 tornadoes hit the USA, causing more than 25 billion dollars in damages.
Before, during and after a Tornado?
Before a tornado:
Sometimes tornadoes do not give weather readers much time to get people prepared to take cover. Here are a few things to do in preparation, especially if you live in a tornado-prone area:
Always be aware of the safer places (Refuge areas) you can go to in your home before a tornado visits. If there is no basement in your home, consider finding a safe place close enough to your home where you can quickly take shelter. Make sure there are signs on the walls showing where the closest safe area is.
If there is enough time, grab a few first aid items and stock up on water and some emergency supplies, that can take you a few days if things get very bad.
Try to keep in touch with your local weather station, and look out for dark clouds and thunderstorms.
Be aware of the weather in your town and the suggested actions you can do to keep safe.
During a tornado:
During an approaching tornado, quickly move to your basement or designated area if you are in a public place. These days, schools, hospitals and many business building have safer places where people can take shelter.
If you are driving, or in a vehicle, make your way to the closest sturdy building and take cover. If there is none around, stay in your car, wear your seat belt and cover your head with your arms or a pillow if there is one. Never try to look into the window, or get out, as there may be flying debris that can smash your windows. Flying objects cause most of the injuries and deaths during tornadoes.
After a tornado:
Lots of injuries occur after tornadoes too. Be careful when getting out of your shelter as damaged objects and structures may fall.
Wear safety garments when walking and working through debris, as there could be broken glasses, exposed nails and other dangerous chemicals.
Do not touch power lines and objects in water puddles as there may be live electrical wires around.
If you have to clean up your home, make sure that you are wearing safety gear and are well aware of the dangers.
Keep records, notes, photos of broken items, in case your insurance company needs them.
Tornado refuge area (shelter)
The destruction of structures and threat to life during tornadoes is usually caused by a combination of three factors: Wind-induced forces, Changes in atmospheric pressure and debris (airborne) impact.
There has been enough study on the factors above and there are effective engineering and architectural considerations that can make a building safe during a tornado.
Buildings with heavy masonry and concrete materials that are well tied to other parts of the structure tend to withstand extreme winds. The weight and strength of the walls are able to stop flying debris that often cause damage to property. They also resist the uplift and lateral loads caused by excessive winds, making the building a better refuge area.
Airborne debris move in all directions and refuge areas must have the capacity to shield people from the threat of flying debris. This is why basements are the best places to seek refuge during tornadoes. For building without basements, the lowest roof, first floor, interior or most enclosed places are safer.
sually, building inspectors can assist you to locate, improve and utilize the best available refuge area, in older and more vulnerable buildings. Long roof spans and large volume open areas such as gymnasiums, auditoriums and cafeterias must be avoided. Also, areas with large expanses of glass and skylights must be avoided.
Make sure you know this preparation tip before a tornado visits. It is a good idea to put “Refuge Area” signs in school or public buildings, because many times, there is very little lead time (The current average lead-time for tornado warnings is 13 minutes) to take refuge.
Iteresting tornado tips
There are some places in the USA, such as Oklahoma, Northern Texas, Nebraska, Kansas and Eastern Colorado, that has more tornado visits that other parts of the USA. The nickname for this belt is called Tornado Alley. (The red area on the map of USA below)
Tornado watch, prediction and warning
Unlike tropical storms or hurricanes, tornadoes cannot be predicted with precision. Is also forms at a relatively short period of time. Therefore, weather experts use strong thunderstorm activity to predict the possibility of tornadoes. Once it is formed, one can see it approaching, but by that time, it is a maximum of 13 minutes away.
A tornado watch means there a possibility of tornado, therefore, stay alert. A tornado warning means the tornado has been sighted by the radar, therefore, make your way to the refuge area.
A vortex is simply the tip that is created by spinning water or wind. If you fill the kitchen sink with water and open the drain, you notice that water rushed down, a phenomenon caused by downdraft. As water goes down, it starts to spin and then it spins faster and faster. This is similar to the vortices (more than one vortex) that occur with tornadoes. As the winds over the land surface rotates, an updraft can send the spinning winds vertical, causing a vortex. Note that there can be more than one vortex reaching downwards from thunderstorm clouds.
People chase tornadoes and storms for reasons such as research purposes and fun. Whiles this is a very dangerous move, it is important that you take extra precaution and safety measures before you engage in this. The force of nature can be catastrophic and people must not joke with it. Stay away if you are not trained to do so.
Damages per year of tornado
A tornado is a violently rotating column of air from a thunderstorm that reaches the ground. Tornadoes usually occur east of the Rocky Mountains during the spring and summer. May is typically the worst month.
On average, 800 tornadoes hit a year. They kill 80 people and injure 1,500 more. Since 2008, that average has increased to more than 1,300 injured a year. The most violent tornadoes have wind speeds of more than 250 mph and leave a damage path a mile wide and 50 miles long.
In 2017, there were 1,400 tornadoes. The first quarter was the worst for insurers in 20 years. Tornadoes were a large part of that. There were 425 tornadoes between January and March. That’s more than double the 205 tornadoes during the same period in 2016. On average, there were 93 tornadoes in each the first quarters of 2014 through 2016. It’s unusual for tornadoes to occur that early in the year. Fortunately, only 35 people died.
The opposite was true in 2018. The first six months saw half the normal amount.
The most damaging tornado ever was May 22, 2011, in Joplin, Missouri. It cost $2.8 billion. That’s $2.9 billion when adjusted for inflation. It was also the most deadly tornado since 1950. Sadly, 161 people were killed and more than 1,000 were injured. More than 500 businesses were severely damaged, affecting 5,000 workers.
The EF-5 tornado was one-half mile wide when it touched down in the western part of the city. It expanded to three-fourths mile in width. It traveled 13 miles in all, hitting the City of Duquesne as well. Winds were 200 miles per hour. It traveled about 10 miles per hour.
Worst Tornado Season
The most damaging tornado season occurred April 25-27, 2011. In that week, 305 twisters hit the Southeast, breaking the 1974 record of 267 tornadoes. The outbreak caused $5 billion in damage. At least two of the storms were EF-5 twisters, producing wind gusts of more than 200 miles per hour.
The tornado outbreak killed 327 people, with 250 dead in Alabama alone. It was the third-deadliest single outbreak in U.S. history. The worst was March 1925, when 747 people died. The second-worst was March 1932, when 332 perished.
That outbreak made April the most active month for tornadoes ever, with 600 tornadoes forming. The previous record was 542 tornadoes in May 2003. It also brought the year’s total to 881 tornadoes, almost half the tornado record of 1,817 set in 2004. (Source: Bloomberg, “Deadly Tornado Outbreak May Be Worst in History,” May 4, 2011)