The Tornado Project’s Terrific, Timeless and Sometimes Trivial Truths about Those Terrifying Twirling Twisters!


How long do tornadoes last?
Most tornadoes last only two or three minutes. The kind that we see in videos and the kind that do the damage we see on the news probably average about 15 minutes.

What is the longest continuous tornado track in recorded history?
The track of the Tri-State Tornado is officially 219 miles, and stands as the record. However, the concept of tornado families was not known in 1925, and this may have been a family of several tornadoes.

How fast do tornadoes move?
The few tornadoes that have been timed seem to average about 35 miles per hour, but every year some are seen to stand still and others are clocked at 60 miles per hour.

Do they ever occur in the mountains?
Tornadoes have occurred in every kind of terrain. In 1987, one may have crossed the Continental Divide in Wyoming’s Teton Wilderness. They are rare in mountainous areas, but a well developed tornado is probably not affected by the shape of the land underneath it

How big in diameter do tornadoes get?
Tornadoes have been known to range in diameter from 3 feet to two miles. The last one recorded to be 2 miles wide was seen near the town of Gruver in the Texas Panhandle on June 9, 1971. These giant ones, however , generally don't have high wind speeds.

Okay, okay, so if trailers don't attract tornadoes, why do so many trailer parks get hit by tornadoes?
There are probably hundreds(maybe more than a thousand) very small tornadoes that touch down in the USA every year, but are not recorded because they do no damage. However, since a mobile home flips over so easily in even the weakest tornado, trailers probably act as “mini tornado” detectors. This makes it seem like tornadoes are attracted to mobile homes, but that is because trailers are the only things that reveal the presence of what would otherwise be an unrecorded event.

How strong a wind does it really take to blow over a mobile home?
Lightweight mobile homes can be flipped by a 60 mile per hour wind. Heavier mobile homes may not go until 70 or 80 miles per hour. And a tied down trailer might stay put at 110 miles per hour.

Where is Tornado Alley?
There are several areas that can be considered “Tornado Alley”. The area from central Texas to Colorado, North Dakota and Minnesota commonly gets this poorly defined label. But there is also a tornado-prone area that extends eastward from Texas to Georgia that can be considered as a Tornado Alley, and still another “alley” from Arkansas to the Ohio River and the Great Lake states of Ohio, Indiana, Illinois and Michigan.

Are there places that are not in Tornado Alley that still get more than the average number of tornadoes?
Florida gets more small tornadoes per square mile than any other state, but so few big ones that most people don't consider it as a “tornado alley”. Southern New England seems to have its own little “tornado alley” in western Massachusetts and Connecticut.

Do they really get tornadoes in California?
California is a very large piece of real estate, with all kinds of curves on the coast, mountains and a huge central valley. With such a varied terrain, storms and air flow conditions manage to create conditions for small and weak tornadoes every year. Tornadoes are certainly not new to California, but despite the high population, no one has ever been killed by one.

How about Hawaii?
Quite a number of waterspouts have come ashore in Hawaii and have been damaging to resorts. Those are counted as tornadoes.

Which way do tornadoes turn?
Cyclonically, of course! Tornadoes turn counterclockwise in the northern hemisphere. Warm air sweeps north, jet streams come in from the west, creating a situation in which the storms rotate counterclockwise. The tornadoes usually rotate that same way. Sometimes opposite direction swirls develop under a thunderstorm. And about 1 in 100 tornadoes rotate clockwise. The situation is just the opposite in the southern hemisphere(well, not quite the opposite, but close).

What is the heaviest thing a tornado has ever picked up?
The Pampa, Texas tornado moved machinery that weighted more that 30,000 pounds. Whether it was slid or picked up, we don't know. A tornado would certainly have no trouble tossing a 2000 -3000 pound van into the air. That has been caught on video. Freight cars are often blown sideways from their tracks. In the huge cleanup after a tornado, no one bothers weighing the debris, so there is no record kept of heavy flying objects, other than cars.

Sometimes you see pink or yellow stuff stuck to everything in a photo of tornado damage--what is that stuff?
Insulation. The pink insulation from the walls of a home has draped trees as much as 50 miles from the point where a house was torn apart.

What does a tornado do to the crops and dirt when it goes over a field?
Depending on the forward movement of the tornado and how strongly the tornado is interacting with the ground, there can be a wide variety of effects. A nearly stationary tornado which has extended to near ground level has been known to dig(actually blow) a trench as much as 3 feet deep. Other tornadoes have gone over wheat fields and just barely bent over the stalks

If a tornado can do that to crops, what can it do to a road?
Most of the time, it doesn't do anything to a road. But intense tornadoes that have extended downward to very near ground level have ripped up hundreds of feet of asphalt pavement and thrown it up to a hundred yards away. Our opinion is that perhaps the edge of the uppermost layer of asphalt begins to “peel” and the rest follows little by little. It is not likely that it comes up all at once. The process has never been observed or photographed, so it is still somewhat of a mystery

In Twister, the pickets on the picket fence went flying off--is that what would happen in a real tornado?
It is not probable that they would fly straight up unless they were right under the strong upward-moving air. It was an interesting special effect, but it was too far from the center of the tornado to imitate what happens in real life. Most farms have long strands of barbed wire, and the wire fences can get rolled into gigantic tangles.

Why are some tornadoes white, some black, and others red? How many colors do they come in?
Most tornadoes are either white, black, or gray depending on how light is striking them. Tornadoes often occur on the west side of a thunderstorm in the late afternoon. Viewed from the west, they would look white in the strong sunlight. Viewed from the east, back lit, they would be very dark in color. All manner of greys are possible. Occasionally, a funnel may pass over a dry field and pick up massive amounts of dirt, taking on the color of the dirt, which is red in many parts of Oklahoma.

Some photos show tornadoes that don't look like they reach the ground. Is it really a tornado if it doesn't reach the ground?
Some tornadoes have circulation that extends to the ground, do damage, but have no visible funnel. If the air feeding into the tornado is warm and dry, there won't be any moisture condensation to make the funnel visible, but it is still a tornado nonetheless. By the same token, there can be a distinct funnel cloud, but no circulation that extends as far as the ground underneath it. Other times there may be circulation all the way to the ground, but we cannot see it, it does no damage, and what should have been recorded as a tornado is left unrecorded.

Is a waterspout a tornado?
Yes, it is, as is its land-based cousin, the landspout. What makes a tornado is not what it looks like or where it occurs, but the weather conditions and airflows that give it life. If the circulation is complete from the surface to the cloud base, then it is a tornado, even if that surface is water. The National Weather Service does not count tornadoes over water(waterspouts) as official tornadoes unless they hit land, but that doesn't make them any less (meteorologically speaking) a tornado.

Does it form in the same kind of weather situation?
There may be dozens of different weather situations that can produce tornadoes. Landspouts and waterspouts don't even need a thunderstorm or a day with severe weather potential.

Is a dust devil a tornado?
A dust devil will never be a tornado. Dust devils form under clear skies in which the sun has strongly heated the ground. The lack of clouds prevents even the tallest dust devil from reaching any cloud base.

What kind of weather do dust devils form in?
A bright, sunny day in which there are just light winds, and not a lot of what meteorologists call “mixing”. The air near the ground must be allowed to develop a very thin hot layer. This layer then breaks, heat surges upward, and the light winds start it spinning.

Sometimes I see little whirls of snow spin “dance” across our hill in the winter ...
These are just eddies, and may take on the characteristics of a true vortex for a few seconds. But without warm rising air, they can't last. Those that last a few seconds are controlled by the curve of the land.

I have heard about outbreaks. What is an outbreak?
If there are six or more tornadoes from a single weather system, it is generally termed an outbreak. Sometimes the National Weather Service doesn't term it an outbreak unless there are 10 tornadoes. If there are only 3, and each one is a killer, the word outbreak will probably be used. The word “outbreak” is a very loose, poorly defined term. Sometimes all 6 (or 10) tornadoes can come from just a single thunderstorm.

I have also heard about tornado families--what are they?
One member of the family is at full strength, while the one behind it ropes out. A tornado family is a group of tornadoes spawned by a single thunderstorm. A “family” has had as many as 7 tornadoes, although two is much more common. The family gets a name based on the most damaging event. In 1991, a tornado passed over an underpass on the Kansas Turnpike, resulting in a famous video. That tornado was the fourth and last member of the Andover tornado family. The Andover tornado was the third tornado from that thunderstorm and it killed 17 people.


What do tornadoes sound like? Do they really sound like a train?
Many tornadoes have been described as sounding like a train. Others have been described as sounding like a jet plane, or a waterfall. The sound probably depends on how strongly the funnel is interacting with the ground. Tornadoes that are passing just above ground level may sound more like bees. The sound of the swirling column has never been recorded without the distortion caused by the wind rushing towards the tornado.

Sometimes we have thunderstorms at night. I worry that a tornado may come down then and wreck our house before we see it. What time during the day are they most likely to happen?
Most tornadoes occur from 5 to 9 PM. They can occur after dark, but are much less likely. A few of the deadliest tornadoes in history have occurred in total darkness. The odds go down after dark, but they don't go to zero. The best advice if you live in a tornado prone area is to be aware of weather conditions and watch or listen to a weather report at least once a day during tornado season.

How did they make the tornado in the movie Twister? Was it real?
None of the tornadoes in Twister were real. All were generated by computer programs which create vortices and add random movement computer programs to every particle in the vortex. It is a mind-boggling use of state-of-the-art computer power.

Why didn't they use a “model”; tornado?
None answered the casting call. No, really! There were plans to build a 40 footer inside a huge building, but it would just look wimpy compared to what could be created in a computer. There were no convincing tornadoes in movies before 1995(the tornado in the Wizard of Oz was a cotton muslin tube, and didn't move like a real tornado--but we liked the movie anyway!) because the computer processing power just did not exist. The Jurassic Park dinosaurs led the way.
By the way, in one part of our upcoming video, entitled “Secrets of the Tornado” we'll show you how you can build a tornado “model” at home, at school, for a science fair or just for fun. We have spent a year perfecting several different designs so they are easy and cheap to build. We have put one of the designs on the web--go to our Workshop to see it.

How close to chasers really get to a tornado?
Every year a chaser finds himself within a hundred yards of a tornado--not always on purpose. Very often these are a surprise and they are not caught on video. They are not large either. When a tornado is large, chasers rarely get closer than a mile, and more often, further than that

Could a tornado pick up a tank truck like in Twister?
No. We have often wondered why the tank truck, weighing perhaps 80,000 pounds or more was picked up, but the pickup truck, weighing 3000 pounds, was not picked up. I guess that is because it wasn't in the script. In real life, the tanker would have been blown over, rolled, and mangled.

Tornadoes really seem to come in all different sizes and shapes--some are long and skinny, some are really wide, some are tall, some are short. Why does this happen? What makes them that way?
There are at least three things you should consider. The first is that a tornado has a life cycle-- it starts thin, gets wider and stronger, and then gets weaker and wider, or perhaps gets thinner, even “ropey.” Another thing to consider that at any one time we probably don't see all of the tornado. Depending on the moisture and dust available, we only see part of the funnel. Sometimes all we see is the central core. Sometimes the central core is clear and we see only the walls. The third consideration is that the air flows are constantly changing and the thunderstorm above the tornado is weakening and strengthening Throw all of these things together, and consider that every thunderstorm is a little different than every other thunderstorm, and you get an infinite variety of possible tornado shapes.

When you see videos of tornadoes, it looks as if the wind is blowing towards the tornado, not away from it. Is it? If so, why?
That giant vortex is pulling in a huge amount of air--this is called “inflow”. The thunderstorm itself is pulling in air--this is called “updraft”. In the movie Twister, everything was flying out of the tornado all the time, and nothing was moving in. In real life tornadoes, both inflow and updraft are essential. The inflow is often warm and humid, supplying the storm with energy.

I have seen a video of a tornado in which it looks like air is moving downward on the outside of the funnel--does it?
There can be air moving downwards on the outside of the funnel as well as in the core of the funnel. The air in the walls of the funnel is moving upward. The downward movement on the outside of the funnel is probably related to an air flow called the RFD, or rear flank downdraft. The RFD may be one of the triggers of the tornado, and moves downward out of the back of the thunderstorm adjacent to the updraft. Since this downward moving RFD is an important ingredient, it is not surprising to see downward movement of air.

Could a person actually get sucked up into the tornado?
Most people killed by tornadoes have been blown sideways, with only a small vertical movement. “Sucked up” is not really an accurate description of being caught in air that is rushing towards the vortex. As soon as debris is carried upward, it is usually spun out of the vortex. Centrifugal force throws things out. To get lifted high, something would have to stay in place through the 100-200 mph winds at the edge of the vortex, and whatever was holding it in place would have to release it at the point in the vortex of maximum upward velocity. Only a very small percentage of all debris is carried aloft, but in rare cases, as in the the Pampa, Texas video, cars and trucks can find their way into that maximum uplift area. It is messy business inside the naturally occurring blender that is the tornado.

How likely is that to happen? Has anyone ever gotten lifted up and carried a ways?
Yes.

How far?
The longest distance is about a mile

Did they live or not?
The man died shortly after rescuers found him. This happened on May 1, 1930, in Kansas.

What about animals? Have they ever gotten sucked up and carried?
Animals have had similar fates. Again, the term “sucked up” is not correct--the animal would be blown upward by air rushing into the vortex. Most likely they will be blown outward near the ground for anywhere from 10 to 400 yards.
It is not unusual to hear about fish, frogs, toads, and salamanders falling from the sky on occasion. When a tornado passes over a body of water that has these animals near the surface(during the breeding season, for instance), they can become “entrained” in the circulation, and may be lifted and carried a short way before dropping to the ground.

How far do things get carried if they are lifted and carried?
The furthest distance a 1 pound object can be carried is about 100 miles. The furthest known distance a photo or piece of paper was carried was a little over 200 miles. In the Great Bend, Kansas tornado of November 10, 1915, debris from the town was carried 85 miles. After passing through the town, the tornado went through or near Cheyenne Bottoms, now a wildlife area. Hundreds of dead ducks fell from the sky 25 miles northeast of the end of the path. And after the Worcester, Massachusetts tornado of 1953, chunks of soggy, frozen mattress fell into Boston Harbor, 50 miles to the east of where it was picked up.

How do they really know how far the stuff was carried by the storm?
When something travels more than a mile into an area where people don't recognize the debris as coming from a certain person’s house, then the return addresses on letters, and names on checks and deeds identifies the owner. If the tornado destroyed just one golf course, and the flag from a putting green is found 50 miles away, one would have to assume that the flag and the golf course are a match.

What is the most likely stuff to travel a long way?
Cancelled checks.

I live in an area where there are a lot of tornado warnings, but not that many tornadoes actually touch down. Why do we get so many warnings?
Most “unrealized” warnings are caused by the appearance of a mesocyclone on Doppler radar. If a mesoscyclone forms inside a thunderstorm, then the thunderstorm clearly has tornadic potential, and warnings will be issued. Sometimes they are called “radar based warnings” as opposed to “spotter based warnings”, which involve a visible funnel. This is one of the more thankless jobs that NWS meteorologists do. If they issue a warning based on doppler radar and a tornado doesn't form, they are criticized for “crying wolf” too many times. They then face the possibility that the public will become complacent and ignore the warnings. On the other hand, if they don't issue a warning even though Doppler shows a mesocyclone, and a major tornado touches down and kills people, they are publicly accused of neglect and incompetence by the media.

Who actually issues the warning?
The warning is issued by the local office of the NWS. A siren may have been sounded by a towns' fire department or civil defense/emergency preparedness director when a funnel surprises a community and is seen by spotters--but that is a different kind of warning

What is a tornado watch?
A tornado watch is issued by the Storm Prediction Center in Norman, Oklahoma. It often covers an area of 20,000 square miles or so, in which there is a potential for even one tornadic thunderstorm.

Is it different than a warning?
The skies may be clear when a watch is issued. A warning means that a funnel has been sighted or that a mesocyclone(often the parent of a tornado) has been detected by radar.

Do I need to go to the basement if there is a watch?
No, but when a watch has been issued, it is time to put a television or radio on, look out the window from time to time, and be more alert to what is happening outside.

You mentioned radar. Are there many Doppler radars in use?
There are about 150 or so Doppler(also called WSR-88D radar because it is the 1988 version of Doppler radar) in the NEXRAD system, fairly evenly spaced throughout the US. However, there are a number of television stations that also have Doppler radar. The antenna is a center-feed, parabolic reflector, is mounted on a steel tower, and covered with a rigid fiberglass dome.

What do they see on Doppler radar--what are they looking for and how do they tell if there is a tornado forming?

Meteorologists look at two radar images. The first shows “reflectivity:”



Tornadoes are too small to be resolved on 88D radar, so meteorologists look for the larger circulations that precede a tornado. “Doppler radar screens show “reflectivity” and “velocity”. The image here is for reflectivity. The colors on the reflectivity radar screen shows the intensity of the rainfall.

The second shows “velocity:”

Doppler radar image
This image is of the velocity radar screen. It shows which way the wind is blowing in relation to the Doppler radar. Green means that the air is moving “inbound” towards the Doppler; red means that it is moving “outbound” away from the radar. If the entire storm is moving towards the radar, there would be lots of green. If the entire storm is moving away from from the radar, there would be lots of red. When the meteorologists examine the Doppler radar image, he or she looks for a place where bright red(the “outbound”) and bright green(the “inbound” color) are positioned next to one another. This denotes some rotation inside the supercell--the mesocycone, which may be spawning a tornado.

Computers then go to work with programs called algorithms to analyze the color differences at different elevations and determine whether it is truly a mesocyclone. If it is, a warning is issued for the area in the path of that storm.

What is a multiple vortex tornado? Is it always stronger that a single vortex tornado?
The individual vortices are easy to see in this 1990 multiple vortex tornado.A multiple vortex tornado is one that has mini vortices inside the bigger main vortex. In a way, it is a tornado inside tornado, and can be very intense, with both big and small vortices to create small areas of incredible damage. A photograph of a multiple vortex tornado was taken in Peotone, Illinois in 1948, but it was not recognized for what it was back then. Dr. Fujita proposed this theory in his research, but it was not accepted as fact for many years. Interestingly enough, there are illustrations from the 19th century that show the same multiple vortex structure. It should be pointed out, however, that single vortex tornadoes can be just as intense as multiple vortex tornadoes.

I have heard that you can tell whether the tornado had a single or multiple vortex structure by looking at the ground afterwards. Is that true?
The tornado that passed over this field had multiple vortices. Multiple vortex tornadoes sometimes leave patterns in corn stubble or other crops that are called “spiral ground markings”. These can best be seen during an aerial survey of the damage path, as shown in this photo. The “marks” are actually piles of broken and shredded corn stalk and debris that have been aligned that way as the vortices passed over it. It is blown into drifts kind of like the lines of of seaweed and detritus you see on a beach after an especially high tide or a hurricane.


Why were so many more people killed in the olden days than now?
There are literally dozens of reasons! Back at the turn of the century there was no such thing as poured concrete. It was not possible to bolt down houses. They just sat on stone foundations, and flew away with people in them. Today there are all kinds of safety codes that require better construction. There were also no “trauma” units, no lightning-quick rescue squads, no antibiotics. People who were mangled and crushed developed infections, gangrene, and tetanus. Sometimes they lingered for weeks before death. Nowadays, if a tornado victim survives the first day or so, it is very likely that they will recover fully. How homes are heated is also a factor. If a house collapsed in the olden days, the overturned wood cookstove might catch fire and burn the occupants of the home to death before rescue workers even knew they were trapped in the house. If the home was in a city, the adjoining homes often caught fire. Prior to the 1920’s, there was no such thing as commercial radio, and much less awareness of what was going on over the horizon. The risk was much greater. SPC watches are now issued so far in advance of the actual onset of bad weather that spotters can be mobilized, emergency workers and supplies readied, and televison weathermen geared up for a live broadcast of a tornado in progress. Television weatherman break into scheduled programming to point out the exact position of a storm whether you want to know it or not! Warnings, watches, awareness, real-time radar broadcast live from a television station ... even at night in the middle of a raging storm, it is still possible to keep totally aware of whether tornadoes are any threat at all.



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